Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION

Official Transcript of Proceedings
NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards
Future Plant Design Subcommittee
Docket Number:
(n/a)
Location:
Rockville, Maryland
Date:
Wednesday, January 14, 2008
Work Order No.:
NRC-2609
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Pages 1-337
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UNITED STATES OF AMERICA
2
NUCLEAR REGULATORY COMMISSION
3
+ + + + +
4
ADVISORY COMMITTEE ON REACTOR SAFEGUARDS
5
+ + + + +
6
SUBCOMMITTEE ON FUTURE PLANT DESIGN
7
+ + + + +
8
MEETING
9
+ + + + +
10
WEDNESDAY, JANUARY 14, 2009
11
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12
ROCKVILLE, MD
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14
The Subcommittee was convened in Room T2B3
15
in
16
Commission,
17
Pike, Rockville, Maryland, at 8:30 a.m., Dr Michael
18
Corradini, Chair, presiding.
19
SUBCOMMITTEE MEMBERS PRESENT:
the
Headquarters
Two
White
of
the
Flint
20
MICHAEL CORRADINI, Chair
21
SAID ABDEL-KHALIK
22
J. SAM ARMIJO
23
GEORGE E. APOSTOLAKIS
24
HAROLD B. RAY
25
WILLIAM J. SHACK
Nuclear
North,
Regulatory
11545
Rockville
DENNIS C. BLEY
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1
2
3
CONSULTANT TO THE SUBCOMMITTEE PRESENT:
THOMAS S. KRESS
4
5
NRC STAFF PRESENT:
6
MAITRI BANERJEE, Designated Federal Official
7
STEVE BAJOREK
8
SUD BASU
9
DONALD CARSON
10
HERMAN GRAVES
11
JOHN JOLICOEUR
12
JOSEPH KELLY
13
RICHARD LEE
14
ALLEN NOTAFRANCESCO
15
JAY PERSENSKY
16
SEAN PETERS
17
STUART RUBIN
18
ANTHONY ULSES
19
20
21
22
23
24
25
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C-O-N-T-E-N-T-S
3
AGENDA ITEM
PAGE
4
ACRS Introduction .................................. 3
5
ARRP Introduction (Overview) ....................... 7
6
Reactor Plant Systems Analysis .................... 31
7
Reactor Fuels Analysis ............................ 64
8
Reactor Nuclear Analysis ......................... 134
9
Reactor Thermal-Fluids Analysis .................. 187
10
Reactor Accident Analysis ........................ 239
11
Hydrogen Plant Analysis .......................... 253
12
Human Factors .................................... 275
13
Adjourn
14
15
16
17
18
19
20
21
22
23
24
25
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P R O C E E D I N G S
3
(8:30 a.m.)
CHAIR CORRADINI: Okay.
4
5
Let's get started.
The meeting will come to order.
This meeting is open to the members of the
6
7
public.
My
name
is
Mike
Corradini,
8
Future Plant Design Subcommittee.
chair
of
the
9
We have with us today ACRS members, or
10
soon to have with us, Dr. Apostolakis, Dr. Bley, Dr.
11
Shack,
12
others will join us later in the day.
Dr.
Ray,
Dr.
Abdel-Khalik,
and
advanced reactors is also present.
15
16
Dr.
Tom Kress is our consultant in the area of
13
14
Armijo,
Ms. Maitri Banerjee of the ACRS staff is
our designated federal official for this meeting.
17
ACRS INTRODUCTION
18
CHAIR CORRADINI:
The purpose of today's
19
meeting is to receive a briefing on and discuss with
20
the staff the NRC's advanced reactor research program.
21
The
research
program
document
has
been
updated
22
recently to address the gaps in the NRC's analytical
23
tools
24
verify NGNP VHTR design and its safety performance as
25
well
and
as
infrastructure
other
R&D
needed
needs,
to
to
independently
review
the
NGNP
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1
application.
2
In the recent past the NRC performed a
3
PIRT
to
4
relevant
5
infrastructure
6
results from these PIRT efforts and the joint NRC-DOE
7
NGNP licensing strategy report provided input to the
8
research program update.
9
develop
NGNP
an
expert
phenomena,
needs
for
assessment
and
the
the
NGNP
of
NRC
safety
R&D
licensing.
and
The
In addition to NGNP the program document
10
also
provides
11
research needs for the staff's independent assessment
12
of sodium cooled fast reactors.
13
Dr.
a
preliminary
Powers,
now
analysis
present,
of
regulatory
and
I
were
14
members of the several PIRT panels, the NRC general
15
counsel has advised us not to provide our views on the
16
work of the specific panels we served on.
17
will not take part in any discussions specifically
18
related to the thermal fluids panel.
Hence, I
19
We have up to 10 minutes for any member of
20
the public who may want to ask questions to do so at
21
the end of the meeting.
22
As a transcript of the meeting is being
23
kept, we request that participants in the meeting use
24
the microphones located near the meeting room when
25
addressing
the
subcommittee.
Participants
should
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first identify themselves and speak with sufficient
2
clarity and volume so that they can readily be heard.
3
We will proceed with the meeting.
And I
4
will call upon Stu Rubin, Stuart Rubin, of the Office
5
of Nuclear Regulatory Research, to kick it off.
6
Stu.
7
MR. RUBIN: Okay, thank you.
8
MS. BANERJEE:
9
Matri
Banerjee.
I
And -
Excuse me, Stu.
just
wanted
to
This is
mention
to
the
10
members that if you are missing any slides, because I
11
anticipated only seven of you to come, and it looks
12
like maybe, you know - if you are missing any slides,
13
and there are going to be 17 sets of slides, please
14
let me know, so I will go and fetch one for you.
15
CHAIR CORRADINI: So actually you reminded
16
me of something I had talked to Stu ahead of time, and
17
I'll ask the members and the staff. There are a number
18
of
19
through
20
research plan.
21
parts
to
the
this
presentation
various
parts
of
to
the
try
to
lead
advanced
We give the speaker some time to
22
develop
23
clarification
24
something is just burning in us to clean it up.
25
reactor
So I would ask that we stick with our
general plans.
their
us
presentation.
question,
try
Unless
to
hold
there
them
is
a
until
And as we always have, about half of this
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is for discussion.
2
discussion on any one of these topics.
3
Stu.
4
ARRP INTRODUCTION (OVERVIEW)
5
6
So we should have ample time for
MR.
RUBIN:
Okay,
again,
good
morning.
Thank you, Dr. Corradini, and the ACRS members.
7
My name is Stu Rubin.
I'm the senior
8
technical adviser for advanced reactors in the Office
9
of Research.
And for this presentation I'd like to
10
provide a very high level overview of the research
11
plan with a focus on the R&D that we will have in the
12
HTDR arena, and in the implementation as it exists
13
today.
14
Research again is focused on safety R&D
15
that we need to conduct to get ready to review the
16
NGNP VHTR license application.
17
And so you know our strategy, for today is
18
to start with a presentation at a fairly high level,
19
this presentation.
20
we go through the presentations, the next one being
21
Joe Kelly who will then bring it down to a low level
22
in terms of our evaluation model, development plans,
23
and then following that we get into the ground level
24
specific technical arena plans that participate in the
25
development of that evaluation plan.
And then to work our way down as
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I think it would be most efficient as you
2
mentioned to kind of hold those detailed questions to
3
those detailed low level presentations.
4
The other point I wanted to make is that
5
we started only a short time ago within the last year
6
and a half, so we are just now starting to get our
7
arms around what we need to do.
We may not have all
8
the
need
9
answers by the time the application comes in.
detailed
answers
yet.
We
to
have
those
10
And the other point I'd make is that I
11
would view this as a first meeting, in that I expect
12
that over the next five years and beyond we will have
13
follow up meetings in areas of focus, thermal fluids,
14
nuclear fuels and the like.
15
actually go through it all today. We are going to do
16
more as time goes on in terms of meeting with the
17
subcommittee.
So we don't have to
18
As far as the focus of this presentation
19
over these two days, first my purpose is to provide an
20
overview of our R&D plans, and then to discuss and
21
identify the technical issues and safety research that
22
was identified within each of the technical arenas.
23
And Joe Kelly will also provide a discussion of the
24
accident
25
together the disciplines of many technical arenas.
analysis
evaluation
model,
which
brings
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Third
even
of
course
over
these
is
we
obtain
feedback
3
subcommittee,
4
recommendations on how we ought to move forward with
5
our plans.
terms
days
to
2
in
two
want
of
our
from
views
the
and
6
And finally we want to support the work of
7
this subcommittee to provide input and recommendations
8
to the full committee on what we need to focus on and
9
how we ought to proceed.
10
Just as a way of background I know Dr.
11
Corradini covered it, but I'd like to give you some
12
additional context, the first version of this plan was
13
issued back in 2003 about five years ago, and it was
14
done because of the HTGRs that were coming in at that
15
time, PBMP principally.
16
on the plan, we actually shut down our R&D activities,
17
because PBMR, or Exxon in that case, had decided to
18
terminate
19
anything going at that time.
the
review.
But by the time the ink dried
So
we
really
didn't
get
20
But it was an approved plan at that time.
21
But then following that, starting in 2005, a number
22
of non-light water reactor design applicants came to
23
the
24
licensing activities, and these of course were PBMR
25
company, PBMR for design certification, and of course
NRC
and
formally
expressed
an
interest
in
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the NGMP and the EPact was a need for us to do a
2
licensing
3
reactor, with sodium fast reactor technical review, so
4
we potentially would have to do.
5
Commission recognizing this issued a SRM to the staff
6
to
7
infrastructure for HTGRs and to a much limited amount
8
for sodium fast reactors.
action,
begin
its
and
Toshiba
development
4S
of
advanced
burner
So in 2005 the
the
technical
9
And so we began to revise the plan, bring
10
it up to date to reflect the work that had been done
11
and the like, and the new kinds of technical issues.
12
And so we did that, and focused on HGTRs principally,
13
and to some extent on sodium fast reactors.
14
2007 we provided that to what is called the Advanced
15
Reactor Steering Committee within the NRC management
16
structure for their review.
17
provided some comments back, and following that as was
18
mentioned, we had some PIRTs, we had five PIRTs for
19
the NGNP, in five technical arenas.
20
additional input from that.
21
And in
They did review it and
So we had the
And also we met for the first time at INL
22
out
23
contractors, and we got a very exhaustive briefing on
24
all the work that they were doing to support design,
25
development and licensing of the NGNP.
at
the
Idaho
National
Laboratories
with
DOE's
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So with all that, we took that in and we
2
revised the advanced reactor research plan, and we
3
sent
4
review and final approval.
it
back
to
the
steering
committee
for
their
5
And during this whole time, because of the
6
Commission direction, we did initiate tasks in 2007,
7
more in 2008, and we are initiating tasks today.
8
So while we don't have an approved plan
9
formally, we are moving forward because of the time
10
needs.
11
In
terms
of
the
infrastructure
or
the
12
actual structure of this thing, it's two parts.
13
is
14
assessment, which really applies the key technical and
15
safety issues that come out of the licensing NHGR, and
16
the second part of the actual plans themselves.
17
are plans that NRC plans to embark upon to do its
18
regulatory research in meeting our goal.
what
we
would
call
an
infrastructure
One
needs
These
19
And so the focus now is on HTGRs and - but
20
there are generic aspects included as well that apply
21
to all advanced reactors - human factors, digital INC,
22
PRA,
23
specific to NGNP but certainly NGNP is a driver for
24
their needs.
25
regulatory
infrastructure.
These
are
not
And so we have compiled our detailed plans
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in the document, and we've also included a limited
2
infrastructure assessment, or what we would call a
3
survey really, and R&D plans for SFRs.
4
Now
again,
the
reason
for
the
5
infrastructure is, we really want to understand what
6
are
7
issues and research needs for these designs.
8
want to identify where are the gaps in what the NRC
9
has in terms of data and information and modeling and
the
key,
and
unique,
the
We also
11
management in order to support a licensing review.
also
to
technological
know-how,
We
that
different
10
12
call
and
specifically
attention
identify
of
our
what
13
experimental
14
developed, and what kind of technical knowledge and
15
know-how does the staff need to develop in order to
16
really be ready to do a review of something close to
17
our expertise for light water reactors, hopefully at
18
that level.
data
and
models
and
code
need
to
be
19
But having said all that, we do expect
20
that the design of the applicant will be responsible
21
for doing much of the R&D that we will need to look
22
at.
23
24
MEMBER SHACK:
Was there a formal process
to figure out who does what?
25
MR. RUBIN: Yes, that's this next slide.
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MEMBER SHACK:
2
MR.
RUBIN:
Okay.
Okay,
that's
the
role
of
3
research.
And there was a lot of debate going on,
4
what should be our plans for doing research.
5
did have management meetings and we worked through
6
what is our role as regulators.
7
agreed to within the Office of Research, and in the
8
office of NRR and NRO.
9
First
we
So we
And this is what was
So this slide summarizes that.
conduct
safety
research
to
10
develop our technical know-how and expertise that we
11
are going to need to review an application for an
12
advanced
13
guidance and criteria for making decisions on these
14
reactors.
reactor,
and
also
the
guidance,
develop
15
We also do research to verify the adequacy
16
of the technical bases for the safety requirements,
17
and the safety criteria that are being proposed by the
18
designer-applicant.
19
Third
we
conduct
safety
research
to
capability
or
20
develop
21
analytical
22
talking
23
confirming the safety performance and confirming the
24
safety margins in the plant designs, and also to use
25
to
an
independent
tools
about
assess
the
and
that
analytical
methods,
after
designers'
me,
and
Joe
will
for
the
purpose
analytical
tools
start
and
of
the
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designers' results that they provide in their safety
2
analysis.
3
And the fourth, we do it to investigate
4
issues,
5
uncertainty, such as the fluid flow phenomena of air
6
and gas, or the emissivity of the reactor vessel wall
7
during conduction cool down.
8
And
9
technical
sufficiently
to
issues,
that
finally
we
scope
out
we
conduct
and
have
feel
safety
validate
large
research
technical
10
issues that have high risk importance, so we can turn
11
it over to the applicant or designer to resolve.
12
CHAIR CORRADINI: So just to clarify that,
13
because Bill asked the question, but I didn't see in
14
the research plan this process laid out, or even a
15
graphic to give some examples of what things would
16
naturally fall in the NRC's role, would naturally fall
17
in DOE's role as the applicant.
18
MR. RUBIN: Right.
19
CHAIR CORRADINI: And would be somewhere in
20
the middle, and you guys are still in a matter of
21
conversation.
Will we get an example of that?
22
MR. RUBIN: I don't have it in front of me,
23
but I thought we had a column in our R&D plans that we
24
called bins or something.
25
graph.
And
those
At least we did that in our
numbers
corresponded
to
these
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bullets.
2
to one or more of these responsibilities.
3
So we justified reactor based on connecting
MEMBER
ABDEL-KHALIK:
If
there
is
an
4
issue missed by the PIRTs, when and where would that
5
issue be captured?
6
MR.
RUBIN:
Well,
as
we're
working,
7
worldwide people are working, and we talk to each
8
other, issues emerge.
9
and phenomenon need to be understood.
And they need to be looked at,
So we view the
10
PIRT we did as kind of a first major effort to get our
11
arms around the issues, but we are always trying to
12
learn about new issues.
13
And to be sure, in the HTR 2008 there were
14
issues presented that may not have been fully explored
15
in the PIRT.
16
go out and seek additional input, but we certainly are
17
listening to everyone and are exchanging information
18
all the time.
So it's not something where we actually
19
So if you -
20
MEMBER ABDEL-KHALIK:
But where on this
21
chart would the boundary between the NRC's role and
22
the applicant's role in identifying and following up
23
on those previously unidentified issues?
24
MR. RUBIN: Well, I mean, once an issue is
25
identified, we would, if it has important implications
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1
in
terms
of
the
2
analysis,
3
would do the R&D to develop the data and to develop
4
the
5
graphite dust would be an example I would point to.
6
It came to our attention through a recent analysis in
7
Germany at Julic that there was a view that there
8
could be a large amount of metallic radionuclides,
9
cesium,
then
modeling
we
to
tied
technical
up
would
expect
account
in
basis
for
the
for
that
that
dust
the
new
that
the
safety
applicant
issue
was
or
-
circulating
10
within the AVR, sufficiently high that it could result
11
in a consequence that far exceeded what the safety
12
analysis had presented in the licensing of that plant.
13
So
that's
an
issue
that
we
need
to
14
understand, get our arms around.
15
knowledge is already working that problem very much,
16
and
17
importance,
18
phenomenon.
19
well.
we
are
20
21
as
we
well,
have
a
okay.
But PBMR to our
So
piece
in
because
of
its
understanding
the
And I'll talk about that in fuels as
But
the
primary
responsibility
is
the
applicant, that being an example.
22
But anyway, this chart is intended to show
23
graphically
all
the
24
information
that
we
25
application, and the small piece in red is really what
amount
will
of
need
R&D
in
and
blue
data
to
do
and
the
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1
we view as what our job is in terms of regulatory
2
research.
3
CHAIR CORRADINI: But this is a very good
4
graphic.
So I guess to just repeat my question as we
5
proceed through the two days, if the staff could be
6
aware
7
clearly
is
8
cross,
and
9
thought it didn't even exist it's sitting out there in
10
the dark blue, when you bring it in, what are those.
11
So examples of those things would help us understand
12
your process.
of
13
where
we
red,
to
MR.
are
what
add
trying
clearly
Said's
RUBIN:
to
is
point
Okay,
understand
blue,
to
okay.
what
where
it,
We
they
where
you
certainly
14
discuss this all the time with management when an
15
issue comes up.
16
is, why isn't the applicant responsible for this.
17
we have to really think that through.
18
We ask - the first question we ask
So
The next graphic really is set up for the
19
next two days.
20
really
21
reactor on the left side, and a dynamic pebble bed
22
core reactor on the other side.
23
little bit about them.
24
25
the
two
I put a graphic in here which is
reactor
Basically
on
types,
the
the
prismatic
block
And I explain a
left
side
on
the
prismatic block reactor side, we call them PMRs, they
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1
have a fixed central annular core which is comprised
2
of
3
vertically stacked on top of one another to form a
4
tall
5
cylinder are graphite blocks, and outside are graphite
6
blocks.
about
thin
1,000
wide
7
prismatic
circular
fuel
boxes
cylinder,
and
that
within
are
that
And the core is periodically reloaded in a
8
batch
basis
much
like
a
9
They're easy to understand.
live
water
reactor
is.
10
The pebble bed reactor on the right side
11
has also an annular core, but it involves moving fuel
12
elements.
13
comprised
14
elements, and I'll show you one later, and these are
15
loaded into that annular space, and they all move down
16
the core together and individually, slowly traveling
17
from the top to the bottom by gravity.
18
gets to the bottom they are removed, looked at in
19
terms of burn up, and if they are well below the
20
design burnup they are returned to the top of the core
21
and dropped back in.
22
fuel cycle, and that's why it's called a continuous
23
online refueling system.
And
of
a
the
bed
annular
of
core
about
is
combined
400,000
pebble
-
is
fuel
And when each
So this continues throughout the
24
In terms of the coolant flows, basically
25
during power operation the vessel inlet, relatively
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1
cool helium comes in at the bottom, travels vertically
2
up close to the vessel wall, then reverses direction
3
and comes down through the core, picking up heat as it
4
travels
5
prismatic fuel assembly or through the open spaces in
6
a pebble bed type reactor, and having picked up that
7
heat and exited below the core and then exits out
8
through that same annular input duct where it came in
9
initially.
through
either
the
circular
channels
on
a
10
So with that background you will have a
11
little understanding of what we'll be talking about in
12
our discussions.
13
Just so you'll know -
CHAIR
CORRADINI:
Just
to
again,
14
clarification on this one, so originally there was
15
going to be a decision point as to which way to go.
16
Is that decision point in terms of time still the
17
same,
18
designs
19
phase?
20
21
are
you
through
going
your
to
safety
have
-
to
your
consider
both
preapplication
MR. RUBIN: We are going to consider both
designs until DOE makes a decision.
22
23
or
CHAIR
CORRADINI:
So
has
their
decision
point estimate changed?
24
MR. RUBIN: The feedback we are getting,
25
and I could defer to DOE, is that we are looking at
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1
some
time
after
2
strategy, maybe later this summer or beyond, and we'd
3
have to talk to DOE.
4
application date?
6
CHAIR
defined
by
the
licensing
CORRADINI:
It's
still
2009-2010
timeframe?
8
9
as
And the issue comes up, well, what is the
5
7
-
MR.
until
that
RUBIN:
time
our
Yes,
correct,
strategy
and
correct.
plan
is
to
So
move
10
forward with research that really can be applied to
11
both kinds of designs.
12
And again this slide lists some of the
13
basic design facets and the safety approach taken by
14
ACGRs.
15
asterisks I would say are different than Fort St.
16
Vrain.
17
core outlet temperatures, perhaps as high as 900, 950
18
degrees.
19
reflector,
20
normal operation they will use - the NGNP at least
21
will
22
exchange heat with a secondary plant, and there may be
23
a direct cycle as well in which the helium directly
24
goes to a helium tower turbine generator.
First of all there - the safety attributes and
But basically the designs involve very high
The core is annular, with a graphite center
different
utilize
25
an
than
Fort
intermediate
St.
Vrain.
heating
During
strategy
to
But there may also be steam generators in
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1
a design, which makes for more complex factor analysis
2
issues for us.
3
must have very low failure rates to meet the design
4
acceptance criteria.
5
It utilizes coded fuel particles.
It
They are metallic pressure vessels instead
6
of prestressed concrete, as Fort St. Vrain was.
7
reactor is designed to rely solely on passive systems,
8
structures
9
characteristics to mitigate design basis accident; not
10
and
components,
and
The
inherent
necessarily beyond design basis, but for design basis.
11
And the dose consequences for these plants
12
were
based
13
specific, rather than a bounding source term.
14
we all know, the license basis will be developed using
15
the PRA and deterministic judgment in a risk-informed
16
manner.
17
on
mechanistic
Again,
these
are
source
the
terms,
technical
event
And as
arenas.
18
The ones that are in red asterisks have an important
19
contribution
or
20
development.
The green asterisk ones are the ones
21
that are generic, and we added H2 production facility
22
in this particular AARP because of the NGNP design,
23
and again I mentioned sodium fast reactors were also
24
included in terms of a survey of the infrastructure
25
needs.
role
in
our
evaluation
model
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1
I'd like to point out in this slide what
2
our priorities are for developing analytical methods.
3
And they're listed in descending order.
4
Our first priority is to develop the tools
5
for
calculating
6
consequences
7
accidents.
8
9
of
the
design
phenomena
basis
and
accidents,
the
and
dose
severe
Our second priority is to have tools that
allow
us
to
understand
the
performance
and
the
10
integrity of the SSCs that are relied upon to mitigate
11
those accidents.
12
integrity and performance of what's called the reactor
13
cavity cooling system during these events, as well as
14
the concrete structures that support everything during
15
these events.
Examples would be confirming the
16
Third and lowest priority is development
17
of tools that will allow us to understand failure
18
potential during normal operation.
19
focus for INL.
20
going to have a long term life expectancy, and they
21
don't want early failures.
22
But
This is a big
They want a design equipment that is
we
view
our
focus
that
as
more
accident
23
prevention,
24
accident mitigation type and analytical tools.
25
and
needs
to
be
really
on
This next slide was - is intended to show
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1
what are the targeted kinds of events that we want to
2
be able to develop tools for, as well as what are the
3
targeted figures of merit.
4
This
was
developed
by
several
meetings
5
with the evaluation model development team, and this
6
is what we came up with basically.
7
is the kinds of events, normal operation, pressurized
8
core
9
events,
heat
up
events,
depressurized
On the left side
pressurized
core
heat
core
up
cool
events,
down
which
10
involve the failure of the heat and pressure boundary,
11
and that with air ingress as another category.
12
then weather and steam ingress events, and reactivity
13
type events.
So that is the spectrum of the kinds of
14
events
we
15
evaluation model for.
16
that
And
want
the
to
be
figures
able
of
to
merit,
develop
as
you
And
an
see
17
there,
18
principal ones that we feel our codes need to be able
19
to display and understand so we can compare those with
20
the applicant's analysis results.
21
there
are
many
CHAIR
more,
but
CORRADINI:
these
are
Again,
some
some
22
clarification.
23
these essentially the same list that Fort St. Vrain
24
have to worry about?
25
MR.
Except for the pebble compaction, are
RUBIN:
I
think
so.
I
think
this
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1
basically covers it.
2
heat
3
reactivity as the basic categories, I think they - all
4
ACGRs will have events that fall into those basic
5
categories.
up,
cool
6
If you look in the categories of
down,
air
ingress,
water
The details may be somewhat different.
I'll give you an example.
water
ingress
event,
a
8
reactivity
9
pressure because of the forming of steam.
event
to
okay,
occur,
that
You could have
7
10
ingress,
and
could
also
cause
could
a
raise
Down the road you could have a valve lift
11
to prevent all the pressurization.
12
have
13
reactor, or you open the reactor later on.
14
could have a reactivity slash water ingress event with
15
a delayed kind of an opening of the reactor, and that
16
could - so there are all kinds of combinations, but
17
they fall into those categories.
an
event
where
you
don't
So you could now
actually
open
the
So you
18
CHAIR CORRADINI: Okay, but the reason I
19
asked my question as I did is, besides the pebble bed
20
design,
21
prismatic, I want to understand that this list here is
22
pretty much the same as Fort St. Vrain, which leads me
23
to my next question, the high temperature operation of
24
the NGNP does not change any of the characteristic
25
accidents one would have to consider, or the factor of
put
that
off
the
table,
if
we
just
had
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1
- you are going to produce hydrogen offsite change any
2
of the accidents you might consider on the reactor
3
side?
4
MR. RUBIN: Okay, let me say that there is
5
no road that is - hydrogen plant or process plant
6
events, okay.
7
we
8
understand it.
don't
The only reasons we don't have that is
have
9
enough
information
yet
to
But basically if you look at it this way,
10
a hydrogen plant is a load on the reactor.
11
could lose your load.
12
13
really
And you
You could have load increases.
Same as you have on fossil - excuse me, on light
water reactors.
14
As
far
as
that
goes,
those
are
small
15
hydrogen plants, only 10 percent let's say of the full
16
capacity
17
increase, decrease type events, heat up and cool down.
18
of
the
reactor.
So
they
are
small
load
What are more interesting, of course, are
19
the IHX failures.
20
sort of another media into the system.
21
start trying to model all that, we want to understand
22
more about what is the design.
23
meeting with NGNP to - excuse me, with INL and DOE to
24
get more information on it.
25
We might have some ingress of some
But before we
So we are going to be
But that is a role we'd like to add in
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1
time.
2
MEMBER ABDEL-KHALIK:
This may come out
3
later, but how well do you think we know the core
4
inlet
5
designs?
flow
distribution
in
either
of
these
two
6
MR. RUBIN: Well, we could have some people
7
here who will talk about CFP analysis, what we're
8
doing.
9
development,
It's not a formal part of our evaluation model
but
to
understand
some
of
the
local
10
effects that we may need to be concerned with in our
11
evaluation model.
12
And to give you an example, it's not your
13
example, exactly, but we believe that there will be a
14
profile
15
theta, okay.
16
certainly
17
balance of plant equipment failure issue.
at
the
exit
which
is
not
uniform
in
And so that's important to understand
for
18
core
downstream
mixing
issues,
for
the
But we also want to understand what is the
19
temperatures
20
nonuniformly distributed.
21
like an air ingress event, you may have this side of
22
the core at a higher temperature than that side of the
23
core in terms of oxidation rates and the like.
24
25
in
the
graphite
box,
you
know,
So if you did have an event
So we definitely are interested in those
kinds of things.
In terms of the inlet side, I'm not
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1
sure we have anything going on that, but on the outlet
2
side we do have some CFD analysis that we are doing to
3
understand those kind of distributions.
4
CHAIR CORRADINI: So Said's actual question
5
leads me to the one where I like your priorities, but
6
the design can feed back to potential radiological
7
effects.
8
temperature and push it further.
9
verify
And let's just take the distribution of
that
you
actually
How are you going to
know
how
the
graphite
10
dimensionally changes as this core ages?
If you were
11
going to get to that later, that's fine.
But this is
12
just another step into the question, and I with all
13
due respect to computers, what if I don't believe it?
14
How are you going to know from some sort of in-
15
service inspection about it?
16
So
17
question potentially going.
that's
kind
of
where
I
hear
his
We can wait on it.
18
MR. RUBIN: Yes, we have someone who is
19
going to talk about graphite and graphite aging and
20
distortion with time, and the implications on thermal
21
analysis and the like.
22
So save those questions.
This is I would call an initial concept or
23
preliminary concept of our evaluation model.
24
say much about it.
25
of the sails of Joe Kelly.
I won't
I don't want to take the wind out
But basically we want to
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1
use this kind of a model which brings together really
2
analytical tools and methods associated with nuclear
3
analysis, thermal fluids analysis, fuels performance
4
analysis, graphite behavior, and also fission product
5
transport..
6
talk about the needs of each other, to make sure the
7
models' inputs and outputs connects.
8
So it involves a team to work together to
And I will let Joe talk about it.
But
9
this is quote our action analysis evaluation model
10
concept at this point, and we can get more into it
11
after Joe and beyond at the detail level.
12
Just to summarize, where we are in the
13
advanced reactor research plan R&D, first of all our
14
focus is on the NGNP VHTGR COL technical review aids.
15
They are not showing us pebble bed at this point or
16
prismatic, but that is really our focus.
17
We also want to be consistent in terms of
18
high importance, low knowledge, type data needs for
19
modeling in terms of the research that needs to be
20
done,
21
several years ago for TRISO particle fuel, and we had
22
one for human factors.
and
we
had
parts
for
the
NGNP,
we
had
one
23
We also want to be consistent with our
24
guidelines for the role of research, to make sure we
25
are not doing what the applicant and DOE needs to be
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1
doing.
And we watch that all the time.
2
We also want to utilize extensively the
3
R&D that DOE is doing, and we are going to do that
4
because it's expected, and there is an MOU that says
5
as much, that we will have access to all their work.
6
And they want to understand from us what exactly the
7
environment set ups and data collection, and how you
8
collect data, needs to be, so that it is good data
9
that will serve both our purposes.
10
Again as I mentioned, for now we have both
11
prismatic and pebble bed reactor designs.
12
DOE makes that design selection, we are then going to
13
focus
14
specific design.
15
clearly
I
on
that
will
say
type
we
of
But when
reactor
incorporated
and
that
cooperative
16
research into our R&D activities.
17
spoken to the European Union RAPHAELE program, people
18
who have a program underway for HGTR type research in
19
fuels, thermal fluids analysis and the like.
We have already
20
We recently talked to the Japanese atomic
21
energy agency representative about potential research
22
that they feel they would be willing to do with their
23
HGTR, very useful type research I would add.
24
We need to talk to INL to see if we can
25
identify some of those proposals that would really be
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1
very useful for both of us.
2
We have also been interacting with the
3
OECD TAREF program, which is really a program to pull
4
together worldwide what facilities exist for safety
5
research for sodium transfer reactors, as well as for
6
high-temperature reactors, and we are now at a point
7
where we want to start talking really seriously about
8
which
9
collectively try to get some research completed at.
10
of
those
And
facilities
finally
we
would
need
the
to
countries
support
the
11
timeline for the NGNP COR application.
12
something that is going to be ready in 15 years; we
13
need to do something that needs to be ready when the
14
COR is submitted, which is 2013.
15
Now
I
put
this
in
We can't do
there
because
Dr.
16
Corradini asked me to walk through the roll out of our
17
presentations, but it's really a dupe of the agenda.
18
And it's intended to really start out high, work our
19
way down, and to do it in that way, and you can see by
20
reading what will be covered at a high level in each
21
case.
22
I will be coming back on fuels, and so we
23
will just work our way down that onion.
24
for me.
25
And that's it
Are there any more questions?
I guess we
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1
are - are we on schedule?
2
3
CHAIR CORRADINI: We're ahead.
We want Joe
badly.
4
MR. RUBIN: Joe, okay.
5
REACTOR PLANT SYSTEMS ANALYSIS (OVERVIEW)
6
MR. KELLY:
be
giving
an
Okay, I am Joe Kelly, and
7
I'll
overview
presentation
of
our
8
evaluation model for the NGNP at the level of the
9
reactor plant system analysis.
10
A simple little roadmap, just what I said.
11
I'll be giving - I'm so used to pointing, I'm an old
12
style presenter, I want to stand up and point, so
13
excuse me, I'm still trying to learn this.
14
So
I'll
be
giving
an
overview
of
the
15
evaluation model, and then below that will be five
16
different presentations giving some of the technical
17
details.
18
will be given by Tony Ulses.
19
Bajorek.
20
MELCOR
21
consequence analysis, Jocelyn Mitchell.
22
23
Thermal fluids, Steve
The accident analysis, which is more the
code,
would
be
Allen
Notafrancesco;
My contents are pretty short.
and
The first,
what is an evaluation model, what does it have to do.
24
25
Fuel analysis will be Stu, nuclear analysis
The second, what is the one that we are
putting together actually look like.
And then the
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1
role of CFD analysis in this.
2
Then if time and your interest permits,
3
I'll give a couple of short examples of some of the
4
CFD work we've done to date.
5
Our evaluation model is straight from the
6
reg
guide.
It's
pretty
7
framework,
8
computer code that all have to work together to go
9
through a design basis accident.
typically
simple.
consists
of
Calculational
more
than
one
And also it includes
10
the assumptions that go along with the use of those
11
codes.
12
For
the
for
the
scope
of
the
one
that
I'm
13
responsible
14
plant systems analysis, and that includes primarily
15
four areas: the nuclear analysis; thermo-fluids; fuel
16
performance; and fission product transport.
development
of
is
the
reactor
17
At the moment it's going to apply to both
18
pebble bed, that's the PBR, and the prismatic modular
19
reactor, or PMR designs.
20
21
Once there is a design decision by the
Department of Energy we will focus that down.
22
I'm going to talk in the way that it's
23
like
24
reality
25
concepts.
three
separate
it's
one
There
evaluation
that
are
the
models,
covers
normal
three
although
in
difference
operations;
the
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1
initial release; and the delayed release.
2
So what are those?
Normal operations,
3
that's fairly obvious.
4
when it is sitting there operating for a long period
5
of time?
6
What does the plant look like
And what we really need, this sets the
7
source term for the initial release.
So it's the
8
generation and distribution of the fission products.
9
What I'm talking about here now is actually within the
10
coated fuel particles within the core.
11
have to worry about the fission products that have
12
escaped the coated fuel particles, the ones that are
13
played out, or absorbed within the matrix graphite.
14
So all those within the helium pressure boundary; the
15
circulating activity due to things like contamination
16
in
17
Brayton cycle, the erosion products that have been
18
activated.
the
helium
19
20
coolant;
or
if
But you also
specially
if
it's
a
And the dust formed radionuclides.
MR. KRESS:
Are you working on a dust
source model?
21
MR. KELLY:
Not yet.
Not yet, but that
22
is something that we obviously are going to have to
23
do.
24
generated, but how much is there.
25
of dust that is important.
And
it's
not
necessarily
how
much
dust
is
It's the inventory
Where can it hang out?
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1
2
MR. KRESS:
it.
3
MR. KELLY:
4
MR. KRESS:
5
But you need attenuator for
Right.
And you'll have to know what
size it is.
6
MR.
KELLY:
And
that
is
a
huge
7
uncertainty at the moment.
8
results, the same people will tell you well, it might
9
be six microns, or it might be point six; it depends
10
on when we measure it.
11
CHAIR
And that's a huge difference.
CORRADINI:
12
magnitude of the inventory?
13
AVR.
14
MR.
You know based on the AVR
KELLY:
Do
they
know
the
They had a lot at the
At
the
AVR
they
had
15
estimates.
16
2008 is that a lot of it had to do with oil ingress in
17
vents, and now you got - it had to do with oil ingress
18
events, and that was the shift from the six micron to
19
the point six micron.
20
that.
21
of expertise here.
22
But the speculation is that from the HTR
They think that's what explains
But you are getting me far outside of my area
CHAIR CORRADINI: What is the name of the
23
person we can ask this of in the two days?
24
responsible for worrying about this?
25
Who is
MR. RUBIN: Okay, let me just use that as
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1
an example.
2
radionuclides actually gets out to the edges of the
3
fuel
4
understand the fission product transport within the
5
particles and the matrix to understand that.
-
the
6
We have a lot of players here.
pebble
We
may
in
in
that
fact
case.
be
How much
You
talking
have
about
to
on
7
contemporary fuels very little in the way of cesium
8
for
9
layers, to get to that point where the dust is then
10
example
getting
through
a
TRISO
particle
fuel
generated.
11
So the first part of the puzzle is how
12
much cesium is available to be bound up in the dust.
13
And that is where the fuels program, and I'll talk
14
about that, starts.
15
The
next
thing
is,
how
much
dust
is
16
actually generated, containing that very large amount
17
of cesium, or very little cesium.
18
is in our graphite program to get our arms around
19
that.
20
That's a part that
The next question is, how is that dust
21
actually transported, and where does it go?
22
have some analysis methods that we are thinking about,
23
CFD analysis, to try to understand how that dust gets
24
distributed
25
thoughts that it goes where it's below the velocity
and
where
it
goes.
There
are
So we
some
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1
profiles, and that might be where the heat exchangers
2
are, okay.
3
And
then
the
next
question
is,
what
4
happens to that dust in an event where it can be blown
5
out of the system?
6
at the beginning of the process you conclude that
7
there is not a lot of say radionucldes in that dust
8
you can forget everything else.
9
10
So
Other kinds of analysis.
that's
in
my
research
plan,
But if
to
get
that.
11
CHAIR CORRADINI: Yes, I'm with you, but
12
let me push that point.
So let's say it's not a lot
13
of radioactive material in it.
14
don't care about the dust?
All of a sudden I
15
MR. RUBIN: No, but you want to get your
16
arms around the magnitude of it, because it could be
17
the difference between requiring large filters or not
18
requiring large filters.
19
they need to understand it.
20
the system.
So we need to understand it;
This is in the venting of
21
CHAIR CORRADINI: Okay.
22
MR. RUBIN: So how much rise or fall is the
23
contribution
24
determination in whether or not you need to provide
25
those
kinds
of
of
activity
mitigation
and
type
dust
will
have
components
in
a
the
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1
system.
2
So want to know if it's a little addition
3
or it's a big addition to that source. We need to know
4
regardless.
5
6
MR.
KRESS:
Will
that
depend
on
the
quality of the fuel actually?
7
MR. RUBIN: Well, a subcase in there is
8
failure of particles due to elevated diffusion through
9
intact coatings.
10
dust as presented by the author of that issue.
11
12
And that is the issue for graphite
MR. KRESS:
We are not dealing with non-
intact coatings, or too thin coatings?
13
MR. RUBIN: I will get into that.
It has
14
to do with the diffusion coefficient through cesium -
15
excuse me, through silicon carbide at the temperatures
16
we are talking about at the burnoffs we are talking
17
about.
18
19
And CHAIR
CORRADINI:
And
it's
only
cesium?
You keep on mentioning that.
20
MR. RUBIN: Well, because strontium tends
21
to be tied up more in the kernel anyway, okay, and the
22
cesium is much more mobile to come out of the kernel,
23
and so that is the one that really is the dominant one
24
in terms of being available for release.
25
MR. KRESS:
Do you know what the chemical
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form of the cesium is yet from those kernels?
2
3
MR.
RUBIN:
Well,
we
will
get
to
my
presentation of it.
4
MR. KRESS:
5
MEMBER BLEY: Let me just sneak one in on
6
that.
7
there
8
explosive
9
surfaces be an issue?
Okay, sorry.
Is it strictly a radiological problem, or is
enough
dust
issue,
in
or
release
a
that
fouling
it
of
could
heat
be
an
transfer
10
MR. RUBIN: We'll go into those questions.
11
MEMBER BLEY: Okay, so you are looking at
12
all of that.
13
MEMBER ABDEL-KHALIK:
Let me just ask a
14
basic question.
15
the maximum allowable volumetric heat generation rate
16
during normal operation at any point in the core?
What physical phenomenon determines
17
MR. RUBIN: Okay, the goal, the goal is -
18
what I should have talked about in my presentation -
19
the goal is to have a passively cooled core for any
20
accident.
21
the maximum power generation or power density you can
22
have in the reactor core, such that when you lose
23
normal
24
processes for passive heat removal, you do not see the
25
temperature rise that goes above some I'll call it
And so you need to do analysis of what is
cooling
and
you
start
developing
those
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design limit for the core.
2
MR. KRESS:
3
MR. RUBIN: Sixteen hundred is used as a
for
that.
Sixteen hundred?
4
guide
5
calculation to see what the - and that's why the power
6
densities on modular ACGRs are so low.
7
about 5 to 10 percent
8
modern
9
because you want to be able to passively cool the core
light
And
water
10
in an accident.
11
MR.
so
you
to
do
that
They are only
power density compared to a
reactor
KRESS:
need
for
that
That's
very
also
one
reason,
of
the
12
reasons for the annular core, you get the fuel out to
13
the
14
traverse radially to get the heat out.
periphery
where
it
has
a
shorter
15
CHAIR CORRADINI: Thank you.
16
MR. KELLY:
distance
to
And the initial release is
17
simply when you have the break you release everything
18
that
19
remobilize dust or plate-out.
20
is what happens much later in time when you are doing
21
a heat up, so you have to model the diffusion out of
22
the intact coated fuel particles as well as the failed
23
one, and you have to worry about either air or steam
24
ingress, and what effects those can have.
is
25
circulating
in
the
helium,
plus
you
can
And the delayed release
And our model will have to model the hold
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up and the retention of the fission products within
2
the confinement or containment.
3
Examples of transients to be analyzed, Stu
4
already showed you his table.
5
over the main five ones with the things you worry
6
about.
7
So
the
I was just going to go
pressurized
loss
of
forced
8
circulation which is - you know, you will hear people
9
talk about P-LOFCs all the time.
What you are really
10
worried about now is the thermal plumes in what would
11
be the inlet or upper plenum.
12
about the temperature of the components up there, and
13
their integrity.
14
For
depressurized
So you are worried
loss
of
forced
15
circulation,
16
analysis, that us light water people are more familiar
17
with.
18
temperature.
19
very good estimate of what is the effective thermal
20
conductivity.
21
looks at that and thinks about it's the reactivity
22
coefficient, but so it will overlap.
this
is
more
like
our
standard
LOCA
And here you are worried about the peak fuel
23
To calculate that you have to have a
So
I realize any nuclear analysis person
it's
the
effective
fuel
thermal
24
conductivity, and also the performance, and if you
25
will,
the
integrity
of
the
reactor
cavity
cooling
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1
system.
2
Following
that
you
go
to
higher
3
consequence accidents, which would be like an
4
ingress following a D-LOFC.
5
worry about the graphite oxidation.
That then leads
6
you
itself,
7
supporting structures for the core.
8
can
9
additional
to
the
occur
integrity
to
the
of
fission
And here you have to
the
coated
core
fuel
particle
11
contain the absorbed fission products.
12
MR. KRESS:
graphite
the
The damage that
release,
mobilization
the
or
particles,
10
of
air
layers,
as
causing
well
which
as
would
And with the water ingress
13
you tend to get CO and CO2, will your models have to
14
deal with those?
15
And hydrogen, right.
MR. KELLY:
That is one, when we get to
16
the
17
MELCOR.
18
And that's why we chose it.
evaluation
19
20
you
will
see
are
using
And MELCOR has a lot of capabilities there.
reimplemented to be more specific for graphite.
MR. KRESS:
You will get countercurrent
flows with multiple species of exothermic reactions?
23
MR. KELLY:
Not in MELCOR -
24
MR.
Can
25
we
Now the models will have to be adjusted or
21
22
model,
RUBIN:
you
come
back
to
that
question when we have our MELCOR expert here.
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1
2
CHAIR CORRADINI: So can I ask you a nonMELCOR question about water ingress, if I'm allowed.
3
4
So where is the water - where are the
sources of water in these point designs?
5
MR. KELLY:
6
know.
7
ingress was not covered.
8
9
Well, part of it, is we don't
And like if you noticed in the PIRT the water
But it typically -
CHAIR CORRADINI: Well, in point of fact it
was mentioned a whole lot.
10
MR. KELLY:
But not in detail.
But there are things like the
11
shut down cooling system which will be a helium-to-
12
water heat exchanger going directly into the core, the
13
designs I've seen, and then Stu can tell you we are
14
not sure what the NGNP design is going to be.
15
know you hear different things.
16
there is always going to be an intermediate loop, but
17
there may be a steam generator in place of an IHX now,
18
in which case you have to worry about steam generative
19
ruptures, and so on and so forth.
Sometimes you hear
20
CHAIR CORRADINI: Thank you.
21
MR.
KRESS:
You
Will
you
need
a
CFD
22
calculation for those thermal plumes you're talking
23
about?
24
25
MR.
KELLY:
Probably.
And
that
is
certainly one of the areas where we would use CFD to
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1
take a look at.
2
And we have already kind of covered the
3
reactivity
events.
4
compaction has to do with seismic events.
5
6
And
of
course
the
pebble
bed
So this is the NRC evaluation model as we
envision it today.
7
MEMBER RAY:
pebble
8
the
9
events, is that what you said?
10
bed
The last statement you said,
MR.
compaction
KELLY:
has
to
Yes.
do
with
In
the
seismic
chemical
11
industry, they actual shake pebble beds or pack beds
12
in order to increase their density.
13
worry
14
packing densities run around 60 percent, and it can go
15
up to -
16
about
the
density
MEMBER RAY:
And so you would
increasing,
because
the
I was just thinking, is
17
there no analog in the prismatic?
18
there no structural function performed by the graphite
19
that might be affected by a seismic event?
20
21
MR. KELLY:
In other words is
I'm sure it can be affected,
but I don't know how it can affect reactivity.
22
MEMBER RAY:
Well, I think the issue, in
23
my mind, you could have failures of the graphite core
24
supports, and have the entire core moved -
25
MR. RUBIN: Correct.
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1
MEMBER RAY:
And then essentially you are
2
moving away from the control rods, because they stay
3
where they are and the core goes down.
4
have a reactivity addition that way, which is also
5
true
6
compaction.
7
negative reactivity for the rods, actually relatively
8
moving away.
in
9
pebble
beds.
So
you
have
So you can
them
from
And also you are losing some of that
MR. RUBIN: That was the big problem we
10
struggled
11
supports.
12
with
years
MR. KRESS:
ago,
failure
of
the
core
Do the designs have a diverse
13
redundant way to - like we introduced boron in the
14
water reactors.
15
MR. KELLY:
The ones I'm most familiar
16
with have control rods which tend to be in the outer
17
reflector
18
shutdown system which are absorber spheres, that are
19
dropped through bore holes and a central reflector.
20
21
region,
and
then
they
have
a
reserve
And you can correct me, is there anything
else?
22
I think that's it.
MR. RUBIN: Yes, the absorber balls are
23
equivalent to liquid injection in a LWR water.
24
diverse way of getting native radioactivity in the
25
core.
It's a
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MR. KELLY:
And when we visited the PPMR
2
facilities they were actually testing things like the
3
absorber balls, the dropping of them through the bore
4
holes,
5
conditions.
at
6
7
prototypic
pressure
MR. KRESS:
and
temperature
The fuel itself, on negative
temperature coefficients?
8
MR. KELLY:
Yes.
9
MR. GRAVES:
Excuse me, this is Herman
10
Graves from the Office of Research.
11
talking
tomorrow
about
12
seismic
concerns
that
13
qualification on the fuel.
14
prismatic core design.
15
MEMBER RAY:
some
we
of
I'm going to be
the
have
structural
with
the
and
seismic
We are looking at graphite
Okay, good, I would just
16
then make the comment that I don't think seismic as an
17
issue is limited to the pebble bed.
18
MR. KELLY:
19
On the left-hand side I have the function
20
of the individual components of the evaluation model,
21
and on the right-hand side the code specific.
22
top part of this, down through the steady state, that
23
is
24
conditions to set up the normal operating conditions.
all
25
to
get
Then
the
the
No, I am learning, thank you.
cross
bottom
sections
half
of
and
the
In the
thermal
figure
is
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1
actually the transient analysis.
2
will use, you will see, for the - well for doing the
3
cross
4
cetera, is the scale AMPX code suite that you've seen
5
before.
section
processing,
And so the codes we
resonance
processing,
et
It's used by both research and NMSS.
6
The
reactor
kinetics
or
reactor
core
7
simulator, that neutronics solution is by the PARCS
8
code, which had already been adapted somewhat for gas
9
reactors.
10
We have more work to do on it, but it's
already been used for a pebble bed.
11
The
thermal
fluids
part
of
the
core
12
analysis is a code called AGREE, which is a module in
13
PARCS.
14
of THERMICS direct.
What it is is a new three-dimensional version
15
MR. KRESS:
16
anywhere.
17
would have been?
18
I don't see TRACE in there
Does AGREE take the place of what TRACE
MR. KELLY:
AGREE is more similar to a
19
subchannel code if you will.
20
of TRACE here.
21
the role of MELCOR is the thermal fluid analysis on a
22
system level, as well as the fission product transport
23
and graphite oxidation.
MELCOR takes the place
When we get to the transient analysis,
24
CHAIR CORRADINI: So one more - because I
25
actually was looking for this thing you call AGREE.
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1
What is it again?
2
Can you just repeat please?
MR. KELLY:
Well it's - actually I've got
3
just a little more detail on a future slide.
4
MEMBER ABDEL-KHALIK:
5
there,
6
earlier.
7
really
8
critical to know the inlet core flow distribution,
9
because that will affect the radial distribution, it
10
let
me
go
back
to
But before we get
the
question
I
raised
At least in the prismatic design, there is
no
cross
flow.
And
therefore,
it
is
very
will affect all your physics parameters.
11
So where in this picture do you get the
12
detailed radial and azimuthal variations of core in
13
the flow distribution, given the fact that you only
14
have one pipe bringing the flow in?
15
MR. KELLY:
16
Well, once it goes through
the plenum -
17
MEMBER ABDEL-KHALIK:
18
MR. KELLY:
Yes, I understand.
But from the plenum to the
19
individual fuel elements is a good question.
And the
20
bypass
largest
21
uncertainties facing these.
22
do with the question that Dr. Corradini raised about
23
who
24
graphite dimensions are going to change. And that is -
is
25
flows
going
in
to
my
-
mind,
how
do
one
of
the
And of course that has to
you
know
MEMBER ABDEL-KHALIK:
how
much
the
But even just the
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1
basic
physics
2
whatever you start out with you'll likely end up with
3
the same flow rate, and if you had highly nonuniform
4
core inlet flow distribution, which you may not know
5
very well, you will not know the core temperature
6
distribution very well, and you will not know the core
7
power distribution very well.
8
issues,
you
MR. KELLY:
don't
have
cross
flow,
Well, if - you see at this
9
point we don't know if the fuel elements are going to
10
contain orifices or not, like in the older designs;
11
they probably won't.
12
of the uncertainties.
13
There
So that helps.
are
cross-flows
That removes one
between
the
14
element blocks, due to the graphite.
15
hope it's small.
16
may have to treat them as uncertainties, okay?
17
may
18
uncertainties.
19
20
have
But again you
But there are uncertainties, and we
to
conservatively
treat
And we
them
as
But the - you know solving a 1-D momentum
equation is not that hard.
21
MEMBER ABDEL-KHALIK:
22
a trivial problem.
23
distribution for a PWR.
24
25
fuel
MR.
I mean this is not
We do not know the core inlet flow
RUBIN:
question another way.
Let
me
try
to
attack
that
I think you are right, we need
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1
to
understand
that.
2
modeling, we will get our arms around it.
3
out it's significant in terms of creating an azimuthal
4
power shift, and therefore a temperature effect on the
5
graphite in the fuel, we may have - this I'm just
6
talking out loud - some sort of hot channel factors so
7
to speak to apply that to the action analysis in the
8
normal operation analysis of particle temperatures and
9
failure
rates.
And
And
do
I
a
think
hot
10
concept, and handle it that way.
11
done.
12
I
see
that
the
If it turns
channel
type
of
a
I mean that can be
When you get into fuels analysis, in terms
13
of
14
accidents, temperature is the key.
15
temperature, the more fission products are mobile, the
16
more failures you may see.
17
temperatures well.
fission
product
release
during
normal
operation
The higher the
You need to know those
18
But if you handle it like in a sector,
19
where a high channel factor, I would imagine that we
20
can handle that in that way, during normal operations
21
to account for those high temperatures, and during
22
accidents as well.
23
24
MEMBER ABDEL-KHALIK:
As long as it's on
your radar screen, that is the important thing.
25
MEMBER SHACK: But I guess the answer to
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1
Said's question is, you are going to calculate this
2
distribution.
3
kind of validation of this.
4
There are no plans for an experimental
MR. KELLY:
Well, we do plan to do what
5
we call an integral effects experiment.
And you would
6
not
it,
7
certainly
8
distribution.
be
measuring
would
9
the
flows
inside
be
measuring
the
but
you
temperature
Now we are not going to have irradiated
10
graphite with leakage channels in it.
11
predefined gaps to simulate what we think the graphite
12
damage might be.
13
CHAIR
CORRADINI:
So
let
There may be
me
turn
this
14
around.
15
put the heat on DOE.
16
either demand a temperature decrement on the outlet
17
gas temperature with this uncertainty, I'm not sure if
18
that is directly a Q triple prime question that Said
19
was
20
temperature solves all problems.
21
Fort St. Vrain, thou shalt not go above 700 to 750C, a
22
lot
23
diminished in need, because you can put in hot channel
24
factors, et cetera.
This is the one where if I were you guys, I'd
asking.
of
25
But
these
So
it
It seems to me that I would
seems
uncertainties,
my
question
to
me
the
outlet
gas
If you go back to a
although
really
is,
there,
is
become
that
the
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1
staff's approach?
Are you going to turn to DOE and
2
your partner cooperative meetings and say, until you
3
show us better, we are going to assume a hot channel
4
factor of X to do our accident analysis?
5
this proceeding?
Or how is
6
MR. RUBIN: Well, again, if you did it -
7
like the role of research, there is a bullet that I
8
talked about, there is a large uncertainty that has
9
important implications.
10
after that.
It's our job to really go
But it's also the job of the applicants.
11
So between us we will have to figure out how we are
12
going to get our arms around the importance of the
13
risk implications.
14
applications of those higher temperatures if they are
15
there.
16
So
And I'll call it the source term
that
is
definitely
on
our
radar
as
17
something that we would want to look at.
18
certainly encourage DOE to do as much as possible in
19
terms of experimental.
20
MR. KELLY:
21
process
with
22
exchange,
23
about.
24
about,
25
permeate
and
But we will
And as we go through this
DOE,
there
they
will
will
know
be
an
what
we
information
are
worried
Because certainly anything that we don't know
we
are
that
going
to
conservatively
conservative
bias
bias.
And
through
our
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1
calculations and see what the effect of it is.
2
the effect is such that the designers can't live with
3
it, then they have to develop a knowledge base so that
4
we can remove or reduce that bias.
5
MR. KRESS:
reactor
7
trouble finding - this may be the wrong place to ask
8
this - finding graphite of the right quality.
9
different sources of graphite had such a wide range of
quality.
11
area.
12
13
a
long
time
ago,
we
had
The
Do you have - this may be the materials
Yes, I will defer this to
Srini's presentation.
MR. RUBIN: I think we'll postpone you on
this one.
16
17
was
MR. KELLY:
14
15
which
Back during my gas cooled
6
10
days,
And if
MR. KRESS:
All right, if you want to put
that in your pocket for tomorrow.
18
MR. KELLY:
So the last thing on this
19
slide that I haven't really touched on is the PARFUME
20
code.
21
performance code for coated fuel particles.
22
not going to use it directly in our evaluation model
23
and actually Stu will talk about it more.
24
going to use it to help inform the selection of the
25
fuel response surface for the coated fuel particle
That's
an
INL
developed
mechanistic
fuel
We are
We are
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1
failure rates, which will primarily be based on the
2
NGNP-specific fuel performance test data.
3
And
of
course
once
from
the
actually
get
confinement
or
4
calculator
5
containment, it will go to the consequence analysis
6
code next.
7
release
we
So what do we have to do in order to make
8
this come to fruition?
9
model development.
10
The first part is the code and
That's the phase we are in now.
The next one is code integration.
There
11
is a lot of different computer codes in that figure
12
that have to work together.
13
back and forth sequentially or in parallel.
14
envision it as an automated workflow for that code
15
suite.
16
They have to pass data
So we
The next step is we are going to perform
17
uncertainty analysis for this plant.
18
some type of statistical approach; we haven't decided
19
exactly what yet, but it will be something like the
20
Wilks method.
21
MR. KRESS:
22
MR. KELLY:
And that will be
Is that the non-power method?
Yes, it goes by a lot of
23
names,
24
there are various flavors of it, which I'm not an
25
expert on.
GRS,
Wilks,
nonparametric,
et
cetera.
And
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1
And
part
of
that
is
that
we
have
to
2
incorporate the model bias and uncertainty factors for
3
those
4
actually do the analyses.
5
MELCOR already has a lot of those.
6
have to make sure it has all the right ones, and that
7
some of the other codes like PARCS and AGREE have them
8
as well.
into
9
all
of
the
computer
codes
we
can
We are fortunate in that
And we'll just
Then we have this great computer model,
10
but
11
validation phase.
12
assessment matrix that will be performed.
we
have
13
14
so
to
prove
it.
And
that's
the
code
So that will be a PIRT-based code
MEMBER BLEY: Can you explain that a little
bit?
15
MR. KELLY:
I can, based on the light
16
water reactor experience, okay?
17
TRACE developer.
18
A year ago I was a
So basically the PIRT has identified the
19
high ranking - the high ranking phenomena.
20
each
21
conditions over which that phenomena was important.
22
would say Reynolds numbers, pressures, that kind of
23
thing.
24
database
25
applicable
of
those
Then
out
for
you
you
go
there
that
then
and
and
determine
look
see
at
what
phenomena,
or
the
the
So for
range
of
I
experimental
experiments
that
range
are
of
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1
conditions.
And then you do the separate effects
2
test, or excuse me, you use the code to simulate the
3
separate effects test for that phenomenon.
4
And you do all of those for all the high
5
ranking phenomenon that you can, and then you also do
6
an
7
effects test data will be there so that you can show
8
that all those models, not only are they validated
9
individually, but they work together well.
integral
10
calculation
And
the
and
hopefully
final
thing
the
is
integral
a
code
11
applicability report, which I know some of you have
12
seen ones for the AP-1000 and the ESBWR.
13
producing something similar for the NGNP.
14
15
We will be
CHAIR CORRADINI: For the codes that you
have showed?
16
MR. KELLY:
17
Just a very brief, what are those codes
18
and what do they do, and then they will be handed off
19
to
20
presentations.
the
21
people
in
Yes.
a
more
detailed
technical
MELCOR is our severe accident code which I
22
know a lot of you have heard of.
23
and heat transfer in the core, as well as fission
24
product transport.
25
It solves 2-D flow
We are -
CHAIR CORRADINI: 2-D?
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1
2
MR. KELLY:
In the core, yes.
It's
radial and axial in the core.
3
The - it has been modified to include core
4
heat transfer and fill models for the pebble bed and
5
prismatic.
6
into it.
7
include the graphite dust.
8
to have fission product release models for the coated
9
fuel particles.
We've also put graphite oxidation models
We will be extending the aerosol models to
10
And then likewise we have
SCALE and AMPX is our nuclear analysis
11
suite.
12
code useable libraries, whereas SCALE gives us the
13
lattice physics and the depletion capability to get us
14
our few group cross sections to K heat and the fission
15
product inventory.
AMPX processes the in depth
16
I mentioned PARFUME.
nuclear data into
TMAP4 is a separate
17
code that has been incorporated into PARFUME.
18
gives
19
performance codes.
20
fuel performance data to develop for our failure rate.
21
This is a function of the fuel temperature and burn
you
the
INL
developed
up.
23
studies to help inform that.
we
fuel
We will be using the NGNP specific
22
And
mechanistic
It
will
be
using
PARFUME's
sensitivity
24
The actual fission product transport that
25
we will talk about now is the diffusion through the
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1
coated fuel particle individual layers in a graphite
2
matrix.
3
code.
4
we will be looking at it to learn what's in it and
5
either include it in its entirety within MELCOR, or a
6
simplified version of it within MELCOR.
That is handled within PARFUME by the TMAP4
DOE has recently provided that code to us, and
7
8
MEMBER SHACK: But the MELCOR will also do
the passive containment cooling calculations?
9
MR. KELLY:
10
11
MR.
Yes.
KRESS:
When
we
talk
about
fuel
performance failure rate -
12
MR. RUBIN: I'm going to cover that next.
13
MR. KRESS:
You are going to talk about
MR. KELLY:
He already gave me a thing
14
that?
Okay.
15
16
saying, you got five minutes.
17
MR. KELLY:
Hey, I have never given a
18
presentation in front of the HUSE in less than two
19
hours.
You are doing good.
20
So MACCS2 is our accident analysis code,
21
and Jocelyn will be talking about that.
22
core
23
kinetics code.
24
been
25
hexagonal.
simulator,
modified
core
neutronics
simulator,
It's 3-dimensional.
for
both
PARCS is the
cylindrical
reactor
It had already
coordinates
and
And it's been benchmarked for the pebble
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1
bed with the OECD PBMR-400 benchmark.
2
which stands for Advanced Gas Reactor Evaluation, is a
3
3-dimensional two-temperature porous body code.
4
basically
5
THERMIX/DIREKT codes.
6
of the coupling is very tight, and it likewise has
7
been benchmarked for the PBMR-400, but also against
8
the sauna experimental test, which is basically what
9
happens after a D-LOFC.
10
a
We
rewritten
have
version
The AGREE code,
of
the
It's
legacy
It's a module with inside parts
to
extend
it
to
the
prismatic
11
core.
12
scale, and puts them in the format that PARCS needs.
GenPMAX just reads the cross sections out of
13
Schedule: it's tight.
14
MEMBER ABDEL-KHALIK:
15
validated for natural convection?
16
MR. KELLY:
17
that.
18
slash MELCOR for that.
19
Was THERMIX ever
I don't know.
I can't answer
But we will certainly have to validate AGREE
That is one of the things in the sauna
20
test.
21
are transmitting the heat radially from the center of
22
the core out to the periphery to the reactor cavity
23
cooling system.
24
and
25
looked great.
You know those are D-LOFC conditions, where you
nitrogen.
They ran those tests with both helium
The
helium
test,
the
calculations
And it has to do with the models for
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1
the effect of thermal conductivity are pretty good.
2
But when you do the nitrogen test, now you are also
3
having a natural circulation cell within that, and you
4
get a lot more - you smooth out the radial penetration
5
because of that.
6
well on that.
7
8
And the codes didn't tend to do as
That is something we have to look at.
MR. KRESS:
What was the heat source of
those experiments?
9
MR. KELLY:
What they did, they had a
10
graphite electrode in the center, pebble bed around
11
it, and then the vessel wall.
12
individual pebbles were instrumented so you could get
13
the radial temperature profile at several elevations.
14
So
on
schedule,
And then you know
code
development,
the
15
initial model development, we need it by September
16
2010.
17
18
That's coming up soon.
CHAIR CORRADINI: You need everything you
showed done at some level in a year and a half?
19
MR. KELLY:
20
But
Yes.
obviously
code
development
will
21
proceed in two stages.
22
we've done some of the assessment, found out where our
23
models are missing things.
24
models, and finish the codes by May 2013.
25
The second stage is after
We need to improve those
Develop new data, any new data that we are
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1
going
to
2
assessment, September, 2012, that's soon.
3
4
use
as
part
MR. KRESS:
of
model
development
and
Is Research developing these
models, or are you farming it out to the universities?
5
MR. KELLY:
Well, for the most part we
6
hope that we can select models that are already there
7
that cover it.
8
have
9
quantify their uncertainty.
a
When we - and then just make sure we
database
to
qualify
those
models,
and
to
Like for example for a
10
pebble bed you would always start with KTA rules.
11
Start
12
uncertainties is right, and hopefully be able to move
13
on.
there,
make
sure
the
quantification
of
the
But you do need to make sure we revalidate it.
14
And the validation against existing data,
15
September `12, against new data, May of `13, and that
16
gives us a code adequacy report in December, 2013.
17
It's tight; it's going to be very hard to meet that
18
schedule.
19
The role of CFD: it's not part of the -
20
it's not explicitly part of the evaluation model, but
21
we will be using it to provide benchmarks as well as
22
possibly
23
system codes.
24
25
develop
or
Examples
select
of
models
places
for
there
it
use
is
in
the
just
a
natural fit, we have already talked about the inlet or
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1
upper plenum in a P-LOFC.
2
lower plenum, the graphite oxidation during an air
3
ingress event.
4
in an IHX.
5
We should also look at the
Dust deposition and lift-off, perhaps
The reactor cavity cooling system, that's
6
a natural one.
7
cells as well as the radiation heat transport from the
8
vessel walls, the reactor cavity cooling system.
9
Because you have a natural convection
We are not going to model that in great
10
detail in MELCOR.
It's going to be a fairly simple
11
model.
12
a fairly simple model is good enough.
But doing that with CFD we can make sure that
13
And
we
talked
a
little
bit
about
core
is
huge
14
inlet
15
uncertainty, numbers for pebble bed are as high as 30
16
percent.
17
through the pebble bed, so we need to understand that,
18
what kind of gaps can develop.
19
the graphite program.
flow
distribution.
While
bypass
a
That is a lot of your flow to not be going
And that comes out of
20
And then we need to know what kind of loss
21
coefficients to use for those gaps in an analysis with
22
something like AGREE or MELCOR.
23
MR. KRESS:
When you talk about graphite
24
oxidation by air, you are not really talking about
25
burning are you?
In a strict sense you can define
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burning versus slower air oxidation?
2
MR. KELLY:
3
Yes.
I can't make that
definition, but -
4
MR. RUBIN: Well, whether it's endothermic
5
or exothermic really depends on the temperature and
6
the availability of oxygen, and there is always a
7
link.
8
availability is, and the temperatures to know if it's
9
exothermic or endothermic.
And you have to see what the actual oxygen
10
11
MR. KELLY:
from what I've seen.
12
13
But I think it is exothermic
MR.
KRESS:
The
reaction
itself
is
exothermic, but there are heat sinks.
14
(Simultaneous speakers.)
15
MR. KELLY:
This was - time and interest
16
permitting
17
ongoing studies.
18
at this point, I don't think I'm going to be showing
19
the last few slides unless asked for.
I
20
21
was
going
to
talk
about
some
of
the
But since I am exactly on schedule
CHAIR CORRADINI: Well, I have a question.
Is
there
a
philosophy
about
using
CFD
in
these
22
advanced reactors?
23
commercial products, or are you going to develop open
24
source models that allow for clear - what shall I say
25
politely?
-
That is, are you going to use
checking
of
it
to
make
sure
it
makes
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1
sense.
Because if you are going to use commercial
2
products that would be an issue.
3
MR. RUBIN: Let me answer that question.
4
That is a question that we could answer if we were
5
interacting with an applicant.
6
CHAIR CORRADINI: If you were what?
7
MR. RUBIN: If we were interacting with an
8
applicant.
9
could see what their plans are for doing a safety
10
If we were in a pre-application review and
analysis.
11
I will say this: in the time that we were
12
doing
a
pre-application
13
certification they did have CFD codes within the suite
14
of codes for their safety analysis.
15
indicator there - and I think they want to use it for
16
things
17
operation and perhaps even the transport during an
18
accident.
like
distributions
with
of
PBMR
dust
for
design
So there is an
during
normal
19
So we are getting glimpses, but we really
20
can't know for sure until we get that suite to look
21
at.
22
not planning to use it within our evaluation model.
23
We are going to use CFD as kind of a tool to better
24
understand local phenomena and how it needs to be
25
accounted for.
I think the answer has got to be yes.
But we are
But once we understand that, we'll go
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1
through things like scaling of temperatures and hot
2
channel factors and that kind of approach.
3
CHAIR CORRADINI: Thank you.
4
Other
questions?
We
are
on
break,
so
5
unless there are more questions from members, let's
6
take a 15-minute break.
7
o'clock.
8
(Whereupon,
9
the
We will be back at 10:00
above-entitled
matter
went
off
the
record at 9:45 a.m. and resumed at 9:59
10
a.m.)
11
CHAIR CORRADINI: Okay, let us get back
12
into session.
13
our list.
You're next on the list, according to
14
MR. RUBIN: Yes, I am.
15
CHAIR CORRADINI: We are ready.
16
REACTOR FUELS ANALYSIS
17
MR.
RUBIN:
Okay,
Are we read to go?
this
first
technical
18
presentation is going to be on the
19
and VHTR fuels performance.
20
over some of the key technical and safety licensing
21
issues, and what our infrastructure development needs
22
are.
23
utilize the advanced gas reactor fuel R&D that DOE is
24
conducting to support the licensing.
25
that extensively.
R&D plan for HTGR
We are going to try to go
And also I'd like to mention that we plan to
We plan to use
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1
Now with regard to the objectives in the
2
fuels analysis arena, basically we want to develop and
3
validate
4
develop data, and really insights into performance of
5
the fuel that can bear on licensing decisions and the
6
like.
independent
7
We
fuels
also
analysis
want
to
methods,
integrate
and
fuels
8
performance in terms of particle failures and fission
9
product
release
from
the
fuel
into
the
accident
10
analysis evaluation model, because that at the end of
11
the day is the purpose of this whole exercise is to
12
account for that, and then see where it goes in the
13
dose implications.
14
We
also
want
to
develop
an
ability
to
15
inspect fuel fabrication facilities, because in these
16
fuel designs the fuel plays such a central role in the
17
safety case, and because fuel manufacture plays such
18
an important role in the performance of the fuel that
19
we need to make sure that it is consistently being
20
made
21
sufficient staff knowledge and know how to effectively
22
review an application in the area of HGTR fuels.
right.
23
And
we
MR. KRESS:
basically
also
want
to
have
If I were to draw an analysis
24
between
25
development, you are looking at the process to ensure
the
fuel
manufacture
and
software
and
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1
liability as opposed to the product?
2
MR. RUBIN: Well, I'll get to that.
We are
3
looking at both, because the state of the art in fuel
4
fabrication
5
percent product acceptance, but 10 percent are process
6
controls.
7
the process controls end up being a product to make a
8
product specification.
9
that as well.
to
assure
performance
is
I'd
say
90
Because you don't understand exactly how
10
Okay,
as
So very important to manage
far
as
the
key
safety
and
11
licensing
12
relates to the evaluation model, first of all, we want
13
to be able to predict fuel particle failure rates
14
during normal operation and during core heat up.
15
we
16
understand the release in theory of other kinds of
17
events
18
reactivity associated events.
want
issues
to
like
do
are
this
water
concerned,
not
only
ingress
especially
for
and
those,
as
but
potentially
it
And
also
large
19
But then not only do you need to worry
20
about particle failures, but you actually at the end
21
of the day you need to know what is deficient in
22
product releases from failed particles, and for that
23
matter, particles that have not failed.
24
be able to assure that those kinds of predictions, and
25
the data on which it is based, are acceptable and
So we need to
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1
conservative where they need to be.
2
We also wanted to understand enough about
3
the fuel performance that we have a handle on changes
4
in
5
changes in important parameters, such as temperature,
6
burn up, power density, fluids, so we understand that
7
if we are going to see if we go past this value of
8
temperature
9
dramatically in terms of fission product transport of
10
what
I'll
call
particle
things
failure
really
start
fractions,
to
or
increase
particle failures.
11
We talked about dust, and I'd put it this
12
way: we want to determine the magnitude of metallic
13
nuclides in mobile graphite dust, so the job of the
14
fuel
15
radionuclides are in there anyway.
16
to the fuels and R&D program to try and pin down, and
17
we'll be talking to DOE and others about how to really
18
get at that answer.
19
performance
And
we
R&D
guy
also
is
want
how
to
much
metallic
And so that comes
ensure
that
the
20
methods that are used to qualify the fuels, and for
21
that matter that they are modeling are appropriate;
22
they do do things a little differently than the actual
23
way the fuel will see its environment in the reactor,
24
and we want to make sure that the way they test is
25
still conservative.
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And lastly the issue of making sure that
2
the fuel is made to the quality standards, and the
3
product and process specifications so it performs as
4
it did in the fuel qualification program.
5
Now I've included this quote to try to
6
kind of make clear that the fuel particle is where
7
it's at in terms of the safety case.
8
from a DOE document in connection with the MHGTR, and
9
basically it says that these are miniature containment
10
vessels, and they need to stay intact, and they need
11
to retain fission products.
This is a quote
12
CHAIR CORRADINI: I'm sure Sam is going to
13
ask a technical question, so I'm going to ask a non-
14
technical one.
15
a fuel rod in al light water reactor?
16
17
MR. RUBIN: Well, when you combine this
with the proposal to have a vented confinement -
18
19
So couldn't I say the same thing about
MEMBER SHACK: This is true even during
accidents, which isn't true in the -
20
MR. RUBIN: Right.
Okay, what am I hanging
21
my hat on now?
22
perform
23
accidents because I don't have that additional barrier
24
to additional barrier that we see in a light water
25
reactor.
during
Back to the fuel.
normal
So the fuel has to
operations
and
all
these
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MEMBER
ARMIJO:
But
if
you
had
a
2
containment on these things they wouldn't have to meet
3
that point.
4
MR. RUBIN: Absolutely.
5
MEMBER ARMIJO:
6
-
7
8
They'd have a much easier
MR. RUBIN: Yes, they'd have a much more
relaxed kind of requirements.
9
CHAIR CORRADINI: I am still, with all due
10
respect, I'll let the members get on me now, I am
11
still
12
different sort of failure and release mobile fission
13
products in a light water reactor and I still have the
14
oxide particles such that I'd have to get in a severe
15
accident
16
differently.
17
space, where I have - I assume what Joe was talking
18
about in terms of accidents, in terms of a pressurized
19
loss
20
depressurized loss of flow with air ingress, I'm still
21
within DBA space.
22
fuel rod standpoint, whether I'm here or there, it's
23
still the first barrier to fission product release,
24
not the only barrier.
25
containments at least in the current French designs
missing
of
something,
before
I'd
start
because
I
talking
can
have
about
it
a
any
So if I'm within a design basis accident
flow,
a
depressurized
loss
of
flow,
So I still would say that from a
Because I have filtered vented
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for light water reactors above a certain -
2
MR.
RUBIN:
Yes.
I
will
get
into
the
3
credits that are taken for other hold up mechanisms
4
and other barriers in an HGTR release analysis, so
5
it's not only the fuel.
6
Those are definitely modeled.
There are other barriers.
7
But if you don't get the particle failure
8
rates down to pre-load numbers, those are not going to
9
work for you unless you put a big filter in the event
10
path, or you make it a traditional containment.
11
CHAIR CORRADINI: All right, that helps.
12
MR. RUBIN: Bu9t it's really a statement
13
that goes with the vented containment concept, and the
14
barriers, and the hold up mechanisms, and how much
15
they
16
releases.
17
of magnitude.
really
18
provide
for
those
attenuations
of
This is the biggest attenuation by orders
CHAIR
CORRADINI:
Because
of
that
19
importance you make a point in your research plan, the
20
Japanese
21
coated
22
temperature, burn up, and are actually pursuing a zirc
23
carbide coating, another coating.
24
the national labs have said, oh, silicon carbine ought
25
to be okay, my question is, has the NRC staff reached
aren't
particle
confident
will
that
meet
the
the
silicon
carbine
requirements
of
And whereas DOE and
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1
that same conclusion that these particles, this type
2
of fuel -
3
MR. RUBIN: I think they -
4
(Simultaneous speakers.)
5
MR. RUBIN:
- several months ago, and he
6
put on what he called a radar plot where he had burn
7
up going this way, temperature going this way, power
8
density going that way, fluence going that way, and
9
the like, and his point was that the NGNP is going to
10
push the envelope in all these dimensions, okay.
11
It is an advanced gas reactor program that
12
in
DOE's
13
particles that will meet those kinds of environments
14
with the failure rates that they need to have.
15
view
that
they
MEMBER ARMIJO:
can
make
silicon
carbide
But generally when you
16
push those boundaries, you do something to improve the
17
-
18
19
MR. RUBIN: I would call it an advanced
particle design.
20
MEMBER ARMIJO:
21
silicon
carbide
22
previous ones?
particle
This is going to be a
that
is
better
than
the
23
MR. RUBIN: Well, we will talk about that.
24
MEMBER BLEY:
25
MR. RUBIN: I have a graph that shows that,
They claim they are.
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1
at least in terms of preliminary tests that Dave Petty
2
has reported on.
3
4
But it's coming.
MEMBER ARMIJO:
It's coming.
The question is, is the
NRC staff comfortable that that is going to work out?
5
MR. RUBIN: I mean pick your poison.
6
could
7
carbide, for which there is a wealth of data, tests,
8
to draw on and compare to, or you could say, I'm going
9
for this advanced form for which there is very little.
10
And if I'm proven wrong, I have perhaps wasted my
11
pick
the
path
of
using
the
design,
You
silicon
time.
12
So I think that they have, through their
13
analyses, through a PARFUME code and other kinds of
14
evaluations, they feel with a oxycarbide kernel, where
15
you suppress all CO release, your pressurization of
16
the particle is going to be kept sufficiently low
17
within
18
envelope
the
power
19
density envelope that they have for the NGNP.
Okay?
20
The UCO is going to let them get there. UO2 I think
21
they
22
particle integrity goals that they have.
are
23
24
the
burnup
and
the
not
envelope
fluence
comfortable
CHAIR
and
the
envelope
that
CORRADINI:
temperature
and
they
can
Without
get
these
derating
the
volumetric power or the exit temperature?
25
MR.
RUBIN:
Well,
let
me
keep
going,
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1
because these are questions I have that I think you
2
will see better clarity when we get there.
3
4
Okay, just - I have a little show and tell
here, I'll get started with it.
5
6
MEMBER SHACK: Stu, so they would use UCO
even for a pebble bed design then?
7
MR. RUBIN: Well, right now the path is
8
UCO, and the reason they are going UCO is first and
9
foremost for the burn ups they want to see they don't
10
want
11
pressurization due to CO formation.
to
see
12
early
particle
failures
due
to
over-
The other thing is they are at a higher
13
power
14
density
15
temperature
16
It's
17
start to move the kernel toward the silicon carbide,
18
and you can actually degrade it that way.
density,
in
called
and
the
and
the
when
you
get
particles,
you
other
kinds
amoeba
of
to
higher
power
introduce
high
failure
effect,
where
mechanisms.
you
actually
19
CHAIR CORRADINI: Non-isotropically?
20
MR. RUBIN: No, it just - it moves across a
21
temperature profile.
22
23
CHAIR
So
independent
of
direction, it's not a gradient.
24
25
CORRADINI:
MR. RUBIN: UO2 fuel that those phenomena
are going to be problematic.
So UCO makes those kind
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1
of go away.
2
catch up with them with these higher burn ups and
3
temperatures that they have to design to.
4
And they have other issues then that may
But anyway, here is a greatly magnified
5
picture of a particle.
6
poppy seed and I'm circulating some examples of the
7
kernel, and believe it or not, there is another one
8
that has the kernel coated with the coating.
9
are two different sizes you will see int here.
10
It's actually the size of a
So there
It's called a TRISO particle because there
11
are
12
particle
13
spherical, and it'll be either UCO or UO2 right now.
14
DOE is pursuing a UCO because of the need to suppress
15
carbon monoxide generation.
three
high
density
contains
a
isotropic
center
layers.
kernel,
high
Each
density
16
The layer is coated with a low density
17
buffer to provide volume for fission gas releases from
18
the kernel, and subsequently the coatings of inner
19
pyrolytic
20
Could have been a silicon carbide layer.
21
outer pyrolytic carbide.
carbon
22
layer,
a
silicon
carbide
layer.
And then an
And so I would point out even at this
23
point
24
particles does take credit for the fission product
25
hold up and attenuation of each of those components
that
the
fission
product
transport
from
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1
separately.
2
test, and for modeling fission product releases from
3
core-wide releases.
4
high density layers, and the kernel for that matter,
5
and how those are going to be approached in terms of
6
developing
7
really come down to the fusion coefficients.
8
9
That's how they are modeled in the model
So you need to keep in mind those
fission
product
MEMBER ARMIJO:
transport,
models
which
What is the density of
the UCO percent of theoretical?
10
MR. RUBIN: It's pretty close.
11
MEMBER ARMIJO:
12
MR. RUBIN: We could ask DOE what that is.
13
It's up in that range.
14
Okay,
just
Like 97, 98?
Yes.
provide
a
little
more
15
background on what we are dealing with.
16
will
17
pebble bed, 10 billion for a prismatic reactor.
18
particles
19
integrity rate for all conditions, normal accidents,
20
even
21
principal barrier and hold up mechanism for release,
22
because the other barriers that we talked about within
23
the reactor and within the confinement system, don't
24
count for that much.
25
is the biggie.
contain
billions,
really
design-base
need
perhaps
to
accidents,
five
maintain
because
An HGTR core
billion
a
for
very
they
are
These
high
the
They do count for some, but this
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1
2
MR. KRESS:
that?
Like how many particles -
3
4
MR. RUBIN: I have one, to back calculate
what those numbers have to be.
5
6
Do you have a number for
MR.
KRESS:
Yes,
you
have
to
back
calculate.
7
MR. RUBIN: Back calculate, right.
So just
8
to point out, a fuel manufacture has really the prime
9
effect
on
coated
particle
properties,
and
those
10
properties really drive the behavior, and then hence
11
the
12
probably
13
affecting the fusion coefficients and the like.
performance
also
of
failure
is
effective
probabilities.
release
in
And
it
terms
of
14
The operating conditions, we talked about
15
temperature and burn up, and also about power density
16
and fluids.
17
is that radar plot.
18
those dimensions, you are challenging the particle to
19
fail.
And those also have an effect, and that
You start going too far into
20
The accident conditions, principally there
21
what is going to change is temperature, and the peak
22
temperature that the particle sees when the accident
23
reaches
24
location, is going to determine whether or not that
25
particle fails.
its
maximum
point,
and
in
that
particular
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1
And so because of all this there is an
2
approach
and
a
3
specific
4
qualification programs that test it both in radiation
5
which is normal operation simulation, and the accident
6
condition which is the heat up, and to collect data to
7
actually see what the particle performance is during
8
these environments.
and
9
requirement
that
manufacturing
they
have
specific
design
radiation
And these tests are done at the design
10
conditions,
so
you
are
actually
seeing
how
the
11
particles - it's going to be the highest particle for
12
the longest amount of time, with the highest burn up,
13
how that one worked.
14
probability.
15
we'll talk about it later, for developing models, for
16
a core-wide particle failure rate.
Okay, in terms of its failure
So that becomes very valuable data, and
17
And again, we talked about because they
18
are projecting I believe they are going to have low
19
particle
20
proposed event in reactor confinement.
21
of fuel forms.
22
is actually the size of a fuel sphere.
23
fuel in there anymore.
failure
rates,
so
they'll
be
proving
the
Now, two kinds
Here is another show and tell.
That
There is no
So - it's all been burnt up.
24
(Laughter.)
25
The intention is design burn up.
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1
(Laughter.)
2
Well,
basically,
this
graphic
shows
a
3
pebble.
4
billiard ball.
5
each billiard ball, or pebble as they call it, and
6
there is about 400,000 of these things in a typical
7
pebble bed reactor.
8
400,000 times 15,000 is billiards, okay, about five to
9
six billion in a core.
10
It's basically as you see the size of a
There are about 15,000 particles in
So if you go through the math,
I would say that the matrix is viewed as
11
durable.
It
12
reactor.
It also provides a hold up mechanism, a
13
diffusion, a coefficient of its own to release of
14
especially metallic radionuclides.
15
credit for in the analysis.
16
But
can
in
be
the
dropped
many
release
times
into
the
And that is taken
of
gaseous
fission
17
products, such as krypton, it doesn't provide much
18
hold up if any at all.
19
So the designers will seek to take credit
20
for
21
modeling a fission product release from particles.
each
22
one
of
the
layers,
and
the
kernel,
in
Okay just so you know, you have probably
23
seen this, here is a prismatic block reactor.
24
actually an hexagonal fuel element.
25
develop that is they take particles and they first put
This is
And how they
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1
them in a fuel compact, each about a half-inch wide
2
and diameter, and two inches long.
3
the finished compacts and they insert them into bored
4
holes in a hexagonal matrix in the box, and then they
5
plug them on either end, and then interspersed between
6
those fuel holes are the flow holes for cooling during
7
normal operation.
8
9
And then they take
Okay, we talked about the particle failure
rates.
What I've thrown up here is what has been -
10
well, let me start by saying this.
11
operators of HGTRs have asked the NGNPR designers to
12
provide a plan in which the dose at the fission area
13
boundary does not exceed one REM, with the intent to
14
get
15
emergency planning outside that.
a
license
16
So
which
the
does
owner
not
Potential owner-
require
specified
significant
request
has
17
resulted in a back calculation of what the particle
18
performance
19
representative of what those back calculations turn
20
out to be.
21
to know fission product transport outside the fuel.
22
And I will go into how they model that.
23
credit for those kinds of hold up mechanisms.
24
end up with a manufacturing defect rate of what is
25
seen there, a normal operation failure rate of 6 X
needs
to
be.
So
this
is
kind
of
And to do the back calculation, you have
But they take
So you
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1
10^-5, and then an accident failure rate of 10^-4, so
2
these
3
requirements for the fuel -
numbers
4
5
are
the
goals
that
the
design
MEMBER BLEY: And what are they defining as
a failure for this failure?
6
MR. RUBIN: Okay, I'm with you on that.
7
But
8
failure rates take credit for also all those other
9
hold up mechanisms that are modeled in the fission
10
I
just
want
to
point
out
that
these
particle
product release calculation.
11
Okay.
12
document.
13
big surprise.
Here is another quote from the same
We need to be able to predict performance;
14
Okay, what I'd like to talk about is our
15
approach for modeling fuel performance, and we really
16
are looking at two kinds of models.
17
it would be a stand-alone model which is a detailed
18
mechanistic finite element computer code that models
19
all
20
behavior and failure, and it's capable of predicting
21
failure for individual particles.
the
important
phenomena
that
The first model,
affects
particle
22
And they also plan to use that model from
23
studying the sensitivity studies to better understand
24
the
25
sensitivity
behavioral
to
particles,
temperature
and
the
changes,
influence,
to
burn
the
up
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1
changes, and the like, as a tool to understand where
2
issues
3
ourselves to better understand fuel behavior.
may
lie,
and
also
as
a
way
of
training
4
The second model is an empirical failure
5
probability model that we want to develop, and we
6
would
7
testing, where they irradiate the fuel and they heat
8
it up and they measure how many particles fail, and
9
they
derive
are
that
able
to
directly
get
a
from
fuel
failure
qualification
probability
based
10
directly on empirical data and not based on trying to
11
mechanistically predict particle failure.
12
MEMBER ARMIJO:
When they do these fuel
13
irradiations, do they do them with prototypic fuel -
14
in
15
something where you have to say, well, it wasn't quite
16
the right shape and size, and it wasn't quite the
17
right fluence, and it wasn't really an HGTR that we
18
irradiated in; it was a lightwater reactor.
19
all these variables, and then you have to do a bunch
20
of adjustments.
prototypic
radiation
conditions.
Or
is
it
You get
21
MR. RUBIN: Absolutely, I agree with you.
22
Two sides to that question: when you do your testing,
23
is the testing being done on particles which were made
24
using the process and everything, just everything in
25
terms of the inspections, the accepted criteria, the
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1
product - that's exactly the same as what you are
2
going to use for the mass production, it's exactly the
3
same thing.
4
take.
5
to change it anymore.
6
process design; we are not going to change the process
7
variable controls or anything.
8
make fuel, and we are going to make 20 batches, and
9
then we are going to mix them up into larger lots, and
That's the approach they are going to
They have to fix all that; they are not going
are
going
to
We're not going to change our
create
a
And we are going to
10
we
particle
distribution,
11
because no particle is exactly the same as another
12
one, which is representative of production variation.
13
So they will try to make the case that
14
they are tests, which will be hundreds of thousands of
15
individual particles in these tests, is representative
16
and bounding of the production fuel that is actually
17
going to go -
18
MEMBER ARMIJO:
19
MR. RUBIN: Future production, but they are
20
going to fix it.
21
22
Future production.
CHAIR CORRADINI: So the recipe will be
fixed?
23
MR. RUBIN: The recipe will be fixed.
Then
24
you
25
representative of the conditions that the fuel will
have
the
question
of,
well,
are
test
reactor
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1
see?
Well, certainly they can control the burnup.
2
They can control the temperatures very clearly.
3
can control fairly good at the ATR the fast flux, that
4
will be accumulated in the particles, and they can
5
control the power densities in the particles.
They
6
So I think with the ATR they will be very
7
- specially in that center hull, will be able to very
8
closely match up with what is projected to be the
9
limiting locations in the VHTR core.
So they will be
10
simulating
the
those
11
locations.
Their test is going to be like 12, 1250.
12
Well, that temperature is calculated to be the highest
13
that
14
uncertainties stacked up.
15
are taking.
any
16
17
particle
will
fuel
in
receive
MEMBER ARMIJO:
with
of
So they are testing to
MR. RUBIN: Well, statistics will come out
of this, and we will get into that.
MEMBER ARMIJO:
21
this fuel to make sure that they are -
22
Yes, but they are pushing
MR. RUBIN: Yes, they are pushing it to the
envelope.
24
25
kinds
So that's the approach they
20
23
all
limiting
make up for let's say statistics or something.
18
19
limiting
MEMBER SHACK: Yes, but your footnote says
that
accelerated
testing
could
be
conservative
or
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1
nonconservative.
2
CHAIR
CORRADINI:
3
what I wanted to ask you.
4
here last time -
5
6
Well,
that
is
exactly
Because when Dave came up
MR. RUBIN: Oh, we already jumped ahead.
Okay.
7
CHAIR CORRADINI: If you want us to wait,
8
but Bill and I were thinking - when Petty came up last
9
time. Dr. Petty came up last time, he inferred that
10
after AGR-1 there would be an accelerated schedule of
11
essentially testing, and to do that - compressing the
12
time - and to do that, the way in which you do that
13
would be modified.
14
you guys reviewed that, and are you okay with it?
15
And my simple question is, have
MR. RUBIN: We've reviewed it to the level
16
of the qualitative units.
17
When you accelerate the testing you have a higher
18
power in the particles.
19
particles will increase.
20
on temperature will be enhanced, and so you could
21
force those mechanisms to occur sooner.
The arguments are these.
And the temperatures in the
The mechanisms that depend
22
However, on the flip side, you reduce the
23
amount of the time. So you push it in faster, but you
24
stop the test sooner.
25
that
conservative?
Now you have to look at, was
And
you
can
accelerate
tests
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1
sufficiently for let's say UO2 fuel where because of
2
the amoeba effect, you will drive that amoeba effect
3
to occur before, but because you stopped it so early,
4
you may have in effect had a non-conservative type of
5
test.
6
The way they approached that was, they
7
used an individual seam particle code, PARFUME, to try
8
to understand the effects, the sensitivity of faster
9
tests, shorter time, on all the failure mechanisms.
10
And they concluded that if they run faster, but within
11
limits,
12
accelerated tests.
they
13
would
still
have
a
conservative
If they went any faster than that, then
14
they
15
furthermore, they might actually fail more particles
16
than would occur otherwise.
17
18
might
not
have
a
CHAIR CORRADINI:
test,
and
Are you comfortable that
PARFUME models all of the failure mechanisms?
19
MR. RUBIN:
20
CHAIR CORRADINI:
21
conservative
We'll get into that.
But I guess I'm asking
-- I guess --
22
MR. RUBIN:
23
CHAIR CORRADINI:
Yes and no, yes and no.
You politely took me
24
through the thinking but I'm getting -- I'm asking a
25
judgment or at least a process question which is what
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1
you said kind of reminds me of what Dave said in his
2
presentation.
3
reviewed that?
Because you're not going to go back
4
and
tests.
5
process and the protocols so that we don't come two
6
years later and you then all say hold out, time out.
redo
7
But I'm kind of curious.
these
MR. RUBIN:
So
are
Has the staff
you
okay
with
the
The agreement is in place.
8
It's called the MOU for NRC participation in the NGNP
9
project.
And that calls for NRC staff to come and
10
look from a regulatory mindset and a safety reviewer's
11
mindset what their testing program looks like.
12
whether or not there are issues with it.
13
CHAIR CORRADINI:
14
MR.
RUBIN:
And
And
Okay.
so
we
haven't
started
15
that.
16
But it hasn't really started yet.
17
because the clock is ticking, and the design needs to
18
move forward, they've already moved away.
They want us to do that.
19
We want to do that.
And so -- but
Now I will say that, that what they are
20
doing now is not on the prototypical fuel.
21
tests, fuel qualification tests, come several years
22
from now.
23
their benefit so that they can get the data they need
24
to
25
design.
make
Okay.
some
Those
So the acceleration was really for
decisions
to
finalize
the
particle
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1
But once you get to the fuel qualification
2
tests -- which they are not there yet -- those are the
3
ones we have to answer that question clearly.
4
5
CHAIR CORRADINI:
following the compressed time --
6
MR. RUBIN:
7
CHAIR CORRADINI:
8
So AGR-1, which is not
No.
-- and AGR-2, which is
what you just discussed --
9
MR. RUBIN:
10
Right.
CHAIR CORRADINI:
-- are not fuel -- from
11
where you consider to be fuel qualification tests.
12
They are essentially background data tests that get
13
them information.
14
15
MR. RUBIN:
Speeding up the development
process not the qualification.
16
CHAIR CORRADINI:
Fine.
17
MR.
you
KRESS:
If
have
to
a
have
a
18
quality of six times ten to the minus five failures,
19
it looks to me like you have to use maybe 50 of those
20
balls,
21
kernel -- I mean one of your little spheres to fail if
22
it is at that quality level.
23
that?
those
24
25
billiard
MR. RUBIN:
failures.
balls
in
a
test
to
get
one
Can you really detect
Well, yes.
They can detect
Not question about it.
They can detect
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1
failures.
2
3
The question is what kind of -- how many
particles do you have to test --
4
MR. KRESS:
That's what I --
5
MR. RUBIN:
-- at what level of confidence
6
to be able to make the statement --
7
MR. KRESS:
8
MR. RUBIN:
9
-- that's exactly --- yes, I just made fuel and
proved that I met that.
10
MR. KRESS:
Yes, that's the question.
11
MR. RUBIN:
Okay.
12
MR.
13
KRESS:
That's the question.
But
you're
asking
that
question thought.
14
MR. RUBIN:
15
it's called a one-sided beta test.
16
MR. KRESS:
17
MR. RUBIN:
Well, what you have is I think
Yes.
And it's the old story of
18
you've got a swimming pool full of white balls and
19
there's a few black balls.
20
10,000 times and they're all white balls, you might
21
conclude well, they're all white.
22
in there that are black.
23
enough.
24
MR. KRESS:
25
MR. RUBIN:
And if you reach in there
Now there's a few
Your sample wasn't large
Yes.
Well, you can do a sample --
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1
and
I'll
2
probably going to use for that -- and so based on that
3
sample size, they can do this one-sided beta analysis
4
and make a statement as to at the 50 percentile, the
5
75 percentile, or the 95 percentile confidence that my
6
failure rate was not above this.
7
8
say
300,000
MR. KRESS:
is
the
number
that
This is 300,000 of the little
coated particles?
9
MR. RUBIN:
Right, right, right.
10
MR. KRESS:
Okay.
11
MR. RUBIN:
Now it's interesting.
12
they're
If you
did a million --
13
MR. KRESS:
Yes.
14
MR. RUBIN:
-- or you did five million --
15
MR. KRESS:
Your confidence level goes up.
16
MR. RUBIN:
-- you could make a statement
17
that is even tighter than what they have here.
18
becomes an economic issue.
19
million and a half particles to drive down that number
20
that they can make a statement of 95 percent .
21
22
MR. KRESS:
But it
Do they want to test a
I don't think you have room in
one radiation test to do that.
23
MR. RUBIN:
No, it's an economic question.
24
MR. KRESS:
Yes, you have to do it over
25
and over.
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1
MR. RUBIN:
the
one-sided
But that's the bottom line is
2
that
beta
3
statement at 95 percent confidence that we do not have
4
more than five times ten to the minus six particle
5
failures even though we saw none.
6
MR. KRESS:
7
MEMBER BLEY:
test,
it
gives
them
Right.
Stu, just for me, can I take
8
you back to the question I asked you earlier?
9
they decide there has been a fuel failure?
How do
You said
10
they can detect them.
11
always have some leakage, right, some diffusion.
What is a fuel failure?
12
MR. RUBIN:
13
MEMBER BLEY:
14
the
You
Yes.
So is it a fusion rate?
Is
it a visual inspection like the picture you showed us?
15
MR. RUBIN:
Well, the thing that they are
16
really measuring is fission gas.
17
online measurements of fission gas.
18
one that they watch closely is krypton, okay, krypton
19
gas.
20
release to birth ratio.
21
number but how many get released is being measured.
They have continuous
And the one real
And there's something called and R over B ratio,
The birth is at a certain
22
Well, there is a signature for how much
23
krypton would be released when one particle fails and
24
so when it blips up to that, they say we have a
25
particle failure.
And you know that blip by having
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1
done prior tests with particles that fail -- that are
2
made to fail.
3
And it has that signature.
So they're waiting for that signature to
4
occur.
5
would say particle failure.
6
They say haven't seen that signature yet that
MR. KRESS:
7
has a short half life?
8
over B ratio.
9
CHAIR
They use krypton because it
And that enters into this R
CORRADINI:
And
it
wouldn't
be
10
released -- it would not be released at all in a
11
normal intact particle.
12
13
MR.
KRESS:
That's
pretty
much
right.
It's a low R over B.
14
MR. RUBIN:
Yes, okay.
This next slide is
15
all the failure mechanisms that have been documented,
16
for that matter, in the TRISO particle fuels PIRT.
17
The first five, I would say, are mechanisms that are
18
generally associated with normal operation.
19
first and the last four are generally associated with
20
accident conditions.
And the
21
And this last mechanism, elevated fission
22
product diffusion through intact coating layers, that
23
is
24
graphite dust.
25
is a sufficient of metallic radionuclides, principally
the
mechanism
that
has
been
associated
with
That even with intact particles, there
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1
cesium, through intact silicon carbide layers to get
2
out
3
removed in the form of dust and then to go travel
4
through the system and eventually settle out and be
5
available to, again, be released.
to
6
the
surface
of
the
pebble
and
then
to
So that is the failure mechanisms.
be
And
7
I'll define a failure mechanism as an elevated release
8
of fission products due to a failure of a particle or
9
due to elevated diffusion rates.
10
MEMBER ARMIJO:
11
MR. RUBIN:
12
MEMBER
Is palladium release --
Which?
ARMIJO:
--
palladium
that
the
13
Japanese are talking about, is that the same mechanism
14
you are talking about here?
15
diffusion through an intact coating?
16
17
MR. RUBIN:
Elevated fission product
Well, I mean you have things
like Silver-110M --
18
MEMBER ARMIJO:
19
MR. RUBIN:
Okay.
-- Silver 110-M diffuses very
20
quickly
through
21
released
into
22
temperature components like in the balance-of-plant.
23
It becomes an occupational hazard for people who are
24
maintenance workers and the like, okay.
25
But
intact
the
I
particles.
system
said
to
And
plate
diffusion
out
because
it's
then
on
low-
it's
not
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clear that diffusion is the mechanism.
2
actually know why Silver 110-M is actually moving so
3
rapidly through the silicon carbide.
4
But I'm not familiar with the palladium
5
being another actor of that sort.
6
hazard.
7
8
MEMBER ARMIJO:
Okay.
Okay.
And being a
Well, it was just
mentioned in the report.
9
10
People don't
CHAIR
chance.
CORRADINI:
Harold
You go ahead, Harold.
11
MEMBER RAY:
hasn't
had
a
I'm sorry.
I think it's better -- what
12
my comment would be in our discussion at the end of
13
the day rather than introduce --
14
PARTICIPANT:
15
MEMBER ARMIJO:
16
Just as a -- how important
is as-fabricated particle quality --
17
18
Stu?
MR.
RUBIN:
Very
important,
very
important.
19
MEMBER ARMIJO:
And how do they actually
20
measure it, you know, as opposed -- you know, all
21
these mechanisms relate to intact particles that are -
22
-
23
24
MR.
RUBIN:
These
are
the
mechanisms.
These are the big ones that make a particle fail.
25
MEMBER ARMIJO:
But if the particles is --
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1
2
MR. RUBIN:
The next one is the things you
are measuring --
3
MEMBER
ARMIJO:
Yes,
I'm
kind
of
4
interested in the quality -- quality control stuff,
5
yes.
How do you measure --
6
7
MEMBER BLEY:
You don't have the krypton
then.
8
MEMBER ARMIJO:
9
MR.
10
RUBIN:
Right.
Go
ahead
How do you find ---
who
are
you
please?
11
MR. LEE:
Questions on the palladium --
12
Richard Lee from Office of Research -- the palladium
13
has to do with the fission products from the
14
because this is a high burn up -- up to like 100
15
gigawatts say per tons, the plutonium used is higher
16
for palladium.
And
It's intact to silicon carbide.
17
MEMBER ARMIJO:
18
MR. LEE:
19
MEMBER ARMIJO:
20
UO2 .
Right.
And --
So that's the one --- you point that out in
your research plan --
21
MR. LEE:
22
MEMBER ARMIJO:
-- correct.
-- that that is what the
23
Japanese are concerned about.
24
is ultimately will that become an NRC concern.
25
MR. RUBIN:
And then the question
Well, again it has to do on
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1
the particle design, on the temperatures it sees.
2
Japanese fuel design, the fuel runs at a much higher
3
temperature than the particles will be operating in
4
the PBMR or the VHTR.
5
design.
It's just a function of their
6
And so --
7
MEMBER ARMIJO:
8
I thought that both of
them had a 950 outlet.
9
10
The
MR.
RUBIN:
No,
I'm
talking
about
the
fuel, the fuel itself, the particle itself.
11
MEMBER ARMIJO:
12
MR. RUBIN:
Okay.
The particle itself sees --
13
its envelope, you know, is even bigger in temperature.
14
Very low burn up, very low burn up for the HGTR
15
because
they
can't
run
it
very
long
because
it's
16
operating at a high temperature.
17
with different service conditions.
18
that in their design they have other issues to design
19
against, palladium being one of them, and the like.
20
Okay.
So you're dealing
And because of
21
Here are the things that -- getting down
22
to the phenomena level, some of the more significant
23
phenomena in terms of the particle itself, which is
24
what you're talking about, you know, checking these
25
characteristics.
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I
mean
there
2
characteristics.
3
properties and chemical properties.
4
There's
are
material
dimensional
and
physical
And I lost track.
There may be 80 different parameters that are checked
5
in
manufacture
of
a
particle.
These
ones
are
6
particularly important for particle failure, for the
7
failure mechanisms I mentioned.
8
And so yes, they will statistically check
9
all of these properties in manufacture that they have
10
listed.
11
a process and it is a random coating process, there
12
will be a spread in the coating layer thicknesses of
13
silicon carbide from one particle to the next.
14
they
15
distributions will have to be within tolerances.
However, there are variations.
will
16
have
But
to
have
those
Because it is
distributions.
distributions
are
And
And
those
really
the
17
important piece of predicting particle failure because
18
it is the tails that stack up in some particle that is
19
the one that is going to fail.
20
Well now if you were to program in your
21
average
22
you'd ever had a failure.
23
analysis or Monte Carlo analysis with those variations
24
are very important for these mechanistic codes.
25
particle,
you
probably
MEMBER ARMIJO:
wouldn't
show
that
And that's why statistical
Stu, we're still seeing in
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1
light water reactor fuel pellets,
2
vanilla fuel, we're seeing even today, manufacturing
3
defects that previously were thought to be unimportant
4
are contributing to failed fuel.
5
MR. RUBIN:
6
MEMBER ARMIJO:
7
And
this
is
a
--
And
UO2
, plain, garden
Okay.
Yes.
this
we're
After all of these years.
fuel
going
hasn't
a
batch
9
process with certain quality control measurements to
10
predict what the same batch process will put -- will
11
produce two years later or three years later?
12
at some point --
14
MEMBER ARMIJO:
15
on
much
experience.
MR. RUBIN:
rely
as
8
13
to
had
It's --
Let me go --- I'd like -- maybe Mike
should --
16
MR. RUBIN:
17
MEMBER
-- let me just --
ARMIJO:
--
show
us
how
the
18
manufacturing -- as manufactured properties, actually
19
can predict or assure that the in-reactor performance
20
will be as expected.
21
MR. RUBIN:
22
MEMBER ARMIJO:
Right.
And that, to me, is a real
23
tough problem.
24
they going to actually pull this off.
25
going to measure --
I've been trying to figure out how are
What are they
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1
MR. RUBIN:
Hey, listen.
2
MEMBER ARMIJO:
3
MR. RUBIN:
-- to assure that --
What they are missing may get
4
through, it turns out to be the important contributor
5
to particle failure rates.
6
MEMBER ARMIJO:
7
MR. RUBIN:
Okay.
Right.
But to their credit, DOE did a
8
study looking back at all the fuel that they have
9
made, especially for the NPR, and looked at how they
10
actually failed.
11
that there were cases where they had separation of
12
layers from the silicon carbide.
They looked down at the PIE and saw
13
They saw that there were those initiated
14
just by failure due to anisotropy, high anisotropy
15
causing a local spot.
16
so
17
performance and mechanisms of failure.
they
were
18
able
to
They saw amoeba effects.
learn
a
lot
The PIRT added to that.
about
Okay.
And
particle
They are
19
using all that knowledge.
20
analytical tools to engineer a particle and engineer
21
the tolerances.
22
actually say what are the tolerances to react?
We
23
have the statistical pack.
It
24
would be great if we could go that far in terms of
25
accepting.
And they're using their
They're using PARFUME as a tool to
Can we go this far?
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1
But as I say, we can't go that far.
But
2
we still may have something that -- and it's called
3
weak
4
There's something you missed, okay.
5
sensitivity
6
impose weak fuel where we impose higher failure rates
7
on particles.
8
see what the effect is in terms of dose and the like.
fuel
9
--
I
think
studies
somebody
when
we're
coined
the
term.
And we can do
done
with
this
to
And we'll get to how we can do that and
MR.
KRESS:
I
presume,
in
regulatory
10
space, you'll have some sort of tech spec limit on the
11
activity and the primary --
12
MR. RUBIN:
That's for sure.
13
MR. KRESS:
And if you go beyond that, you
14
have to shutdown and do something.
15
MR. RUBIN:
Yes.
16
MR. KRESS:
That's the way you control the
17
quality, after the fact.
18
19
MEMBER ARMIJO:
Yes, but it's after the
fact.
20
MR. RUBIN:
21
you are monitoring failed particles.
22
MR. KRESS:
23
MR. RUBIN:
The difficulty with that is
Yes.
And if you have the other
24
failure mechanism where you have an intact particle
25
and
you
have
high
diffusion
through
an
intact
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100
1
particles, your activity is not going to pick that up
2
because it is metallic, it's ground up in dust, it's
3
going
4
monitors.
to
plate-out,
it's
going
to
bypass
those
5
And so you have an accumulation of fission
6
products in the system and never know it because you
7
are watching the wrong thing.
8
CHAIR
CORRADINI:
I
think
--
just
to
9
interject -- I think we need to move on but I think
10
Sam's point is that when we get back together, since
11
we will get back together, let's just talk about fuel
12
manufacturing recipe and the QA related to is, I think
13
is an issue that gets us all a bit --
14
MR. RUBIN:
Yes, a big issue, in fact
15
we've developed an inspection protocol, it's about 50
16
pages long, and it gets into every single aspect of
17
making good fuel.
18
So we can go in there and look.
MEMBER RAY:
Mike, wait.
On this issue of
19
tech spec, though, it doesn't seem to me if we're
20
talking about accident containment function that tech
21
specs are a legitimate way to say well, if we exceed
22
the tech spec, we'll just have to do something.
23
Unless
you
can
correlate
what
you
see
24
during normal operation with the accident condition in
25
some certain way, I'm not sure how you do that.
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1
MR.
RUBIN:
Well,
I
mean
you
have
to
2
understand what all of the sources of radionuclides
3
are in your system to keep on top of that.
4
fission gases are through the measurements that you
5
talked about.
6
in the AVR, they had some systems in place that were
7
able to keep book on the amount of dust that was being
8
generated
9
intricate system to tell them what was going on there.
and
The
But the other ones, the metallics, now
other
metallics.
It
was
a
very
10
But even there they really were not able
11
to understand the full amount of dust that was being
12
generated in the plant.
13
respects.
14
MEMBER RAY:
So it is a black box in many
In the light water reactor
15
containment, you pressurize the damn thing every so
16
often and you measure the leak rate.
17
pretty straightforward way to do that.
18
MR.
RUBIN:
Okay,
Don
I mean that's a
Carlson
would
19
probably
20
called pulling fuel out from time to time and putting
21
it into an actual condition test and doing the PIEs to
22
actually see how the fuel is doing and seeing if it is
23
within
24
Okay.
25
like
the
to
jump
envelope
of
MEMBER BLEY:
in.
the
And
there's
qualification
something
program.
Stu, you said something that
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102
1
I think is real interesting and important and that
2
after you do all these -- after they do all these
3
tests and there is sampling on the process looking for
4
fuel, you have to look at all the uncertainties.
5
it is the tails that matter because you have so many
6
of these things.
7
MR. RUBIN:
8
MEMBER BLEY:
And
That's right.
And the standard techniques
9
for looking at QA and for looking at distributions do
10
a good job with estimating the central tendency, the
11
middle of the distributions, but do a lousy job out in
12
the tails.
13
convince yourselves that you are covering yourselves
14
really well.
15
I hope you're doing something to really
MR.
RUBIN:
I've
lassoed
one
of
our
take
look
at
the
16
statistical
17
statistics that they were going to do not only for the
18
qualification testing but for the manufacturing side.
19
That's an important issue to make sure they're doing
20
people
to
kind
of
a
the right statistics.
21
And from what I've read, they've evolved
22
over
23
quote/unquote, we feel we're doing the right kind of
24
sampling and statistical analysis to prove our case.
25
But we haven't looked at that.
the
years
in
what
they're
doing
to
today,
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1
MEMBER BLEY:
Okay.
Sometimes for this
2
kind of thing you need some kind of extreme value or
3
something almost like PRA --
4
MR. RUBIN:
5
MEMBER
6
BLEY:
--
to
find
out
the
key
We
need
to
move
him
things that are driving it.
7
MR. RUBIN:
8
CHAIR
9
Yes, I agree.
Okay.
CORRADINI:
along.
10
MR. RUBIN:
Move me along.
Okay.
So the
11
first thing is I mentioned this PARFUME code, DOE has
12
been developing it for many years.
13
one
14
mechanisms it models and the data that it has in it.
15
And they are going to improve it with additional data.
of
16
the
best
that
is
around
I would view it as
in
terms
of
the
And our plan is to ask the DOE -- we
17
already have -- to obtain that code.
18
use it again as a learning tool to do sensitivity
19
studies to better understand the tails, to understand
20
if the fuel is not made right, what would be the
21
implications on fuel performance and the like.
22
would use it in that way.
And we want to
And we
23
And finally, we would use it to help us
24
understand how variations in temperature, burn up, and
25
the like would effect core-wide changes in particle
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104
1
failure rates.
2
Now let me talk about that because that is
3
a different model that we want to develop.
4
just kind of impractical, in my mind, to just kind of
5
link directly to MELCOR.
6
run times are long.
7
it.
8
PARFUME is
It's a finite element.
The
It has a statistical package in
And at the end of the day, you don't know
9
if it is valid anyway.
Okay.
So we need to come up
10
with another approach.
And the approach we're taking
11
is not any different really than the designers have
12
used over the years.
13
failure fraction based on actual test data.
And that is to establish a
14
And that test data would come from the
15
actual fuel qualification tests of the final product.
16
This is the way we're going to make it.
17
This is the irradiation particle failure rates.
18
is the accident condition particle failure rates.
19
And
to
use
that
data
to
This is it.
back
This
out
a
20
particle failure fraction as a function of temperature
21
and
22
defensible that way.
burn
up
based
upon
data
directly.
It's
more
23
But to use PARFUME because it let's you
24
get below the surface to understand why things can
25
change in that space, temperature burn up space, to
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105
1
help us shape, if you will, that map, that response
2
surface that we plan to put together.
3
different
4
generating particle failure rates.
than
applicants
worldwide
And that's no
have
used
for
5
And one can think of doing that two ways:
6
as a conservative way and also a best estimate way.
7
You can use the statistics.
8
come up with two different kinds of response surfaces.
9
And depending on whether the Commissions says okay,
10
it is okay to use the best estimate response surface
11
for the BDBAs but we want to use the conservative one
12
for the DBAs, you know, we can do that.
13
You can use PARFUME to
Or they may say no, I just want you to use
14
the conservative one for both.
15
estimate mechanisms to work with but not the fuel.
And fine.
Other best
16
And so we want to obtain it for that.
17
Excuse me -- we want to develop this response surface
18
so we can predict core-wide R, Z, and time for normal
19
operation and transients.
20
use it to see what the applicants have come up with.
And we also feel we could
21
But in the near term, because we don't
22
have that data, either the experimental data or data
23
in PARFUME that drives the models, we would use data
24
from the German fuel just to kind of get the code
25
going.
Okay.
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1
Okay.
2
MEMBER ABDEL-KHALIK:
3
burn
up
4
characterize --
5
the
Now so the idea would be --
only
independent
MR. RUBIN:
Are temperature and
variables
that
would
No, no, I think I told you
6
that there is fluence, there is power density, there
7
are other variables.
8
ones, then you -- let's say you are conservative on
9
those, you then can -- and that's how they are going
10
to run their tests, okay, they're going to run their
11
tests with a conservative fluence and a power density
12
and the like.
But if you bound those other
So you've already bounded that.
13
And now you just work off the variables of
14
temperature and burn up to drive a response surface.
15
Okay.
16
to say those other variables -- you've got a gazillion
17
variables
18
experiment in a conservative way.
That's the approach that is taken by applicants
but
we're
going
to
cover
those
in
the
19
And we're going to just limit ourselves to
20
a couple of variables that we're going to input into
21
our analysis tool.
22
23
MEMBER ABDEL-KHALIK:
Does that make sense
though?
24
25
So the idea would be to --
MR. KRESS:
Actually, this is the way the
fission product release models for LWRs in MELCOR were
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107
1
developed.
Almost exactly that way.
2
MR. RUBIN:
Right.
3
MR. KRESS:
And so it's almost a parallel
4
process.
5
CHAIR CORRADINI:
So it is an empirical
6
input for the moment until the data gives you a better
7
number for the empirical model you input.
8
MR. RUBIN:
Well, you use the empirical
9
model that is based on the representative tests that
10
are the qualification tests, that are bounding tests.
11
And that's the basis for your response surface.
And
12
there are particles in the core that will be less than
13
that bounding test.
14
In any event, the idea would be to be able
15
to
16
operation based on the maximum fuel temperature and
17
the
18
during the heat up would be also fuel temperature but
19
that is changing in time, R, Z, and time, and burn up.
come
burn
up
with
up.
a
And
failure
for
fraction
particle
for
failure
normal
fractures
20
And so what you end up with -- and this is
21
just for illustration -- is that kind of response
22
surface, okay, which shows that as you increase in
23
temperature moving from right to left, for particular
24
burn up you're going to start to increase additional
25
particle
failure
rates
which
then
now
have
to
be
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108
1
accounted
2
source term.
3
for
in
And
your
this
source
will
be
term,
time-dependent
applied
R
and
Z,
so
4
you're seeing sectors, in R and Z, changing in time,
5
moving across this response surface, having additional
6
particle
7
product release for now failed particles.
8
to keep inventory and book on how many more particles
9
have failed in what location and do the source term
10
fails
and
then
going
through
the
fission
So you have
analysis on that basis.
11
So the model is a response surface.
12
CHAIR CORRADINI:
Okay.
So let's just use
13
this to illustrate.
14
essentially six times ten to the minus fifth?
15
16
MR.
So down at the left, at 900, is
RUBIN:
I'm
doing
this
for
illustration.
17
CHAIR CORRADINI:
I understand.
But the
18
numbers seem to match up so I just want to make sure
19
I'm not off base.
20
21
So for a fuel operating temperature in the
range of 900 to 1100C, right--
22
MR. RUBIN:
23
CHAIR CORRADINI:
24
is what you are shooting for.
25
MR. RUBIN:
Yes.
-- the failure fraction
Yes, I tried to -- I did this
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109
1
over the weekend so it would be consistent with what
2
their goals are, okay.
3
say that that is the way it is yet, okay.
4
CHAIR CORRADINI:
But I don't have the data to
And then until that data
5
is available, there would be a dummy set of data into
6
the --
7
MR. RUBIN:
8
CHAIR CORRADINI:
9
MR. RUBIN:
10
Right.
-- MELCOR analysis.
Right.
CHAIR CORRADINI:
So let me ask.
What is
11
known -- what is the experience out of Fort St. Vrain
12
that you can use in this --
13
MR. RUBIN:
14
CHAIR CORRADINI:
Well --- in terms of the type
15
-- the fuel, the type of operating conditions in terms
16
of exit gas temperature and volumetric heating.
17
18
MR.
RUBIN:
--
the
methodology
--
the
methodology is much the same.
19
CHAIR CORRADINI:
20
MR. RUBIN:
Okay.
The plot is grossly different
21
-- grossly different because they had BISO fuel and
22
they had TRISO fuel.
23
conditions went to 100 percent.
24
mean heat-ups went to like 3,000 degrees, okay, they
25
went to 100 percent.
And some of their temperature
During heat-ups, I
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110
1
And
they
had
to
account
for
that
100
2
percent particle failure rates.
3
core went that high, it went off the cliff.
4
the basic idea is the same but the shape will change
5
dramatically with the fuel and the conditions it will
6
see.
Okay.
7
tests
9
model?
with
10
Okay.
So
But the methodology is the same.
MR. KRESS:
8
If that sector of the
temperature
MR. RUBIN:
Do you envision steady state
to
develop
this
empirical
Well, this empirical one is
11
let's say 1,200.
12
1,250 that they are running their fuel testing at.
13
1,250 would be the last temperature at which you'd
14
have a flat kind of a response surface, not giving
15
credit for any temperatures lower than that in the
16
core.
In the case of NGNP, I think it is
So
17
But once they get above that, now you are
18
into an accident heat up and then you start to see
19
increases.
20
qualification for irradiation is done at.
21
22
So that last step is where their fuel
MR. KRESS:
Yes.
But when you run the
test, you'll do it at constant temperature.
23
MR. RUBIN:
Yes.
However, however, for
24
pebble bed, it is interesting, it is cyclic.
25
up and down because you are putting the pebble in at
It goes
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1
the top.
2
MR. KRESS:
3
MR. RUBIN:
4
MR. RUBIN:
As it travels down, it gets
MR. KRESS:
10
12
Then you go around and come
hotter and hotter and hotter.
9
11
MR. KRESS:
back again.
7
8
The top is the coldest spot
because that's where the cold is.
5
6
Oh, that's right.
MR.
So you have a sawtooth.
Yes.
RUBIN:
And
so
their
approach,
I
believe, is to do a sawtooth fuel qualification test.
And also max steady.
13
Okay.
But you have to look at both.
This
is
particle
failure.
We
14
haven't even gotten to fission product transport yet.
15
But particle failures are what drive the big fission
16
product transport piece.
17
Okay.
I don't know how much time you want to
18
give me.
19
last graph was really the heart and soul of our source
20
term right there.
21
This is really the heart and soul -- that
MEMBER ARMIJO:
Stu, what are the various
22
mechanisms by which a particle would start it out,
23
intact, meeting all the quality requirements, what are
24
the mechanisms by which they fail?
25
why don't thousands fail?
And if one fails,
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1
2
MR. RUBIN:
That one, right there, that's
the list.
3
MEMBER ARMIJO:
If everything is the same
4
and there is one mechanism or two, why don't all of
5
them fail?
6
MR. RUBIN:
Well, PARFUME actually has
7
several built in.
8
for sure, I believe it has the second one, I believe
9
it has the third one.
10
one.
11
have the sixth one.
I think it has -- the first one,
I believe it has the fourth
I believe it has the fifth one.
12
It may even
It doesn't have the accident-related ones
13
for oxidation effects and reactivity effects.
14
will be able -- through the next code I'm going to be
15
able to talk about -- calculate what the diffusions
16
rates are.
17
And it
But it has all those models.
MEMBER
ARMIJO:
In
one
of
the
little
18
figures in this handout, there's a picture showing a
19
crack in the pyrolytic carbon layer --
20
MR. RUBIN:
21
MEMBER ARMIJO:
Sure.
-- but the silicon carbide
22
doesn't seem to be cracked yet.
23
that concentrates stress?
24
MR. RUBIN:
25
MEMBER ARMIJO:
Is that a mechanism
Yes.
So it seems it me there
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1
would be, you know, some finite number of mechanisms
2
that cause these failures and people would understand
3
how each of these works as a function of burn up --
4
MR.
RUBIN:
Well,
it's
not
like
a
5
predictor/corrector.
6
failure mechanism.
7
we make the particles so that that particular kind of
8
phenomenon will not occur.
9
10
MEMBER
What they find is yes, this is a
What can we do to modify the way
ARMIJO:
Or
will
happen
less
frequently because --
11
PARTICIPANT:
they
12
--
13
dramatically reduce the debonding and the cracking,
14
okay, which were the failure mechanisms of the old NPR
15
fuel.
16
have
And so they have engineered
engineered
MEMBER ARMIJO:
their
coating
process
to
And if they had a quality
17
control test in fabrication that would confirm that
18
that, in fact, is the case, that they're making much
19
higher
20
that.
21
quality,
then
MR. RUBIN:
I'd
be
more
comfortable
with
At the end of the day, the
22
irradiation in the particle failures, probably zero.
23
It's not the end of the story.
24
PIE where you'll actually start to look at individual
25
particles and you look to see what they look like.
You have to go do a
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The other thing they are going to do is
2
they are going to run tests where fuel will be driven
3
so hard that they will fail.
4
kind of data to --
5
MEMBER ARMIJO:
6
MR. RUBIN:
And they will need that
I agree with that.
-- okay -- and then they'll
7
want to see what the mechanisms are in those tests.
8
Okay.
9
And the reason you need those tests --
10
11
MEMBER ARMIJO:
To get statistics for the
PIE is going to be tough.
12
MR. RUBIN:
-- the reason you need those
13
tests is you need something to validate your code
14
because if you have a test where no particles ever
15
fail, how do you validate your failure model?
16
have to drive them to fail particles and then simulate
17
that to say that I was able to simulate that failure
18
way beyond the design limits.
19
MEMBER ARMIJO:
So you
Okay.
I agree conceptually.
But
20
I think it is really tough in PIE when it is on these
21
tiny little particle basis to get the statistics, you
22
know, something was leaking in let's say one sphere
23
and then what do you do?
24
how many were leaking?
25
MR. RUBIN:
How do you inspect to find
Yes, I agree with you.
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1
2
MEMBER ARMIJO:
I fail to understand how
they are going to do that.
3
MR. RUBIN:
They are looking at more than
4
one particle.
They're looking at dozens, if not -- I
5
don't know that number in their PIE.
6
massive effort into itself.
7
move on.
But
9
release part --
11
now
here
is
CHAIR CORRADINI:
check?
MR. RUBIN:
13
CHAIR CORRADINI:
product
So may I give you a time
Okay.
MR. RUBIN:
So I'll let you decide
Okay.
Let me just say this
slide --
17
18
fission
what you want to emphasize.
15
16
the
In 15 minutes, you are to be done.
12
14
But I think we need to
So that's the particle failure.
8
10
But it is a
CHAIR
CORRADINI:
I
can
blame
Sam
but
we're all to blame.
19
MR. RUBIN:
Right.
No, but you're asking
20
your questions in the right presentation.
21
you that.
22
(Laughter.)
23
CHAIR
24
that.
25
back in 2009?
CORRADINI:
I must note that.
Thanks.
I'll give
Appreciate
Will we get our assessment
Sorry, it was a joke.
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MR.
RUBIN:
Okay.
Here
again
is
the
2
summary of the components of a particle and the fuel
3
element for that matter.
And the idea is to model all
4
those
to
5
transport data and fission product modeling of fission
6
product transport for each of those models.
components.
And
develop
fission
product
7
And if you look at how you would apply
8
that, well, I would apply it for different kinds of
9
particles -- there's something called contamination
10
which is heavy metal that is in the fuel ball, let's
11
say, from manufacture due to the fact that there is
12
going
13
naturally but also because some of it gets in there in
14
the process of making the particles.
to
15
be
some
sort
of
heavy
metal
in
there
So contamination, what can I take credit
16
for?
17
or OPyC.
18
delays in the matrix.
I can't take credit for the kernel, IPyC, SiC,
19
I need to take credit for any hold up and
The next one is a failed silicon carbide
20
layer.
21
determine how many of those you have.
22
case, do we want to model hold up in the kernel, IPyC
23
-- no.
24
beyond.
25
There are methods available in manufacture to
And in that
No kind of hold up in the SiC and then hold up
Failed particles, you'd only be banking on
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1
the kernel providing some hold-up mechanisms.
2
then the matrix and graphite.
3
would model all of that.
4
And
Intact particles, you
Now how do you do that?
Before I get to
5
that, this is a part of diffusion coefficients versus
6
temperature that were based on fuel that was made and
7
tested in German, U.S.A., Japan, and Russia in many
8
cases.
9
coefficients.
And
they
were
able
to
develop
these
Okay.
10
So here you have the basic information you
11
need to then plug into a model to calculate what the
12
diffusion
13
Okay.
14
all together.
rates
are
through
each
of
layers.
But then you need a tool to actually pull that
15
And
a
code
has
been
developed.
16
called the TMAP4 code.
17
tritium migration analysis program.
18
that
19
calculations
20
normal operation.
was
21
those
developed
of
Okay.
It's
And that stands for
This is a code
in
the
labs
to
tritium
for
diffusion
actually
do
reactor
for
And the basic modeling in there, it's a
22
basic kind of a diffusion code.
23
configured with data and geometries to actually do
24
this -- to solve this problem.
25
1D
diffusion
equation.
It
And it can be then
And so it solves the
also
accounts
for
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1
chaptering if needed in any and all layers.
2
You
can,
in
principle,
model
intact
3
particles, failed particles, and so forth, simply by
4
how you set up the modeling in the particular run.
5
You can specify the fission product generation rate on
6
the inside and then it go.
7
and the like, it will calculate what the diffusion
8
rates are for various species of radionuclides.
9
And based on temperatures
And you put in the -- for now we have just
10
what I showed you.
NGNP and DOE are going to develop
11
that specific for the NGNP fuel.
12
model Soret diffusion in any layer, which is important
13
for the buffer layer because there is a big delta T
14
there.
15
model there.
16
modeled with the Soret diffusion.
And so it can also
And that's probably the one that you would
And I think that that is the one that is
17
And it can handle temperature profiles,
18
which are cyclic or steady state, and keep book on
19
temperatures in various layers at different times, and
20
modified diffusion rates.
21
the chugging along of different diffusion -- fission
22
products through those layers.
23
So it's keeping track of
And it can do this for normal operation
24
and then transition to an accident heat up.
25
And
it
is
being
used
now
as
a
powerful
Okay.
tool
to
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1
actually analyze test data, okay, of fuel performance.
2
But what you end up with at the end of the
3
day, as a key point, is that the fuel temperature is
4
the most important parameter in all of this.
5
are other things but that is the key that drives the
6
whole model.
7
locally to know how much releases you are getting for
8
all these mechanisms.
9
There
So you have to understand temperatures
MR. KRESS:
This sounds a whole lot like
10
the Boothe model that's in the MELCOR now for light
11
water reactors.
12
MR. RUBIN:
13
MR.
14
Yes.
KRESS:
They
use
an
effective
diffusing coefficient, which is an arrhenius thing --
15
MR. RUBIN:
Right.
16
MR. KRESS:
-- and then it look to me like
MR. RUBIN:
This is how it is done for
17
--
18
19
many years in Germany, in South Africa, and China.
20
They do take credit for all of that.
21
The question is can you put a code like
22
this
23
dimensions?
into
MELCOR
24
MR.
25
temperatures --
and
KRESS:
keep
As
book
long
as
on
you
all
those
have
the
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1
2
MR. RUBIN:
temperatures --
3
4
Yes, as long as you have the
MR. KRESS:
-- and the transients, yes,
you can do it.
5
MR. RUBIN:
Right.
So our plan is to
6
obtain the code under the MOU.
7
code about two weeks ago and the manuals and some
8
datasets that they've already put together.
9
So
we
could
We already did get the
start
using
the
code
and
10
understanding the mechanisms and become more familiar
11
with
12
conduct sensitivity studies on temperature and burn up
13
and the like to try to see how things are going to
14
change.
15
temperatures
16
have, which is an issue for dust generation.
fission
product
Okay.
transport
in
particle
fuel,
Like cesium diffusion with higher
and
higher
burns,
with
the
models
we
17
And in the long term, to get the data from
18
DOE to change the diffusion coefficients specially to
19
our fuel.
20
Okay.
Now
And that's part of that plan.
what
are
we
going
to
do
for
the
21
evaluation model?
22
starting
23
directly as kind of a brute-force addition the MELCOR
24
code for calculating core-wide diffusion and release
25
versus temperature and burn up and time for all these
that
There's two choices there and we're
now.
It's
to
evaluate
using
TMAP
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1
kinds of fuel, which you will know from the first part
2
we did on failure rates, and for manufacture.
3
Or following that, we might -- I'll call
4
it simplify the diffusion and release models.
5
codes develop an effective diffusion model where they
6
take the chain of diffusion models and the one over
7
the effective one, and one over the first one, and one
8
over the second one, and one over the third one, and
9
you can generate one diffusion coefficient for all the
10
layers.
11
Okay.
Some
So that's the approach taken by one.
It
is
going
to
become
managing
the
12
complexity of the time of the calculational scheme
13
within MELCOR to see if it will work.
14
getting started with that.
But we're just
15
And so once we've made that decision on
16
how to account for these various types of particles,
17
we're going to utilize that together with the particle
18
failure rate piece, which will tell us when we have to
19
shift over to -- we've got more failed particles at
20
this point in time, at this point in the reactor,
21
we've got to go to a different TMAP calculation for
22
those particles.
23
And so what we end up is a fission product
24
release verses time or source term versus time for the
25
entire from those two together.
In the near term,
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we'll use those diffusion coefficients that came from
2
the TECDOC for the old German fuel.
3
will hopefully get the data from DOE for our fuel
4
specific.
5
And I, long term,
I'd like to quickly run through -- this
6
was all for just helium in the system.
7
talked about other kinds of events.
8
kinds of events we've talked about water ingress, air
9
ingress, and reactivity events.
10
I haven't
The other three
These curves on the
right show the effects of water ingress into the fuel.
11
And
the
of
principle
mobilization
13
particles.
14
the
15
mobilizing the release from failed particles.
Okay.
particles
is
products
out
is
12
16
fission
effect
of
the
failed
The phenomena of actually failing
not
as
big
an
issue
as
actually
And you see there when the steam hit the
17
particles, it went up by an order of magnitude.
18
then settled down because all of -- in this case, I
19
think it was krypton-88 was actually taken out so the
20
number, it came down in time because it had just all
21
been released.
And
22
So we need to be able to model his for
23
water ingress events if -- if we see water ingress
24
within the licensing basis as an important kind of
25
event.
Okay.
Because it is expensive to do these
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1
tests.
2
And so if plants are going to have steam
3
generators, we definitely to get data for NGNP fuel.
4
Okay.
5
get in from the shutdown cooling system and other heat
6
exchangers, you will have some level of moisture in
7
there.
Even without steam generators because water can
8
And all the data you have now is based on
9
fuel which is not really representative of the NGNP
10
fuel, neither in burn up or temperatures.
11
is UCO but we just don't see it -- I personally feel
12
it's not necessarily representative of the fuel that
13
was used to generate these curves.
14
So
I
believe
we'll
have
Some of it
to
do
some
15
testing.
16
right now, are kind of not committed to doing these
17
tests.
They're going to look at it.
18
--
there
19
generators,
20
putting that into their plan.
if
DOE will have to do some testing.
are
then
going
they're
to
be
I think that now
plants
definitely
They,
with
going
to
steam
start
21
So for now, again, the strategy is use the
22
data we have as a means to kind of run the codes,
23
MELCOR codes, to account for these phenomena.
24
the long term, use the data that might come out of the
25
NGNP program.
And in
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MEMBER RAY:
I didn't ask this earlier but
2
I thought about it.
3
application that would have this greater probability
4
of water ingress?
5
system water --
6
7
Why is it just a steam generator
Isn't the reactor cavity cooling
MR. RUBIN:
It is.
But it is outside the
reactor vessel.
8
MEMBER RAY:
Well --
9
MR. RUBIN:
You have to find a means to
10
get that water into the reactor.
11
12
MEMBER RAY:
And you're saying that's not
MR. RUBIN:
I think the PIRT didn't -- I
credible?
13
14
think there was concern that those tubes could fail
15
and then kind of leak over to the reactor vessel, hit
16
the vessel wall, and maybe caused a local temperature
17
change
18
vessel.
19
20
that
could
But
to
be
see
mechanism
that
get
for
the
into
the
core, I don't think anybody saw that as a pathway.
MEMBER RAY:
22
MR.
Okay.
RUBIN:
The
pathways
that
are
traditionally used are the heat exchangers that are --
24
25
failure
actually
21
23
a
MEMBER
RAY:
No,
I
understand.
Nevertheless, I wondered about that.
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1
CHAIR CORRADINI:
So just to make sure I
2
understand, so it's really just the mass fraction of
3
water in whatever gas is near the graphite and the
4
fuel.
5
6
MR.
RUBIN:
This
shows
it
is
a
partial pressure --
7
CHAIR CORRADINI:
8
MR. RUBIN:
9
thing
Well, okay.
-- partial pressure of the
steam at the site of the particle.
10
CHAIR CORRADINI:
11
MR. RUBIN:
Right.
If you do that higher for more
12
particles, you are going to force more release for
13
more particles.
14
to
15
curve.
get
you
16
So steam generators are a candidate
going
CHAIR
higher
on
that
CORRADINI:
So
is
17
decision by the staff?
18
have communicated to the DOE that --
19
20
MR. RUBIN:
partial
pressure
this
a
policy
Or is this something that you
No, I haven't communicated --
they're seeing this when you are seeing this.
21
CHAIR CORRADINI:
22
different
23
generator,
24
basis.
25
question
does
then.
water
MR. RUBIN:
Okay.
If
ingress
So let me ask a
there
go
into
is
a
the
steam
design
You've got that right.
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CHAIR CORRADINI:
2
MR. RUBIN:
Okay.
Of course.
I do believe for
3
the M/HTGR with steam generators water ingress was the
4
limiting event.
5
argument was it was not a high probability of having
6
that many tubes fail.
7
point of view, it was the limiting event.
8
CHAIR CORRADINI:
9
MR. RUBIN:
CHAIR
MEMBER BLEY:
the thinking.
is
one
at
Or kind of what is driving
Is it -I would assume you guys
know because you're always talking -MR. RUBIN:
I know but it is not public
information.
22
CHAIR CORRADINI:
23
MR. RUBIN:
24
there
Does DOE want to get up and
CHAIR CORRADINI:
20
21
But
answer that question?
18
19
CORRADINI:
MR. RUBIN:
16
17
Well, if you want to talk to
least?
14
15
So which of the point
DOE in the hall, you probably can ask them that.
12
13
But from a sheer consequences
designs has a steam generator in the point design?
10
11
Now from a risk point of view, the
Okay.
Oh, excuse me.
That's why I'm saying
that.
25
CHAIR CORRADINI:
Okay.
Thank you.
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MR.
RUBIN:
And
2
decision.
3
don't have steam generators.
they
haven't
made
a
They may decide to choose a plant that
4
Okay.
The same thing for air ingress,
5
basically you have mechanisms that can fail particles
6
in that case.
7
the outer pyrolytic carbon layer.
8
away.
9
the
10
One of the mechanisms is you oxidize
It kind of goes
And it takes away its compressive function on
silicon
carbide,
drives
the
silicon
carbide
stresses up.
11
They go from negative to positive in any
12
failed particles.
13
attack the silicon carbide and form SiO or SiO2.
14
can be self sustaining and fail the particle that way.
15
And
SiO2
tends
And then you also can directly
to
create
a
barrier
for
SiO
continued
16
attack by the accident, depending on the temperature
17
by and large.
18
But in any event, there is data -- limited
19
data on the failure rates and the releases due to air
20
ingress or air being exposed to the particles.
21
you can see those effects on these curves.
22
basically done for fuel spheres, nine percent FIMA,
23
and the temperatures were maybe not typical of what we
24
would see in the NGNP.
25
And
They're
So there is a big question mark in my
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1
mind.
It would be hard to make the case that this --
2
these
test
3
application for air ingress events.
4
at least a few tests to see what the effects would be
5
on the fuel specific to your plant.
6
data
could
used
in
a
licensing
You'd want to do
At this point, the technology program from
7
DOE,
8
irradiated fuel.
9
them lately about that.
10
be
they
may
include
air
ingress
testing
with
I think -- we have not talked to
So we don't know if they made
that decision or not.
11
So in the meantime, we'll use the test
12
data we have.
In the long term, we'll work with DOE
13
to get additional data to model these effects.
14
And finally, reactivity events, you can
15
see from this part that depending on the level of the
16
energy pulse into the particle, you could drive the
17
particle failure right up to 100 percent.
18
The question came up very early on is, you
19
know, what are the -- what are the effects of pebble
20
compaction of the entire active core moving away from
21
the control rods in terms of reactivity addition?
22
we need to do some analysis.
23
The
pebble
bed
reactor,
because
it
So
is
24
continuous online fueling, it has very little, if any,
25
excess
reactivity.
So
the
potential
for
a
large
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1
reactivity addition in pebble bed is said to be small.
2
So these events become nothing more than kind of heat
3
up events.
4
If one were to postulate a rod ejection,
5
those kinds of reactivity additions get you into these
6
kinds of curves.
7
CHAIR CORRADINI:
8
MR. RUBIN:
9
10
Yes.
A rod ejection would.
Okay.
And at least for
example in HGTR, that was one of our limiting events.
They
actually
postulated
that
as
11
licensing basis, rod ejection accident.
12
a limiting event for them.
13
Now
whether
or
not
the
part
of
their
And it became
risk
informed
14
approach to licensing the NGNP will, in fact, say with
15
the deterministic bounding event and pose that, we
16
don't have the answer to it yet.
17
on our radar.
But it is something
Okay.
18
So this problem or this performance issue
19
will rise and fall with the what the risk informed
20
licensing event selection ends up with.
21
And so let me just wrap up here.
Fuel
22
fabrication, we talked about that.
23
make clear the differences in fuel performance, R over
24
B ratio over a burn up for a different manufacturer.
25
The blue, the lower part was the range of particle
This part tries to
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1
failures.
2
And by the way, if you take those numbers
3
and divide them by .01, let's say, you get the failure
4
rates.
5
running it at higher temperatures.
Probably .1 for the NGNP fuel because they are
6
But you can see that the old NPR fuel, the
7
way it was made, performed relatively poorly -- really
8
very poorly.
9
was the gold standard for many years.
The German fuel, the way they made it,
10
We're starting to see now in Japan and now
11
in the AGR program that we are meeting and beating
12
those standards with the particle failure rates in
13
operation, which is very encouraging to meet those
14
goals that I talked about in here.
15
So this makes clear that manufacture is
16
important.
17
have variations from lot to lot.
18
way to kind of have a regulatory oversight of that.
19
And we've come up with the next inspection line.
20
And even when you fix manufacture, you can
But it's true.
So we want to have a
We're just inspecting what
21
we know -- what they have concluded what they know.
22
What about what we don't know?
23
at other ways to monitor that in the reactor and the
24
like.
25
So
in
summary,
Then you have to look
integrity
and
fission
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1
product retention is the key to the HTGR safety case.
2
Fuel behavior in fission product release depends on
3
how
the
fuel
is
made,
4
accident conditions.
its
operating
history,
and
5
We're developing, with the help of DOE,
6
analytical tools and data to develop our expertise to
7
assess all of that in fuel failure as well as fission
8
product release.
9
those both into the evaluation model.
10
And we want to be able to integrate
And we have
some strategies to do that.
11
We need to pursue the issue of graphite
12
dust
in
terms
of
the
amount
of
metallic
13
products that are bound up in all of that.
14
fuel performance guys' piece to answer.
fission
That's the
15
And we do, if it's not already clear, plan
16
to extensively utilize DOE's work products in helping
17
us to build our databases.
18
to a number of other international groups to see where
19
we can supplement that and have kind of confirmatory
20
data from others in developing our models.
And we've already talked
21
And as I spoke about last, the ability to
22
inspect the fuel production facility is something --
23
we've developed a kind of a template for that even
24
now.
25
So that's it for me.
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1
2
CHAIR CORRADINI:
Further questions for
Stu?
3
MEMBER ARMIJO:
In use of these codes that
4
are submitted by let's say Idaho, this TMAP4, would
5
you,
6
regulatory work?
7
codes,
8
analysis that, let's say, a utility or a vendor would
9
submit.
10
when
you
would
get
into
a
licensing,
start
the
Would you, if you chose to use those
you
go
through
the
same
review
and
Here's our licensing topical report and then
you review it?
11
MR.
12
issue.
And
13
experience,
14
ourselves.
RUBIN:
I'll
the
That's
defer
NRC
to
doesn't
a
Joe
code
Kelly.
impose
validation
With
requirements
his
on
15
MR. KELLY:
No, that's correct.
16
MR. RUBIN:
Yet what is our standard for -
17
-
18
MEMBER ARMIJO:
Well, in this case it is
19
an Idaho DOE code given to the NRC to use that they
20
claim --
21
MR. RUBIN:
22
MEMBER ARMIJO:
Yes, it's a box, a black box.
Right.
And then you would
23
have to go through it and make sure that black box
24
worked.
25
MR. RUBIN:
Sure.
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MR. KELLY:
Yes.
And what we're using
2
TMAP4 for now is the MELCOR developers are looking at
3
it to see what they may need to do within the MELCOR
4
code, whether they can take their current model and
5
then
6
implement TMAP4.
change
7
it
or
whether
they
need
to
actually
And what we would do is the verification
8
part.
That we would, you know, find the data sources
9
and do the code assessment against it.
10
to
11
uncertainties involved in using that code.
make
sure
we
have
12
MR. RUBIN:
13
one more this morning?
an
Okay.
And then try
understanding
of
the
Are we scheduled to do
14
CHAIR CORRADINI:
15
MR. RUBIN:
Okay. Tony Ulses, you are the
17
MR. ULSES:
All right.
18
CHAIR CORRADINI:
16
We are.
man.
Could you take your seat
19
over there, Stu, if you don't mind.
20
MR. RUBIN:
21
CHAIR CORRADINI:
22
to block the screen so they can't see it.
Okay.
23
MR. RUBIN:
24
CHAIR CORRADINI:
25
I doubt you are trying
Okay.
You can stand and move
around if you feel like it.
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1
MR. RUBIN:
2
CHAIR CORRADINI:
3
MR. ULSES:
4
mentioned, my name is Tony Ulses.
5
of Research.
6
about our advanced reactor research plans in the area
7
of nuclear analysis.
8
9
That's okay.
Whatever you like.
I thank you, Stu.
As was
I'm in the Office
And I'm going to be talking to you today
As we go forward in this and, you know, as
we
discussed,
obviously
we're
going
to
have
many
10
meetings on this topic.
11
Stu and I talking together quite a bit because we
12
obviously recognize there is a real strong linkage
13
here between these two technical areas.
14
going to be driving some of our thinking.
I expect you're going to hear
And it's
15
What I want to do today is I want to kind
16
of walk you through our thinking, what we've done so
17
far, and I want to also mention here as we get into
18
this that this is an area that we are really just
19
getting started on.
20
We have done some work that we were able
21
to accomplish back in the -- back when we were doing
22
the PBMR work before it stopped, as was mentioned this
23
morning in the pre-application area.
24
we've done some very basic assessment of it.
25
relatively
comfortable
with
it.
And that work
But
we're
We're
just
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1
literally getting started and kind of formulating our
2
plans.
3
This
is
a
statement
that
is
actually
4
literally right out of the advanced reactor research
5
plan.
6
This is an extremely high-level document.
And this is obviously a guideline statement.
7
But the way that we've been interpreting
8
this is we've almost gotten to the point in light
9
water reactor space where we can almost take nuclear
10
analysis for granted.
11
we're so accurate, we can get, you know, the actual
12
power and the fuel thing relatively accurately.
It is down to the point where
13
The expectation, as we go forward with the
14
work related to the NGNP project, is we're intending
15
to take those methods and try and move them forward so
16
we can retain that same level of accuracy as we're
17
trying to analyze this.
18
And it's really -- because we realize that
19
the actual fuel performance of these systems is so
20
critical.
21
obviously,
22
calculation.
23
have methods that are accurate so that when we get to
24
the licensing process, the actual tech staff, at that
25
point, will have the ability to do proper sensitivity
And
you
obviously
know,
one
the
of
power
prime
predictions,
inputs
to
that
So we want to assure ourselves that we
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1
studies to be able to really have an opportunity to
2
fully understand this system as we go forward.
3
All right.
4
CHAIR CORRADINI:
But would that statement
5
hold if I had a gas outlet temperature of 700 to 750C
6
versus 900C?
7
In other words, can I be sloppier?
MR. ULSES:
Well, you know, that's the
8
question really of margin versus accuracy.
9
a question that will obviously get fleshed out in the
10
And that's
licensing process.
11
And that's ultimately up to the applicant.
12
You know how accurate do they want to claim their
13
methods
are
versus
how
much
uncertainty
14
willing to accept.
15
that will be fleshed out in that process.
are
they
And so that's an issue, you know,
16
What we're really thinking about here --
17
and then this actually goes to a question that was
18
brought up earlier this morning -- is the question --
19
I mean how do we really assure ourselves that we fully
20
understand the system?
21
actually go into the system and do analysis where we
22
can say, you know, vary the parameters, do sensitivity
23
studies studies, make sure we understand the margins
24
In other words, are we able to
of the system and how it behaves.
25
That's really more where we're thinking
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1
right now with trying to retain the same level of
2
accuracy that we have.
3
valid and it's one that --
And your question is certainly
4
CHAIR CORRADINI:
5
MR. ULSES:
6
Well, that's fine.
-- would get nicely fleshed
out on the license basis.
7
CHAIR
CORRADINI:
differently.
But
asked
my
9
applicant what sort of hot channel factors could you
10
live with if it was 750C, 850C, 950C, or the heat
11
generation rate was X, Y, or Z?
12
in which you can operate.
13
going to have to decide what an acceptable level of
14
uncertainty is.
the
So you know the space
It's based on what you are
I mean have those trait study calculations
been done that the staff is aware of and looked at?
17
MR. ULSES:
Well, the short answer to that
18
question is no.
19
level of detail at this point.
20
staff
term
question
16
the
me
8
15
Has
let
We have not engaged INL down to that
And as I said, this is
--
21
CHAIR CORRADINI:
22
MR. ULSES:
Okay.
-- an area we're just getting
23
started on.
24
know, we will discuss as we go forward within this
25
technical area.
And certainly one of the areas that, you
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1
CHAIR CORRADINI:
2
MR. ULSES:
Okay.
This is basically kind of the
3
picture of our code suite.
4
the plan that we have as we go forward, as we intend
5
it,
6
already have.
Within the SCALE code suite, over the
7
past
six
8
accurate
9
necessarily tied to any particular system.
is
we
five
intend
or
methods
10
to
leverage
years,
with
We, you know, we have --
the
we've
high
systems
developed
fidelity
that
we
extremely
which
are
not
What that really means if it allows us to
11
use
12
frankly,
13
arena.
14
this as we go forward because that's obviously, you
15
know, a real high-level statement.
those
systems
and
with
actually
relatively
move
them
up
little
into
effort,
the
HTGR
And, you know, I'll get into more specifics on
16
But the point I want to make on this is
17
that we really have three areas of application here.
18
We're going to be working within the SCALE code system
19
itself to make the necessary modifications, be sure we
20
have the validation data that we need to validate
21
those tools.
22
We're going to be looking in the area here
23
in yellow, which is really the area where we take the
24
cross sections we calculate from the SCALE system.
25
And we put them into a form that can be used within
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1
the evaluation model, which, in this case, is going to
2
be PARCS code.
3
what we use for our normal diffusion area solver.
And then obviously PARCS itself is
4
And the AMPEX 2000 code is the one where
5
we actually take the raw evaluated data and we go in
6
and we actually process it to the point where we can
7
work
8
working -- within SCALE, we're actually working with
9
actual continuous energy data now but there's actually
10
not a lot of processing that goes out between AMPX
11
down to SCALE.
with
it
in
SCALE.
But
since
we're
actually
12
We're actually able to work with extremely
13
high resolution data at the level of what I would
14
traditionally call a lattice physics calculation.
But
15
that's
for
16
these systems, that word.
not
17
necessarily
appropriate,
you
know,
Now one other point to make on this slide
18
is
19
configuration control.
20
modern FORTRAN languages.
21
that we're going to need a lot of new physics to
22
PARCS.
23
code.
24
work is in the actual cross-section parameterization.
that
25
all
of
these
codes
are
currently
under
They've all been updated to
And we don't anticipate
We already have an arc data Z solver in the
We already -- the one area where we may have to
And what I mean there is, you know, the
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1
way that we model now is we model a fuel ascender in
2
the light water reactor space.
3
is an isolated ascender.
4
these HTGRs.
And we assume that it
That may or may not work for
5
We may have to actually go in and add some
6
additional physics as we try and couple those nodes
7
together in the nodal diffusion theory solver.
8
is something that is going to be fleshed out as we go
9
forward in our research plan.
10
That
So this is basically a discussion of the
11
area that we have been focusing thus far.
12
is, you know, one of the real strong challenges in
13
these
14
resonances?
15
is, again, we're using the existing codes, existing
16
tools that we have within SCALE.
17
types
of
systems,
how
do
we
And this
process
the
And the methodology that we've developed
You know right now we use a continuous
18
energy,
19
process resonances within SCALE.
20
able to do is we've been able to go in and actually
21
handle the multiple layers of heterogeneity in this
22
fuel by essentially leveraging that tool.
23
one-dimensional
What
we're
24
actual
25
actual kernel model.
pebble
--
well,
transport
doing
we
is
theory
code
to
So what we've been
we
start
with
an
actually
start
with
an
And we go in and we do a one-
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141
1
dimensional
2
kernel.
3
spectrum.
transport
And
we
use
theory
that
calculation
to
get
a
on
that
representative
4
And then we use that spectrum to go in and
5
reevaluate an actual -- a new spectrum, which we can
6
then move out to the actual level of the pebble or the
7
actual compact itself.
8
want to make sure, you know, we actually retain the
9
necessary information as we go forward.
10
Again, the idea there is we
And
then
from
we
need
to
there,
once
we
get
the
or
the
11
information
12
compact, then we're prepared to go and model what
13
would be analogous to like a light water reactor fuel
14
assembly, for example.
15
model
CHAIR CORRADINI:
the
pebble
And the reason you need
16
to do this level -- remind me since I'm not a good
17
neutronics person -- is because of the heterogeneity
18
of these small link scales?
19
MR. ULSES:
Right.
Basically what we're
20
worried about there is the actual effect of spatial
21
energy sub-shielding --
22
CHAIR CORRADINI:
23
MR. ULSES:
Okay.
-- on the resonances.
And we
24
want to retain this level of detail so, again, we'll
25
have the ability to understand whether or not some of
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1
the
other
methods
2
actually simpler, whether or not they have the level
3
of
4
predictions that we need as we go forward with the
5
system.
accuracy
10
to
give
MR.
question.
ULSES:
Wow,
the
are
kind
of
What is the meaning
well,
that's
a
good
head to be honest with you.
MEMBER
ABDEL-KHALIK:
It's
ten
centimeters.
MR. ULSES:
14
MEMBER ABDEL-KHALIK:
It's pretty big, yes.
A few centimeters at
least.
16
MR. ULSES:
17
MEMBER ABDEL-KHALIK:
18
us
which
I couldn't answer that off the top of my
13
15
now,
of the path of the neutron in silicon carbide?
11
12
fidelity
right
MEMBER ABDEL-KHALIK:
8
9
there
And --
6
7
and
out
Right.
So why is this level
of detail important.
19
MR.
ULSES:
Well,
because
20
necessarily
21
expect that your point is well made.
22
going
23
pebble itself.
to
--
see
within
a
lot
the
of
actual
power
pebble
we're
not
itself,
I
I mean we're not
variation
across
the
24
But the question that we want to have the
25
ability to answer is we want to be able to retain the
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1
ability to model the effects of the pebble to pebble,
2
for example, so we see if I have a high burn-up pebble
3
next to a low burn-up pebble, you know, what is the
4
actual effect of the power within that node?
5
And also what you see here is that this
6
work here has been able to be done with the existing
7
tools that we have.
8
to do was go into SCALE and take the tools that we
9
already have and rearrange them so the sequences we
10
So this really was -- all we had
run such that we could retain this level of detail.
11
So it really wasn't that much work at all
12
to actually accomplish this.
It was more a question
13
of -- we didn't have to add new physics or new tools
14
to do this.
15
leverage it and use it as we went forward.
16
CHAIR CORRADINI:
We had it in there so we decided to
But to answer Said's
17
question a bit differently, if it weren't a pebble
18
reactor, it was a prismatic, is it -- is your real
19
technical concern is when you go from the core to the
20
reflector and you cross that boundary that you can't
21
accurately get those heterogeneities as well as if I
22
go into the core region where I've got the coolant
23
channel, the moderator, and then the equivalent of
24
essentially the fuel rod, the compact, I can't get the
25
right measurement of how I get absorption if I have a
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1
power change?
2
That's what I thought was the reason you
3
had to go through this detail.
4
struggling.
5
MR. ULSES:
That's where I'm still
Certainly.
Well, the issue
6
of, you know, you mentioned essentially the reflector
7
interface with the core itself.
8
9
CHAIR CORRADINI:
Right.
That one I can
see.
10
MR. ULSES:
That's an area that we've been
11
discussing considerably as the reason for the need to
12
do this --
13
CHAIR CORRADINI:
14
MR. ULSES:
Okay.
-- in order to have the right
15
spectrum.
16
be
17
appropriately assess applicant methods.
able
It's more an issue in my mind of we want to
to
18
retain
And
if
the
we
level
have
of
the
detail
so
fidelity
we
in
can
these
19
tools, it gives the staff, when it gets down to the
20
licensing
21
whether or not the simplifications that may or may not
22
be
23
appropriate.
imposed
24
25
phase,
in
the
an
ability
applicant
CHAIR CORRADINI:
to
fully
method
are
understand
actually
So this is your method
of experimental independent verification of what the
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1
applicant is going to show you?
2
MR. ULSES:
I would -- well, obviously,
3
you know, this isn't experimentation.
4
the ability to fully --
5
CHAIR CORRADINI:
6
MR. ULSES:
7
This gives us
Verification.
Sure, exactly.
You know we
are retaining a considerable amount of information.
8
Now I'll show you a summary on this slide.
9
I'm just going to go through a couple of -- well,
10
this is essentially a summary of what I just said
11
here.
12
have.
Again, we're using the existing systems that we
13
What you'll see traditionally out there is
14
the use of Dancoff factors to allow for the spatial
15
effects when you are doing resonance processing.
16
know it is not an invalid method.
17
many years.
18
in these HGTR systems.
19
You
It's been used for
That's what has been used traditionally
But,
again,
our
methods
will
give
the
20
staff the ability to assess those methods with a fully
21
independent set of methods.
22
what we're doing here.
That is the intent of
23
We have added the ability into SCALE to
24
handle the hexagonal boundary systems on the pebble or
25
when we're looking at the prismatic block fuel.
And
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1
we
have
added
2
capability for the double heterogenic systems, however
3
we have not extensively tested that at this point.
4
That's something that is ongoing right now.
5
I
in
a
wanted
depletion
to
mention
and
just
a
a
branching
couple
of
6
sample calculations that we've done so far with these
7
systems.
And, again, these are extremely preliminary.
8
This is work -- this particular problem here was one
9
where we set up using some start-up testing from the
10
HTR-10.
11
International Reactor Physics Evaluator Handbook.
This
problem
is
available
from
the
12
And, you know, this gives us -- this is an
13
example of what I said earlier that we have comfort
14
that the methods are working effectively.
15
this is a simple evaluation of the criticality of the
16
system with a certain pebble height.
17
see
18
particular configuration when compared to the critical
19
experiment.
here,
20
the
actual
And
we
are
calculation
continuing
You know
And as you can
is
to
one
for
work
on
this
this
21
problem and we're going to work on the control outlook
22
calculations.
And that work is currently underway.
23
And, again, this is just an example of one
24
set of data that we currently have that we have been
25
looking at.
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We have another problem here, the HTTR --
2
MEMBER ABDEL-KHALIK:
What is the pebble
3
volume density that was used in the analysis part of
4
it?
5
MR. ULSES:
That's a level of detail that
6
I can't actually answer.
7
by Oak Ridge for us as evaluation.
8
of how they model would actually have been part of the
9
input for the specification for the --
10
This is work that was done
MEMBER ABDEL-KHALIK:
The actual detail
I mean isn't that a
11
knob that one can change to come up with whatever
12
results you want?
13
MR.
ULSES:
Right.
But
one
of
the
14
advantages of using a problem that has been accepted
15
for
16
Handbook is that it has gone through a large amount of
17
vetting, it has been reviewed by at least two or three
18
independent reviewers.
19
there is assumed to be correct.
20
MEMBER
21
the
International
Physics
Evaluation
And so all the information in
ABDEL-KHALIK:
So
the
volume
fraction of the pebbles --
22
MR. ULSES:
23
this problem obviously.
24
25
Reactor
Is going to be an input to
MEMBER ABDEL-KHALIK:
-- is specified as
part of the input?
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MR. ULSES:
It's going to be specified as
2
part of the specification, exactly.
3
to be specified by the information that was provided
4
in the handbook.
5
MEMBER ABDEL-KHALIK:
6
MR. ULSES:
is
Okay.
And, again, the expectation of
7
this
8
extremely well vetted.
It has been reviewed by one or
9
two individual people.
And so we have a significant
10
handbook
And it is going
that
this
information
been
level of comfort in the information that is in there.
11
MEMBER ABDEL-KHALIK:
12
MR. ULSES:
13
has
Okay.
Thank you.
It's not accepted until it
reaches that level.
14
This is just another example.
This is an
15
example
16
problem has not been actually officially accepted into
17
the handbook.
18
through that evaluation.
from
HTTR.
And,
again,
this
particular
But it is in the process of going
19
And, again, this is just another example
20
of where we have applied these methods to a set of
21
experimental data.
22
we've done thus far with the double-het methods is
23
actually working as we expect.
24
was actually done down at Texas A&M with the help of
25
Oak Ridge, using the SCALE code system.
And we have comfort that what
And, again, this work
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So we move on, if we go back to -- again,
2
just to refresh your memory, this figure here, what I
3
just talked about here was the work we've done on the
4
SCALE system itself.
5
discussing
6
GenPMAXS scale and the PARCS.
7
what
And then I'm going to move into
the
GenPMAX
actual
is
current
basically
state
just
of
sort
the
of
8
translator.
9
just takes the processing out of SCALE and it puts
10
It doesn't really do any physics.
a
them into a form that PARCS can use.
11
CHAIR CORRADINI:
12
MR. ULSES:
It
It actually --
Code process.
Right.
It uses a series of
13
partial derivatives based on the relevant variables,
14
those being, for this case, it's going to be like the
15
fuel temperature, what the condition of the monitor
16
is.
17
collapsed cross-sections that it needs as it is going
18
to a solution.
So it can recreate the actual values of the
19
For
PARCS,
again,
as
I
mentioned,
we
20
currently have a cylindrical solver in the code.
21
currently works with -- we currently have an N-group
22
solver with upscattering.
23
I think PARCS is, with the exception, again, of having
24
to maybe having to assess what we may or may not need
25
to
additionally
It
The bottom line on this is
parameterize
as
we're
going
from,
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1
again,
the
fine
2
essentially
3
diffusion
4
information to make sure that we can recreate the
5
relevant reaction rates.
6
going to be researching, looking at.
a
detail
lump
of
solver,
calculation
material,
how
we
to
which
can
what
is
is
a
nodal
translate
that
That is an area that we're
7
And that is currently the only area that
8
we expect we're going to actually put a considerable
9
amount of research on within the PARCS code itself.
10
And just, again, this is a real quick sample problem
11
of the application of PARCS.
12
benchmark, which has been mentioned previously.
13
There
are
This is the PBMR-400
five
different
code
14
calculations.
15
test.
16
that were presented at a conference last year.
17
this is a transient which was a withdrawal of 200
18
seconds.
19
is performing as well as the others.
And,
again,
this
This is not based on data.
is
a
code-to-code
These are results
And
And, again, we're showing here that the code
20
The little wiggles you see on here, those
21
are artificial effects from the rod cusping models as
22
the rod transitions from node to node.
23
couple of the codes that don't have a decusping model
24
so
25
that's a numerical artifice of the calculation.
that
leaves
those
little
wiggles
There are a
in
there
but
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All
right,
let
me
move
on
2
right.
3
the PIRT itself.
4
a guide of our research.
5
we're not locking ourselves into the PIRT.
here.
All
So now I'm going to move into a discussion of
6
And, again, we're using the PIRT as
But I want to emphasize that
And actually you are going to see a couple
7
of
8
modifications based on some recent research.
9
that's a point I want to definitely make as we move
10
things
in
here
where
we've
actually
made
some
And so
forward here.
11
This is not -- you know, we're not moving
12
into
13
continuing to engage with the international community.
14
this
with
tunnel
vision
on
this.
We're continuing to engage with our partners.
We're
And
15
obviously we'll be also engaging with INL considerably
16
as we go forward here.
17
This is essentially the heart and soul of
18
a nuclear analysis.
19
the flux and the power.
20
right, then I can get anything else right.
You know the ability to predict
I mean if I can get this
21
And so this is an area where we're going
22
to be focusing a considerable amount of attention.
23
Essentially the first bullet, I mean that's obviously
24
a statement of the obvious.
25
I mean, you know, we have
to fundamentally understand this system.
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And this is why I've been so concerned
2
about trying to retain a large level of accuracy in
3
these methods.
4
to use what we call the TSUNAMI methods in SCALE,
5
which
6
tool suite within SCALE.
is
7
a
As we go forward, I expect we're going
sensitivity
and
CHAIR CORRADINI:
8
just embedded in the model?
9
MR.
ULSES:
uncertainty
application
That's something that is
It's
just
another
SCALE is not one code.
code
10
sequence within SCALE.
It is
11
a sequence of 20 or 30 different actual independent
12
codes which work under a series or sequence of driver
13
modules.
14
SCALE.
15
we're going to try and utilize that tool to help us
16
understand the sensitivities of these systems as we
17
move forward.
And this is just another sequence within
It is already there.
18
It preexists.
And we
We expect we're going to take a multi-
19
tiered approach to this.
20
some small-scale studies, which are actually currently
21
underway.
22
doing
23
pebbles, modeling compacts so we can understand the
24
basic physics.
25
We're going to start with
And, again, we're going to be looking at
models
that
--
you
know,
modeling
isolated
We're going to try and use the data that
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1
we currently have for this phase.
2
- we have the HTTR data, we have HTR-10 data, we have
3
some data from the PROTEUS facility which was a PSI.
4
And, again, this is all data that is available in the
5
International Reactor Physics Handbook.
6
the
7
develop our understanding of the system.
data
8
that
we
We're
are
going
going
to
to
And that's really -
use
develop
And that is
to
essentially
very
detailed
9
models of what we expect the NGNP system to look like.
10
Obviously the design, at this point, is not fixed.
11
But the point of that is that we want to make sure
12
that we understand that we haven't missed anything as
13
we go forward in this system.
14
We want to be able to have a very detailed
15
model of the system so we can look at the linkages
16
between
17
sensitivities of the system to make sure that we have
18
a solid understanding of the physics, and that we have
19
what we need in the tool set as we get down to the
20
licensing phase.
21
SCALE
and
PARCS,
so
we
can
look
at
the
And, again, as I mentioned, we're going to
22
work on preparing the PARCS interface.
23
going to really go on in a couple of phases.
24
going to start on developing a simplistic interface
25
now so we can get that part of the project moving
And that's
We're
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1
forward.
2
But as we get into it, it is very likely
3
that we may find that we need to modify that again.
4
And, again, in order to make sure that we can retain
5
the necessary information that we would need to get
6
the power out of that code, which obviously we're
7
going to then give to the fuel guys so they can model
8
the fuel.
9
And that leads into the next bullet, which
10
is, you know, we certainly recognize there is a very
11
strong linkage here between the fuel performance and
12
the power and the fission product release.
13
is an area that we are going to be working on as we go
14
forward as well.
15
And that
This is sort of my vision of the current
16
expectations as we go forward on the system.
17
the pebble systems are definitely going to be much
18
more complex.
19
stochastic nature of the system.
20
very hard to define what is the burn up of a pebble at
21
a given location in that system.
I expect
And that's given, you know, the general
It is going to be
22
Now as we go forward in this, it may very
23
well turn out that that is not a large contributor.
24
But that is something we need the ability to retain
25
the level of fidelity to understand that because it
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1
maybe
something
2
important.
that
as
we
go
forward,
that
is
3
Certainly the ability to homogenize that
4
information, in other words the pebbles, and then when
5
we get into the PARCS level of analysis, to then pull
6
out the specific detail.
7
kind of the analogue to what we call like a pin power
8
reconstruction methodology.
9
the ability to actually model what we expect.
And what I mean there is
In current LWRs, we have
You
10
know the individual power in the individual fuel pin,
11
we want to retain the ability to have that level of
12
fidelity as we go forward.
13
One of the other challenges for pebble
14
systems, it is going to be really hard to validate
15
predictions because as hard as we've seen it thus far
16
out in the international community, no one has been
17
able to figure out a way to instrument a pebble to
18
actually tell me what the individual power of the
19
given pebble is within the system.
20
And that's going to be an where we are
21
obviously going to be engaging with INL and, you know,
22
with others in the international community to try and
23
get our hands around it.
24
This goes back to the question you brought
25
up when we get into the licensing phase -- you know,
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1
margin versus accuracy.
2
need to add some margin on because we're unsure of the
3
level of accuracy?
4
not going to be a problem.
5
6
Is that an area where we will
Or maybe it is an area where it is
That is something that we haven't fleshed
out yet at this point.
7
But I just --
CHAIR CORRADINI:
So in the past -- in the
8
past operation of I guess it was the AGR, which is a
9
pebble design, there's no in-core instrumentation that
10
tells you what the flux is at a location?
11
MR. ULSES:
That's correct.
There was no
12
in-core instrumentation in that reactor at all as we
13
understand it.
14
You know -- what
15
CHAIR
--
CORRADINI:
But
you
don't
16
necessarily need it on the pebble.
17
maybe spatially so that as the pebbles pass through
18
that spatial location, that helps you?
19
MR. ULSES:
Right.
You just need it
But as I understand
20
it, there was no instrumentation on the pebble bed
21
system.
22
MEMBER ARMIJO:
23
MR. ULSES:
24
We knew the burn up.
Right.
And that was measured
--
25
MEMBER ARMIJO:
And if you did PIE, you
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1
might
be
able
2
temperatures --
to
get
3
MR. ULSES:
4
MEMBER
5
some
idea
of
--
but
the
maximum
Right.
ARMIJO:
it's
very
qualitative.
6
MR. ULSES:
The only real experiment that
7
I'm aware of thus far that made an attempt to measure
8
the local conditions in the pebble bed were the melt
9
wire experiments that were run through the ADR.
10
MEMBER ARMIJO:
11
MR. ULSES:
Okay.
And as I understand it, those
12
experiments didn't necessarily live up to expectations
13
at this point.
14
obviously going to continue to follow.
And that is another area that we're
15
You know as for what the current plans of
16
INL for this issue are -- again, this is an area where
17
we haven't really actually engaged them yet.
18
is something that is obviously going to be important
19
to talk about.
20
Okay, what we need to do to validate the prediction of
21
the model.
22
And it
How we are going to be able to that?
MEMBER ARMIJO:
It seems to me the real
23
challenge is to find out what is the hottest pebble or
24
groups of pebbles in this core as a function of it.
25
MR. ULSES:
Right.
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1
MEMBER
ARMIJO:
In
2
conditions.
3
and where they've been, that's
4
5
MR. ULSES:
Right.
7
MR. ULSES:
8
MEMBER ARMIJO:
And that's one of the
-- that's --
It's a problem.
-- it's so much different
when -- in your core, you know where everything is.
10
MR. ULSES:
11
MEMBER ARMIJO:
12
MR. ULSES:
Right.
It stays put.
It's not to say that it is an
insurmountable challenge but --
14
15
accident
reasons -MEMBER ARMIJO:
13
or
If you don't know exactly where they are
6
9
normal
MEMBER ARMIJO:
Oh, I know.
I'm just
saying --
16
MR. ULSES:
-- but it is an area where,
17
again, we need to engage with INL and, obviously, any
18
future applicant.
19
point I tried to make earlier on this.
20
I mean this also goes back to the
That's one of
the reasons why I want to attain a significant level
21
of accuracy in our methods.
So, you know, that may be
22
an area that we can explore if it is an issue.
23
I want to talk -- I'm sorry --
24
MEMBER ABDEL-KHALIK:
25
If you do have in-
core instrumentation, what information would it give
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1
you?
2
MR. ULSES:
of
the
Well, it's going to give me a
3
measurement
flux
or
the
power
at
4
location.
5
ability to predict which pebbles are there.
6
we have pebble-flow models.
a
given
And then obviously we have to have the
You know
They exist.
7
Obviously we're going to be using them in
8
our evaluation models of any type of pebble system.
9
But it gives me the analogue of say, for example, the
10
tip that I have in an LWR or like an LPRM system.
11
12
MEMBER ABDEL-KHALIK:
Right.
But those
essentially measure steady state data.
13
MR. ULSES:
14
MEMBER
Right.
ABDEL-KHALIK:
But
I'm
just
15
wondering if you would ever be able to measure steady
16
state data in this system given the stochastic nature
17
of the positioning of individual pellets.
18
MR.
ULSES:
Well,
that's
a
very
good
19
question and one that I, right now, would say we don't
20
have our hands around.
21
going to be continuing to engage INL on as we move
22
forward.
23
24
CHAIR
I mean it is one that we're
CORRADINI:
All
you
need
is
LaGragian flux meter.
25
(Laughter.)
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160
1
MR. ULSES:
Is that all?
2
CHAIR CORRADINI:
3
MR. ULSES:
Follow the particle.
You know, the point I want to
4
make with this slide is this isn't something that
5
we've lost track of.
6
list of things to talk about.
7
engage in this discussion as we go forward because
8
we're not sure exactly whether or not it is an issue.
9
And
as
This is an area that is on our
you
point
And we are going to
out,
it
may
not
be
10
something we can really measure.
11
deal with it in licensing space in another way.
12
it is not going to be a problem.
13
that we need to make sure we engage in a discussion
14
with INL and also any future applicant.
15
But
the
next
And we'll have to
Maybe
But it is something
bullet
are
the
common
16
challenges, again between a pebble versus a prismatic
17
system.
18
graphite.
19
I'll touch more on that in a little bit here.
Again, the issue of neutron scattering on
And that's really a properties issue.
And
20
And when you get into the top point of
21
these systems, you have -- and also at the bottom --
22
you have some voided areas, which leads to a lot of
23
neutron streaming.
24
any type of nuclear analysis code suite.
25
That's obviously a challenge to
We're going to be seeing enrichments that
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1
are larger than what we are used to in light water
2
reactors.
3
issue to make sure that we have the data that we need
4
to validate the tools.
5
there.
That's really more of a data validation
I don't see any real problems
It's just an issue we have in the data.
6
And
obviously
the
multi-layer
7
heterogeneity, which is an issue that we've already
8
discussed here today.
9
MEMBER ARMIJO:
Are all these fuels in
10
these pebbles, are they all the same enrichment?
11
are there going to be different enrichments?
12
MR.
ULSES:
I
guess
right
now
13
understand
14
enrichment.
15
don' really have an answer to that right now.
it,
they're
going
MEMBER ARMIJO:
17
MR. ULSES:
the red gum balls are.
19
be
as
using
I
one
That's really more a DOE question.
16
18
to
Or
MR.
I
You don't know?
We don't even know where all
Can you imagine --
CARLSON:
I
have
a
little
extra
20
information on that.
21
to fuel the initial core with a lower enrichment.
22
then go to a -- progress to an equilibrium enrichment
23
that they use little by little.
So that there will be
24
in
core
25
enrichments.
the
early
life
The last I heard PBMR was going
of
the
two
And
different
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MR. ULSES:
Well, but from a standpoint of
2
actually being able to make sure we have the methods
3
to
4
question.
5
having to track where this stuff is.
6
All right.
handle
the
system
is
more
a
data
validation
But obviously it is also a question of
Let's see here.
So, again,
7
I'm walking you through what came out of PIRT in this
8
area.
9
ability to predict decay heat.
The other area that was highlighted was the
What we're currently
10
planning on doing in this area is we're going to stay
11
involved in standards work.
12
But the next bullet is a statement that
13
within SCALE, we use the ORIGIN code, which is what we
14
use to do -- to actually do our depletion calculation
15
of isotopics.
16
spectrum, it's going to give me a relatively accurate
17
prediction of what isotopics are there.
18
this really goes back to the spectrum and the weighted
19
cross sections is the key to a successful ORIGIN
20
As long as I can give ORIGIN a good
So really
prediction.
21
And within this area, we would expect --
22
and, again, this is an area that we are going to have
23
to discuss with INL and any applicant -- is that we
24
would expect to see some relevant calorimetric data in
25
order to assess any models.
And this is kind of
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similar to what you would see in like an ANS 5.1-type
2
standard, is that there is actually very little data
3
there and most of that is code calculations.
4
there is some data to actually validate the basics of
5
what the standard is telling you.
6
But
The next item that was raised is spatial
7
xenon instability.
8
should
9
similar to what we do right now in the operating fleet
be
able
Where I expect to go on this is we
to
disposition
this
analytically
10
for BWRs.
But obviously this is something that would
11
have to be confirmed as part of any start up physics
12
program just to assure ourselves that we're not going
13
to have a xenon instability problem.
14
I'm not aware of any problem with xenon
15
instability in an existing operating HGTRs or any past
16
operating HGTRs.
17
consider.
But that's something we need to
18
Reactivity coefficients, this is certainly
19
one of the other areas which is very significant that
20
came out of the PIRT.
21
a statement of the obvious.
22
a fundamental understanding of phenomena here to make
23
sure that, you know, we know how the system is going
24
to behave.
25
And, again, this is essentially
You know we will require
We will require measured data in order to
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evaluate the code predictions.
And, again, this is an
2
area that I'll touch on a little later.
3
an area where we're going to be engaging INL to ensure
4
that we have the necessary data that we will need.
But that is
5
My expectation is that the SCALE to PARCS
6
interface will strongly influence these conditions.
7
Again, this goes back to the discussion of, you know,
8
have I properly captured all the physics in that
9
linkage to ensure that I can recreate the relevant
10
reaction rates within a calculation.
11
area that we're working on.
And that is an
12
Now this next bullet is an area where we
13
have actually used some recent work to actually go
14
beyond what we studying when we looked at the PIRT.
15
There is some work by a researcher by the
16
name of Dagan.
17
It's
18
indicates
19
assumptions
20
scattering resonances maybe non-conservative.
He's working in Germany right now.
Karlsruhe.
And
that
that
he's
done
essentially
some
are
way
in
the
some
of
we
work
which
the
basic
treat
neutron
21
So what we're planning on doing is we're
22
going to go in and modify the CENTRM code which is --
23
that's
the
name
of
our
continuous
energy
one-
24
dimensional transport code that we use to do resonance
25
calculations to assess the impact of this.
And if
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this turns out to be a problem, then it is an area
2
where we're going to need some high temperature data
3
to assess this.
4
Right now the work by Dagan suggests that
5
it may have anywhere on the order of a ten percent
6
impact on the fuel temperature coefficients.
7
again, this is all very preliminary.
8
that we are just working on.
9
area where we have -- you know where we are reacting
But,
It is something
But, again, this is an
10
to what we see in the community out there.
11
making the necessary changes.
And we're
12
And, again, we expect that we are going to
13
be doing a large amount of sensitivity and uncertainty
14
calculations in this area to ensure that we understand
15
system performance and behavior.
16
So this is kind of a wrap up really of all
17
the slides which discuss the PIRT finding.
18
the main issue I want to discuss here is the need for
19
validation data.
20
focused right now.
I think
And that is really where we are
21
We have been discussing amongst ourselves
22
and we will be engaging with INL here really soon in
23
discussing what data is there, what data we expect we
24
are going to need, where we see that we may or may not
25
have some holes in the database in order to validate
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1
these particular areas of analysis.
2
Again,
we
will
be
establishing
very
3
detailed models of pebble and prismatic systems to
4
allow us to explore sensitivities and uncertainties
5
and
6
detailed calculations and the PARCS-type analysis.
to
look
at
the
linkage,
again,
between
the
7
And we will definitely be planning to take
8
advantage of the large amount of international data
9
which is currently out there within the community.
10
And,
11
discussing with INL as we go forward.
again,
12
13
14
that
The
is
next
an
area
couple
where
slides
we
will
be
just
sort
of
summarize what we see as the current sources of data.
These
are
the
facilities
15
operating.
16
high on our list of interests.
that
are
currently
So obviously they're going to be pretty
17
The HTTR in Japan, as has already been
18
mentioned, is a very well documented facility that is
19
currently operating.
20
have done -- they have already released some data
21
through
22
International Reactor Physics Handbook program.
the
23
IAEA
And they are -- you know they
program
and
also
The HTR-10 is in China.
through
the
And, again, they
24
have also released data also.
It is currently in
25
operation.
know
But,
you
know,
we
that
there
is
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1
additional data at these facilities that we would be
2
interested in.
3
will be engaging with INL because obviously our data
4
needs
5
facilities.
6
are
And, again, this is an area where we
going
to
be
very
similar
from
The ASTRA facility is in Russia.
7
critical facility.
8
the PBMR folks in South Africa.
9
critical facility.
10
from that as well.
these
It is a
They are currently working with
It is a zero-power
But there is some relevant data
11
These are examples of facilities that have
12
operated but there is a considerable amount of data
13
that exists.
14
experiments that were done at PSI.
15
zero-power critical facility.
I've already mentioned the HTR-PROTEUS
Again, this is a
16
One of the areas that we are interested in
17
is they actually did some activation foil measurements
18
within this core, within one of the cores, which would
19
give us some spatial information.
20
that we intend to explore.
21
And that is an area
The VHTRC facility was a facility that was
22
designed as a precursor to the Japanese HTTR.
23
again, this is an example of a critical facility.
24
25
And,
And then the DRAGON facility was one that
was done under the auspices of the OECD.
We know
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there
is
a
considerable
2
facility.
3
out and recreate it.
amount
of
data
from
this
The challenge is going to be to actually go
4
There is a program underway through the
5
OECD to try and capture the reports that were actually
6
written
7
trying to pull them together into a repository so they
8
are usable by researchers and by regulators that want
9
it.
as
a
part
of
this
project.
And
actually
10
The next slide is examples, again, of the
11
prototypical facilities that we may be able to utilize
12
some information from.
13
these is they use some pretty unique fuel cycles.
14
example, Fort St. Vrain used an HEU thorium-type fuel
15
system.
That doesn't mean that the data is worthless
16
to us.
But it is certainly not prototypical of what
17
we are going to expect to see in the NGNP system.
The one issue with some of
For
18
And obviously pebble bed cores that have
19
been operating, the AVR is definitely going to be of
20
interest to us.
21
There
22
there on that.
23
to what we can from that facility on what we need.
is
a
That is a well-documented facility.
considerable
amount
of
information
out
And we're going to be working actively
24
Neutron scattering in graphite is another
25
area where we are reacting to work that has been done
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recently in the community.
2
done at NC State which was funded by a DOE grant where
3
they have actually gone out and tried to study the
4
effect of radiation on graphite scattering properties.
5
6
There has been some work
And they have concluded that there is an impact.
And
so we are continuing to follow this work.
7
And I know that they are planning to do
8
some more work in this area.
The studies have been
9
preliminary at this point.
10
to do some more research.
And we will continue to
11
follow these developments.
And if we need to make
12
code modifications, we will do so as necessary as we
13
go forward.
They are actually planning
14
But, again, I wanted to point this out as
15
an area where we're not locked into our PIRT process
16
here.
17
are trying to follow relative developments and make
18
the necessary changes as we go forward.
19
We're staying engaged with the community.
We
This is also more of a summary slide of
20
most of the things I've already talked about.
21
thing that we are working on now is we know that right
22
now we do not have access to any data on actually
23
depleted fuel pebbles.
24
want to have the ability to evaluate our models.
25
So
we
are
One
And that is one area that we
actually
working
on
what
is
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going
to
2
problem that we're going to be presenting to the OECD
3
next month.
4
us a considerable amount of information to help us
5
guide the assessment and also any further development
6
that we need to make on those methods.
7
be
a
code-to-code
comparison,
a
standard
And we expect that that is going to give
I
mean,
you
know,
obviously
as
we
go
8
forward with this, we will need to have access to
9
data.
But it is the kind of thing where we can't wait
10
until we have the data because then the methods aren't
11
going to be ready.
12
work with right now.
13
problem that is going to allow us to move forward.
14
And then we'll assess as the data becomes available.
And we have to have something to
So this is an example of a
15
We're working to refine the list of data.
16
And, again, this is an area where we are going to be
17
engaging INL and we're going to make sure we try and
18
leverage
19
community.
20
what
is
One
out
of
the
there
in
areas
the
we're
international
going
to
be
21
focusing on is trying to identify where we have holes
22
in the database, areas that, you know, we may need to
23
do some initial research on.
24
25
We're going to continue working on our
scoping studies.
And we're going to work on detailed
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model development.
2
to allow us to understand, again, the linkage from
3
SCALE to PARCS because it is an area where we think we
4
may not fully understand that.
5
And, again, this is really driven
And it is is an area
that we want to make
6
sure we have our hands around.
7
those assessments based on what we currently have from
8
the HTR-10 and from the HTTR.
9
And we're going to do
And for the longer term, again, the main
10
emphasis of this slide is data.
We intend to get as
11
much -- you know we intend to identify the data needs
12
and we will use that data to validate our codes.
13
I mean that is the area where we are going
14
to be spending most of our effort on over the next
15
three or four years is in code validation.
16
essentially
17
essentially done other than, obviously, going back and
18
feeding back on what we learned from our assessments.
19
most
of
the
actual
MEMBER ABDEL-KHALIK:
FORTRAN
Because
work
is
What methods did the
20
Japanese use to design HTTR and what methods did the
21
Chinese use to design the HTR-10?
22
MR. ULSES:
Well, that's a question that I
23
actually can't answer to be honest with you.
24
is an area where we will be engaging with them to
25
figure that out.
But that
As was mentioned, we've already had
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a discussion with the JAEA folks about HTTR.
2
And
we
will
work
to
continue
those
3
discussions in consultation with INL as we go forward
4
to try and learn from their program and learn what
5
they did.
6
back and say traded off uncertainty versus accuracy.
And also how they may have, you know, gone
7
You
know
question
but
in
that
is
licensing.
obviously
the
You
how
8
perennial
9
accurate do you need versus uncertainty and versus the
10
margin in your system?
11
will engage with them on as we go forward.
12
know
So that is something that we
And I think that the Chinese used actually
13
the
14
program.
15
used for the HTR-10 program.
16
sure about that.
German
code
suite
that
was
used
in
the
AVR
I believe that is the code suite that they
17
CHAIR
But I'm not 100 percent
CORRADINI:
The
fact
that
the
18
Chinese reactor, just for reactor physics purposes, I
19
guess, I'm curious, the fact the Chinese reactor is
20
not
21
cylindrical -- it's totally fueled all the way to the
22
center
23
change things relative to the reactor physics?
an
24
25
annular
as
was,
I
core
I
design
thought,
can
but
the
is
AVR,
understand
a
how
it
essentially
does
that
from
a
thermohydraulics standpoint but does it really much
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matter in terms of what you can gather from their
2
experiments or their information?
3
MR. ULSES:
No, I think the only that
4
would be, you know, lacking is obviously the effect on
5
the power distribution, you know, from the annular
6
core.
7
the
8
methods, there really shouldn't be --
But from the basics of actually understanding
accuracy
9
and
the
applicability
CHAIR CORRADINI:
10
MR. ULSES:
11
CHAIR CORRADINI:
12
the
physics
Okay, all right.
-- a problem.
I didn't think so.
I
was just curious.
13
14
of
MR. ULSES:
You know that data should be
directly applicable to the assessments.
15
So, again, as we go forward, we're going
16
to work hard to use our sensitivity and uncertainty
17
methods to ensure we understand this system.
18
We have to work a little bit on SCALE
19
execution
20
Again, you know, we have accurate methods.
21
going to work on SCALE execution speed.
22
in
23
ongoing.
place
24
25
speed.
to
do
And
PARCS interface.
It
that.
also,
is
a
little
slow
right
now.
We're
We have plans
And
that
work
again,
back
to
is
the
actually
SCALE
to
That is is an area that we have to
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explore.
We have to make sure we understand that when
2
we are going from our detailed methods to the nodal
3
diffusion
4
information in there which is relevant to the ability
5
to recreate the power exclusions.
6
MEMBER ABDEL-KHALIK:
theory
methods
that
7
take to run a problem?
8
MR. ULSES:
9
MEMBER ABDEL-KHALIK:
10
MR. ULSES:
we
don't
lose
any
How long does it
In SCALE?
Right.
Well, you know, for a series
11
of a few pebbles, it is on the order of a couple of
12
minutes.
13
that calculation up to looking at actually trying to
14
run with thousands of pebbles, obviously, you know,
15
that run time is going to increase.
It is not a huge run time.
But as we scale
16
I don't have in mind right now what I
17
would accept as an acceptable run time for a large
18
system calculation.
19
with an overnighter myself.
20
satisfaction and gratification our of a code.
You know I'm usually comfortable
I'm not one for immediate
21
But, you know, if I can get the run time
22
down to the order of a day or so for a calculation, I
23
think I'll be satisfied with that.
24
MEMBER SHACK:
25
MR. ULSES:
Get a bigger computer.
Exactly.
These methods run
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pretty fast on modern CPUs.
2
doing
3
about modeling 20, 30,000 energy groups within that
4
system.
continuous
5
And,
energy
you
And, you know, when we're
calculation,
know,
we
can
we're
achieve
talking
those
6
calculations literally in like an order of minutes.
7
It's not a huge computational burden.
8
9
So, again, in summary -- wow, I finished
really early -- okay.
We sort of recognize that this
10
is
part
11
evaluation model to support licensing units.
12
are moving forward with that expectation.
a
very
important
13
We
are
working
in
on
the
--
ability
we
are
of
the
And we
certainly
14
aware of the need to have a solid interface between
15
the nuclear analysis methods and the fission product
16
release.
17
predict the flux of power profiles which obviously
18
impact the ability to get the burnup.
19
isotopic distributions which are relevant to the fuel
20
performance.
21
circle.
We need to have the ability to actively
And also the
So it is all kind of linked in a big
22
But it all really gets down to the fuel.
23
It actually always fundamentally gets down to the flux
24
and the power.
25
the rest of it right.
And if I can get that right, I can get
That's what we're after.
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What we see as the key nuclear analysis
2
challenges -- and, again, this is sort of kind of a
3
summary
4
validate our methods to be able to predict reactivity
5
of the system.
6
way to handle the stochastic nature of burnup.
7
obviously the ability to homogenize and then be able
8
to recreate that information to a sufficient level of
9
detail to do that analysis.
10
We
11
multilayered heterogeneity.
12
talked about here but we're certainly aware of is the
13
reactivity effects of moisture ingress.
of
the
PIRT
--
we
are
going
to
have
to
We are going to have to figure out a
have
to
be
able
to
handle
And
the
One area that I haven't
14
From the standpoint of the codes, that's
15
going to be more of an input in how we model what
16
moisture is there.
17
know that, then I can calculate the reactivity.
And if that's in the system, if I
18
And then we have to be able to reliably
19
predict fuel isotopics, which, again, is integrally
20
linked to the fuel performance studies.
21
Where we're going on this is we're going
22
to take a phased approach to this.
23
start with small-scale studies.
24
those up.
25
understand this system at every step along the way.
We're going to
We're going to scale
And we're going to try and make sure we
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1
We are going to be working on the SCALE to
2
PARCS interface.
We have to work on the MELCOR to
3
PARCS
4
handing data back and forth between the codes.
linkage.
That's
more
of
an
issue
of
just
5
And then I think the key point I want to
6
leave with you from this presentation is that we're
7
definitely focused on the need for code assessment and
8
for the need to get access to validation data as we go
9
forward.
10
And
then
also
as
I
mentioned,
11
looking
into
12
graphite
because
13
part of the performance of the system.
14
15
the
neutron
that's
scatter
obviously
a
we
are
properties
of
very
important
And that's a summary of where we are in
the area of nuclear analysis.
16
CHAIR CORRADINI:
17
MR. ULSES:
18
MEMBER ARMIJO:
Questions?
Questions?
Where does the effect of
19
changing
graphite
with
20
irradiation, does that get into to your codes?
Into
21
your analyses?
22
thermal
conductivity
Or not?
MR. ULSES:
Yes, basically I provide them
23
an input.
24
know,
25
actual graphite is going to see.
how
of
In other words, I'll provide them, you
much,
how
much
neutron
irradiation
the
So it is going to be
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1
one of those things where we are going to have an
2
iterative-type solution.
3
Again,
I'll
give
them
the
necessary
4
fluence.
5
people who are going to tell me the temperature.
6
then I know the temperature and I can
7
MEMBER ARMIJO:
okay.
MR. KRESS:
Okay, so there will be --
Doesn't it seep back though in
the moderation?
12
MR. ULSES:
13
MR. KRESS:
14
them the power.
Right.
10
11
And
So it's all one big circle.
8
9
And then that is going to go to the thermal
Dust, definitely, yes.
Yes, okay.
You need that in
your --
15
MR. ULSES:
16
CHAIR CORRADINI:
Right.
Right.
So this is more of a
17
process question than a technical question.
18
still back to core flow bypass or where does the gas
19
go compared to where you think it goes?
But I'm
20
So when I asked that, Stu said well, if I
21
think I heard it right -- I could have been wrong --
22
well, are you asking about how big the channels are
23
versus how big the bypass is?
24
growth question.
25
Well, that's a graphite
Go ask the materials guys.
And what I'm kind of worried about is I
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1
heard -- I could have misheard -- compartmentalization
2
of a cross-cutting problem that I think would, even
3
though it is a normal operation problem, would effect
4
any sort of associated accident analysis.
5
to know where the gas goes.
6
Said asked about the plenum.
guys
what
you
8
issues that you need to know something that effects
9
neutronics,
10
materials?
11
and then somebody takes the lead?
effects
I
would
fuel
call
So how are
7
12
handling
So I need
cross-cutting
performance,
effects
You all get in a room and argue about it
MR. ULSES:
How is this done?
Well, I'll just take it real
13
quick.
14
meet rather frequently and we discuss what we are all
15
doing.
16
forward.
17
18
And make sure that we are lined up as we go
I don't know if you want to add anything
to that, Stu, or not.
19
20
See, from a process perspective, I know we
MR. RUBIN:
Well, you are very right.
We
don't want to be --
21
CHAIR CORRADINI:
22
I never inferred that.
23
MR. ULSES:
24
I mean --
I never inferred that.
I don't know that we argue too
much but we do talk a lot.
25
MR. RUBIN:
And our first step was to
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1
create that chart: what are the events?
2
figures of merit we want to create?
3
that's an event, a figure of merit.
4
from who to get what I need to put out to the next
5
guy?
6
start to reveal.
7
make sure that we are not in silos because if we are,
8
we're never going to get this job done.
Okay.
9
And so okay,
What do I need
And so that continuous communication will
And we'll write those all down and
CHAIR CORRADINI:
10
What are the
MR. RUBIN:
Right.
We have to explain what I need
11
to give you, my fission product release, and I listed
12
all those things.
13
spatial
14
assignment.
And there's time dependency and
dependency.
15
And,
okay,
that's
your
You've got to do that.
Now if we miss a phenomena, then we're,
16
you know, in trouble.
17
those inputs and outputs, we're set up to have those
18
working group meetings periodically and make sure we
19
are all working to the same kind of sheet music of
20
everybody is doing what they have to do to pass to the
21
next person.
22
But in terms of communicating
CHAIR CORRADINI:
So the reason I asked a
23
question such as that is then is somebody given --
24
let's just talk about core bypass phenomena and how it
25
effects accident analysis and associated source term.
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1
Is
somebody
given
the
lead
that
then,
therefore,
2
there is an appropriate lead on the DOE side that you
3
guys are in communication?
4
Because then the question is all right, so
5
this is an issue.
6
aspect, a thermal hydraulics aspect, what is DOE doing
7
that we don't have to do or choose to verify or choose
8
to duplicate to make sure we confirm their work?
9
is the connection made to then the DOE lead in this?
10
It has a materials aspect, a fuels
MR. RUBIN:
How
Well, we're just setting up
11
our communications channels to start that process of
12
talking
by
13
thermal
hydraulics,
14
fuels.
But
15
connect
16
connect discussions.
peer
we
to
--
nuclear
also
discussion
17
peer
have
that
thermal
to
to
they
hydraulics
nuclear,
get
have
into
with
fuels
to
to
that
cross
our
cross
Okay.
It is a to-do.
We know we have to do
18
that.
19
relationships.
And
20
already
to
21
meetings where they will go through a methods review
22
where we will hear and see what they are faced with.
23
And
24
issues.
We are just getting started exchanging those
make
25
started
sure
we
will
attend
that
we
some
are
It is a to-do.
be
attending
or
of
periodic
their
recognizing
those
have
same
We haven't gotten started.
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1
But that is on our list of got to do that.
The only
2
way to get smart is to talk to people and learn more
3
about what they know.
4
CHAIR CORRADINI:
5
MR. RUBIN:
6
Do you want to add to that?
7
MR.
8
All right.
We're going to do that.
JOLICOEUR:
Yes,
This
CHAIR CORRADINI:
Yes, just pull the mic
MR.
JOLICOEUR:
John
Jolicoeur
12
Research.
13
cooperative work between the two agencies.
14
we
15
interagency agreement.
17
have
We have signed an MOU with DOE for the
not
yet
completed
is
But what
implementing
an
That's currently under review.
near future.
CHAIR CORRADINI:
19
you said?
20
still completing?
21
Could you repeat what
So you signed the MOU but what are you
MR.
JOLICOEUR:
Implementing
an
interagency agreement between the two agencies.
23
24
from
And we expect it to be completed here in the very
18
22
John
to you.
11
16
is
Jolicoeur from Research.
9
10
Okay.
The MOU is just a big framework document.
Then you have to have
25
--
CHAIR CORRADINI:
So at this point, if you
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1
call up somebody at DOE, they'll say time out.
2
don't have the implementation.
3
MR. JOLICOEUR:
We
I can't answer you.
Yes, they will talk to us
4
but at this point we haven't shared peers, as it were.
5
We don't have peers lined up with peers yet because
6
we
don't
have
7
doing that work.
8
9
the
implementing
agreement
to
We expect to start very soon.
CHAIR CORRADINI:
Okay.
Maybe I lack the
appreciation of how much legal handshaking there has
10
to be.
11
issue?
12
just management upon management?
Is that because of the applicant-regulator
Or is that what it comes down to?
13
MR. JOLICOEUR:
Or is it
It is the way the MOU is
14
structured.
15
document.
16
DOE funding for us so that we can then engage --
17
18
I
mean
the
CHAIR CORRADINI:
to money.
MOU
is
a
big
framework
And then the implementing agreement provide
Okay, okay, now we get
Okay.
19
(Laughter.)
20
MR. RUBIN:
21
start
Let me just say -- let me just
say -- we have -- we have their planning documents --
22
CHAIR CORRADINI:
Thank you.
23
MR.
we
RUBIN:
--
have
their
planning
24
documents
25
integrated code development strategy or graphic is not
for
code
development.
Okay.
With
our
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184
1
locked up.
2
written down so far as to what their linkage issues
3
are from one discipline to the next.
4
Okay.
And we understand what they have
We get periodically -- monthly -- their
5
monthly
reports
and
6
development area.
7
is the face to face --
part
of
that
is
their
code
What we haven't really started yet
8
CHAIR CORRADINI:
9
MR. RUBIN:
Okay.
-- in real time.
And we need
10
to have peer-to-peer but we also need to have system
11
level guys to system level guys.
12
CHAIR CORRADINI:
13
MR. RUBIN:
14
No, I understand that.
That's the part we haven't
started yet.
15
CHAIR
16
process question.
17
early break but to get John to clarify.
18
me a bit.
19
essentially defines the method of interaction during a
20
pre-application phase between the DOE and the NRC?
21
even beyond?
22
23
But
I
mean
just
a
I don't want to take away from our
So you helped
Are you also saying that this -- the MOU
MR. JOLICOEUR:
Or
Actually, the MOU is --
actually --
24
25
CORRADINI:
CHAIR CORRADINI:
Or the implementation or
whatever the hell the thing is?
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1
2
MR. JOLICOEUR:
Yes, the current MOU is
really pre-application, if you will.
3
CHAIR CORRADINI:
4
MR. JOLICOEUR:
5
CHAIR CORRADINI:
6
MR. JOLICOEUR:
Just pre-pre-application.
when pre-application begins.
8
CHAIR CORRADINI:
Okay.
So we're in pre-
pre-application protocol?
10
11
Okay.
So a new one will come up
7
9
Pre-pre- or just pre-?
MR. JOLICOEUR:
Right, right.
This is
just cooperative work between the two.
12
MR. RUBIN:
Here is the genesis of this.
13
The Energy Policy Act has a piece in there that said
14
that the Secretary of DOE shall engage with the NRC to
15
get the NRC's input into their activities so that they
16
are doing their research in a way that is responsive
17
to the safety requirements for this plant.
18
So
based
on
that,
I
forget
what
the
19
subsection was, we wrote an MOU that is going to allow
20
us to participate in basically their R&D.
21
focus of it.
22
CHAIR CORRADINI:
23
MR. RUBIN:
24
CHAIR CORRADINI:
25
MR. RUBIN:
That's the
Fine.
Okay.
That helps.
And that now is in place.
Now
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1
we have an interagency agreement that takes us to the
2
next
3
working points of contact?
4
What are they sending us?
level.
And
the
next
is
what
are
the
What is the periodicity?
What are we sending back?
5
CHAIR CORRADINI:
6
MR. RUBIN:
7
CHAIR CORRADINI:
8
level
You got it.
Details to follow.
I'm happy now.
Thank
you.
9
Sorry.
Other questions?
10
(No response.)
11
CHAIR CORRADINI:
Okay.
12
to thank the morning's presenters.
13
this afternoon.
14
We're -- I want
And we have more
We'll break until our official start time
15
of one-thirty.
16
(Whereupon, the foregoing matter went off the record
17
at 12:14 p.m. to be reconvened
18
in the afternoon.)
All right -- for lunch.
19
20
21
22
23
24
25
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1
A-F-T-E-R-N-O-O-N
S-E-S-S-I-O-N
2
1:30 p.m.
3
4
CHAIR
CORRADINI:
Why
don't
we
get
started.
5
Steve
Bajorek
will
take
us
through
6
discussions of thermal fluids research versus thermal
7
hydraulics versus heat transfer.
8
MEMBER SHACK:
9
(Laughter.)
10
11
MR. BAJOREK:
would come up.
12
13
14
With the momentum equation.
I wasn't sure whether that
Now we know.
Thank you very much for that introduction.
I'm Steve Bajorek from Office of Research.
Good
afternoon.
15
Yes, what I'd like to do is talk about our
16
thermal fluids research.
17
we've
18
hydraulics although by design, we're trying to keep
19
the hydraulics out of this.
20
thermal fluids or TF for abbreviations.
stumbled
over.
Yes, that is a word that
We
like
to
say
thermal
So we've been calling it
21
What I'd like to accomplish in like, you
22
know, my 45 minutes are three different parts of the
23
presentation.
24
25
First I'd like to describe the thermal
hydraulics research objectives.
One of the things
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1
we'd
like
2
presentations is to lay out a picture on how these
3
various disciplines fit together in order to help us
4
develop the regulatory framework and to develop the
5
evaluation models.
6
how thermal fluids fits into all of that.
7
to
accomplish
today
in
all
of
our
And I'm going to try to describe
I want to outline what we are considering
8
the major thermal fluid issues for gas reactors.
9
as part of that, I want to talk a little bit about the
10
PIRT rankings, which ones have given us the most
11
concern, given us the most -- are most interesting to
12
us,
13
those.
outline
14
our
overall
approach
to
dealing
And
with
And finally, point out what we think from
15
the
16
products, how does it relate to the evaluation model
17
development?
18
information?
thermal
fluid
research,
what
are
some
of
the
You know how are we going to use this
19
Tony Ulses did a really nice job at the
20
end of his presentation in kind of outlining one of
21
the biggest concerns in several of our's work and that
22
is in coming up with the right experimental data in
23
order to benchmark our models, benchmark our codes or
24
various parts of the evaluation model.
25
big concern in the thermal fluids area.
And that's a
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1
We have a lot of processes, some fairly
2
well understood, some of them being driven into new
3
ranges of conditions which are going to give us larger
4
uncertainties
5
conditions
6
developed.
than
where
we
the
may
have
expected
correlations
may
at
the
have
been
7
So I want to outline where some of those
8
data needs are, where we think we can get some of that
9
experimental data, what are some of the facilities
10
which are available for that.
11
First
in
research
of
here
objectives,
13
evaluation
14
elements of that.
15
to obtain or generate the integral and the separate
16
effects data that is either going to go into the code,
17
the evaluation model assessment or into development
development.
to
And
support
the
thermal
model
is
the
12
18
fluids
terms
there
the
are
two
First, we're going to be looked up
for some of the new models.
19
In terms of the hierarchy on where we will
20
get that experimental data.
21
steps
22
processes.
23
some of the issues.
we're
going
to
take
There are three different
in
each
one
of
these
And I'll try to outline this as we look at
24
First and foremost, we're going to look at
25
Department of Energy and the applicant to supply that
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190
1
data
for
assessing
2
correlations.
the
models,
assessing
the
3
We will be able to start interfacing with
4
DOE here as soon as the interagency agreement is in
5
place but we would look to work very closely with
6
Department of Energy in order to make sure that the
7
data that they are developing satisfies our needs as
8
well as theirs.
9
We're also looking at collaborating and
10
entering
into
agreement
with
international
11
organizations.
12
the HTR integral facility in China, HTTR in Japan.
13
We've started to talk with both of those groups about
14
gaining better access to the experimental data.
We've talked about a couple of those,
15
Some of it has been released in part of
16
the international IAEA cooperative research program.
17
So we see a little bit of that and are convinced that
18
pursuing more data from those facilities is going to
19
be very useful and helpful to us.
20
all of that yet.
21
those international agreements.
22
We're
But we don't have
And what we're going to do is pursue
also
working
with
RAPHAELE,
that
23
project, in order to gain some of their work into the
24
gas reactors.
25
project,
task
We are also working in the CSNI TAREF
on
advanced
reactor
experimental
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191
1
facilities,
where
we've
reviewed
the
2
facilities that are available worldwide.
experimental
3
The next step in that process is to work
4
with the roughly ten or 12 international groups that
5
want to be part of the TAREF to outline what the tests
6
are, share data, perhaps do some cooperative research
7
with
8
available
9
organizations.
one
or
more
to
10
of
all
Third,
those
of
if
the
we
facilities
and
make
collaborating
don't
get
the
it
research
data
from
11
Department of Energy that fulfills our needs and we
12
can't get it from international partnerships, we would
13
conduct some of our own independent experiments.
14
like to leave that go to the third level of, you know,
15
as part of the decision.
16
We
have
two
routes
by
which
we
We'd
could
17
pursue
18
Hydraulic
19
development.
20
has
21
mechanisms
22
experiments at a couple, three different universities,
23
give us some data that we would need on a timely
24
basis.
that
been
25
right
now.
Institute.
One,
We've
we
used
have
this
our
for
Thermal
TRACE
Up until this point, almost everything
light
that
water
would
related.
allow
MEMBER SHACK:
us
But
to
run
this
is
small-scale
This is Purdue?
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1
MR. BAJOREK:
2
There are some other universities which
3
are associated with that but it's primarily Purdue
4
that runs that.
5
We've
also
Thermal hydraulic?
recently
Yes.
entered
into
a
6
cooperative agreement with several universities that
7
would help supply us with some work for PARCS, MELCOR,
8
and, if necessary, running some of the experimental
9
tests that we might find necessary.
10
The second element of the thermal fluids'
11
objectives would be to take these data, look at the
12
correlations, the models that are currently existing,
13
and try to evaluate those to see whether those are
14
suitable for MELCOR, determine what the uncertainties
15
are compared to the existing and new data, and use
16
that to be factored into the evaluation model as we do
17
some of the either uncertainty calculations or make
18
changes to that code.
19
MEMBER ABDEL-KHALIK:
20
how
21
currently?
large
22
is
MR.
this
effort
BAJOREK:
Just for reference,
under
the
third
bullet
Right
now,
the
Thermal
23
Hydraulics Institute, with respect to gas reactors, is
24
fairly small.
25
MEMBER ABDEL-KHALIK:
No, in general, what
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1
is the size of this effort even though it is now
2
focused on water reactors?
3
MR. BAJOREK:
Typically for the Thermal
4
Hydraulics Institute, there would be work to support
5
three or four different experimental programs.
6
reason I'm hesitating -- and I'm not sure in a public
7
format whether I could talk about the dollar value.
8
9
MEMBER ABDEL-KHALIK:
Okay.
MR.
Thermal
The
Then we'll
skip it.
10
BAJOREK:
The
Hydraulic
11
Institute,
12
interfacial and area concentration.
13
other large-diameter pipes for drift flux so there are
14
usually
15
experimental programs.
for
two
16
example,
or
we're
three
looking
at
work
for
We've run some
relatively
small-scale
The second one, there are provisions in
17
there
18
separate effects test work.
19
to pursue that and to go ahead is still yet to be
20
made.
21
forward in a timely fashion.
for
doing
some
integral
test
work
or
some
The decision on whether
But it is a mechanism to allow us to move
22
As I think Joe Kelly put up in one of his
23
timelines, we need to have this model ready in 2013.
24
If you start marching backwards in terms of assessing
25
the data, developing the models, building facilities,
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1
the time to get going is on us if not already behind
2
us.
3
MEMBER
Do
organizations,
I
either
these
have
test
facilities
5
facilities with medium- and high-temperature gas?
MR. BAJOREK:
mean,
of
4
6
--
ARMIJO:
Not specifically, no.
At
7
the end of the presentation -- and if you flip back to
8
the next to the last page -- I've put a table in
9
there.
It is two pages.
And it shows the major
10
thermal fluids facilities available for gas reactor
11
processes that I am going to go over.
12
One,
it's
only
two
pages
long.
There
13
aren't too many of them.
14
organization that runs them, there aren't too many in
15
the U.S.
16
U.S. outside of Idaho and Argonne on that list.
17
they are relatively few and far between.
18
And if you look at the
In fact, I don't think there are any in the
So
One thing I would say for work that we
19
have
20
megawatt
21
requirements for doing a number of tests that were on
22
the
23
AP1000.
done
order
24
25
with
DC
of
Oregon
power
the
State
supply,
APEX
is
okay,
facility
CHAIR CORRADINI:
they
have
and
that
the
we
a
one
steam
used
for
But just to be -- to say
it differently, just point of information, so one is
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1
essentially the old PUMA -- oh, PUMA, I've got it
2
wrong -- PANDA -- I'll get it right.
3
4
MR. BAJOREK:
time.
You were right the first
PUMA.
5
CHAIR CORRADINI:
I'm sorry, I got a P --
6
I got my Ps confused.
7
facility and derivatives thereof.
8
is the APEX facility and derivatives thereof.
9
The first one is the PUMA
MR. BAJOREK:
And the second one
Right?
Correct.
10
CHAIR CORRADINI:
11
MR. BAJOREK:
Okay.
And a lot of -- at least the
12
thermal hydraulic work, having the steam, having the
13
electrical supply, you know, DC current, high current,
14
sitting in a low ripple power I think gives you a lot
15
of capability.
16
we've used at least in that work up until now.
17
18
So that's, you know, one aspect that
MR. KRESS:
we used a lot of electrical simulators for fuel.
19
MR. BAJOREK:
20
MR. KRESS:
21
With LWR integral experiments,
Yes.
What are you going to do for
pebble beds?
22
MR. BAJOREK:
That's a tough one.
We've
23
talked about this.
24
that
25
graphite heater where the central reflector was, push
have
been
One idea -- there are two things
done.
One
has
been
to
put
in
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a
196
1
the pebbles, and measure the temperatures on the other
2
side.
3
but not really heating the pebbles.
But that is instrumenting a few of the pebbles
4
One idea that, you know, I've thrown out
5
to a few people, is creating a heater that you might
6
want to think of as meatballs on a shish kebab skewer.
7
You can bring in the electrode, put the windings, and
8
then build an encasement around each of those.
9
Of course, you don't get to shuffle the
10
balls
around
11
Something like that might be feasible.
12
13
and
CHAIR
change
porosity
CORRADINI:
That
very
has
easy.
been
done
before for debris bed cooling --
14
MR. BAJOREK:
15
CHAIR CORRADINI:
16
MR. BAJOREK:
17
CHAIR
18
the
Okay.
-- for many years --
Okay.
CORRADINI:
--in
simulated
experiments both for the LMFBR days and the LWRs.
19
MR.
BAJOREK:
Okay.
But,
you
know,
20
something like that would give us a way of giving
21
power to the balls and instrumenting those.
22
know,
23
electrical fuel rod simulators for reflood experiments
24
that it is certainly different and may be much more
25
difficult to fabricate.
I'd
have
to
imagine
at
least
But, you
compared
to
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1
Something that I think we might have to
2
take a look at, if we're looking at packed beds of
3
some
4
reflector,
5
impact, they're going to give us much different heat
6
transfer and pressure drops that we would out in the
7
far field, out in the center of that.
type
8
9
of
a
where
size
where
bypass
is
conditions
going
to
near
have
a
the
major
But it is an area that we're interested
in.
We've talked about it.
But with the preliminary
10
nature of the development work at this point, we don't
11
have an answer to how you do that yet.
12
MR. KRESS:
Thanks.
13
MR. BAJOREK:
I appreciate that.
What I'm going to do on the
14
next
15
parameters or, excuse me, the phenomena and processes
16
from the PIRT that were identified in thermal fluids
17
areas as being highly important but having a fairly
18
low knowledge level.
19
related to that.
three
or
four
slides
is
just
outline
the
And just a couple of the issues
20
What I'm going to do next then is I'm
21
going to take each one of these four major issues and
22
lay out what are the problems that we see in those and
23
what is going to be our general approach to what those
24
are.
25
relatively quickly just to save time and not duplicate
So I'll go through these next couple of slides
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198
1
the effort here.
2
Four areas, the first of which would be
3
the core and the vessel thermal fluids area, we can
4
talk
5
conductivity question --
about,
6
7
you
know,
the
MR. KRESS:
effect
of
thermal
Does that thermal conductivity
include radiation heat transfer?
8
MR. BAJOREK:
9
MR.
10
core
All three of them.
KRESS:
So
it
is
a
function
of
function
of
temperature then?
11
MR. BAJOREK:
12
MR. KRESS:
13
MR.
Yes.
Okay.
BAJOREK:
It
is
a
14
temperature, emissivity of the surrounding media, the
15
fluid
16
because this is kind of useful to that question and
17
the core and the vessel questions.
18
challenges in thermal fluids areas?
properties
as
well.
I'll
jump
ahead
here
Where do you get
19
In each one of the major paths for heat
20
flow from the core all the way out to the concrete,
21
you
22
convection are all important in various parts of that
23
half.
24
of flow-types of conditions where natural convection
25
is the dominant convective mechanism, now you start to
will
find
that
radiation,
conduction,
and
Now especially when you start to go to the loss
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199
1
find that radiation, convection, and conduction, they
2
kind of compete with each other.
3
mode
4
dominant.
5
dominant.
problem.
In
In
some
other
cases,
cases,
the
It is a combined
radiation
could
convection
can
be
be
6
But because you are looking at relatively
7
small differences between those two or three different
8
processes, it is difficult to assert in your models
9
whether you are compensating one or the other.
Or
10
whether you are getting all three of those processes
11
correct at the same time.
12
And you see that not only in the core
13
where
14
thermal radiation is carrying most of the heat -- 60,
15
70 percent or so.
16
the
17
relatively small amounts bu they are all in there.
for
rest
18
19
depressurized
of
loss
of
forced
cooling,
Conduction through the gas, most of
that,
pellet-to-pellet
conduction
And depending on the accident, one may be
more important than the other.
20
21
a
MR. KRESS:
Do pellets actually have a
contact area?
22
MR. BAJOREK:
Very small.
In some of the
23
work that we've done so far, they've looked at the --
24
those three different paths and that pellet to pellet
25
is almost negligible compared to everything.
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200
1
Some
of
the
existing
models,
though,
2
however, say that that term is dependent on I guess
3
they call it the pellet pressure.
4
many pellets --
5
6
MR. KRESS:
9
How many bottles are smashing
down on it?
7
8
It depends on how
MR. BAJOREK:
dependent
parameter
Oh, yes, so it is a scaling
and
those
have
been
based
on
relatively small-scale beds.
10
Now we're looking at now something with
11
several hundred thousand pellets, eight meters high.
12
That parameter might be a little bit more important.
13
But I think at this point in looking at it, we would
14
still look at radiation and conduction as being those
15
major contributors.
16
17
MR. KRESS:
the void fraction?
18
MR. BAJOREK:
19
MR. KRESS:
20
23
MR.
So you would need to know the
BAJOREK:
You've
got
to
know
the
porosity, the emissivity, the gas thermal properties.
There are five or six different parameters.
24
25
Yes, oh yes.
packing fraction.
21
22
Those things will depend on
MEMBER ARMIJO:
But the variability of the
geometry of all those pebbles as a function of height
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1
from the top to the bottom, is that all included in
2
your analysis?
Is that what you are going to try and
3
be able to do?
How do you do that?
4
MR. BAJOREK:
5
MEMBER ARMIJO:
6
says this is what you are going to have?
7
In the analysis --
MR. BAJOREK:
Is there an input that
Or --
In the evaluation model, at
8
least as I understand it, as we model the reactor, the
9
various rings or regions of that reactor could have
10
different porosities.
11
porosity near the radial reflectors, near the walls,
12
than there would be in the center.
13
14
There will likely be a high
How that varies from the top to bottom, I
haven't heard.
15
MEMBER ARMIJO:
Is there already a model
16
existing that DOE has or Idaho or somebody that could
17
be an input to yours?
18
And you can verify it?
MR. BAJOREK:
Yes, I don't know if it was
19
on one of those earlier diagrams with the evaluation
20
model.
21
I think it is called Peb. Bed.
CHAIR CORRADINI:
22
model that people are using.
23
verified is --
24
25
MR. BAJOREK:
There is a South African
Whether or not it is
They are using that model --
I mean there is a code that is under development to
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1
try
to
estimate
2
porosities in there.
3
the
flow
of
pebbles
in
the
local
But --
MEMBER ABDEL-KHALIK:
But the conduction
4
part, these are all sort of mono-dispersed beds.
5
there must be, you know, a lot of old data for the
6
conduction part which you can separate from the total
7
effect of conductivity if you want to validate the
8
data.
9
And
The radiation part, I can see will be very
10
difficult
11
dependent.
12
how the particles are arranged.
13
because,
you
know,
it
is
few-factor-
And that will just depend on, you know,
MR. BAJOREK:
Yes, the correlations that I
14
am familiar with generally use a porosity.
15
emissivity
16
uncertainty contributors.
17
we are aware of.
18
that in the long term.
19
as
a
couple
of
the
major
And the
variables
or
It's, you know, something
We are going to have to look into
But you are right.
There are models and
20
correlations that are there.
21
not necessarily for helium and its conductivity --
22
usually for air, nitrogen, I think argon, things which
23
are of more interest to the chemical industry, you
24
know, and their use of packed beds.
25
So
we
have
to
They have been developed
make
sure
that
those
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203
1
correlations
are
2
temperatures
likely
3
But
4
contribution.
radiation
5
6
applicable
than
could
MR. KELLY:
they
to
have
actually
much
been
have
higher
developed.
a
higher
This is Joe Kelly in Research.
Maybe I can put that into perspective a little.
7
At the temperatures you see in a D-LOFC,
8
now these are not exact numbers but they are close --
9
the radiation component would give you an effective
10
thermal conductivity of 20.
11
pellets, through the pebbles, through the gas for the
12
next one, about five.
Conductivity through the
13
And pebble-to-pebble contact, about one.
14
So the uncertainty -- I mean the value of
15
the pebble-to-pebble is less than the uncertainty in
16
the radiation part.
17
MEMBER ABDEL-KHALIK:
It is sort of the
18
same problem as the dry cask storage where you have to
19
worry about both conduction and radiation.
20
MR. BAJOREK:
And back to the issue of the
21
porosity, there is a large database in the chemical
22
process industry because they use packed beds all the
23
time.
24
go away from a wall.
25
about five pebble widths.
And it kind of like a damped sine wave as you
And is, in effect, going in
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1
Now in our case, we've got two walls.
And
2
if you look at the current PBMR-400 design, it is only
3
15 pebbles across the annular core.
4
Now
you
can
take
Okay.
those
models
for
the
5
varying porosities, put that into your porous body
6
code.
7
coefficient is right because those are developed for a
8
bed as a whole, not for reaching of higher porosity.
But
then
you
are
not
sure
if
your
drag
9
And one of the things we've done at this
10
point in CFD is to model the region of the porous bed
11
near a wall.
12
that are significantly less in the KTA rules.
13
that's one of the things that we are going to have to
14
look at to see what the radial profile of the flow
15
rate is.
16
And what we get are loss coefficients
So
Okay, so to kind of move ahead, I think
17
we've kind of covered the core and vessel.
18
are
19
emissivity.
20
are well aware that bypass, you know, what goes on
21
near
22
considerably different and yield much different fuel
23
temperatures, which is ultimately what we need to get
24
at.
going
25
the
to
be
important.
We
need
Properties
to
know
the
We need to know the porosity because we
wall
and
away
from
the
wall
can
be
Air ingress, I'll talk about this a little
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1
bit more in our approach, a couple of the issues that
2
are raised here are what we called duct exchange flow
3
or
4
molecular
5
little bit over the past few years where it used to be
6
people were considered mainly with diffusion effects,
7
air diffusing into the lower plenum and throughout the
8
system.
lock
exchange
flow.
That
diffusion
in
things
9
More
that
recently
I
think
contributes
have
it
with
changed
has
kind
a
of
10
dawned on everybody that that way of thinking came
11
about because the pipes were at the bottom of the
12
vessel.
13
If the cross-connect pipes are over on the
14
side, now we have this lock exchange flow which is a
15
term comes from civil engineering, looking at cold
16
water flowing underneath warm water in a stream or a
17
river.
18
into they system much rapidly as helium escapes.
In much the same way, we can get air moving
19
So duct exchange flow is a phenomena that
20
we're very interested in because now this brings air
21
and
22
potentially the fuel within several minutes following
23
a break to the system as opposed to several hours as
24
had been the viewpoint several years ago.
25
CHAIR CORRADINI:
oxygen
in
contact
with
the
structures
and
Is that independent of
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1
the break size?
2
I would think not.
MR. BAJOREK:
Not, not necessarily.
Could
3
I hold off on that because I have a couple of figures
4
that we'll talk about -- about what we're looking at
5
in that area.
6
7
MEMBER ABDEL-KHALIK:
been given to the building being inerted.
8
9
And no thought had
MR. BAJOREK:
Not that I am aware of.
I
haven't seen that suggestion.
10
So
right
now,
because
that
and
because
we
can't
always
11
guarantee
12
scenarios
13
confinement, we're still going to need to build that
14
into our evaluation models.
15
we'd have to go there.
where
you
would
there
have
may
be
accident
oxygen
in
the
Even if it were inert,
16
RCCS performance, this was another set of
17
phenomena that were highly ranked but relatively low
18
phenomena,
19
because of those properties and behavior of the RCCS,
20
potentially a participating media.
again
dominated
by
thermal
radiation
21
If we have this graphite dust being blown
22
out of the reactor vessel into the cavity, it is going
23
to change the problem from one of surface-to-surface
24
radiation
with
25
would
participating
be
convection
to
and
one
where
capturing
that
some
media
of
the
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207
1
thermal radiation changing the flow.
2
RCCS failure assumptions which could lead
3
to either a symmetry if we fail one out of the two
4
RCCS tube banks, which are a part of the system, or if
5
you fail both of those in a very much beyond-design
6
basis event where now the concrete thermal response
7
might come in to play.
8
9
MR. KRESS:
Isn't the dust likely to be
gone before you really need to calculate this?
10
MR. BAJOREK:
11
MR. KRESS:
12
MR. BAJOREK:
13
Okay.
MR. KRESS:
15
MR. BAJOREK:
MR. KRESS:
MR.
BAJOREK:
MR. KRESS:
We
think
so
but
that's
It may effect the transient
early on.
23
MR. BAJOREK:
24
Internal
25
So you're worried about the
something that we're going to have to --
21
22
By the time the fuel gets up
maximum temperature.
19
20
Yes, a little bit early on.
to its maximum temperature --
17
18
I think it is going to be
something early on.
14
16
I think so.
Yes.
side
heat
transfer,
the
RCCS
processes that were identified were parallel channel
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208
1
interactions, instabilities in the tubing, and some of
2
what I would call just normal uncertainties associated
3
with boiling.
4
One
where
we've
actually
concerned
5
ourselves a bit more over the last several months has
6
been the one that we've referred to as graphite dust.
7
I think you've heard at this point a lot of where
8
this is fitting in.
9
From the fuel standpoint where graphite
10
dust is a sink for the fission products, we are -- our
11
question there is how much of the fission products
12
diffuse through the pellets or the fuel and can become
13
embedded in the graphite dust?
14
We would look to the graphite research to
15
help us understand how quickly the dust is generated,
16
what is the size of those particles, what is the shape
17
of those particles?
18
what we're interested in is from the thermal fluids
19
standpoint
20
transported through and out the system.
21
is
Okay.
how
It could effect -- because
easily
those
particles
are
So that's from the thermal fluids point of
22
view, graphite dust is a twofold problem.
One, its
23
effect
and
24
participating media that we just talked about.
25
for us to determine either the correlations or develop
on
circulation
within
the
cavity
the
But
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1
the data that would help us develop models for MELCOR
2
to tell us how much of that dust, once we know where
3
it is at, is transported out into the confinement and
4
throughout
5
filter system.
the
6
7
system
potentially
CHAIR CORRADINI:
MEMBER BLEY:
9
CHAIR CORRADINI:
cavity
What about a combustion
Explosion.
Well, let's just call it
a combustion hazard.
11
12
the
hazard?
8
10
into
MR. BAJOREK:
Could I hold off on that
just as a --
13
CHAIR CORRADINI:
Well, the reason I asked
14
the question is you've said this is just -- you called
15
it a PBR?
I don't remember what you called it.
16
MR. BAJOREK:
17
CHAIR CORRADINI:
18
MR. BAJOREK:
19
Pebble bed.
Why is it just that?
Oh, we don't think there is
going to be a whole lot of dust for a prismatic.
20
CHAIR CORRADINI:
21
MR. BAJOREK:
Why?
You don't have the relative
22
motion between the graphite to the extent that you do
23
in a pebble bed.
24
25
CHAIR
CORRADINI:
phenomenological dust generator?
And
that's
the
You're not going to
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1
have high velocity helium gas going through the duct
2
work continually eroding, smoothing corners?
3
MR. BAJOREK:
In taking a look at the AVR
4
experiments, okay, there was evidence that there was a
5
considerable amount of graphite dust.
6
they have see that in the HTTR.
7
CHAIR CORRADINI:
I don't think
What is a considerable -
8
- just so I -- I don't even know historically what did
9
they consider a considerable amount?
10
kilograms?
MR. BAJOREK:
I think it is on the order
of several dozen kilograms.
13
MR. RUBIN:
14
MR. BAJOREK:
15
Ten
A hundred kilograms?
11
12
A kilogram?
kilograms.
It's like 20 or more I think.
Yes.
It was several dozen
I don't remember the number.
16
Since you asked the question, I'll jump
17
ahead on the graphite dust.
18
is we've basically done a literature survey to help us
19
characterize
20
think
21
distribution has been seen.
the
someone
amounts
talked
--
about
What we have done so far
several
kilograms.
the
to
.6
six,
I
size
22
A lot of uncertainty on whether that was
23
prototypical of the fuel that we are going to see,
24
okay, but that is what we have to go on at this point.
25
So
we're
at
least
looking
at
that
as
a
starting
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1
point.
2
But as you pointed out, one of the things
3
that has popped out of our initial literature survey
4
is that of detonation or combustion.
5
three things for detonation.
6
You
have
to
have
You kind of need
a
7
concentration of a combustible particle.
8
dust, for example, graphite, sugar --
9
PARTICIPANT:
10
11
MR.
sufficient
Okay, coal
Flour.
KRESS:
Yes,
almost
any
burning
material.
12
MR. BAJOREK:
Yes, something with carbon
13
in it.
14
an oxidizing agent, oxygen, okay, and you need to have
15
an ignition temperature at least in to -- the question
16
to the person who was in charge of this, can we rule
17
this out?
18
least have all three of those.
19
You need to have that.
And you need to have
And his answer was well, not yet.
Now
whether
that
is
a
major
You at
issue
or
20
concern in the long run, we don't know.
21
something that we are going to have to address or at
22
least we are going to have to go back to the applicant
23
and ask them to address that because we have not been
24
able to rule it out at this point.
25
MR. KRESS:
But it is
When we transport aerosols and
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1
LWRs,
2
particles, the assumption is that they stick together.
3
Is that a good assumption for this graphite dust do
4
they
manage
MR. BAJOREK:
touch
each
other,
the
They aglomerate.
I don't
know.
7
MEMBER BLEY:
8
MR. KRESS:
9
to
you think?
5
6
if
They are charged.
Yes, they are charged.
That's
why -- you would expect that would keep them from
10
touching each other even.
11
know if there have been any experiments on that or
12
not.
But I don't know.
13
MR. BAJOREK:
14
CHAIR CORRADINI:
I don't
Okay.
The reason that I asked
15
the original question though was the energy content of
16
a
17
equivalent of the pressurization of all of the helium.
18
You can double your peak pressure in any building you
19
build but you have to consider based on just a few
20
dozen kilograms of graphite combusting.
few
21
dozen
kilograms
of
graphite
dust
is
the
The detonation doesn't worry me because
22
you've got all of this helium buffer.
23
almost like a cold burning accident versus a cold
24
detonation accident.
25
MR. BAJOREK:
Right.
It would be
But it is an issue
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1
that I think has gained more visibility over the last
2
couple of years.
3
reports that PBMR, Incorporated is looking -- actively
4
looking into this.
5
The group that went to South Africa
So it is something -- it is on our radar
6
screen.
7
have to make sure our codes can at least transport and
8
track
9
incorporate its effects on the natural circulation and
10
We're going to follow it.
the
location
of
the
We're going to
graphite
dust
and
everything else that goes in the system.
11
With respect to core and vessel thermal
12
fluids, our approach --
we've initiated a project now
13
using CFD to look at existing correlations to examine
14
some sensitivities in the core.
15
mentioned this is how we've determined that there are
16
near-wall and far-wall effects.
I think Joe just
17
We've used CFD to help say that hey, this
18
is a sensitivity that we are going to have to be very
19
sensitive to.
20
properties.
21
We've also taken a look at gas mixture
Very early on we wanted to try to make
22
sure
23
generic to a prismatic or a pebble bed.
24
getting
25
various constituent gases.
--
we
were
looking
properties
right,
at
things
mixture
which
rules
could
be
You know
for
these
So we've identified those.
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1
And I think those are going into MELCOR at this time.
2
Our next approach would be to take a look
3
at applicant and DOE data in order to benchmark and
4
assess the models that go into MELCOR.
5
to be insufficient or come too late in the schedule,
6
we would consider running our own separate effects
7
tests.
8
Okay.
9
MEMBER ARMIJO:
10
If those prove
I'm going to jump over that.
Good.
I didn't understand
that picture anyway.
11
MR. BAJOREK:
Air ingress, we've already
12
talked a little bit about lock exchange.
13
process where we are concerned about the counter flow
14
of fluids with different densities, their ability to
15
flow past one another.
16
This is the
As we mentioned, the initial view had been
17
that air ingress was diffusion limited.
18
start
19
orientation,
principally
horizontal,
20
finding
yes,
get
21
significantly early.
22
process that is relatively difficult to calculate.
to
take
that
a
look
we
can
at
breaks
air
But as we
of
into
different
we've
the
been
system
Just recognize that this is a
23
Other issues with respect to air ingress
24
is there's not a tremendous amount of information on
25
natural circulation in a scaled facility.
This might
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1
also feed back on concerns about flow distributions
2
coming into and out of the core.
Okay.
3
We have calculations that suggest there
4
are certainly differences between near-wall and far-
5
wall.
6
upper plenum if you define the geometry.
You may be able to do CFD calculations for an
7
But no one has been able to go and measure
8
velocity distributions in tests like HTR, HTTR that
9
gives us the ability to benchmark the codes and give
10
us some of the assumptions that we might want to even
11
bias
12
conservative.
13
major shortcoming in addition to getting similar types
14
of natural circulation conditions and flow patterns in
15
a reactor cavity so that we are able to evaluate the
16
RCCS performance.
our
models
17
in
order
to
make
sure
they
are
So that's -- we recognize that is a
Graphite oxidation also identified as an
18
issue in the evaluation model.
19
MEMBER
ABDEL-KHALIK:
Could
you
just
20
explain to me this locks change process?
21
you have to totally depressurize the system before --
22
MR. BAJOREK:
23
MEMBER
24
takes place?
25
And wouldn't
Yes.
ABDEL-KHALIK:
--
this
process
So it really is much later -MR. BAJOREK:
It's early.
It would be
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1
right after what we would call a blow-down phase.
2
wouldn't -- you know, if there was a rupture to the
3
system --
4
MEMBER ABDEL-KHALIK:
5
MR.
BAJOREK:
--
We
Right.
you
would
vent
down
6
fairly rapidly depending on the size of the break.
7
Once that has -- once you've reached an equilibrium
8
pressure between the vessel and the confinement, then
9
this lock exchange would occur.
10
MEMBER ABDEL-KHALIK:
11
MR.
12
calculations,
13
accident.
14
15
BAJOREK:
we're
MEMBER
If
looking
at
recall
minutes
But
the
into
it
an
is
a
concentration gradient-driven process.
MR. BAJOREK:
17
MEMBER ABDEL-KHALIK:
Yes.
So it is a diffusion
process.
19
20
I
ABDEL-KHALIK:
16
18
Okay.
MR. BAJOREK:
Diffusion but also density
different.
21
MEMBER ABDEL-KHALIK:
22
MR. BAJOREK:
Oh, I see.
Okay, the helium is at say
23
an outlet temperature of 900, 1000 degrees C.
24
the air is sitting in the confinement at 100 degrees
25
C.
Well,
And just because the difference in those fluids,
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1
there is a considerable density difference between the
2
nitrogen or the air and the helium.
3
CHAIR CORRADINI:
But back to my original
4
question about this -- he brought it up -- it's his
5
fault -- if I'm pointed down, it is purely diffusion.
6
If I'm pointed up, the buoyancy-driven plume would
7
augment it.
8
9
If I'm sideways, I would think that it is
break
size
dependent.
If
I
have
a
little
break,
10
frictional effects could shut it down then it just
11
goes back to diffusion.
12
could have essentially two counter-flowing streams.
13
MR. BAJOREK:
If I have a big hole, then I
Break area -- yes, break
14
size is going to be part of it as well as break
15
orientation.
16
MEMBER RAY:
17
CHAIR CORRADINI:
18
I just want to make sure
I understood, that's all.
19
MR. BAJOREK:
20
MEMBER RAY:
21
Is there no break --
Yes.
Is there no break in the head
area assumed?
22
MR. BAJOREK:
That's a good point because
23
what we have done is we've kind of run with that
24
question a little bit.
25
other CFD.
We've seen some results from
What happens if you have a break in the
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1
large counter-flow pipe.
2
Okay, well we go back to this classic lock
3
exchange in a great big flow area.
Well, one of the
4
questions that we had following well, there is a lot
5
of penetrations in the upper head.
6
pebbles have to come in.
That's where the
7
So we said well, is this also a concern?
8
So part of our early approach in trying to understand
9
the
issues
better
is
we
used
a
--
well,
we
had
10
somebody come and set up a CFD model and we asked him
11
to make a prototypical-sized upper head.
12
knew
13
dimensions.
the
14
hemisphere,
approximately
And we just
volume,
and
Get some prototypical temperatures of what
15
we might think is going on there.
16
down has ended, how quickly does air get into that
17
system?
18
kind of a significant amount?
19
show what some limited experimental data shows?
Okay.
Assume that blow-
And does it get into there with any
And could CFD kind of
20
And it is that you get the maximum of air
21
ingress into the system not for a horizontal situation
22
or a vertical situations.
23
But it is about 60 degrees.
And in calculations, we are able to come
24
fairly close to that.
25
show is for -- and I can't remember what size of a
And what these figures here
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1
break this was -- but, yes, if you do have a break in
2
the upper head where you would have a control rod
3
drive, you will have penetration of air in at least
4
the calculations were showing it was of the several
5
ten to 20 kilograms fairly early such that oxidation
6
in the vessel of any fuel up in that region would be
7
at least an issue or a concern to us.
8
9
MR. KRESS:
lock
exchange
coming
in,
10
reacting and getting hot, and hot air going out.
In
11
the long term, isn't that what you have?
12
meant
Early on, I was assuming this
you
MR. BAJOREK:
had
cold
air
Depending on where the break
13
is,
14
oxidizes the graphite structures, and that plume then
15
goes up into the core.
our
concern
16
MR.
17
somewhere, yes.
18
would
KRESS:
MR. BAJOREK:
be
that
And
the
gets
air
comes
trapped
up
in,
there
Well, I don't think it is
19
trapped
20
eventually go up through the core into the down-comer.
21
It would reverse the natural direction or the initial
22
there
but
the
circulation
pattern
would
direction of the flow.
23
But it wouldn't be one of the air coming
24
into the lower plenum and going back out.
25
going elsewhere into the system.
It would be
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In this set of calculations I had the --
2
she is a graduate student who did this -- model the
3
rest of the vessel and try to follow the plume down --
4
actually
5
plenum and back up.
going
down
the
down-comer
into
the
lower
6
So we were able to at least use CFD to
7
help get a handle on the problem and give us some
8
indication that yes, break orientation, break size are
9
going to be important on certainty contributors.
And
10
that we can't just write off breaks -- small breaks to
11
the top of the vessel right off hand.
12
have to do more work to rule those out of the design
13
basis.
We're going to
14
In terms of air ingress and kind of the
15
work that we've been doing at this point, I talked
16
about
17
understand what is going on.
18
our thermal hydraulics institute to set up a small
19
separate effects test where we would look at helium,
20
this lock exchange with helium within a vessel, air
21
outside of the vessel, and change the break area, the
22
orientation, and the break shape itself.
23
the
exploratory
CFD
calculations
to
help
us
We have started to use
When you set up these models in a code, do
24
you often want to assume that it is circular?
25
we want to know what happens if it is a larger crack.
Well,
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1
So we're trying to develop some of the database that
2
we are eventually going to be able to use to go to
3
MELCOR and give us what you might call a break model
4
or an air ingress model, give us indication on how
5
much air is going to get into the system if we know
6
the conditions inside and outside the system.
7
we're starting to move in that direction.
So
8
Outside of that, we would want to talk
9
with Department of Energy to deal with air ingress.
10
We feel that there is going to be a need for some type
11
of integral test system in order to look at air into
12
the system.
13
natural circulation and the processes within inside
14
the vessel.
15
And how that contributes or augments the
RCCS
performance,
issues
that
were
16
identified in the PIRT were one, a lack of prototypic
17
data for circulation within the cavity, how you would
18
model thermal radiation, a lot of uncertainty as to
19
what would be the emissivities of the vessel, the RCCS
20
panels themselves.
21
Again, you see this, especially in the
22
RCCS, but a number of the thermal fluids, lack of
23
data, insufficient data.
24
approach is first of all, we view this as being very
25
crucial,
very
important
This is an area that our
in
the
overall
success
of
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1
licensing a gas reactor design because this is our --
2
you know in a way one of the major heat sinks to the
3
system -- our intent here is to participate with the
4
work that is being planned at Argonne where they have
5
an RCCS test set up.
6
I
know
they
are
in
the
process
of
7
refurbishing that facility because of the size.
And
8
as far along as they are, it would be our intent to
9
participate in those tests, helping to outline what
10
needs to be -- what type of data we need to get out of
11
that and we would look forward to the interagency
12
agreement being in place so we could start dealing
13
with them more directly.
14
And, of course, the third avenue there is
15
if those tests were to go away or fall significantly
16
behind schedule, we would look to other test data,
17
possibly internationally or, unless we got forced into
18
running our own RCSS tests.
19
CHAIR CORRADINI:
So -- maybe this is the
20
wrong time to ask this question so I'll register it
21
then you can decide where to answer it.
22
At
what
point
23
inter-visitation
24
confirmatory information?
25
to
be
of
essentially
does
information
the
MOU
versus
allow
for
independent
I assume calculations have
separate
and
confirmatory.
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1
Experiments are essentially shared by this process?
2
MR. BAJOREK:
I believe that is what the
3
memorandum would allow.
That we would be sharing
4
data.
us
5
Department of Energy.
And
it
enables
6
Stu?
7
MR. RUBIN:
to
work
jointly
with
Yes, I mean we have a common
8
concern.
And we believe that the experiment type
9
Steve
talking
10
agree,
11
experiment, make sure it is set up right with proper
12
instrumentation and so forth.
13
to the data while we attend the tests.
was
we
14
will
about,
when
collaborate
CHAIR
that's
on
signed,
setting
up
they
that
And we'll have access
CORRADINI:
Right.
I
guess
my
15
question is a technical question and also in some
16
sense a licensing question about what sorts of things
17
are clearly confirmatory because you have to make an
18
independent
19
doing it with them.
20
21
judgment
about
safety
adequacy
versus
And I'm assuming calculations have to be
separate and experiments can be shared.
22
MR. BAJOREK:
Yes, well keep in mind that
23
the
24
evaluations is different from ours.
suite
25
of
codes
that
they
CHAIR CORRADINI:
are
using
for
their
Okay.
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1
MR. BAJOREK:
would
be
2
we
3
assessments.
4
the same correlations that they are using.
5
going to have independent calculations.
6
be confirmatory but how good our correlations are may
7
be
these
data,
doing
our
own
8
experimental data.
We aren't necessarily going to be using
pointing
9
taking
So what we would be doing is
back
to
a
jointly
CHAIR CORRADINI:
10
MR. BAJOREK:
11
Current
So we are
Those would
shared
set
of
Thank you.
Okay.
progress
with
RCCS
performance,
12
not as much as in the other areas.
13
preliminary CFD calculations to help us understand how
14
we would model this gray gas of the participating
15
media.
16
They
are
very
preliminary.
17
really have results on those yet.
18
plans have not be started yet.
19
that interagency agreement.
20
We've done some
We
don't
And experimental
So we have to wait for
Graphite dust, I think we talked about
21
some of this already.
22
operation,
23
significant
24
fission products.
25
abrasion,
amount
of
As we mentioned, during normal
vibrations,
could
generate
graphite
particles
with
a
the
We don't have a whole lot of experimental
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1
data on this yet.
2
out of the AVR.
3
graphite
4
ingress into the system.
5
graphite isn't necessarily the same as what we would
6
be using in the VHTR at Idaho.
dust
7
8
We've tried to glean what we could
But as we mentioned, some of that
may
have
MEMBER RAY:
been
due
to,
I
guess,
oil
And the pebbles and the
But I guess you are still on
graphite dust but --
9
MR. BAJOREK:
10
MEMBER
Yes.
RAY:
--
I
heard
the
exchange
11
earlier just speculating -- combustion isn't the word
12
I'm search for, Mike.
What is it?
13
CHAIR CORRADINI:
14
MEMBER RAY:
Detonation.
Detonation wasn't thought to
15
be an issue.
16
vessel.
17
the confinement building presumably where it is not so
18
obvious to me that it isn't a hazard there.
I interpreted that to be within the
But the blow-down transports this stuff into
19
Is anything that you are doing going to
20
look at that?
21
explosion kind of model?
22
You know in the classical flower silo
MR.
BAJOREK:
23
identified it as an issue.
24
plans.
25
how
At
this
point,
we've
We don't have any concrete
The first thing we need to do is to understand
much
is
being
generated
and
how
much
of
it
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1
actually gets transported from the vessel on out.
2
MEMBER RAY:
Okay.
All right.
But I
3
guess the point is you would consider it not just
4
within the vessel as a hazard.
5
MR. BAJOREK:
Oh, no.
No, actually the
6
initial thought was this would be a problem in the
7
reactor vessel cavity itself until we started to think
8
that gee, you can actually have air ingress very early
9
in time where you could have a higher concentration of
10
the particles.
11
So we are going to have to take a look at
12
in vessel and in the cavity and elsewhere within the
13
system.
14
and we haven't thought it through.
15
So it's -- but it is a relatively new issue
MR. LEE:
Steve, under the fission product
16
transport part -- this is Richard Lee from Research --
17
the dust explosion issues is addressed and the peer
18
reviewers have identified that as in the confinement.
19
So it is something that we will keep track
20
of under MELCOR because in the containment, carbon
21
dust explosion, that can be monitored easily.
22
need
23
particles, the easier you can combust it.
24
be evaluated.
to
25
know
is
what
MR. KRESS:
the
size.
The
Just we
finer
the
So that can
I'll bet you have to have an
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ignition source rather than self igniting.
2
do, I don't see that you get that inside the vessel.
3
4
MR. LEE:
MR. KRESS:
This is
Oh, in the confinement, you'd
probably have some ignition sources.
7
8
Not inside the vessel.
in the confinement.
5
6
And if you
MR.
LEE:
That
was
considered
by
the
experts.
9
MR. KRESS:
10
question
11
happening in there.
12
about
in
Yes, I was just addressing his
the
MR. LEE:
vessel.
I
can't
see
it
And earlier you also asked about
13
the -- earlier someone asked about the content amount
14
of dust in the system, if you look at page eight in
15
the volume three report, it is between ten and 50
16
kilograms for the test reactor and the expert, the
17
peer review -- I mean the PIRT members thinks that for
18
the power reactor, it would be higher, maybe up to
19
about a factor of ten.
20
For prismatic reactor, it is a factor of
21
at least ten less.
22
of dust in kilograms.
23
That's the estimate for the amount
MR. BAJOREK:
So, you know, the graphite
24
dust and all of its issues, it is on our radar screen.
25
We are trying to get our hands around it at this
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1
point.
2
information, there is a lot of uncertainty in all of
3
these.
4
5
CHAIR
allotted time.
6
7
And it is clear that just on the preliminary
CORRADINI:
MR. BAJOREK:
your
So I'm not --
to jump.
9
MR. BAJOREK:
That's fine.
We've covered some of these.
I'm trying to be selective on -- I'm trying to pick
out the slides where I get the easiest questions.
12
13
over
Well, that's why I'm trying
CHAIR CORRADINI:
11
are
But Al seems very calm.
8
10
You
CHAIR CORRADINI:
That's fine.
I figured
that.
14
MR. BAJOREK:
Experimental database, one
15
of the things that we have started is to compile what
16
facilities would be very useful to us, what data could
17
be available if we get the right agreements.
18
As
I
mentioned,
we
are
trying
to
19
participate in a couple of international exercises.
20
One, the TAREF to identify experimental facilities,
21
try to gain access to some of that experimental data,
22
RAPHAELE, another project that is ongoing.
23
24
MR. KRESS:
Where is TAREF located?
T-A-
R-E-F, where is that located?
25
MR. BAJOREK:
Oh, that's part of CSNI.
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TAREF stands for Task on Advanced Reactor Experimental
2
--
3
4
MR. KRESS:
But I don't know where the experiment zone is.
5
6
Yes, but CSNI is in Paris.
MR. BAJOREK:
That's not a facility.
It's
a project.
7
MR. KRESS:
8
MR. BAJOREK:
9
MR. KRESS:
10
looking at experimental facilities.
11
Oh, it's a project.
It's a task.
I'm sorry.
MR. BAJOREK:
12
the scaling of it was?
13
MR. KRESS:
14
(Laughter.)
15
MR. KRESS:
16
MR. BAJOREK:
Okay.
I thought we were
You were going to ask what
Yes.
Okay.
Thank you.
Yes, this is basically the
17
major facilities that have been either operated, run,
18
or
19
emphasize
20
reactors, we would go on for several pages.
21
each one of those, we'd have lots of experimental
22
data, a number of tests which would be available for
23
us to develop evaluation models.
planned.
And
that
if
I
think
we
did
the
point
this
for
that
I
would
light
water
And for
24
If you go through this list, you'll find
25
basically there are -- you have tests at Idaho to help
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for CFD qualification, the Mear facility.
2
got the Argonne facility for RCCS.
3
And we've
Just about everything else on that list,
4
unless I missed something, is international.
5
overseas.
6
colleagues there to make that data available to us.
We need a partnership with some of our
7
8
MR. KRESS:
CSAR?
It is
This would be different from
Or would it follow under there?
9
MR. BAJOREK:
We don' necessarily get that
10
data through CSAR per some of those agreements.
11
have to pursue that.
12
experimental facilities out there to generate the data
13
even
14
temperature gas reactors.
if
everyone
15
So we
But there are relatively few
goes
and
starts
to
develop
high
But we are looking towards these to help
16
us
17
performance.
18
help us for air ingress, several proposed by PBMR,
19
Incorporated which would help us with some of the
20
vessel thermal fluids.
So we are looking at these as
21
potential
help
22
experimental needs.
with
23
24
potentially
integral
test,
RCCS
There are a couple there which would
avenues
to
MR. KRESS:
us
with
our
data
and
On your previous slide, there
are a lot of UTs out there.
25
effects
Which one is that?
(Laughter.)
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1
2
MR.
Basin.
This
is
like
UT
Western
I know I don't have that right.
3
4
BAJOREK:
CHAIR CORRADINI:
That's the reactor that
will never get built.
5
MR. BAJOREK:
Irving Basin -- I knew it
6
was some basin.
7
was it might be a prismatic but it is in the very,
8
very
9
debating whether to even keep it on this list at this
10
preliminary
point.
stages.
It
is
proposed.
I
was
But I just wanted it to be complete.
11
12
But that's the one, I think the idea
MEMBER
ARMIJO:
GA
doesn't
have
any
heating test facilities?
13
MR. BAJOREK:
They have some facilities
14
for
15
along those lines.
16
to
17
circulation in a large region, nothing that is going
18
to really help us on the evaluation model development.
looking
go
and
19
at
look
components,
pumps,
heat
exchangers,
But nothing where we would be able
at
core
thermal
CHAIR CORRADINI:
fluids
or
natural
Do you plan to have all
20
the
21
making -- when I asked Stu about things relative to
22
fuel,
23
conversation
about
24
their tests.
But eventually when there has to be fuel
25
--
let
his
me
reverse
answer
qualification,
my
was
they
fluence
they
are
last
question
haven't
and
going
time
to
since
started
and
enter
power
into
I'm
the
for
the
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1
conversation.
2
I assume DOE will be invited into your
3
conversation if you choose to do experiments about the
4
scaling of the experiments you do so that they might
5
share in the data so that there is an open discussion
6
about scaling, et cetera.
7
MR. BAJOREK:
8
CHAIR CORRADINI:
9
MR. BAJOREK:
10
Yes.
Is that correct?
Yes.
CHAIR CORRADINI:
Okay.
And then let's
11
take one of the examples, the RCCS.
Am I allowed to
12
ask in open session is it a water design, an air
13
design, or to be determined.
14
MR. RUBIN:
15
CHAIR CORRADINI:
16
MR.
17
Both.
RUBIN:
Both right now?
Both
designs
are
being
proposed.
18
CHAIR CORRADINI:
19
MR.
BAJOREK:
Open possibilities.
I
think
they
are
being
20
proposed but I thought the facility right now was
21
water.
22
23
MR. RUBIN:
But the vendors have
different --
24
25
Okay.
MR. KELLY:
Joe Kelly from Research.
When
we went to Idaho last spring and they showed us their
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experimental program, for the natural conduction test
2
facility, which is going to be the RCCS, they showed
3
planned experiments for both the natural convection
4
air
5
planning on doing both.
and
6
7
water.
So
at
the
moment,
they
were
But the status is they're just cleaning
out the old experiment from 20 years ago.
8
9
the
MR.
KRESS:
General
question
on
these
facilities --
10
MR. BAJOREK:
11
MR. KRESS:
look
at
the
Yes?
-- I recall there was once a
12
proposed
range
13
scaling analysis that would name a facility as an
14
appropriate scale, did anything ever come of that?
15
MR. BAJOREK:
16
water reactor facilities?
17
MR. KRESS:
18
MR. BAJOREK:
of
PIE
values
and
the
Oh, the one with the light
Yes.
Yes, the basic conclusion
19
out of that is after you do your scaling evaluation,
20
the better approach would be to look at that range of
21
PIE values for those higher-ranked values, set up a
22
conceptual model and range those because some of those
23
distortions --
24
25
MR. KRESS:
general for all of them.
Of course they wouldn't be
It would be specific to a
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given application I would think.
2
MR. BAJOREK:
3
MR. KRESS:
4
MR. BAJOREK:
5
MR. KRESS:
6
MR. BAJOREK:
Yes, yes.
Okay.
Yes.
I mean --
Thank you.
-- we did it for a boiling
7
water system but you could take that same general
8
approach for pressurized water, light water system,
9
you could do it for gas reactors.
10
11
MR. KRESS:
So it's --
I would assume there would be
something like that come up at some point.
12
MR. BAJOREK:
Yes.
And the scaling will
13
be an important question mark as we start to look at
14
the integral facilities because it is clear that you
15
don't want to have a facility full height and full
16
radial scale.
17
scale pebbles to get the five pellets away from the
18
wall and preserve everything.
You don't have the power.
How you
19
And it is almost inevitable that when we
20
scale this, there are going to have to be distortions
21
that are going to have to be dealt with.
22
group
23
investigating it.
24
25
ranging
Our
is
probably
outlook
on
the
the
And that PIE
right
way
infrastructure
of
or
experimental data needs, we find that the separate
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effects data exists for a number of these processes
2
but most of these are out of our reach.
3
either
4
international organizations.
5
pursue that data.
6
planned
We
by
DOE,
may
need
they're
in
the
They are
hands
of
We are going to have to
our
own
separate
effects
7
tests, possibly an interval test to fill in the blanks
8
between the needs that we have, which are looking at
9
regulatory criteria and in some cases looking at the
10
CLFs associated with the system.
11
We
are
interested
in
those
accident
12
scenarios which are design basis but also those ones
13
which go well beyond the design basis.
14
and the applicant is more focused on AOOs, anticipated
15
transients, and the design basis.
The designer
16
So our needs overlap but there are some
17
exclusive areas that we are going to have to take a
18
look at.
19
The
technical
staff
feels
that
we
are
20
going to need access to a well scaled integral effects
21
facility in order to look at things like multiple
22
system failures, CLF effects, system interactions.
23
The point that we like to make is that in
24
every other design certification, the staff has relied
25
upon
usually
not
one
but
several
scaled
integral
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1
facilities in which to draw its regulatory decisions
2
and develop evaluation models.
3
first-of-a-kind engineering that is going into the gas
4
reactor, we don't see that as being any different
5
here.
6
And because of the
So in summary, we have initiated some of
7
the thermal fluids research.
We are just scratching
8
the surface on a lot of these issues.
9
to identify what they are, what the data needs are
10
going to be, and where we are going to have to go from
11
here.
We are trying
Our primary focus is the evaluation model.
12
I haven't said a whole lot about CFD but
13
just to close with this, we are using CFD to help
14
guide our decisions.
15
intend to make it an integral part of the evaluation
16
model but depending on the issue, depending on the
17
design, we may have to augment our experimental data
18
needs in order to provide information to assess and
19
quantify CFD if we get into situations where we need
20
to know local details within the RCCS, a vessel wall,
21
lower plenum structures.
22
So
we're
As Joe pointed out, we don't
leaving
that
off
right
now.
23
We're not forgetting about it.
24
because we don't have enough design information in
25
order identify which specific tests we would want to
But that's primarily
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1
require for that situation or what might be the tool
2
we might need.
3
MR. KRESS:
In terms of your need for
4
integral experiments, is the fact that you are going
5
to
6
facility change your perspective on that?
7
used?
have
8
9
sort
of
CHAIR
a
demonstration
CORRADINI:
plant
Can
it
on
a
DOE
Can it be
be
the
experiment, is that what you are asking?
10
MR.
BAJOREK:
Well,
we
haven't
talked
11
about this and got the staff opinion.
12
you my two cents' worth on this.
13
nuclear core, you are limited on your instrumentation
14
and how risky you want to be.
So I'll give
When you have a
15
With AP 1000 and the APEX facility, the
16
electrically heated core, you could fail one valve
17
after the other after the other and if you got a
18
little bit too aggressive with the facility, we knew
19
that John Groom, the operator, was very quickly going
20
to go over there and hit that scram button and it
21
would be no problem.
22
you are using HTR or HTTR.
You don't have that liberty if
23
If I'm looking at tests that might involve
24
air ingress, you certainly can't use any kind of a
25
nuclear core.
But, you know, we're still going to
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need that type of experimental data.
2
And I think, especially for the pebble
3
bed, it is that question on instrumentation that is
4
going to be very, very difficult experimentally to
5
deal with.
6
are, we want to know what the flow distributions, both
7
into and out of the core, we are going to want to know
8
what the flows are out on the reactor cavity.
9
We want to know what those bypass flows
Whether you go with an optical technique
10
or
hot
wires
11
limitations on where you can effectively put those and
12
under what conditions they are going to last without
13
constant calibration.
14
15
or
CHAIR
thermocouples,
CORRADINI:
Okay.
(No response.)
17
CHAIR
CORRADINI:
Since
we're
other
a
bit
behind, thank you, Steve.
We'll turn it over to Allen.
20
MR.
We're okay.
NOTAFRANCESCO:
(Laughter.)
23
CHAIR CORRADINI:
sorry.
25
We're
not
behind.
We just messed up the timing, that's all.
22
24
their
Any
19
21
got
questions?
16
18
they've
Ready?
Go ahead.
I'm
I was just writing notes to myself.
MR.
NOTAFRANCESCO:
I'm
Allen
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1
Notafrancesco.
2
the
3
plan.
accident
4
I am going to give you the overview of
analysis
section
within
research
We are at a point where we are going at a
5
lower level and more detail.
6
the
7
details going into our analytical code.
status
8
9
the
of
the
I am going to provide
implementation
of
some
of
the
Some of this stuff was discussed already
as part of the evaluation
model.
Clearly we want to
10
-- the first bullet leads to that.
11
provide an evaluation model and develop validating,
12
utilize the accident source term and fission transport
13
analysis
14
licensing
15
release, dose assessment, and PRA analysis.
16
models,
in
tools,
the
knowledge,
various
areas
of
That we want to
and
support
fission
for
product
That's a big global evaluation model.
The
17
next bullet is really what I'm trying to do within
18
code space, integrate the fuel nuclear, the thermal
19
fluid models into an accident source term and fission
20
product transport analysis models and tools for the
21
evaluation of HTGR.
22
This is basically a diagram showing the
23
complexity from the fuel kernel outside the break, the
24
different processes and physics we need to capture in
25
the code.
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But the bottom line, we want to calculate
2
normal operation and transient behavior for the entire
3
system,
core,
4
thermal
fluids
5
transport
6
oxidation effects.
vessel,
and
the
processes,
7
As
confinement,
8
MELCOR code.
9
are there in place.
fission
including
mentioned
integrating
product
the
earlier,
dust
we
the
release
and
the
selected
the
Basically we believe a lot of the models
And it won't take too much to
10
modify.
11
accidents in one code.
And this way we can do DBA and beyond DBA
12
Okay, this slide, what this does is --
13
what I did is I took the PIRT on the left side --
14
these
15
them against some of the MELCOR packages to show you
16
that we have the modeling in place.
17
are
important
And
processes
we've
and
discussing
cross
referenced
burning,
possible
18
detonation, there are models in MELCOR.
19
they will have to be assessed based on the medium that
20
we're dealing with.
21
To
get
the
ball
rolling
in
Obviously
the
HTGR
22
analysis, we took on initial activities that we knew
23
were deficient.
24
INEL had a MELCOR version to look at HTGR.
25
who is the developer, is also doing the development,
And some of the key tasks we did was
Sandia,
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1
which the HTGR neglected to mention.
2
So Sandia got the INEL code.
3
at the models.
4
was
5
MELCOR.
to
look
6
And that's one task.
at
CHAIR
the
helium
They looked
The other task
properties
CORRADINI:
Al,
modeled
could
you
in
just
7
repeat what you said?
8
MELCOR 2.X that Idaho has as it was modified by Idaho.
9
I guess I'm -- so there is a
And Sandia is modifying the Idaho --
10
MR. NOTAFRANCESCO:
11
CHAIR CORRADINI:
12
MR. NOTAFRANCESCO:
No, no.
Okay.
-- it is an old model
13
so they are looking at it to see if there is any value
14
to taking anything out of it.
15
CHAIR CORRADINI:
16
MR. NOTAFRANCESCO:
17
CHAIR CORRADINI:
18
MR. NOTAFRANCESCO:
It's a 1.82.
19
CHAIR CORRADINI:
Okay, so you're using
20
MELCOR 1.82 modified by Idaho?
21
using --
Who is they?
Okay.
Or I should say DOE is
22
MR. NOTAFRANCESCO:
23
CHAIR CORRADINI:
24
MR. NOTAFRANCESCO:
25
2.1.
Sandia.
Right.
Okay.
Our current model is
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1
CHAIR CORRADINI:
And so the modifications
2
or the tool that the NRC is using is not the Idaho
3
MELCOR.
It's the modified Sandia code.
4
MR. NOTAFRANCESCO:
5
CHAIR CORRADINI:
6
MR.
I'll get into --
Okay.
NOTAFRANCESCO:
--
because
what
7
happened is since it was an old MELCOR model, there
8
were several tricks done to simulate things.
9
think things could be done better.
10
CHAIR CORRADINI:
11
MR.
And we
Okay.
NOTAFRANCESCO:
For
example,
the
12
second bullet is where we going to update the core
13
package.
And I'll get into a little detail on that.
14
CHAIR CORRADINI:
15
MR.
Oh.
NOTAFRANCESCO:
Okay.
Okay?
And
also
16
incorporate the graphite oxidation models of steam and
17
oxygen.
18
that have been pursued over the past year or so for
19
both the pebble bed and the prismatic designs.
20
So, again, those are the initial activities
Now where we are today is these initial
21
attempts, we've got the reports in house.
22
received them.
23
to provide you some initial status of when I read it.
24
They have to be peer reviewed and we'll have to get
25
back with Sandia because we see some little problems
We're looking at them now.
We just
I'm trying
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1
we need to pursue.
2
But basically there were two models from
3
the
INEL
modification
4
oxidation of graphite of heat structures and diffusion
5
of the air and helium.
6
that
Sandia
cited.
And
Right now we're not doing anything with
7
that but it was identified.
8
think we may have -- they used the correlation that is
9
in the literature for oxidation, for example, bu they
10
applied
11
directly.
it
to
heat
Nothing really useful.
structures,
not
to
the
I
core
But I'll get to that point.
12
The other thing is the helium properties
13
in MELCOR.
14
the ideal gas law modeling in MELCOR, trying to get
15
the density of helium, showed reasonable results.
16
that was positive.
17
That was compared against NIST data and
So
Just to expand the point on the updating
18
of the MELCOR Corp. core package.
19
light water reactor to what we see with these gas
20
reactors, we needed to customize the core in the sense
21
of
22
graphite as a core model, and the reflectors and stuff
23
like that.
24
be nodalized specifically for that whereas the INEL
25
work obviously we didn't have advantage of that.
geometry
and
materials
pretty
Clearly from a
much,
putting
in
So we've customized something that could
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1
This next slide, basically what I tried to
2
do was to glean the important phenomena.
3
that on the left side based on the PIRT, provided the
4
status
5
taken.
6
that we're making in that area.
of
where
are
and
the
approach
that
was
And you could tick off some of the progress
7
8
we
And I put
And, again, this phenomena was in that
NUREG for the status and our approach.
9
CHAIR CORRADINI:
10
The PIRT NUREG?
MR. NOTAFRANCESCO:
The PIRT NUREG.
So
11
what I did is I took what was the initial activities
12
we
13
implementation.
did,
take
14
the
processes,
MEMBER ABDEL-KHALIK:
and
correlate
our
Which bed effective
15
conductivity correlation or model has been added and
16
tested.
17
where Steve was talking about.
I mean that tells me that you're way ahead of
18
MR.
NOTAFRANCESCO:
Well,
we
have
a
19
correlation in there and we have discussions about
20
what type of correlation.
21
of -- it needs to be -- when I say tested, it means
22
that it is working in the code, not assessed against
23
data, okay?
So it's just a correlation
24
CHAIR CORRADINI:
25
MR. NOTAFRANCESCO:
It functions.
It functions.
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1
MEMBER BLEY:
2
MR. NOTAFRANCESCO:
3
The code generates stuff.
I was careful.
I said
tested, not assessed.
4
MR. BAJOREK:
Allan, this is Steve Bajork,
5
one of the things that I think we want to do with
6
MELCOR
7
operating soon.
8
testing out the models.
is
9
you
want
to
get
it
up
and
running
and
That gives you a way of at least
I think what it is using right now is
10
basically a debris bed porous media correlation.
11
comparison
12
Schl_nder, which is an effective thermal conductivity
13
for packed beds, it's not too far off.
14
between
that
correlation
and
In
Zehner-
So at least at this point, it gives you a
15
way of starting MELCOR.
16
have looked at the data would recommend that they put
17
in
18
similar to that --
19
MEMBER
something
like
20
temperature
21
highly nonlinear?
a
But I think those of us who
Zehner-Schl_nder
ABDEL-KHALIK:
effects
because
of
And
or
it
radiation
something
includes
so
it
is
22
MR. BAJOREK:
23
The German one accounts for things like
Which one?
24
emissivity and porocity effects.
25
believe it is only porocity.
The German one?
The one in MELCOR, I
Oh, excuse me, that's
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1
right, it is only temperature.
2
counts for several other parameters.
3
CHAIR CORRADINI:
But the German one
But to generalize what I
4
think we're hearing is is that when you say this has
5
been
6
functional in MELCOR to be tuned to the appropriate
7
data or basic information in the future.
8
fair way of putting it?
addressed,
9
that
is
they
that
model
--
Is that a
11
dominant,
12
would be highly non-linear in terms of its dependence
13
on
14
temperature dependence, you might be testing the code
15
and you may be getting conversions whereas if you have
16
a higher order correlation, it may not.
temperature.
17
would
And
if
case,
But I guess my
concern
you
this
Yes.
10
as
in
a
Okay.
MEMBER ABDEL-KHALIK:
is
made
say,
you
MR. NOTAFRANCESCO:
18
it, right.
19
the one we chose.
20
then
radiation
this
don't
is
correlation
have
the
right
This has radiation in
This modified Z-S has radiation, at least
MR. BAJOREK:
21
think it is in there.
22
empirical fit.
23
if
Well, the one in MELCOR, I
I think it is more of an
MR. NOTAFRANCESCO:
Right.
Conductivity
24
is not the -- that came out of the PIRT but we are
25
recognizing radiation as part of the process.
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1
MR. BAJOREK:
But I think you point is
2
that we're getting MELCOR operating at this point.
3
But, you know, selecting more appropriate correlations
4
is still an open issue.
5
MR. NOTAFRANCESCO:
Right.
We want to put
6
in the building blocks to build the plant at the end
7
of the day, get it going, and then we'll go back and
8
iterate.
9
analysis.
And
then
ultimately
how
we
do
10
So that was the early phase --
11
CHAIR CORRADINI:
a
plant
So can I torture you one
12
last -- or ask one last question to follow Steve's?
13
So here's where, I guess, I was going to ask -- here
14
is a good place to ask when you use -- Steve used the
15
term CFD to help guide, I assumed that somewhere in
16
this you will do a CFD calculation to help guide what
17
you might choose to do in this regard.
18
you
19
geometries and various temperatures and see what the
20
functional dependence would be.
would
actually
--
you
can
21
MR. NOTAFRANCESCO:
22
CHAIR CORRADINI:
23
this, right?
24
way.
25
Because then
essentially
in
Yes.
That is a way to attack
Not the right way necessarily.
MR.
put
NOTAFRANCESCO:
Well,
again,
But a
we're
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1
going to put the building blocks to make it work.
2
We'll use CFD later for insights to see how good our
3
models are.
4
built.
But as a minimum, we want to get a plant
5
CHAIR CORRADINI:
6
MR. NOTAFRANCESCO:
Great.
Fine.
And get the building
7
blocks in place.
That's the theme which you will see
8
here.
9
phase and the phase we have now is to do the rest of
And that's what we're doing -- is the initial
10
the plant.
11
and the pebble bed.
12
And when I say plant, both the prismatic
Sandia is working with Texas A&M to set up
13
the deck.
14
we're looking at.
15
subset for now just as a benchmark of reference.
16
obviously we'll conduct the assessments of relevant
17
data when available.
18
These are some of the accident classes
It's just we're taking a small
And
Also where we are currently in the plans
19
is to get Sandia PARFUME and TMAP4.
20
TMAP4.
21
line with this and with MELCOR in general is we're
22
going to take complex models and have it technically
23
consistent within the MELCOR framework.
24
25
They already have
They are going to analyze it.
And the bottom
We don't want something too detailed and
when the rest of the model is less detailed.
So what
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1
we're going to take insights from other sources and
2
embed it in MELCOR to get a calculation.
3
4
5
This
was
discussed
before.
The
other
thing that Texas A&M is to put some kind model for the
reactor and cavity and cooling system.
6
issues
were
7
cooling.
discussed
about
the
And these
make
up
of
the
8
Other issues we are going to go after is
9
the plant components, heat exchangers, gas turbines.
10
And
11
Sandia is pontificating now on how to model some sort
12
counter-current flow.
this
other
13
issue
about
CHAIR CORRADINI:
air
ingress
modeling,
That's a good word.
I
14
was going to say usually the noun in from of that is
15
not that noun.
16
17
MR.
NOTAFRANCESCO:
Well,
until
I
see
results, I'll use words like that.
18
Other
plant
activities
we're
going
to
19
chase
20
resuspension
21
benchmarking experimental validation, that was touched
22
on before.
23
after
is
the
modeling,
fission
product
identifying
liftoff
the
areas
and
of
These transients are going to be slow and
24
long.
25
pursing in MELCOR space is trying to look at different
So one of the issues we're also going to be
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1
runtime
optimizations,
2
parallelizations, and other schemes to make it run
3
faster.
4
Again,
in
what
I've
format
steps,
done
the
here
is
code
just
phenomena
I
to
5
summarize
6
discussed: the status and our plan of approach.
7
to be more organized in all the phenomena that is
8
perking out there and demonstrate to you guys that
9
were insistent with the PIRT.
10
PIRT
time
just
And
In summary, we have made progress with
11
MELCOR 2.1.
12
PIRT.
13
mentioned
14
coordination with the other programs to make sure we
15
are a success.
And we're going to be consistent with the
And follow the assessment activities.
before,
we
are
going
to
have
16
So that ends my presentation.
17
CHAIR CORRADINI:
18
Dr. Lee?
19
MR. LEE:
Good.
And as
extensive
Questions?
Tom, you asked about the cesium
20
form.
Doing the PIRT we discussed about the cesium
21
form.
Basically in the reactor system itself, this
22
will be a metallic form because it is a helium system.
23
Once it gets out into confinement, it would be an
24
oxide form.
25
CHAIR CORRADINI:
And does that impact
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1
what could be combustion and essentially would have
2
been vaporized and be transported out of the particle?
3
MR. LEE:
We can consider everything under
4
MELCOR frameworks.
5
have data to support it.
6
7
MR. KRESS:
form?
How is it that it was in metal
Why doesn't it combine with the iodine?
8
9
It's not a problem as long as you
MR. LEE:
I think all of these things
going to be considered to see what there is.
10
the
11
graphite?
12
answer.
13
very closely.
cesium
also,
how
does
it
interacts
Because
with
the
That's a major questions that we have to
That's why we talked to the graphite research
14
Dana
Powers
mentioned
about
what
he
15
observed in the end reactors, how the graphites look
16
like.
17
the behaviors.
18
all of these so we may do some detail modelings.
19
then try to take some simplified treatment under the
20
Melcor framework.
There are some tunnelings appearing because of
21
22
MR.
So we need to
KRESS:
how we can account for
Weren't
there
And
some
resuspension tasks in the CSAR program?
23
MR. LEE:
The resuspension, we are looking
24
in the resuspension not just for gas reactor but for
25
light
water
reactor,
especially
with
the
acoustic
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1
vibration type resuspension.
And we are pursuing that
2
with the PSI Porche Institute because they are doing
3
some separate effects experiment.
4
So under the cooperative severe accident
5
research framework, we are going to be discussing with
6
them to do this resuspension experiment.
7
meantime, we can also ask them to put some carbon on
8
those surfaces.
9
treatment.
10
an aerosol.
11
So in the
And look at the in treatment and
So it is the same thing. It's treatment as
So we will be doing those.
CHAIR
CORRADINI:
Okay.
Let's
12
break if we might.
13
to move up the hydrogen analysis discussion?
14
15
Is that all right?
take
a
Or do you want
Sud, do you want to make that call?
Stu
is pointing at you.
16
MR. BASU:
17
CHAIR CORRADINI:
18
suggest
19
right.
we
take
a
I'm okay.
break
Well, I was going to
until
20
MR. BASU:
21
CHAIR CORRADINI:
Do you want to --
3:15
if
that's
all
Yes, that's fine.
All right.
Good.
Let's
22
take a break then.
23
(Whereupon, the foregoing matter went off the record
24
at 2:56 p.m. and went back on
25
the record at 3:17 p.m.)
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1
CHAIR CORRADINI:
2
So
3
Dr.
Basu
is
Let's get started.
the
stand
in
for
Mr.
Hudson.
4
MR. BASU:
Yes.
5
CHAIR CORRADINI:
6
MR. BASU:
Sud?
Thank you.
I think somebody
7
already designated two of us as odd couples because
8
I'm sitting in for Nate Hudson and Jay will be sitting
9
in for Valerie Barnes.
10
MR. KRESS:
11
Well, they had another reason
for calling you the odd couple.
12
(Laughter.)
13
MR. BASU:
14
(Laughter.)
15
CHAIR CORRADINI:
16
I'm sure.
And, you, too, George.
Happy New Year.
17
MR. BASU:
18
Professor Apostolakis?
19
business.
20
21
Yes, I'm sure.
I'm wondering what happened to
All right.
Happy New Year, Jay.
Now we are in
Happy New Year to
you all.
22
Okay.
So this is going to be a little
23
short presentation.
24
slides or go through all the slides.
25
I'm not going to wade through the
Nate Hudson has a family emergency so he
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1
couldn't be here so I'm giving the presentation for
2
him.
3
It's the research plan for hydrogen and
4
process plant analysis.
5
misleading.
6
doing the hydrogen process plant analysis for that
7
plant.
8
process plant analysis as to its impact on the reactor
9
safety.
We
10
The title is a little bit
We are actually not in the business of
are
in
the
business
of
doing
hydrogen
So that's what the focus of our research
11
plan
12
develop independent and confirmatory safety analysis
13
tools
14
implication of the hydrogen or any other process plant
15
operations on the NGNP or the reactor safety.
is
16
to
about.
The
support
the
objective
staff
is
very
review
of
simple,
the
to
safety
And, of course, the tools and methods to
17
be
18
perform the confirmatory safety analysis, not unduly
19
conservative, but also for phenomena that are unknown,
20
for processes that are unknown.
21
those things, we'll work on those things that, you
22
know, we like to assure ourselves that there are going
23
to
24
predictive capability.
implemented
be
25
safety
should
margins
be
in
accurate
our
and
to
And I'll come to
analysis
MEMBER ABDEL-KHALIK:
adequate
and
in
our
What you are trying
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1
to do is essentially set the boundary conditions?
2
MR. BASU:
Set the boundary conditions in
3
a way.
But as you go into it and analyze it -- as I
4
go into it, you'll see that the boundary conditions
5
themselves are not quite known at this point, okay.
6
7
MEMBER ABDEL-KHALIK:
conditions the right one?
8
9
MR. BASU:
Well, the interface between the
two.
10
11
Is the word boundary
MR. RUBIN:
What are the hazards that it
poses?
12
MR. BASU:
Okay.
So here is the cartoon
13
that I'm going to spend time on, in fact the rest of
14
my talk I'll just keep that in large part.
15
the reactor plant here, the NGNP or the HTGR plant if
16
you will.
17
You have
And then you have the process plants.
And
18
here, of course, in this cartoon, there are two plants
19
shown.
20
hydrogen co-generation.
21
perspective, the NGNP technology envelope definition,
22
if you will, is that ten percent of the process goes
23
to hydrogen generation.
24
25
For NGNP, if you recall, the focus is on
So
if
megawatt-thermal,
And, again, to put things in
you
roughly
are
talking
about
50
about
a
600
megawatt-thermal
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1
goes to hydrogen generation.
2
MEMBER APOSTOLAKIS:
3
also producing hydrogen?
4
else?
5
6
MR.
it
could
be
any
Any application.
MEMBER APOSTOLAKIS:
So what if you have
some other hazardous materials there?
9
10
Or it could be someplace
Well,
processing applications.
7
8
BASU:
Is the second plant
MR. BASU:
Yes, you can.
And that is
going to be -- yes, exactly.
11
So, okay, so what are the issues?
There
12
are basically three categories.
13
the operation of the process heat plant, if you will,
14
the hydrogen co-generation being one of them bu then
15
there
16
characteristics of the plant will have some impact on
17
the reactor plant in a couple of ways.
are
other
One is the -- during
applications,
the
operational
18
One is that the transient in the hydrogen
19
plant, and I'll say hydrogen plant but it could be any
20
of
21
hydrogen
22
operation or the mode that the reactor is going to see
23
in terms of the mass balance and energy balance.
the
24
25
processing
plant
plants,
can
the
actually
transient
impact
the
in
the
reactor
The upset conditions in the hydrogen plant
can also impact the reactor plant.
So what we did
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1
here
is
we
kind
from
a
2
release
3
reactor safety in a number of ways.
4
through the mass and energy balance, as I mentioned.
5
And
6
materials, material performance.
7
the effect of corrosive and toxic byproducts on the
8
reactor operation in terms of the operator dose and
9
operator exposure, et cetera.
then
list
a
processing
the
10
of
effect
The
few
things.
plant
of
could
corrosive
detonation
Chemical
effect
the
First of all
byproducts
on
And then, of course,
was
mentioned
in
the
11
context of dust.
12
which
13
issue.
14
unconfined hydrogen explosion.
15
if the byproduct is oxygen, as it may be from one
16
particular
17
high
18
electrolysis,
19
gas.
produces
Here,
We, of course, in a hydrogen plant
hydrogen,
of
course,
hydrogen
temperature
the
20
And
21
concentrations,
22
reactor safety.
23
The
hydrogen
we
are
that
oxygen
if
it
that
is
could
transport
process
is
is
thinking
is
of
an
the
And then, of course,
co-generation
--
detonation
a
high
heavy
generating
also
--
have
that
the
temperature
ground-hugging
in
an
flammable
impact
processing
on
transport
24
system, the transients -- and I mentioned that all the
25
times
in
chemical
plant
that
get
reactor
trip
or
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1
component failures.
2
the
3
processing failure and piping factors, and so on and
4
so forth.
intermediate
And some of the components are
heat
exchanger
tube
failures,
the
5
The third category that has an impact and
6
it is going on the other side is whatever is happening
7
in the reactor plant is going to be -- the process
8
plant and a particular issue here is the trace amount
9
of tritium that is generated in the reactor plan which
10
isn't transported through the intermediate loop to the
11
process plan.
12
in
13
product.
the
And the possibility of that ending up
consumer
product,
the
ultimate
consumer
14
So that is an area that we recognize and
15
we need to be able to address that either in some form
16
of administrative control, tech spec control, and so
17
on and so forth.
18
So these are the three main categories of
19
issues
20
processing to the high-temperature gas reactor.
that
21
22
are
related
to
coupled,
co-located
If there are no questions on this, then I
will -- yes?
23
CHAIR CORRADINI:
24
MR. BASU:
25
CHAIR CORRADINI:
There is a question.
There is a question.
So I remember when you
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first were discussing this in the context of license
2
training, you and Stu were up, there was a distance
3
beyond which it just becomes some industrial facility
4
in the region thereof, all right, and within some
5
distance it has to be considered both feed forward,
6
which is essentially stuff that happens in the NGNP
7
that can effect the hydrogen plant.
8
back, which is some sort of gaseous effluence or some
9
sort of feed back of the process plant effecting the
10
And then the feed
reactor.
11
Are you taking the -- are you trying to
12
think independently of the DOE about these sort of
13
initiators?
14
colleagues are thinking in this regard?
15
16
Or
are
MR. BASU:
you
waiting
what
your
segue to what I was doing.
CHAIR CORRADINI:
18
MEMBER
Okay.
APOSTOLAKIS:
I
have
another
question.
20
MR. BASU:
21
MEMBER
22
see
I think you gave me the good
17
19
to
So --
APOSTOLAKIS:
So
when
you
say
safety issues --
23
MR. BASU:
24
MEMBER APOSTOLAKIS:
25
help you develop your R&D program I suppose.
Yes.
-- this list will
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MR. BASU:
2
MEMBER
3
Yes.
APOSTOLAKIS:
You
want
to
understand those.
4
MR. BASU:
Yes.
5
MEMBER APOSTOLAKIS:
I'm wondering whether
6
there are additional safety issues if you consider a
7
major
8
disable parts of both plants --
9
external
event
MR. BASU:
10
MEMBER
like
an
earthquake
which
may
there
any
Yes.
APOSTOLAKIS:
--
are
11
safety issues that perhaps would be raised there and
12
we have to understand?
13
MR. BASU:
14
answer your question.
15
external fire, those have already been incorporated
16
into the traditional design and safety analysis of the
17
reactor plant if the reactor plant was a standalone
18
plant.
Okay.
Let me see if I can
Earthquake, external flooding,
19
The issues that I brought up here are the
20
issues that are unique to the couple and co-located
21
plants, process plants to the reactor plant.
22
MEMBER APOSTOLAKIS:
But it is unique to
23
have a major earthquake effecting the reactor and a
24
chemical plant.
25
MR. BASU:
Absolutely.
But that will be
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1
taken care of in the complex external load from the
2
earthquake to the reactor safety.
3
MEMBER RAY:
What he is saying is have you
4
thought about an earthquake at the reactor?
5
about an earthquake at the reactor combined with one
6
of these --
7
MR.
8
hydrogen plant.
9
10
BASU:
Earthquake
MEMBER APOSTOLAKIS:
MR. BASU:
12
MEMBER APOSTOLAKIS:
Well, most likely it
It will.
MR. BASU:
If it damages the
And that's through one of these
three categories.
16
17
the
reactor, I assume.
14
15
damaging
How
will.
11
13
Yes.
MEMBER APOSTOLAKIS:
Well, I don't know
about that.
18
MR. BASU:
19
MEMBER APOSTOLAKIS:
20
(Laughter.)
21
MEMBER BLEY:
No?
What am I missing?
I don't know.
Well, one thing you might be
22
missing is you may have opened up air pathways into
23
the plant that wouldn't normally be there if you'd
24
look a the hydrogen plant in isolation.
25
MEMBER RAY:
Yes, and our envelope for
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toxic gases isn't seismically.
2
MEMBER APOSTOLAKIS:
3
MR. BASU:
What I think --
If I have an upset in the
4
hydrogen plant, if I have an accident in the hydrogen
5
plant, I open up that pathway anyway.
6
7
MEMBER
MR. BASU:
it
would
If there was the intermediary
MEMBER APOSTOLAKIS:
All we're suggesting
here, Sud, is it would be nice to have a little story.
12
MR. BASU:
13
MEMBER APOSTOLAKIS:
14
think
loop because of an accident --
10
11
I
behoove you --
8
9
APOSTOLAKIS:
Right?
No, I -Don't try to explain
it now.
15
MR. RUBIN:
Here is the rub.
We're not
16
going to license the hydrogen plant.
17
to really regulate the plant.
18
assure that the frequency of events is not caught --
19
what kind of --
20
We're not going
What oversight can we
MEMBER APOSTOLAKIS:
No, that's not what I
21
mean, Stu.
That's not what I mean.
I mean if I do a
22
traditional seismic analysis for the nuclear reactor
23
where you have a hell of a lot of authority, right,
24
now I have to worry about the co-located facility
25
suffering from the same earthquake and maybe releasing
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1
bad stuff or doing other things.
2
And
I'd
like
to
That's
understand
I'm
the
possibilities
4
whether there is a need for additional safety issues
5
to be put there or to be investigated.
6
saying because this is kind of unique here.
MR. BASU:
all
what
3
7
are.
Right?
saying.
And
That's all I'm
No, your point is well taken.
8
In terms of whether or not an earthquake or any other
9
external load could cause damage to both plants and
10
the possibility of that we need to look into.
11
Once
that
happens,
phenomena-wise,
it's
12
not going to be -- at least in my mind, I haven't seen
13
--
14
different from the phenomena that we have identified.
I'm
not
15
aware
of
anything
CHAIR CORRADINI:
that's
going
to
be
I think, though, you
16
guys are in violent agreement.
17
asking you to do is to go away and at least make sure
18
it is enveloped within what you are considering.
19
20
MEMBER
APOSTOLAKIS:
My
agreement
is
grudging.
21
(Laughter.)
22
CHAIR CORRADINI:
23
I think all George is
Good, George.
I think
as long as you determine its envelope.
24
MR. BASU:
25
MR. RUBIN:
Okay.
I think you can imagine the
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1
failure modes and effects in the worst case for that
2
plant.
3
that.
4
that
5
possibilities
6
hazards.
And we want to make sure we can accommodate
Okay, we're not going to say you can't build it
way.
7
8
are
want
to
enveloped
make
in
us
sure
that
looking
at
the
the
The people who will
do the PRA will definitely have to worry about this.
MR. BASU:
You are absolutely right.
I
agree with you --
11
12
we
MEMBER APOSTOLAKIS:
9
10
But
MEMBER APOSTOLAKIS:
Now the question is -
-
13
MR. BASU:
14
MEMBER APOSTOLAKIS:
-- quite strongly.
-- the question is
15
whether
16
issues or other issues that they would need answers
17
to.
18
they
will
have
some
issues,
chronological
And these answers should come from this program.
That's all I'm saying.
And if you say no, that's
19
fine with me.
20
because that's really the phenomenological threat in
21
my mind.
But we'll wait and see what will be
22
MR. BASU:
23
MEMBER APOSTOLAKIS:
24
MR. BASU:
25
MEMBER APOSTOLAKIS:
Yes, if there are -Seismic.
-- we're in agreement, George.
Okay.
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MR.
BASU:
If
there
are
any
new
2
phenomenological issues that come up, we definitely
3
are going to look into that.
4
At this point, I've not.
Okay, now how do we --
5
MEMBER
ABDEL-KHALIK:
In
the
second
6
category of events that you are looking at, why is
7
this
8
removal event that may be caused by something within
9
the plant itself?
any
10
different
than
MR. BASU:
any
other
decreased
heat
It is not in theory but now --
11
I mean you have already designed the coupled plant to
12
deliver
13
operation.
14
there is a load falling operation in the other plant
15
or load rejection in the other plant you have to find.
part
16
17
your
process
heat
for
the
other
And now you have to find a heat sink if
So in that sense but in theory, transientwise, it is not.
18
19
of
I mean phenomena-wise, it's not.
I'm just trying to recognize that these
are the issues that one has to look into.
20
MEMBER
21
wondering
22
something that --
23
if
ABDEL-KHALIK:
you're
MR. RUBIN:
spending
a
But
lot
of
I'm
time
just
on
Here's something we're not
24
privy to yet and this is why we have to talk to DOE,
25
they are writing requirements for this plant for the
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1
various vendors.
And one of the requirements that one
2
could think of is a requirement to design a plant
3
where events, transients that occur in the hydrogen or
4
processing plant would be buffered in some way through
5
dump systems, through control systems, so it would not
6
perturb the reactor much at all, notwithstanding I do
7
believe that those kinds of requirements are being
8
looked at so that a plant -- this hydrogen production
9
plant, which who knows what the reliability is going
10
to be -- that they could be tripping off every day --
11
okay -- you don't want to have to deal with that in a
12
full transient of that -- even though it won't be --
13
it will be ten percent, I believe.
14
MEMBER ABDEL-KHALIK:
15
MR. RUBIN:
Right.
I mean you want to not have
16
that -- even that as an issue.
17
can engineer away that kind -- there are 100 percent
18
load reject systems available in nuclear plants.
And there are ways you
19
MEMBER ABDEL-KHALIK:
20
MR. RUBIN:
And that's what we're talking
MR. BASU:
I think I'm going to answer
21
Right.
about here.
22
23
your question, the second part of that in a minute or
24
so because I'm going to go back to -- Mike was asking
25
me now what.
We have these phenomena identified, what
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do we do?
Where do we go from here?
2
I'll tell you what is happening in the
3
HTGR involving design work, which is evolving.
In
4
NGNP we define the technology envelope as ten percent
5
processing going into hydrogen plant.
6
There is some kind of thinking going on in
7
the industry to be able to utilize the processing for
8
more than ten percent.
9
10
CHAIR CORRADINI:
sorry.
Say that again.
I'm
I didn't understand what you say.
11
MR. BASU:
Industry is looking into the
12
utilization of processes for more than ten percent.
13
In other words, less than 90 percent for the nuclear
14
electricity production.
15
the
16
possibility.
licensing
17
18
And more than ten percent for
application.
We don't know.
Okay?
So
that
is
a
We're not clear yet.
And it could be -- it could be as high as
80 percent processing --
19
CHAIR CORRADINI:
20
MR. BASU:
21
CHAIR CORRADINI:
22
MR. BASU:
Of a smaller plant.
What?
Nothing.
Now what happens, going back to
23
your question, if it is at ten percent, it's kind of
24
no, never mind what is happening in the processing
25
plant.
But if an 80 percent load is taken by the
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1
process plant, then any upset that is happening at he
2
process plant and if it is a single process plant or
3
any other transients, I think we need to --
4
5
MEMBER ABDEL-KHALIK:
any different than a turbine plant?
6
7
MEMBER
10
BLEY:
Terminally,
I
wouldn't.
Besides, you've got a lot of graphite.
8
9
Why would that be
MEMBER ABDEL-KHALIK:
I mean I'm raising
the question because, you know, you want to devote
your resources to things that actually are important.
11
MR. BASU:
Right.
12
MEMBER ABDEL-KHALIK:
And if this turns
13
out to be irrelevant under any and all circumstances,
14
then maybe you ought not spend a lot of time on this.
15
16
MEMBER BLEY:
Except that the first one,
the chemical release --
17
MEMBER ABDEL-KHALIK:
18
only on the second part.
19
MEMBER BLEY:
20
MR. RUBIN:
view,
they're
Yes, I'm focusing
Yes.
I think from a designers point
21
of
looking
at
trying
to
design
the
22
control system in ways to accept the full reject and
23
not have the reactor trip.
24
of view, you are right.
25
terms of the loss of load.
But from a sinking point
I think it is bounding in
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1
2
MEMBER APOSTOLAKIS:
a PIRT?
3
MR. BASU:
4
MEMBER APOSTOLAKIS:
5
Yes.
Well, the PIRT was
never wrong.
6
(Laughter.)
7
MEMBER APOSTOLAKIS:
8
CHAIR CORRADINI:
9
MR. BASU:
Okay.
This is a PIRT pride.
It's a living PIRT.
10
MEMBER APOSTOLAKIS:
11
MR. BASU:
12
Is this the result of
It's a living PIRT?
So we'll not -- we'll take into
consideration your suggestion.
13
In terms of what we are doing or what we
14
are planning to do -- and let me answer your question,
15
in terms of the hydrogen explosion issue, we have a
16
very large amount of database from LWR --
17
18
MEMBER
unique.
19
ABDEL-KHALIK:
That
I
agree
is
And you need to look at.
MR. BASU:
Well, we will look into it but
20
I'm also saying that we will benefit from the database
21
that we generated under the LWR program.
22
large amount of database on the chemical dispersion,
23
the plume modeling, so on and so forth.
24
25
We have a
And then, again, we're going to reap the
benefit of that database.
This is in the context of
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1
light water reactor but it equally applies to this.
2
And we're going to be looking to the applicability of
3
this.
4
regard.
So there may not be any new R&D coming in this
5
In fact, we have RegGuide 1.78 that's on
6
the control room habitability against the chemical and
7
toxic release.
8
brought to bear.
A lot of that information then may be
9
The transients in chemical plant that ill
10
lead to reactor -- potentially reactor trip, we will
11
look
12
earthquake, and others.
into.
So
load
facts
has
been
brought
up,
13
This point that I'm trying to make is that
14
there is already a large amount of database on many of
15
these
16
program.
17
ourselves.
phenomena
And
that
we
we
will
generated
look
into
under
those
the
to
LWR
inform
18
And then if at that point we find that
19
there are some data missing, some information missing
20
and
21
generate, then we'll set up -- we'll let that then
22
define our program coding.
that
23
the
applicant
or
DOE
are
not
So this is a work in progress.
going
to
We're not
24
doing anything at the moment.
25
the necessary information that will inform us as to
We have gathered all
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1
what needs to be done in the future.
And we will sort
2
of define our program and design our program.
3
So that's, in a nutshell, and you have the
4
handout but I, you know, I think I basically mentioned
5
everything that is in the handout.
6
CHAIR CORRADINI:
7
(No response.)
8
CHAIR CORRADINI:
9
MEMBER ABDEL-KHALIK:
10
MR. BASU:
11
MEMBER
Other questions?
Thank you.
On the next slide --
The next slide.
ABDEL-KHALIK:
--
you
want
to
12
develop an evaluation model to predict response of a
13
reactor
14
production plant and vice versa.
15
to
transients
MR. BASU:
undertaking
the
hydrogen
Why the vice versa?
Well, here it is.
I already
16
said that I did not intend to go through the slides.
17
The slides were prepared by Nate Hudson.
18
perspective in mind.
19
cannot --
I really cannot -- you know, I
20
CHAIR CORRADINI:
21
MR. BASU:
Reconstruct it?
Yes, interpret what he may have
22
in mind when he talked about vice versa.
23
think vice versa applies.
24
25
MEMBER ARMIJO:
plant's problem.
He had a
I don't
But -Well, that's the hydrogen
They should evaluate what happens if
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they --
2
MEMBER
3
problem, too, though because --
4
MEMBER
5
ARMIJO:
But
No,
I
it
mean
is
from
our
their
standpoint --
6
7
APOSTOLAKIS:
MEMBER APOSTOLAKIS:
-- if something bad
happens there --
8
MEMBER ARMIJO:
-- no but from them coming
9
back to the reactor is an issue but from them -- from
10
the chemical plant's standpoint if the reactor shuts
11
down, if they've got a problem, they should say that's
12
a possibility and this is how we'll handle it.
13
14
MEMBER BLEY:
stops.
I mean --
15
16
Well, their reaction just
MEMBER ARMIJO:
Yes, well, it may not be
so easy depending.
17
MEMBER APOSTOLAKIS:
I remember that many,
18
many
19
because
20
information.
21
Regarding what hazardous materials they would carry
22
and so on?
years
23
24
the
ago,
the
chemical
Is
MR.
Midland
owner
that
BASU:
plant
refused
a
If
was
to
correct
I
cancelled
supply
some
recollection?
remember,
vaguely
something like that.
25
MEMBER APOSTOLAKIS:
Something like that.
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MR. BASU:
Also there was this --
2
MEMBER APOSTOLAKIS:
Have you guys -- is
3
the situation not different?
4
operators and the owners of these facilities would be
5
willing to cooperate with you and answer the questions
6
you might have?
7
8
9
MR. BASU:
Well, these facilities will be
-- in the regulatory space will be controlled by
agencies like EPA.
10
11
Do you expect that the
MEMBER APOSTOLAKIS:
Well, I assume that -
-
12
MR. BASU:
So we may have to -- we may
13
have
14
regulatory agency.
15
the
16
demand some information and then expect that they will
17
provide the information.
to
initiate
operator
18
or
dialogue
with
the
corresponding
I don't know whether we can go to
owner
of
a
chemical
MEMBER APOSTOLAKIS:
facility
and
Well, who -- maybe it
19
is not your problem but somebody should worry about it
20
it seems to me.
21
it?
22
Are high level people worried about
MR.
RUBIN:
Well,
we'll
certainly
23
communicate that.
24
hazards and make sure we have protection against those
25
kinds of chemical hazards.
We need to know what are those
And DOE is -- we'll look
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1
to them to provide that for us.
2
Other issues are what are the security
3
requirements?
4
over those security arrangements.
5
6
Okay?
And we don't have regulatory
What will they be?
They are what they are for chemical plants in the
United States.
7
How good that is, I'm not privy o bu I
8
suspect it is a little different than ours.
9
are the implication?
10
11
CHAIR CORRADINI:
MR.
RUBIN:
I
think
CHAIR CORRADINI:
is
Homeland
It's not -- okay -- I
thought it was FEMA.
16
MEMBER APOSTOLAKIS:
17
CHAIR CORRADINI:
18
MR. RUBIN:
19
it
Security.
14
15
Who is the regulatory
agency that deals with --
12
13
And what
There is no CRC.
Okay.
And that's another whole issue
of security and the implications of that relationship.
20
CHAIR CORRADINI:
21
(No response.)
22
CHAIR CORRADINI:
23
MR. BASU:
24
CHAIR CORRADINI:
25
DR. PERSENSKY:
Other questions for Sud?
Okay.
Thank you.
You're welcome.
Jay, are you up?
I am up.
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CHAIR CORRADINI:
Okay.
2
DR. PERSENSKY:
Good afternoon.
It is
3
always good to be the last person because it makes you
4
want to get out of here faster and hurry up and not
5
ask any questions.
6
going to start this off by asking for some sympathy.
7
As Stu said, I'm here replacing Dr. Barnes or subbing
8
for Dr. Barnes who messed up her knee skiing.
9
can't be around.
10
And besides that, you know, I'm
And so they asked me to help out.
So she
And I
11
actually postponed my trip to Hawaii for one day so I
12
could do this.
13
George.
So let's have some sympathy here,
What's this Jay, what are you doing here?
14
Okay,
now
that's
over,
let's
move
on.
15
You're not going to get any sympathy from this group,
16
I can tell.
17
I am -- one of the reasons George asked
18
that question is because I am a re-employed annuit and
19
I actually retired last January.
20
through the end of March as a re-employed annuit to
21
try
22
transfer since I had been here for something like 30
23
years in the human factors area.
24
us have been here that long.
and
25
help
out
the
staff
But I'm back here
with
some
knowledge
And not too many of
So anyway, the other thing I'd like to
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1
start off with is I understand, you know, the focus
2
has been on the NGNP but one of the things about human
3
performance
4
topic.
5
is
that
It's
it
hard
really
to
is
focus
on
a
cross-cutting
one
particular
6
design because so much of what we would be doing from
7
the human factors standpoint would cross over any of
8
the advanced reactor designs as well as some of the
9
work that might be going on for new reactors and as we
10
see PIRT plants upgrading or updating their control
11
rooms.
12
So a lot of the work that we're going here
13
does cross cut.
14
lot that focuses directly on the NGNP.
15
Sud's presentation, I think that there is some support
16
here -- more support for some of the things I'll be
17
talking about.
18
And to be honest, we haven't done a
But hearing
Now what do we plan to do here?
And
19
really a couple of things.
20
seeing and what we have seen in the licensing of the
21
new
22
technologies even in the human factors area that are
23
taking place and are being used for licensing purposes
24
in
25
performance modeling.
reactors
terms
of
is
that
the
One is that what we are
there
human
--
are
a
they're
lot
using
of
new
human
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1
They're using rapid prototype.
So there
2
are some things out there we haven't been able to --
3
we're trying to get a better handle on in terms of
4
understanding
5
kinds of evidence that we typically have looked at in
6
the past.
7
how
those
tools
might
play
into
the
The other is that we have to look at what
8
are the new concepts of operation?
I mean we've just
9
talked a lot with Sud here about -- all right, well,
10
you've got the nuclear plant over here.
11
the
12
interactions are there?
13
transients?
14
is going to have to be doing?
hydrogen
plant
over
here.
You've got
What
kind
of
Are there any types of new
Is there something new that the operator
15
Are there going to be new tools that he's
16
going to -- issues that he is going to have to be
17
addressing,
18
And, again, thinking more broadly about all different
19
types of advanced reactors.
different
types
of
accident
scenarios?
20
We hear things from the PBMR people about
21
one person operating several units by him or herself
22
from his basement part-time.
23
concepts of operation that need to be considered.
24
expect that there will be.
25
And
the
current
So there may be new
regulatory
guidance
We
we
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1
have out there, though it is fairly consistent or
2
fairly good for the new reactors, we're not sure that
3
it is really going to be as good in all conditions for
4
the advanced reactors.
5
changes.
So we would be looking for
6
Unfortunately I didn't get the new -- I
7
did make a new slide where I combined some of these
8
things so what you have in front of you really is -- I
9
have a couple more slides that I pulled together here.
10
But, you know, what kinds of issues?
11
course,
12
potential for human error.
13
decrease?
14
kinds of error?
the
one
we
are
interested
in
is
the
Is there an increase?
A
How is it -- is it going to be different
15
16
main
Of
This would also, of course, lead to some
of the HRA work that is going on.
17
One of the big things that I look for from
18
a human factors perspective is the lack of situation
19
awareness, which is really a phenomena in the human
20
factors area of basically knowing what is going on
21
now, what has gone on in the past, and what you can
22
expect in the future.
23
And as we've heard, I know from a lot of
24
places
25
current control room, look around because he has all
that
a
seasoned
operator
can
walk
into
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279
1
of his displays, he has all of his alarms, he has
2
everything in front of him and can pretty well figure
3
out what is going on at the plant when he walks into
4
the plant, that he has a quick awareness of what is
5
happening.
6
Whereas if you walk into a new type of
7
control room and if you see the little picture down at
8
the bottom there, what you have is a bunch of computer
9
screens
that
may
or
may
not
be
on
the
kind
10
information that you want at the time.
11
great because you can get all kinds of information.
of
And it is
12
But on the other hand, you get what is
13
called the keyhole effect because you are only looking
14
at one thing and you have to navigate through several
15
screens to actually get to the information that you
16
might want at the time.
17
18
MEMBER APOSTOLAKIS:
Jay, coming back o
your safety issues --
19
DR. PERSENSKY:
20
MEMBER APOSTOLAKIS:
Right.
-- where would you
21
put -- or is it an issue that maybe two different
22
groups of people will get to coordinate their efforts
23
in an emergency.
24
25
DR. PERSENSKY:
Well, actually one of the
things, and you'll see it, in terms of the actual
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1
projects that we're talking about or topical areas is
2
the concept of teamwork and communication.
3
those is, in fact, distributed decision-making.
4
you make decisions in that type of situation.
5
So, yes, that is the heart of it.
6
Another issue, and we hear this a lot from
7
the industry, is the lack of adequate adequate staff
8
out
9
things with any kind of experience.
there,
10
people
that
can
actually
And one of
How
Yes.
operate
these
I saw Dave DeSonjas in the audience but I
11
see he left.
12
year, a rule -- a new fitness for duty rule.
13
of
14
requirements -- fatigue management requirements that
15
we have before in terms of a requirement.
that
16
I mean right now we just put out -- last
fitness
They
for
have
duty
to
rule
apply
And part
included
those
by
fatigue
I
think
17
October -- no, I forget the date now but sometime this
18
-- I think it is October of this year.
19
already
20
sufficient staff to met what amounts to some reduced
21
hours that would they would have to hire new people to
22
actually fill in for that.
23
beginning
to
hear
voices
about
And we're
not
having
And, you know, I'm talking to operators,
24
talking to plants.
25
the new plants, taking people from existing plans.
And they are concerned about with
So
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1
there
is
still
a
need
---
this
is
more
of
a
2
sociological issue -- but a need to get out there and
3
figure out how we could encourage the development of
4
staff.
5
One of the licensing issues that has come
6
up is the fact that we're now talking about depending
7
on
8
opposed o the analogue that is out there now.
9
--
digital
as
we
technology
know,
digital
10
rapidly.
11
tomorrow or the next day.
12
Buy
a
and
computer
computer
technology
today,
technology
And the
changes
it's
an
as
very
antique
And our currently regulatory framework may
13
not necessarily be able to adjust as rapidly.
14
those are some problems that we have been discussing.
15
And also the training and development of NRC staff.
So
16
As I said, I've been here for a long time.
17
leaving -- we have a few new people but without of a
18
lot of experience and we're trying to bring them along
19
but the rate both in terms of the research end and in
20
the licensing end is not quite what we need.
21
MEMBER BLEY:
22
DR. PERSENSKY:
23
MEMBER BLEY:
24
DR. PERSENSKY:
Yes?
25
MEMBER
--
BLEY:
I'm
Jay?
Yes?
Before you leave that one --
you
talked
about
the
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1
reduction in situational awareness in some new design
2
control
3
anywhere?
4
new ones as -- operators talking about how much a
5
better view they get of the plant.
rooms,
6
have
you
seen
the
opposite
effects
I've heard people talk about some of the
DR. PERSENSKY:
I think what we are seeing
7
is with the large view -- the large overview display,
8
that there may be -- a number of people have said that
9
is better.
10
But even with that, we don't have any
guidance on how to evaluate those.
11
MEMBER BLEY:
12
DR. PERSENSKY:
13
MEMBER
14
That's true, yes.
So --
BLEY:
Is
there
any
work
in
know,
we
progress trying to figure out how to do that?
15
DR.
PERSENSKY:
Well,
as
you
16
participate in the Halden reactor project.
17
is one of the things that we have encouraged them to
18
put into their general program as a way of trying to
19
assess that because they do have a facility to do
20
that.
21
Anecdotally,
I
have
heard
And that
that
from
22
actually some of the existing light water reactors
23
where
24
adjunct so we didn't have to review it necessarily,
25
the operators have been very happy with it and have
they
have
put
something
like
that
in
as
an
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1
learned
2
everything else at the same time.
3
difference between having it and not having it at all.
4
to
use
it
quickly.
But
they
still
have
So there is a
So --
5
MEMBER BLEY:
Is it -- let me sneak in a
6
question for you.
7
your slides.
Is there a timetable for when you folks
8
think
be
9
guidance on how you might review these things and
10
you'll
I didn't see it.
coming
together
I skimmed through
with
some
of
understand what they need to be effective?
11
DR. PERSENSKY:
to
develop
a
Not really.
more
precise
I mean we're
12
trying
13
factors.
14
plan but that went by the wayside some years ago.
plan
for
human
And we used to have a human factors research
15
So there's now a push to begin to develop
16
that again.
17
having more schedule.
18
19
the
And part of that would be, of course,
MEMBER BLEY:
Right now you don't have a
place in the advanced reactor plan?
20
DR. PERSENSKY:
21
MR. RUBIN:
22
DR. PERSENSKY:
Yes, we're in there.
But it is generic.
It's very generic and it's
23
kind of amorphous right now.
24
of the other issues that might help because some of
25
the things we are working on.
But let me get to some
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1
2
MEMBER
APOSTOLAKIS:
Is
there
human
factors branch now?
3
DR. PERSENSKY:
There is a human factors
4
and reliability branch in research.
5
Peters is back there.
6
we're in the division of risk assessment.
7
8
a
And I see Sean
He is the branch chief.
MEMBER APOSTOLAKIS:
And
And how many expert
on human factors are in that group?
9
DR.
me,
in
PERSENSKY:
that
We
branch,
now
yes,
you
11
wouldn't consider me an expert anyway, I know that --
13
CHAIR CORRADINI:
14
(Laughter.)
16
MEMBER
APOSTOLAKIS:
I
didn't
say
anything.
18
19
I'm glad you got that
on.
15
17
--
not
counting
(Laughter.)
have
--
10
12
we
have
DR. PERSENSKY:
We have four people on
board -- five?
20
MR. PETERS:
21
DR.
Yes, five.
PERSENSKY:
Oh,
If you count Val.
if
you
count
Val,
22
okay.
23
level advisor, she's there.
24
them will be leaving for school under our development
25
program.
Val -- she's not in the branch but as a senior
So there's five.
One of
So she will be gone for a couple of years.
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1
2
MEMBER
DR.
PERSENSKY:
The
the
human
human
reliability
people, we have three of them now.
5
MEMBER APOSTOLAKIS:
6
DR. PERSENSKY:
7
So
reliability people are --
3
4
APOSTOLAKIS:
Okay.
All right.
In NRO, the
new reactors, there's probably four plus Dave.
8
MEMBER APOSTOLAKIS:
9
DR. PERSENSKY:
10
as well.
11
agency.
12
point.
Okay.
And NRR has I think four
So that is the total of human factors in the
We don't have anybody in NMSS or FSME at this
13
MEMBER APOSTOLAKIS:
14
DR. PERSENSKY:
All right.
Now what are we looking at
15
here and you've probably seen something like this.
16
We're going from the large, expansive control rooms to
17
the more cockpit style where the crew interaction is
18
much more defined with the analogue systems as opposed
19
to going through some computer -- the physical versus
20
virtual HSIs, parallel access, serial access, these
21
are
22
differences.
all
23
the
kinds
of
things
that
we
see
as
So this is actually a modified control
24
room.
25
And
It has both digital and -- this is the Beznau.
this
is
a
conceptual
design
from
the
PBMR.
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1
Again, those are the kinds of things we're looking at,
2
this major kind of change that is going to occur.
3
As
far
as
developing
our
plan
or
the
4
topics that are here, most of it actually comes from
5
something called the human factor -- NUREG/CR-6947.
6
MEMBER BLEY:
7
DR. PERSENSKY:
8
When was that done?
That was published just
about a month or two ago.
9
MEMBER BLEY:
10
Okay.
DR. PERSENSKY:
It was finally published.
11
It was the results of a PIRT in human factors where
12
we looked at a number of issues that had been collated
13
from
14
vendors, talking to some of the users, looking at what
15
is going on internationally as well as looking at what
16
is
17
nuclear industry.
both
going
18
looking
on
So
in
at
the
we
vendor
documents,
digital
spent
a
world
lot
talking
outside
of
time
to
of
the
with
the
19
petroleum industry, for instance.
20
coal-fired
21
They've got a lot more digital systems already in
22
place than we see in the nuclear industry.
23
24
industry
or
the
The other is the
fossil
MEMBER APOSTOLAKIS:
power
industry.
Are our digital I&C
experts involved in this work?
25
DR. PERSENSKY:
We do coordinate quite
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1
closely with Dan Santos, who is our digital I&C SL
2
than we had in the past with Steve.
3
We've been also working on another thing
4
that I'm going to bring up next.
5
mention
6
couple of projects, one on operations under degraded
7
I&C conditions which is where you might have some
8
faults in the I&C condition even to the extent of
9
complete failure.
right
10
11
now
MEMBER
we
have
funded
APOSTOLAKIS:
I just want to
and
Do
under
we
way
a
understand
those degraded conditions?
12
DR. PERSENSKY:
What we used in this --
13
what we're using here is trying to use the work that
14
the
15
categorization of those types of faults -- or whatever
16
faults they come up with.
I&C
17
people
are
doing
to
MEMBER APOSTOLAKIS:
establish
some
We have been asking
18
the I&C people to identify failure modes of systems.
19
So evidently they have been done.
20
DR. PERSENSKY:
Yes, I think they are on
21
tomorrow, aren't they?
22
MR. RUBIN:
23
MEMBER APOSTOLAKIS:
24
MR. RUBIN:
25
DR. PERSENSKY:
Yes.
Oh, they are?
Yes, they are.
So you can ask them some
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1
more.
2
MEMBER BLEY:
3
MEMBER APOSTOLAKIS:
4
DR. PERSENSKY:
5
PIRT
and
some
6
involved with.
7
8
other
MEMBER
Okay.
That we got from both the
workshops
BLEY:
actually in progress?
9
I didn't notice that.
Is
that
we
that
have
work
been
that
is
Or is it just slated --
DR. PERSENSKY:
It is in progress right
10
now.
We've established a framework from the work that
11
we've gotten from the I&C people in the Oak Ridge
12
project that's going on.
13
more of the human factors aspects into it.
And we're now trying to fit
14
But I mentioned before the methods and
15
tools are changing in terms of what human factors
16
people can use, what designers are using to actually
17
replace sometimes human factors people.
18
don't need that.
19
The
Somehow we
We'll just use this model.
other
that
we've
got
going
on
is
levels
of
20
looking
21
automation effect personnel.
22
into questions, particularly of situation awareness
23
and workload.
at
24
25
levels
of
automation,
how
And, again, this gets
One of the issues that, you know, somebody
said
some
time
ago
when
we
started
talking
about
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advanced reactors, well, we don't need to worry about
2
human factors anymore because everything is so slow,
3
they don't have anything to do.
4
don't worry about it.
5
6
And
concept
of
underload
is
also
something that we've seen in other phenomena.
7
8
the
And, you know, so
MEMBER APOSTOLAKIS:
Can we get a copy of
this NUREG, Maitri?
9
MS. BANERJEE:
This NUREG/CR-6947?
10
MEMBER APOSTOLAKIS:
11
MS. BANERJEE:
12
MEMBER APOSTOLAKIS:
13
DR. PERSENSKY:
Yes.
Okay.
Thank you.
And to get back to --
14
somebody asked the question -- one of the things we're
15
also working on in the human factors standpoint, and
16
you've
17
steering committee on I&C for the new reactors, and
18
where we have one of the task working groups on that
19
and we've been working to develop guidance in the area
20
of
21
displays.
heard
minimum
22
a
couple
inventory
Operator
of
of
manual
presentations
the
large
action
from
controls
is
credited
the
and
in
23
safety
24
which we put out an interim staff guidance on all of
25
these now but we are getting a lot of feedback on
analysis
and
also
computerized
procedures,
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needs
to
improve,
2
computerized procedures.
3
especially
in
the
area
of
We do participate in the Halden reactor
4
project.
5
with them.
6
that
7
organizational factors that is part of the NEA/CSNI
8
Group.
9
not yet published -- CSNI has approved a technical
we
We just started a new three-year agreement
And one of the other issues and I think is
work
with
the
working
group
on
human
and
And they have just recently published a -- no,
10
opinion paper that is not yet published.
11
give you all the details on it.
So I can't
12
But they have proposed in this technical
13
opinion paper a set of research that should be done
14
for advanced reactors as well.
15
how we can merge these two things.
So we're looking at
16
As far as what you would see in the plan
17
that we published for the ARRP, the topics are these
18
nine topics.
19
I mentioned a couple of them before:
Concepts of operation, how you deal with
20
concepts of operations, functions and tasks?
21
the people going to be doing?
22
they are doing, especially if you are dealing with
23
numerous different areas?
24
25
The
function
What are
How do you assess what
allocation
and
automation?
How do you balance automation with personnel review?
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Another part of using the digital system
2
is, in fact, they may be much more complex than the
3
analogue systems because they could be almost like a
4
black box in trying to know it.
5
opacity of being able to understand what is behind
6
some of the things.
7
training and procedures and other aspects of human
8
factors.
9
The other is the
And that relates, of course, to
Workload variations, I mentioned that, and
10
transitions.
11
you know, how many people do you need?
12
qualifications of those people?
13
And it gets to the question of staffing,
What are the
Teamwork and communications, George asked
14
about distributed decision-making.
15
area would fit.
16
each one of these overall topics.
17
That's where this
There are a number of projects under
Computer-based procedures, we see that as
18
a fairly major issue.
19
ISGs that the industry has actually come back to us
20
with a lot of questions on.
21
unanswered questions there.
As I said, it is one of the
And there are a lot of
22
We just had one of our new people look at
23
-- do a little literature search and they came up with
24
30 different issues related to computerized procedures
25
that we need to try to address in some way from the
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1
literature.
2
Alarm
management
has
been
a
long-term
3
issue to try to get away from the waterfall effect.
4
And how does it really play out in a digital system?
5
And, again, the human factors methods and tools.
6
Right now these are the projects for which
7
we have funding in `09 or plan funding for `09 and
8
`10.
9
NUREGs 0711, and that is supposed to say 0700, which
10
are the two primary documents that we use in the human
11
factors -- that we and our regulator friends use in
12
the human factors area.
You'll see that one of these is the update of
13
One is the process -- the entire human
14
factors
15
0700,
16
Interface.
17
of telephone cords.
18
You're wireless now.
19
regard to what does this thing really look at.
engineering
is
details
process.
on
the
The
HSI,
other,
the
which
Human
is
System
And this gets into the colors and lengths
I'll bring it up before you do.
But a lot of the issues with
20
And we're also working with the standards
21
committees as much as possible to try and get them to
22
develop some of these standards that we can endorse.
23
IEEE is working on a computerized procedure standard
24
right now that they are trying to get out.
25
MEMBER APOSTOLAKIS:
There seems to be a
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lot of work going on, Jay.
And I'm wondering does the
2
staff seek ACRS advice on these things?
3
have to?
Or they don't
Or what?
4
DR. PERSENSKY:
No -- well, we have not --
5
because we have haven't had a plan, we have not had as
6
many opportunities to interact with you.
7
that, again, is part of this overall planning process
8
that the new management wants us to go through.
9
sure there will be more opportunities.
10
MEMBER APOSTOLAKIS:
I think that
I mean these projects
11
sound very interesting.
12
have -- or useful maybe -- to get a supplement.
13
I'm
So it would be interesting to
MEMBER BLEY:
And, you know, that one you
14
mentioned on operations under degraded I&C is one I
15
think we would really be interested in hearing where
16
you are headed.
17
MEMBER APOSTOLAKIS:
That's also touching
18
on our work with the I&C people with failure modes and
19
so on.
20
this?
So who is the right person to talk to about
21
22
DR. PERSENSKY:
That man right back there,
Sean.
23
MEMBER APOSTOLAKIS:
24
DR. PERSENSKY:
25
contacted
us
with
regard
Okay.
And in addition, EPRI has
to
trying
to
do
some
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1
collaborative work.
2
yet but there are some areas that they are interested
3
in that we also have a common interest in.
4
We haven't defined what that is
Okay, now what are we going to do with all
5
this when it is done?
6
follows on from the TWG work, is making sure that the
7
industry knows what they are getting themselves into.
8
9
10
And part of it -- and this
In a sense, what to expect.
get that license?
What do I need to do to
And that is one of the ways we're
trying to make it as transparent as possible.
11
What do we need to do to enhance safety or
12
maintain safety and deal with any kind of regulatory
13
action that is necessary?
14
perspective, what we do is we develop the technical
15
basis for whatever tool we're using, whether it is a
16
regulatory
17
guidance change.
18
for.
guide,
and
And really from a research
SRP
change,
or
inspection
That's what our research is used
19
And that's what we, again, try and make
20
sure that whenever we put out a new guide, that the
21
basis for it is clear.
22
So there's transparency there.
Sort of as an ending slide, I mentioned
23
the
24
actually -- and part of the reason for that CSNI-TOP -
25
- and just, you know, for complete transparency, Dr.
CSNI
work.
What
we
are
hoping
to
do
is
to
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Barnes and I played a role in writing that TOP, we
2
hope to have more international cooperation, to be
3
able to leverage some of the work because as George
4
was kind of hinting at, I think, our staffing and if
5
you really look at our budget, it is such that the
6
more leveraging we can do, the better off we are.
7
Well, the Halden program is part of the
8
EOCD so they are going to be taking advantages of that
9
as well.
And another topic that has come before -- I
10
think has come before you as well -- is this issue of
11
new research facilities.
12
primary research facility, in terms of having a full-
13
scope simulator is Halden.
14
15
As I said right now, our
And the Commission has asked us in the
past to look and see whether or not --
16
MEMBER APOSTOLAKIS:
17
letter supporting that idea.
18
letter two years ago.
19
DR.
PERSENSKY:
I thought we wrote a
This Committee wrote a
Supporting
the
--
and
20
there's been a Commission paper that went out that
21
we're doing a pilot test on that right now.
22
there's not much human factors involvement because one
23
of
24
develop a simulation research facility.
the
25
more
expensive
parts
of
MEMBER APOSTOLAKIS:
that
would
But
be
to
What is CSNI-TOP?
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DR. PERSENSKY:
2
This
is
3
they've
4
well.
the
one
that
I
developed
this
integrated
was
mentioning
that
research
says
plan
as
And we want to integrate with them.
5
6
Technical opinion paper.
MEMBER
APOSTOLAKIS:
Who
is
our
representative on this?
7
DR. PERSENSKY:
8
And if you really want to know the future
9
10
of
control
rooms,
it's
Dr. Barnes.
that
CHAIR CORRADINI:
12
(Laughter.)
13
DR. PERSENSKY:
Actually he's at home.
And with that, if there are any questions,
if not, you can go home.
(Laughter.)
18
MS. BANERJEE:
19
CHAIR CORRADINI:
20
MEMBER APOSTOLAKIS:
Any questions for Jay?
Do we have a human
CHAIR CORRADINI:
We'll discuss it at the
DR.
According
retreat.
24
25
That was sneaky.
factors subcommittee?
22
23
his
Is he NRC this guy?
17
21
in
This is one of the Halden virtual settings.
15
16
sitting
basement with a virtual control room and he can do it.
11
14
guy
PERSENSKY:
to
the
--
looked that up, as a matter of fact.
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1
MEMBER APOSTOLAKIS:
2
DR. PERSENSKY:
3
longer a human factors subcommittee.
4
be.
I noticed that there is no
5
MEMBER SHACK:
6
CHAIR CORRADINI:
There used to
We trimmed it out.
Questions to Jay before
7
we broaden the discussion?
8
(No response.)
9
CHAIR CORRADINI:
10
Oh, okay.
Okay.
Thank you very
much.
11
DR. PERSENSKY:
Thank you.
12
CHAIR CORRADINI:
What I wanted to do was
the
our
13
to
14
questions of anybody else during the day.
15
I'd like to broaden -- just general comments from the
16
folks for the day's events because we're going to have
17
another full day tomorrow.
see
18
19
if
members
MEMBER
and
APOSTOLAKIS:
consultant
Are
we
had
any
And then
writing
a
letter in February?
20
CHAIR CORRADINI:
No, it turns out.
But
21
we are to write a letter.
I was informed today that
22
staff -- unnamed staff can't support a letter writing
23
in February but -- so we will look -- take it upon
24
ourselves to possibly March or April to write a letter
25
on the research plan.
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So I'm open to members' comments.
2
MEMBER APOSTOLAKIS:
3
CHAIR CORRADINI:
On what we've heard?
Well, if we have nothing
4
about what we've heard, I want to broaden it because
5
Harold and I talked briefly outside and I want to ask
6
actually the staff since we've got them here about
7
some policy issue -- questions that relate to the
8
research plan.
9
MEMBER APOSTOLAKIS:
Well, my only comment
10
is that this issue of external events and like the
11
research I think ought to be explored a little better.
12
CHAIR CORRADINI:
13
MEMBER APOSTOLAKIS:
14
So if I might -Is that what you're
asking for?
15
CHAIR CORRADINI:
Well, before I even do
16
that, Maitri reminded me that since this is an open
17
meeting and I think we may have -- or we did at least
18
at the beginning of the day, members of the public in
19
attendance,
20
comment.
if
there
was
21
(No response.)
22
CHAIR CORRADINI:
23
going
to
be
any
public
The public has left the
building.
24
So, George, I'm sorry.
25
MEMBER APOSTOLAKIS:
Let me repeat.
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1
mean my only comment is that I'd like to see a better
2
story on what safety issues may arise when you have a
3
major
4
that would effect both the reactor and the chemical
5
facilities.
external
event,
in
particular
6
CHAIR CORRADINI:
7
mode event that effects both.
8
9
10
MEMBER
earthquake,
So some sort of common
APOSTOLAKIS:
Yes.
explore what kinds of issues would arise.
And
then
I mean you
can't wait until PRA guys come in.
11
CHAIR CORRADINI:
12
MEMBER RAY:
13
an
Other comments?
Yes, I have -- do you want me
to launch?
14
CHAIR CORRADINI:
Well, before you launch
15
where I think you are going to go, I want to see about
16
presentations.
17
MEMBER ABDEL-KHALIK:
I have a big picture
18
question about how realistic is the timeline.
19
you
20
verifying it so that you can actually use it by 2013
21
and
22
experiments, this is a dream world.
23
the timeline?
talk
an
24
25
about
element
completing
of
that
is
CHAIR CORRADINI:
an
evaluation
a
possible
When
model
set
of
and
NRC
How do you view
I think he's addressing
at the last staff member standing in front of the room
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1
-- or sitting.
Stu?
2
MR. RUBIN:
3
CHAIR CORRADINI:
4
the big bucks.
5
with us.
6
Okay.
This is where you earn
Please come to the front and help us
MR. RUBIN:
Okay.
We're struggling with a
7
number of issues.
One is what is the timeline?
8
is the real COL application date?
9
Or is going to start slipping as events between now
10
and things that need to be decided in the future start
11
to slip so we may have more time?
12
We don't know.
13
Another
What
Is it still 2013?
That's one aspect.
budgets,
okay.
14
We're operating under a continuing resolution.
That
15
causes
16
work, okay.
us
aspect
budgetary
issues
is
our
in
terms
of
initiating
17
Assuming it was the best case scenario, we
18
had all the money, are we going to be able to get
19
there?
20
identified
21
stopper.
22
that it is just never going to come together in the
23
time frame, you've got to help me out if you can point
24
to what those specific issues are.
25
Right now I would say we don't -- we haven't
something
If
that
is
going
to
be
a
show-
you feel you just kind of vaguely think
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CHAIR CORRADINI:
Well, let me through one
2
at you.
Since I'm not allowed to use anything about
3
TF, so I'll use fuel, the thing that concerns me most
4
is is the fuel irradiations in ATR and how they are
5
going to play out and if you are going to buy into --
6
staff that is -- is the staff going to buy into the
7
protocol about compressing the irradiation time at the
8
higher power.
9
And if that's not the case, what is going
10
to have to be redone or what is going to have to be
11
lengthened?
12
fuel irradiations, I can't see you making the schedule
13
that has been laid out to us by DOE and you guys are
14
coordinating with that.
15
head.
16
And as soon as you start lengthen the
MR. RUBIN:
So that's one that pops in my
One thing you have to realize
17
is if they cannot ultimately have their plant licensed
18
because of those issues, then everything slips.
19
with that slippage, we have more time as well.
20
And
Okay.
It's not like well we have to be done but
21
they're going to have to stretch out.
22
to have to live with the date that we start out with.
23
In
other
words,
we're
all
24
time.
25
slippage due to any -- for any reason.
Okay.
They're going
slipping
in
So there's that whole issue of schedule
If they are
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slipping, we're buying time at the same time.
2
But your technical issue of accelerated
3
irradiation, we're going to have to look at that.
4
the fuel qualification program, I have not heard that
5
that is part of the plan.
6
For
I know they are getting into that in some
7
of
the
earlier
tests
but
once
you
get
into
fuel
8
qualification then the risks start to increase because
9
you are actually pushing the fuel harder than you
10
would otherwise.
11
failures, oops, we've really tripped over ourselves
12
here by doing that.
13
And if you start seeing particle
CHAIR
CORRADINI:
So
is
a
way
of
14
summarizing what you are saying to Said is that you
15
are trying to -- you feel there is no show-stoppers
16
that makes NRC the blockage to make the schedule if it
17
is maintained?
18
hear you saying?
Is that a way of interpreting what I
19
MR. RUBIN:
20
this data for doing our modeling.
21
too.
22
for their models.
23
those in time, then they are slipping.
24
25
Okay.
Well, in other words, we need
But they need it,
They need to provide the technical basis
Okay.
And if they can't deliver
MEMBER ABDEL-KHALIK:
Okay.
But your job is to -
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MR. RUBIN:
2
MEMBER ABDEL-KHALIK:
3
It needs another application.
-- do an independent
assessment.
4
MR. RUBIN:
But the data, we're looking
5
for the data.
6
they are going to incorporate but the basic data, if
7
we
8
simulating the core in terms of burn up, in terms of
9
power level, in terms of temperature, in terms of
feel
that
10
fluence,
11
simulation
12
acceptable.
13
14
We may not use the same models that
if
the
we
tests
don't
for
that
were
have
valid
any
in
issues
qualification,
terms
with
the
of
that
data
is
You go off and you model it how you want
to.
We'll go off and model it the way was want to.
15
MEMBER BLEY:
I guess, though, where you
16
first started -- let me just take it organizationally
17
-- I haven't seen anything in the presentations that
18
lays out a detailed project plan, how you get from
19
where you are to the end, identifying all the key
20
places where it could go awry.
21
22
And without that, I'd say categorically
you don't have a chance to get there.
23
24
CHAIR
CORRADINI:
Just
as
a
point
of
information --
25
MR. RUBIN:
Let me respond to that.
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CHAIR CORRADINI:
-- yes you can -- but a
2
point of information, you look at section five, there
3
are dates on all of their bulleted points.
4
could draw a PIRT chart or whatever the heck it is
5
form that.
6
MR. RUBIN:
7
CHAIR CORRADINI:
So one
It's more than a PIRT chart.
In each one of their
8
points, they've got dates where certain things have to
9
be complete.
10
11
MR. RUBIN:
has that kind of information.
12
13
We need a project plan that
MEMBER BLEY:
Including the key places
where things could go awry.
14
MR. RUBIN:
Jennifer Ewell, our Division
15
Director, has asked us for that.
16
together.
And we will get that
You are absolutely correct.
17
MEMBER BLEY:
Okay.
18
MR. RUBIN:
We need to have a project
19
schedule.
20
MR. KRESS:
In the LWR work to develop the
21
fission product release models, we had to fuel that
22
had
23
built up in it and we had to re-irradiate it to get
24
some of the short lives back.
already
25
been
irradiated
MR. RUBIN:
with
fission
products
Yes, and I pointed that out.
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MR. KRESS:
And then we would take those
2
and stick them in a hot cell and heat them up and hold
3
them
4
accident
5
correlate the rates at which fission products came out
6
as a function of temperature and burnup and what else.
7
We could do about one or two tests a year
at
different
temperatures
conditions.
And
corresponding
then
grab
samples
to
and
8
with the small samples of fuel.
9
you are going to have to have a lot of data on the
10
fission product release from these particles and from
11
the things.
12
extent of data to make an empirical model which, by
13
the way, I like, the empirical model, in that time
14
frame.
15
Now I just can't --
And I just can't see you getting that
It's going to take a lot of data.
MR. RUBIN:
We haven't challenged Dave
16
Petty and his staff in terms of having the throughput
17
capability to get all of that data we need.
18
have heard that they want to buy additional furnaces
19
for additional accident testing, heat-up testing, so
20
they can run more irradiated fuel through those tests
21
to get data faster.
But we
Okay.
22
MR. KRESS:
Yes.
23
MR. RUBIN:
But I don't know if there are
24
any choke points where it's just not going to work
25
out.
But they recognize that.
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1
2
MR. KRESS:
Those are tough experiments to
do.
3
MR. RUBIN:
Sure.
Sure.
I think that
4
would mean providing more equipment to PIE and to
5
accident
6
reason.
7
8
test
that
irradiated
CHAIR CORRADINI:
fuel
for
that
very
I held off Harold before
because he is going to to take us --
9
MR. LEE:
Mike, I think we did look at the
10
-- the staff did look at INL, the fuel campaign that
11
they are undertaking at ATR.
12
same thing that Tom just mentioned.
13
get the empirical data for the releases.
14
15
And our concern is the
Is that how do I
And I think we do have some comments that
we
have
compiled
but
until
the
implementation
16
agreement is in place, we can not convey them until
17
then.
So we kept those in mind.
18
The adequacy of that so-called fission --
19
studying the fission product releases, we looked at it
20
already.
21
earliest possible chance.
22
So we will be discussing with them at the
MR. RUBIN:
We believe that the licensing
23
strategy for the NGNP also was looking at that very
24
issue, the timeliness of data that you need to use in
25
your models for licensing.
And what is the strategy
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1
whereby
you
2
lower operating temperatures, restricting the burnups,
3
things of that sort where you start to really lower
4
particle failure rates, release rates, even perhaps
5
adding filters to vent systems, really just -- I guess
6
they are compensatory measures.
7
can
take
compensatory
measures,
okay,
And just allowing the plant to operate at
8
much lower power levels.
9
know, power being generated in the particles is much
10
Okay.
So the amount of, you
lower, for example.
11
to
So
there
mind
to
are
If
we
are
13
absolutely must meet the date, there are things that
14
you can do.
CHAIR CORRADINI:
date.
that
coming
16
the
thoughts
12
15
meet
those
really
Harold, you had some
questions.
17
MR. KRESS:
Is the date somewhat arbitrary
19
MR. RUBIN:
Yes, it is.
20
PARTICIPANT:
21
CHAIR
18
22
anyway?
It is written into law.
CORRADINI:
We've
been
known
to
break the law.
23
MEMBER RAY:
On Christmas Eve, Maitri gave
24
us a very comprehensive memo on this in advance of
25
this meeting.
And I just want to refer to two points
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1
here
and
then
ask
2
actually.
3
staff members here.
the
question
of
the
members
I don't expect to address it to any of the
4
But in talking about the NGNP licensing
5
strategy report basis document and licensing report to
6
the Congress, she indicated that the top four issues
7
included number one, defense in depth measures --
8
MS. BANERJEE:
9
MEMBER RAY:
Policy issues.
What?
10
MS. BANERJEE:
Policy issues.
11
MEMBER RAY:
What did I call it?
12
technical policy issues.
13
thought I'd read that.
14
MS. BANERJEE:
15
MEMBER RAY:
What did I call it?
I
Oh, I'm sorry.
Yes.
And -- well, I may not
16
have so -- it's a policy issue, right.
17
agree on that.
18
Oh,
I think we all
But then it indicated further on in the
19
memorandum
20
developing regulatory guidance for implementation of
21
Commission policy statement on defense in depth for
22
advanced reactors may be on hold as the staff plans to
23
recommend the Commission doesn't work on the policy
24
statement -- be put on hold.
25
And
that
the
then
third
proposed
elsewhere
milestone
either
here
on
or
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1
someplace else -- at least I gathered the rationale
2
for
3
comprehensive
4
judgement about the policy statement.
5
exchanges in e-mail among the members back and forth
6
that I won't go into.
that
was
7
related
PRA
In
any
for
for
such
event,
meeting,
the
do
need
reactors
to
see
before
a
making
And we had some
the
question
we
intend
is
this
have
any
8
subcommittee
9
discussion among the members or with staff on this
10
question?
11
direct it back to anybody else.
to
at
I'll direct it to the Chairman but you'll
12
CHAIR
CORRADINI:
Well,
let
me
add
13
something -- fuel to the fire.
14
traffic we had to each other, it was my impression
15
that we kind of broke up into two quasi-camps on this.
16
I guess in the e-mail
I don't even know what they called the camps.
17
But from my perspective, I want to -- I
18
kind of want to make the staff say something about
19
this
20
because
21
issues.
or
at
I
least
am
22
understand
struggling.
how
There
you
were
are
thinking
four
policy
Harold mentioned one but it kind of comes
23
down
24
performance
25
criteria,
to
containment,
criteria,
or
the
performance
the
--
containment
containment
system
the
building
performance
performance
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1
criteria for this machine -- and how it may differ
2
depending upon the licensing basis events that you are
3
considering,
4
outside the design base.
5
what
And
is
given
in
the
that
design
this
base,
defense
what
in
is
depth
6
policy statement has been put on hold or is being
7
delayed a bit, where does this leave you relative to
8
your policy questions that you have for the NGNP?
9
That's what I'm kind of struggling with myself because
10
to me, the containment performance criteria -- the
11
containment
12
important in this sort of design.
13
system
performance
criteria
is
quite
So not just the staff -- I guess the other
14
--
15
curious what the staff thinks about this because we're
16
going to have to wrestle with this as we go forward.
I'm
sorry,
17
18
just
MR. RUBIN:
the
members
but
I'm
very
Well, I don't want to speak
for Mary Drouin who is going to be here tomorrow --
19
20
not
CHAIR CORRADINI:
Oh, you are going to put
it on Mary?
21
MR. RUBIN:
Well, I mean her piece in this
22
is the risk informed infrastructure.
23
of that is the defense in depth requirements.
24
you
25
environment.
construct
defense
in
depth
in
And a big piece
a
How do
risk-informed
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And she has been spearheading the work we
2
have done so far in developing a draft, if you will,
3
of a defense in depth policy paper.
4
aware of the reasons why these decisions are being
5
made.
6
7
So she's more on top of it.
10
So tomorrow
is the time to ask that question.
8
9
And she's fully
CHAIR CORRADINI:
to the members.
Okay.
So then I'll turn
So I'll throw out just one point to
kind of feed this for Harold.
And then Maitri.
11
I guess my feeling is is that if you don't
12
have a containment system with this reactor, you are
13
betting too much on the design, whatever the point
14
design might end up to be.
15
There was some staff documents about what is going on
16
in Fort St. Vrain and apparently with the PCRV and the
17
BISO,
18
confinement structure with certain requirements.
TRISO
19
whatever
fuel
And so I looked back.
it
was,
there
was
a
To me that is at least a minimum that has
20
to be here.
21
defense in depth, particularly because you'd have a
22
lot of passive systems that you'd yet to prove will
23
actually function over the multi days.
24
25
And regardless of what the policy is on
MR. RUBIN:
Well, the paper that Mary was
preparing had in it as a very important piece the
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policy
position
2
advance reactors.
3
parallel with what appeared in the technology-neutral
4
framework under defense in depth.
5
And
on
containment
requirements
for
And that statement was very much
so
Okay.
that
was
Okay.
the
direction
we
were
6
going in.
7
with there is postulated challenge events to the core
8
to be defined and then go through an analysis of the
9
fission
product
10
containment
11
challenge event.
can
And I think what you are dealing
releases
provide
Okay.
and
to
defense
ensure
in
depth
that
the
for
that
And that was the idea.
12
That might be beyond what you might --
13
well, you would be beyond what you would get from a
14
PRA.
15
five steam generator tubes failing or maybe it is that
16
and a valve opening up.
17
18
Okay.
And we'd all have to agree -- maybe it is
Or maybe the RCC doesn't work
for two days, okay, you can find a lot of challenging
events and we'd have to decide what that would be.
19
That was the concept in the technology-
20
neutral framework.
21
case, particle failures heating up, caps failing due
22
to a chemical attack or what have you, and making sure
23
that your containment was okay for that.
24
25
And
The challenge to core, in this
we'd
all
be
happy
with
containment if that kind of event were to occur.
that
And
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that would be an engineering judgment.
2
MEMBER RAY:
And is that the way a policy
4
MR. RUBIN:
For defense in depth, it's a
5
deterministic judgment.
3
gets set?
6
MEMBER RAY:
Well, I'm asking about the
7
idea that there is this mandate to address a policy
8
matter
9
something happens.
10
but
we're
going
to
put
it
on
hold
until
It sounds like Mary will turn a
crank and we'll get a lot of information --
11
MR. RUBIN:
Well, she could talk to you
12
privately as to the reasons behind that.
13
go back to the original paper of I think SECY-03-0059,
14
it talked about the options for developing defense in
15
depth for PBMR at that time and non-LWRs.
16
But if you
And one option was case by case.
Okay.
17
We can take each plant on its own and make a decision
18
on that one case and we'll decide.
19
generic concept or policy at the end of the day but we
20
have figured it out.
21
22
We may not have a
So --
MEMBER RAY:
Well, okay, then that is the
MR. RUBIN:
We may have stepped away from
policy then.
23
24
the generic policy paper.
25
options.
But so there are other
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1
2
MEMBER
APOSTOLAKIS:
A
clarification
question -- what is it that has been postponed?
3
MR. KRESS:
The submittal of a policy --
4
CHAIR CORRADINI:
The presentation we got
5
last meeting where Mary made the presentation about
6
their developing a policy paper on defense in depth,
7
that activity is being postponed.
8
MEMBER APOSTOLAKIS:
9
CHAIR CORRADINI:
10
Postponed until when?
Maitri, I'll leave it to
you.
11
MS.
BANERJEE:
Well,
yes,
what
is
12
happening is staff is writing a SECY paper to the
13
Commission, expected towards the end of February where
14
they are going to identify why it is premature to
15
start working on a policy paper on defense and depth
16
and how to go forward from here.
17
CHAIR CORRADINI:
18
MS. BANERJEE:
Oh, I see.
So we are going to get a
19
copy of the draft SECY paper and hopefully then we can
20
decide whether we want to take it up and want to talk
21
to the staff, have another presentation or not.
22
MEMBER APOSTOLAKIS:
Well, so this SECY
23
will argue why they are postponing it.
24
MS. BANERJEE:
25
MEMBER APOSTOLAKIS:
Yes.
But it doesn't answer
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to the question until when.
2
MS. BANERJEE:
I think they are also going
3
to say, you know, tie up their schedule of developing
4
this policy paper with some additional work that is
5
going on in the risk-informed performance-based area
6
with, you know, HTGR and all this work.
7
is -- you know, until a certain time.
8
see a logical --
9
MEMBER
APOSTOLAKIS:
And say this
So I expect to
Now
a
previous
10
Commission told us explicitly not to get involved in
11
policy issues.
12
can't get involved here at all.
13
Is that still valid?
MS. BANERJEE:
Otherwise we
No, my impression is these
14
are areas that ACRS would like to get involved in.
15
I'm not sure.
16
17
MEMBER APOSTOLAKIS:
order.
18
MEMBER SHACK:
Well, I think his is a
19
technical policy issue.
20
(Laughter.)
21
MR. KRESS:
22
MEMBER APOSTOLAKIS:
23
on.
Since when do you take orders?
It was policy.
Come
Unless we have a different Commission now.
24
25
That was an explicit
MEMBER SHACK:
We've certainly be involved
in technical policy issues and that's been a long
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1
mission.
2
3
MR. KRESS:
But containment is a technical
MR. RUBIN:
There have been many meetings
matter.
4
5
on the technology-neutral framework.
6
is fraught with policy issues.
7
in it.
8
9
MEMBER RAY:
And all of that
So we've been involved
I don't know how you stay out
of it honestly on this level.
10
MEMBER BLEY:
Well, you raised it in the
11
context of that last meeting.
12
last
13
organizing a process that would lead to a SECY that
14
would put forward a policy decision.
meeting
was
staff
was
15
CHAIR CORRADINI:
16
MEMBER
17
BLEY:
were, you know, on track.
My impression at the
well
on
its
way
to
Right.
And
it
seemed
like
they
There was more to be done.
18
I don't quite get it but I guess I'd have
19
to see the arguments they are making now about why it
20
should
21
extremely useful, as the rest of this process goes
22
forward, to have that defined.
23
be
postponed.
It
CHAIR CORRADINI:
seems
--
it
would
be
Well, I mean -- I guess
24
it is a cart before the horse sort of thing but it
25
seems to me without that, to ad hoc develop something,
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1
the staff for the NGNP project.
2
3
MR.
RUBIN:
We
will
make
regulatory
decisions.
4
MEMBER APOSTOLAKIS:
5
big deal is.
6
the big deal?
7
I don't see what the
All the review stuff, we do.
MEMBER RAY:
All right.
What is
Then the big deal
8
-- since I started this -- would be you are going to
9
make policy after you--
10
MEMBER APOSTOLAKIS:
11
MEMBER RAY:
12
Do it.
-- after you applied policy.
In other words, you are applying policy but you don't
13
know what it is.
14
done it, I guess.
15
We'll figure it out after you've
MEMBER APOSTOLAKIS:
There are some real
16
safety issues I submit.
17
difference because we will review here whatever these
18
guys are doing.
It really doesn't make a
And, you know, pass judgment.
19
Now what you are saying, Harold, is that
20
sounds very odd that we establish policy after we have
21
implemented something.
22
23
But
terms
of
real
safety
issue,
I
frankly don't see a difference.
24
25
in
I agree.
MEMBER SHACK:
I mean there was an SRM,
too, that sort of said exercise the technology-neutral
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framework --
2
MEMBER APOSTOLAKIS:
3
MEMBER SHACK:
Yes.
-- including some of this
4
defense in depth concept on a reactor concept just to
5
see how it all worked out.
6
that, you know, that's what we're going here is we're
7
sort
8
really applies to a real case.
of
9
10
going
through
And you can sort of argue
that
process
MEMBER APOSTOLAKIS:
to
see
how
it
And the Commission
may very reasonably wait until the results of this.
11
MEMBER SHACK:
Well, I'm not sure, you
12
know, that could be part of the argument for holding
13
off is to just actually go through a more concrete
14
case than trying to decide policy in the abstract.
15
16
MEMBER BLEY:
again tomorrow in Mary's talk.
17
18
This will no doubt arise
MR. RUBIN:
I will advise Mary that she
need to be ready.
19
(Laughter.)
20
MR. RUBIN:
As I understand it, go from
21
the letter that you signed April 30th -- if I read it
22
anyway -- Mary will be talking about a partially risk-
23
informed approach as the option that we are trying to
24
implement here.
25
CHAIR CORRADINI:
Correct.
Out of four
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options --
2
3
MR. RUBIN:
I think we dropped partial.
It is risk informed.
4
MEMBER RAY:
I see.
All right.
Because
5
option two was partially, option three was fully.
6
I was going to say --
7
CHAIR CORRADINI:
We've managed to kind of
8
-- we've landed in between the two I think.
9
MEMBER APOSTOLAKIS:
10
between
a
11
informed?
12
13
partial
What's the difference
risk-informed
CHAIR CORRADINI:
And
and
a
full
risk-
It's like being a little
pregnant.
14
MEMBER RAY:
You know, George, we actually
15
get into some debates, as we did in the e-mail over
16
this very issue because to me the real question is
17
between risk informed versus risk based which we never
18
confuse that.
19
20
MEMBER APOSTOLAKIS:
MEMBER RAY:
22
MEMBER APOSTOLAKIS:
That's correct.
It's not risk based.
We know that.
24
25
That has
been settled.
21
23
All right.
MEMBER RAY:
All right.
Swell.
Then I
was simply going to ask what's the difference between
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partially and fully risk informed.
2
MEMBER APOSTOLAKIS:
3
MEMBER RAY:
4
CHAIR CORRADINI:
5
Boy, you are in a very certain mood these
And I'm saying none.
Good.
That settles that.
6
days.
But let me just push -- let me just push the
7
point because I think -- I thought I saw where Harold
8
was going with this but let me tell you what worries
9
me.
What concerns me about at least this reactor,
10
this design -- or not concerns me -- what I concern
11
myself
12
behavior, which we seem to focus on but the short-time
13
behavior of what is the limiting accident that is
14
going to essentially cause a pressurization?
15
how you handle that initial pressurization.
about
in
this
design
is
not
the
long
time
And then
16
Because unless that is thought through,
17
you can literally have opened the confinement building
18
or the building, the system, and then any further
19
failure down the line, you essentially have now a
20
bypass.
21
22
MEMBER APOSTOLAKIS:
And you think that
the policy statement on this --
23
24
You have no --
CHAIR CORRADINI:
No, no, no.
No, that
isn't my point.
25
MEMBER RAY:
Yes, just tell me what the
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answer is and that's okay, we'll move on.
2
MEMBER APOSTOLAKIS:
3
MEMBER
RAY:
Between what?
About
whether
--
you
are
4
basically saying it is not important or it is not
5
timely or whatever to address this issue.
Okay.
6
But, you know, I'm still hung up over the
7
fact that I've watched us get to a place on another
8
technical subject, and I won't mention what it is at
9
this moment but you all know what I'm talking about,
10
in which steps were taken, steps, steps, steps, every
11
time looking back to the step before.
12
And then finally you get way down here
13
where you are doing something that you think might be
14
a bad idea but after all, you had all these precedents
15
going
16
further down the road.
back
17
18
time,
each
CHAIR CORRADINI:
one
just
a
little
bit
He's worried about a
slippery slope is what I think he's saying.
19
20
over
MEMBER RAY:
Okay.
Fine.
But if we can't
have a policy on defense in depth now, okay.
21
But I think we ought to be aware that, you
22
know,
23
Commission does have a policy on defense in depth.
24
think
25
anyway.
normally
that
is
speaking
what
they
people
think
would
on
the
think
18th
the
floor
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1
And if we don't have one because we can't
2
figure it out, that's as good as answer as any, I
3
suppose.
4
5
CHAIR CORRADINI:
I'm going to step back.
You guys are having too much fun.
6
George, you're up.
7
MEMBER APOSTOLAKIS:
if
we
think
of
I think we all feel
8
better
this
exercise
without
9
existence of a policy statement, like Bill said.
the
As a
10
first test of the technology-neural framework and the
11
ideas behind defense in depth, we will have a lot of
12
opportunities to influence that.
13
14
15
And
then
that
may
be
will
go
to
the
Commission when they formulate their policy statement.
And I'm pretty happy with that.
16
MEMBER
RAY:
Well,
as
I
told
you,
we
17
recently had an example here in another realm where
18
statistical
19
behavior which turned out to be dead wrong.
20
once.
inferences
were
drawn
about
economic
More than
21
And I'm just concerned that we will all
22
talk ourselves into the same mindset the way those
23
geniuses did.
24
here.
25
So that is why I'm raising this issue
MEMBER
APOSTOLAKIS:
I
would
have
to
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understand better what you mean so maybe this is not
2
the right place.
3
4
CHAIR CORRADINI:
Invite him to dinner and
you will.
5
MEMBER BLEY:
6
just said resonates a bit with me.
7
there's
8
neutral framework that can get its test here.
9
having
10
a
a
de
test
facto
I think something George
policy
before
through
you
The idea that
the
actually
technology-
anchor
And
it
in
concrete isn't a bad idea.
11
And if it moves forward along the lines we
12
heard the last time with that as something of a de
13
facto way to do that, I think that is very good.
14
CHAIR CORRADINI:
So if we went -- if Mary
15
were
16
there's -- just if I might just push the point a bit -
17
- if we were to ask at what level do I have fuel
18
integrity, fuel rod or fuel pellet integrity that I
19
can remove a barrier, the staff has an example of
20
where that would be?
21
in 1860.
22
I'm getting it.
here
23
now
I
could
ask
her
and
she
And that's what I guess
MEMBER APOSTOLAKIS:
This committee will
24
look at this issue on its own merits.
25
somebody
there
say
Because I don't think I see it
It doesn't exist.
said
would
is
a
policy
to
Not because
have
an
extra
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1
barrier.
We are an independent group.
2
know why you worry about it.
So I don't
3
You think there is going to be a committee
4
letter that says we really think there ought to be a
5
barrier but there is a policy.
6
CHAIR CORRADINI:
There's no policy.
7
MEMBER APOSTOLAKIS:
It will be totally
8
different added comments because somebody will write
9
them.
10
(Laughter.)
11
MEMBER APOSTOLAKIS:
I really don't see
12
any issue.
And I would have to understand better
13
where
14
comfortable if I understand where he is coming from.
15
But everything else that has been discussed in my mind
16
is a non-issue.
Harold
17
is
coming
from
in
order
to
feel
Definitive.
MEMBER RAY:
Well, George, precedent, I
18
think,
19
suggest.
20
is a test.
21
implying that well, maybe we'll change our mind the
22
next time.
weighs
23
more
heavily
here
than
you
would
In other words, as Dennis said, well, this
We'll try it out and see how it works,
But that's not the way it works.
You make
24
this
25
application but every one like it from now on.
decision,
you've
made
it
not
only
in
this
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1
2
MEMBER BLEY:
I've seen it in some other
areas.
3
MEMBER RAY:
You're darn right.
4
MEMBER APOSTOLAKIS:
But what has been
5
tested here is, in fact, the whole DNF -- not just the
6
defense in depth part, the whole technology-neutral
7
framework.
8
the first time that somebody is trying seriously at
9
least in a federal agency -- there are other places
10
If you guys decide to use it, it would be
where it has already been tried.
11
CHAIR CORRADINI:
12
MR.
13
decision.
RUBIN:
Stu, you had a --
Well,
it
was
a
management
It just didn't come out of thin air.
14
And one of the issues is the policy issue,
15
as it was being crafted, was technology-neutral, okay,
16
and you try to be all things to all technologies.
17
And
when
you
do
it
at
that
level,
it
18
becomes difficult to kind of understand how it applies
19
to
20
technologies
21
coolant.
specific
22
technologies.
where
the
fuel
And
is
there
are
dissolved
in
some
the
There is no particle, okay.
Now what is my defense in depth?
Exactly,
23
and so you start having different kinds of concepts.
24
Is this universal statement, how does this really work
25
for me?
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So does it make sense to go forward with a
2
technology-neutral statement or maybe we need to be
3
technology specific.
4
in this case.
5
6
And that's maybe more tractable
And so I think that's the path we're going
down is a more technology-specific case.
7
MEMBER APOSTOLAKIS:
And that, in fact, if
8
you are very careful with that formulation may take
9
care of some Harold's concerns because then a decision
10
here will not bear a precedent for other decisions.
11
But we'll see.
12
listen.
We'll see.
13
CHAIR CORRADINI:
14
MS. BANERJEE:
15
I mean I'm willing to
You are really?
Maitri again.
Commission SRM said --
16
MEMBER APOSTOLAKIS:
17
MS. BANERJEE:
18
What did you say?
The Commission -- I said my
name Maitri Banerjee -- I have to say my name.
19
20
What the
MEMBER APOSTOLAKIS:
Okay.
I'm sorry.
I
heard something else.
21
MS.
BANERJEE:
What
staff
--
what
I
22
understood from attending this meeting is the staff is
23
saying
24
consider the licensing -- the option development of
25
licensing option paper -- a position paper for NGNP.
the
Commission
paper
wanted
the
staff
to
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And then use the experience from the PBMR
2
reactor pre-application review.
And they are saying
3
from development of licensing paper, it's not -- they
4
haven't gotten much experience and PBMR work is on
5
hold.
6
you know, some ideas on that.
So they need to do more work to come up with,
7
MEMBER RAY:
8
context of this was more PBMR work.
9
That's where I read that the
MS. BANERJEE:
And in terms of option two
10
or option three that, George, I think you asked, staff
11
is still working on -- they are still struggling with
12
it.
13
how to develop DBAs and beyond-DBAs from DBA --
And they are having meetings with INL and DOE on
14
15
MEMBER APOSTOLAKIS:
DBAs.
16
17
They are -- not the
MS. BANERJEE:
LBEs -- LBEs comes from
PRAs.
18
CHAIR CORRADINI:
They're trying to decide
19
where to draw the line once they get all their LBEs on
20
a piece of paper, I think, is what she just said.
21
22
MS. BANERJEE:
Right.
And then, you know
how do you --
23
CHAIR CORRADINI:
24
line?
25
design basis?
Where do you draw the
What is design basis?
And what is beyond
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MS. BANERJEE:
So you have your LBEs from
2
PRAs and then you are going to draw out your DBAs and
3
beyond-DBAs
4
events.
5
three.
6
day -- was alluding a lot of people.
And
13
to
use
things
option
--
two
design-basis
versus
option
George, I think that as
we understood it -MEMBER APOSTOLAKIS:
There is a concept of
design basis in the TNF.
11
12
how
those
CHAIR CORRADINI:
9
10
all
And the clear definition is -- what I saw that
7
8
and
CHAIR CORRADINI:
Well, there isn't.
But
there is in the licensing strategy for this machine.
So to the extent --
14
MEMBER APOSTOLAKIS:
15
CHAIR
So --
CORRADINI:
No,
I
guess
my
16
interpretation -- my understanding of the memo and
17
what
18
discussions about NGNP is is that we will -- from the
19
lessons learned of NGNP, we will take the TNF further.
all
that
we've
heard
is
when
we
had
the
20
But for the NGNP, there will be things
21
that are in the design base and there will things that
22
are out of the design base.
23
MEMBER APOSTOLAKIS:
24
CHAIR CORRADINI:
25
It will be a hybrid.
Yes, that's why it is 2-
3 versus 4 or whatever.
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MEMBER APOSTOLAKIS:
By the way, when you
2
say option two and three, these are not the ten years
3
ago option two and three.
4
MS. BANERJEE:
No these are the option two
5
and three in the licensing strategy bulletin.
6
MEMBER APOSTOLAKIS:
There is a strong
7
record forgetting about options in this agency.
8
don't worry about it.
9
(Laughter.)
10
MR. RUBIN:
So
Well, the basic difference
11
between option two and option three in the selection
12
of
13
selected bounding events.
events
is
the
concept
of
MEMBER APOSTOLAKIS:
15
MR. RUBIN:
For this reactor.
MEMBER
APOSTOLAKIS:
MR. RUBIN:
20
MEMBER APOSTOLAKIS:
Supplement
by
the
Yes, from the PRA.
I've always wondered
--
22
23
For this
licensing basis events.
19
21
For this reactor.
license.
17
18
deterministically
Okay.
14
16
a
MR. RUBIN:
And so you can continue with
that as your licensing policy forever --
24
MEMBER APOSTOLAKIS:
25
MR. RUBIN:
Oh, I hope not.
-- or you can, as
confidence
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1
builds with the PRA, experience and the like, to relax
2
that.
3
4
MEMBER APOSTOLAKIS:
Again, we're getting
into discussions here that require Mary.
5
MR. RUBIN:
6
MEMBER
Yes.
APOSTOLAKIS:
But
I've
always
7
wondered in the TNF what exactly -- how would the LBEs
8
be scrutinized by the agency?
9
me how that would happen.
10
MEMBER BLEY:
11
Well, they didn't get that
far to define it.
12
MEMBER APOSTOLAKIS:
13
MEMBER BLEY:
14
But the idea was they would
MEMBER APOSTOLAKIS:
MEMBER
BLEY:
That
All right.
kind
of
detailed
analysis --
19
MEMBER APOSTOLAKIS:
20
MEMBER BLEY:
21
Okay.
That's my understanding.
17
18
So it's not there.
be scrutinized at the level of the DBA.
15
16
It was never clear to
That's what --
-- LBEs which were a limited
set.
22
MEMBER APOSTOLAKIS:
That's right.
23
where the practical issues came up.
24
the TNF --
25
MEMBER SHACK:
That's
But there is --
It was clear it was part of
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them.
And as you said, the real question is do you
2
pick those licensing basis events based on strictly
3
the PRA?
4
the
5
deterministic ones but look at the PRA and see if
6
there
7
really ought to be -- you know, we didn't want the old
8
LWR case where we picked out design basis events and
9
found out we left out important things.
two
Or well, you know, we argued when we wanted
and
were
a
half
was
additional
to
licensing
10
MR. RUBIN:
11
MEMBER SHACK:
okay,
basis
pick
events
some
that
No, we're not doing that.
That really was what we
12
were trying to avoid here.
13
informed option two and a half.
14
yes,
And that is our risk-
MEMBER APOSTOLAKIS:
That's correct.
But
15
there is also, because the staff is very clever, there
16
is a long discussion on the LBE.
17
says and the staff is free to pick any sequence they
18
like and declare it a design basis or an LBE.
19
that.
I love it.
(Laughter.)
21
MEMBER APOSTOLAKIS:
But let's wait until
tomorrow.
23
24
I like
I really love it.
20
22
Then at the end, it
CHAIR CORRADINI:
Okay.
Other comments?
Questions?
25
MEMBER ARMIJO:
I have a comment on the --
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first of all, I thought the research plan was very
2
well written and very comprehensive.
3
through it I just kept -- you know, the cash register
4
kept turning around.
5
(Laughter.)
6
MR. KRESS:
But as I read
It is an enormous set.
You
7
know unless a lot of that stuff is already available,
8
it's going to take an enormous amount of time as well
9
as money.
And part of the -- so I don't think there
10
is a chance that you will ever meet those dates.
11
that goes for DOE.
12
And
Because first of all, the design hasn't
13
been selected.
14
be prismatic or pebble.
15
going to be a gas turbine or a steam generator.
16
You don't know whether it is going to
You don't know whether it is
There's -- fuel development takes a lot of
17
time.
18
irradiations on the fuel.
19
technology that was pretty well established when ABR
20
was operating.
21
graphite, all this stuff.
And you're still what I would call like scoping
And you are resurrecting a
But it is all being resurrected -- the
22
So I think the staff could push back to
23
DOE and say you guys have got to make up your mind on
24
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25
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1
2
CHAIR
CORRADINI:
And
the
size
of
the
machine.
3
MEMBER ARMIJO:
-- and the size of the
4
machine and back off on your 950 until we have some
5
experience that we know that this fuel will work.
6
else you'd better start developing some better fuel if
7
you are insisting on the 950.
8
9
Because
that's
an
enormous,
amount of work that is in that plan.
10
a good plan.
11
it.
12
all the money you wanted.
Or
enormous
I thought it was
But I don't think there is money behind
I don't think there's even time even if you got
13
So that's my comment.
14
MEMBER SHACK:
I would say, you know, the
15
customer is always free to choose what he wants as
16
long as the staff could say you have to give me enough
17
evidence to convince me it will work.
18
CHAIR CORRADINI:
19
MEMBER SHACK:
Right.
And the longer he waits,
20
the less -- to me, that's the customer's choice.
21
he wants to go for 750 or 950, that's his business.
22
As long as the staff is willing to dig in and say if
23
you want to go 950, I need all of the data that you
24
want -- that I need to make that safety decision.
25
MR. RUBIN:
If
It's a bargain we have on this
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1
strategy.
2
MEMBER APOSTOLAKIS:
3
DOE to do anything.
4
data.
5
The staff cannot ask
I mean no.
MEMBER ARMIJO:
Besides asking for
This is unusual.
This
6
isn't the licensee coming to the staff.
7
little bit co-development, government co-development.
8
MEMBER BLEY:
9
MEMBER ARMIJO:
This is a
Under law.
10
MEMBER BLEY:
11
MEMBER ARMIJO:
Under law, okay.
Yes.
And so the staff could
12
simply say hey look, for 950, we're going to need a
13
hell of a lot of data.
14
this time, this date, to license this machine, you
15
know, time is running out.
16
decisions.
17
And you want us to be ready by
You have to make some
CHAIR CORRADINI:
But it's my -- I don't
18
disagree with your comments.
19
are very good.
20
those internal discussions now and has had them for
21
the last couple years.
22
23
But it is my impression DOE is having
MEMBER ARMIJO:
You could tell they hey,
your licensing on this schedule is at risk.
24
25
I actually think they
CHAIR CORRADINI:
No, it wasn't a slip of
the tongue because they have been mulling over this
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1
for a while.
2
longer than a couple of years.
3
not exactly sure if the staff has any dog in this
4
fight.
5
schedule.
6
discussion.
They
observe
that
MEMBER APOSTOLAKIS:
very clear earlier.
9
they
can't
meet
I think Stu made it
He said, you know --
MR. RUBIN:
10
11
can
My only worry is I'm
And that's about the only way into this
7
8
Harold and I are quite aware of that for
If they slip, we slip.
MEMBER APOSTOLAKIS:
-- yes, if you slip -
-
12
MR. RUBIN:
It's an agreement.
You look
13
to your part of the bargain of staying on schedule,
14
we'll keep up with you.
15
broken.
16
talked
17
drives you to certain temperatures.
18
may not be for hydrogen but may be for process heat
19
that may not require those temperatures.
If they don't, the bargain is
But the question of temperature, the ENACT
about
20
a
hydrogen
plant.
A
hydrogen
plant
The interest now
Okay.
So there are some issues now.
Can we
21
lower them?
22
final on that or they are still sticking with their
23
hydrogen goals.
24
25
And we're not sure if they are firm and
CHAIR CORRADINI:
any
temperature.
You can make hydrogen in
Electrolysis
does
very
well
--
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1
electricity at ambien conditions.
2
MEMBER BLEY:
I had one comment -- and Jay
3
is gone -- that's too bad -- on the human performance
4
presentation.
5
I'm disappointed that, you know, for many
6
years the people in human performance have argued they
7
really need to be involved up front as design and
8
development go ahead.
And I think so far we're missed
9
a golden opportunity.
While they are in the plan, it
10
is more a catalogue of things -- what they know and
11
what they don't know rather than a plan of how of how
12
to move forward in the research to mesh up with the
13
research plan.
And I think they really need to get on
14
the
lay
15
performance work is going to integrate with the rest
16
of the development.
ball
and
out
a
plan
17
CHAIR CORRADINI:
18
MEMBER
19
make comments tomorrow, right?
20
CHAIR
for
Okay.
APOSTOLAKIS:
CORRADINI:
how
the
human
Thank you.
Everyone
Correct.
can
also
I'm
just
21
trying to, you know, save us -- so that when it is
22
fresh in your mind, I get I down.
23
MEMBER SHACK:
Well, I would, just as a
24
comment, I would support Steve's contention that, you
25
know,
you
should
not
build
this
thing
without
an
NEAL R. GROSS
COURT REPORTERS AND TRANSCRIBERS
1323 RHODE ISLAND AVE., N.W.
(202) 234-4433
WASHINGTON, D.C. 20005-3701
www.nealrgross.com
337
1
integral test for the thermal fluids part.
2
MR. KRESS:
3
CHAIR
I second that motion.
CORRADINI:
Yes,
but
the
integral
4
test -- if we're going to get into that, the integral
5
test, before you start picking it, it is going to be a
6
very difficult integral test given --
7
8
MR. KRESS:
It will be the most difficult
one they have done.
9
CHAIR CORRADINI:
Yes.
All right.
And I
10
guess I think we have to see the scaling analysis of
11
it before I'd buy into anything that I'd want to call
12
integral.
13
MR. KRESS:
14
MEMBER
15
integral test.
That's right.
ARMIJO:
Bill
(Laughter.)
17
MEMBER APOSTOLAKIS:
bad
So you guys don't
believe in simulation?
19
CHAIR CORRADINI:
20
will adjourn for the night.
21
8:30.
22
23
say
He said integral test.
16
18
didn't
Anything else?
So we
And pick up tomorrow at
(Whereupon, the above-entitled meeting of
the ACRS meeting was concluded at 4:58 p.m.)
24
NEAL R. GROSS
COURT REPORTERS AND TRANSCRIBERS
1323 RHODE ISLAND AVE., N.W.
(202) 234-4433
WASHINGTON, D.C. 20005-3701
www.nealrgross.com
Advanced Reactor Research Plan
for
Accident Analysis
Allen Notafrancesco
Office of Nuclear Regulatory Research
January 14, 2009
1
Accident Analysis R&D Objectives
• Develop, validate and utilize accident source term and fission
transport analysis models, tools and knowledge to support
NRC licensing application reviews in the areas of HTGR
source term, FP release, dose assessment and PRA analysis.
• Integrate the TRISO fuel, nuclear and T-F models into the
accident source term and fission product transport analysis
models and tools for the NRC HTGR accident evaluation.
2
HTGR Mechanistic S-T and FP Transport Calculation
Must Model Many Complex Phenomena
Helium Pressure
Boundary (HPB)
Reactor Building
HPB Break
UO2, UCO
Graphite Dust
Reactor Bldg Vent
M-285(7)
8-27-01
Fuel
Vent Filter?
3
Accident Analysis Methods
• Calculate normal operation and transient
behavior for the entire system (core, vessel,
confinement), integrating thermo-fluids and
fission product release/transport processes
including dust, and graphite oxidation.
4
Selected MELCOR Code
• Code includes most of the capability to build
upon for HTGR analysis for Design Basis
Accidents (DBA) and beyond DBA accidents
events (e.g., air and water ingress)
5
Current MELCOR Modeling Capabilities
Phenomena from PIRT MELCOR “Packages”
Decay Heat
Decay Heat
Aerosol Dust Deposition Radionuclide (RN)
Cavity Filter
Performance
Flow Path (filter model w/RN)
Combustion of
Flammable Gas
Burn
Core Coolant Flow &
Properties
Control Volume Hydrodynamics & Flow
Path
Reactivity temperature
feedback
Core
6
Initial Activities for PBR & PMR
• Review INL MELCOR version for HTGR
and review He-Air thermal-physical
data/correlations for expected conditions
• Update Core Package (COR) to model
HTGR core fuel and structural material
components
• Incorporate graphite oxidation (steam and
air) models
7
Review of INL MELCOR
Modifications and He-Air Data
• INL Modifications to MELCOR
– Oxidation of graphite Heat Structures
– Diffusion of air in helium
• He-Air Properties in MELCOR compared
to NIST data (range is 300-1500K, 0.110MPa)
– Ideal gas law modeling is reasonable
8
Update MELCOR Core Package
• HTGR cores implemented as new reactor
types PBR (pebble bed) and PMR
(prismatic block) into MELCOR 2.1
• PBR pebble fueled and unfueled zones
• PMR fuel compacts and graphite prismatic
blocks
• Graphite reflectors (inner and outer
annular elements)
9
MELCOR Modeling Capabilities Related to Core
Phenomena from PIRT table
Status
Plan of Approach
Graphite Oxidation of Fuel
Components
Added and tested
Added graphite oxidation in steam and air
to MELCOR
Pebble Temperature Profile
Added and tested
Modify MELCOR fuel profile to add sphere
fuel modeling
Bed Effective Conductivity
Added and tested
Added packed bed correlation for
conduction and radiation
Fuel and Graphite Blocks
Radial Conduction
Added, PBR tested.
Graphite Blocks to be tested
with PMR input file.
Expanded MELCOR core conduction model
by adding radial heat transfer
Pebble Bed friction factor and
heat transfer
Completed
Using packed bed friction factor and heat
transfer
He coolant properties
Reviewed properties from
NIST
MELCOR can model He adequately
CO/CO2 reaction products
Added oxidation, need to
add the ratio model
Kim and NO model for CO/CO2 ratio will be
implemented in MELCOR.
Point Kinetics
Preliminary testing
performed
Reflector components
Added and needs testing
10
Accident Analysis Strategy
• Develop MELCOR input models for PMR and PBR
designs (SNL in partnership with Texas A&M)
• Perform analyses of accident classes
– loss-of-forced circulation (pressurized)
– loss-of-forced circulation (depressurized with air
ingress)
– ATWS
– water/steam ingress from secondary system
• Conduct code assessments against relevant plant
benchmarks
11
Fission Product Release & Transport
Modeling
• PARFUME and TMAP4 insights will be used for
CFP failure rate predictions and fuel fission
product releases
• Devise simplified models/methods to incorporate
into MELCOR framework
12
Thermal-Fluids Improvements
• Implement Reactor Cavity Cooling System (RCCS)
model
– Removal of heat from the reactor vessel using
either air or water as the RCCS cooling medium
– Radiation and convection heat transfer with
participating medium (gray gas and dust effect)
• Plant components
– Heat exchangers
– Secondary system components (gas turbine,
compressor)
• Stratified flow air ingress modeling (counter current
flow)
13
Other Planned Activities
• FP lift-off and resuspension modeling
• Identify areas requiring benchmarking and
experimental validation
• Improve code numerics for slow and long
transients for HTGR analysis
– Time-step optimization (e.g., convergence
criteria, subcycling)
– Code parallelization
– Optimization of numerical schemes and
solution strategies
14
Models to be Added to MELCOR for HTGR
Modeling
Phenomena from PIRT table
Status
Plan of Approach
RCCS Modeling
TAMU is assigned to add an
RCCS to the PBR core input
Use existing CVH, FP and HS
radiation models in MELCOR
Air Ingress (Countercurrent Flow)
SNL is evaluating this problem
Improved Balance of Plants
components
SNL will try to use existing
Mechanical and Heat Exchanger
models in MELCOR
Fission Product Release model
Awaiting review of INL codes
SNL will review the models in INL
codes and devise a simplified
model for fission product release.
Liftoff/Suspension of Dust
Plan to perform literature search
on entrainment
Re-entrainment model to be built
in MELCOR
15
Summary
•
HTGR model extensions in MELCOR 2.1 are
well underway
– Development informed by past work and
PIRT
– Assessment activities will follow
– Extensive coordination with other programs
is required
16
Advanced Reactor Research Plan
for
Reactor Consequence Analysis
Jocelyn Mitchell
Office of Nuclear Regulatory Research
January 14, 2009
1
Reactor Consequence Analysis R&D
Objective
• MACCS2 code itself is technology-neutral
• MACCS2 input now developed for LWR
technology
• Objective to consider any important
differences in input stemming from
advanced reactor technologies
2
Licensing Issues
related to Reactor Consequence Analysis
• Offsite consequence analysis is the final
aspect of PRA
• Mix of radionuclides and the chemical
forms may be different for advanced
reactors
3
Technical and R&D Issues
(Reactor Consequence Analysis)
• Other analyses would give the inventories of
produced radionuclides
• Other analyses would provide the chemical
forms of the released material
• This effort would determine if there are new
biologically important nuclides and determine the
dose conversion factors for the appropriate
chemical forms for all nuclides
4
R&D to be started between now and FY 09
• None
• Await input from other areas
• Techniques well developed, so no
need to start earlier
5
Advanced Reactor Research Plan
for
Fuels Analysis
Stuart D. Rubin
Office of Nuclear Regulatory Research
January 14, 2009
1
HTGR Fuels Analysis
Objectives:
• Develop, validate and utilize HTGR fuel behavior and fuel
fission product transport analysis models, methods and insights
to support safety and licensing reviews.
• Use the HTGR fuel behavior and fuel fission product transport
methods and data for developing an accident source term for
normal operation and accident conditions for use in the NRC
accident analysis evaluation model.
• Develop NRC inspection capability to independently assure the
production fuel supply quality.
• Develop NRC staff technical knowledge and capability to
effectively review the fuel performance aspects of an HTGR
licensing application.
2
Key Fuel Safety and Licensing Issues
•
Predicting fuel particle failure rates during:
Normal operation, core heat-up, air ingress, water ingress, large
reactivity insertion events
•
Predicting fuel fission product release during:
Normal operation, core heat-up, air ingress, water ingress, large
reactivity insertion events
•
Establishing the margins to significantly increased particle failure rates
and fuel fission product release during normal operation and accidents
•
Determining the magnitude of metallic radionuclides in mobile graphite
dust
•
Confirming the adequacy of fuel qualification irradiation and accident
condition testing methods
•
Providing regulatory assurance of the quality of the fuel fabricated over
fuel supply lifetime
3
Background
“The key (HTGR) concept is the coated
fuel particle, which serves as a miniature
fission product containment vessel.” 1
1
DOE-HTGR - 90257
4
HTGR “TRISO” Coated Fuel Particle
Porous Carbon Buffer Layer
Dense Inner Carbon Layer
Dense SiC Layer
UCO or UO2
Fuel Kernel
Dense Outer Carbon Layer
5
Background
•
An HTGR core contains billions of coated fuel particles (CFPs)
•
To meet dose acceptance limits: FP release from fuel heavy metal contamination, CFP
defects from manufacture, CFP operational failures, CFP accident failures and, intact
CFPs - must all be very low
•
Fuel manufacture has a prime effect on: CFP properties, performance and FP release
•
Fuel operating conditions have a strong effect on: CFP performance and FP release
•
Fuel accident conditions have a strong effect on: CFP performance and FP release
•
Design and manufacture-specific fuel irradiation and accident condition test data are
needed to: develop and validate the fuel behavior and fuel FP transport models and to
qualify the fuel for licensing
•
Due to the projected low levels of fuel FP release and circulating activity, HTGR plant
designers propose a low pressure vented reactor confinement building.
6
Pebble Bed Reactor Fuel Element
7
Prismatic Block Reactor Fuel Element
8
HTGR Fuel Particle Integrity Requirements
To meet dose acceptance criteria at the site boundary, CFP
initial defects, irradiation failures and accident condition
failures must not exceed (i.e., design limits) about….
+
+
< 6X10-5 manufacturing (un-irradiated) defect rate
< 6X10-5 normal operations (irradiation) failure rate
< 1X10-4 accident (heat-up) failure rate
…..crediting fission product transport holdup and retention
mechanisms within the fuel element, core graphite structures,
helium pressure boundary surfaces, confinement building
surfaces and release dispersion characteristics.
9
Background
“Successful operation (of the HTGR)
is dependent on predictable
performance of the fuel.” 1
1
DOE-HTGR - 90257
10
Fuel Particle Performance:
Single Particle Behavior/Failure Modeling
11
Particle Integrity: Failure Mechanisms*
CFP Failure Mechanisms:
•
Pressure vessel failure (SiC layer rupture)
•
PyC irradiation failure (dimensional change)
•
PyC layer de-bonding from SiC layer (SiC local stress riser)
•
Kernel migration (SiC layer degradation)
•
SiC failure due to fission product attack
•
SiC failure due to decomposition (elevated temperature)
•
SiC failure due to oxidation (air ingress)
•
Particle failure due to rapid energy deposition (reactivity insertion)
•
Elevated fission product diffusion through intact coating layers
* TRISO-Coated Particle Fuel Phenomenon Identification and Ranking Tables (PIRTs) for Fission Product
Transport Due to Manufacturing, Operations, and Accidents (NUREG/CR-6844)”
12
Particle Integrity: Important Phenomena
Particle Property Phenomena*
Kernel:
fission gas release; CO production; swelling during
rapid reactivity events
Buffer layer:
interconnected void volume, cracking/failure
PyC layers:
anisotropy, Poisson’s ratios (elastic and creep),
strength, bonding to SiC, CTE, elastic modulus,
irradiation-induced dimensional change, creep
SiC layer:
strength, elastic modulus, CTE, irradiation-induced
swelling and creep
All of the Above:
Variation in dimensions and material properties
Operational and Accident Condition Phenomena
Normal operations:
Fuel element surface temperature and kernel power
(to calculate CFP radial temperature gradient) fast
fluence, kernel burn-up,
Heat-up accidents:
Fuel element max surface temperature, fast fluence,
kernel burn-up, CFP irradiation temperature history
Reactivity events:
Kernel burn-up, irradiation temperature history;
kernel energy deposition and rate, kernel max
transient temperature
Oxidation events:
SiC oxygen or H20 partial pressure; SiC temperature;
SiC time at temperature
* Property values can change with irradiation, temperature; CFP manufacture-specific irradiation and accident condition test data
needed for most material properties
13
NRC Fuel Particle Performance Analysis
Model Development and Use
• Obtain multi-dimensional behavior, finite element PARFUME
code, models, data and manuals from DOE/INL
• Evaluate PARFUME via code-to-code and code-to-data
benchmarks
• Conduct sensitivity studies to evaluate variations in important
phenomena, qualification test program adequacy, etc
• Use PARFUME to develop NRC staff knowledge of CFP
performance and behavior to prepare for licensing reviews
• Update PARFUME with NGNP-specific CFP materials data,
irradiation test data, accident condition test data when available
• Use PARFUME sensitivity studies to inform selection of CFP
failure rate vs. fuel temperature and B.U. to be used in NRC
accident analysis evaluation model
14
Fuel Particle Performance:
Core-Wide Particle Failure Rate Modeling
15
NRC Core-Wide Particle Failure Rate Model Development
NRC Accident Analysis Evaluation Model (EM)
•
Establish CFP failure fraction based on NGNP CFP failure fraction design
requirements and NGNP fuel qualification program CFP failure fraction data.
•
Establish CFP failure fraction versus fuel temperature and burn-up based on the
above NGNP failure fraction requirements and data
•
Use PARFUME to inform the development of conservative and best estimate CFP
failure fraction versus temperature and burn-up
•
Commission decisions on mechanistic source term calculation and use will determine
where conservative or best estimate CFP failure fraction versus temperature and
burn-up will be used in EM for normal operation, transients, DBAs and BDBAs
•
Utilize the selected CFP failure fraction function in the NRC accident evaluation
model to predict number of CFP failures in the core vs. R, Z and time for normal
operation, transients, DBAs and BDBAs
•
Compare the NRC CFP failure fraction function to the NGNP COL applicant’s CFP
failure fraction function
•
Near Term: Utilize a CFP failure fraction versus fuel temperature and burn-up based
on German reference fuel qualification (irradiation and heat-up) test results
16
NRC Core-Wide Particle Failure Fraction Model*
Z
Particle failure fraction (normal operation)
FF = f {max fuel operating temp, B.U.}
Particle failure fraction (accident heat-up)
FF (r, z, t) = f {fuel accident temp (r, z, t), B.U.}
* To be based on NGNP fuel qualification test data
r
17
Particle Failure Fraction vs. Fuel Temperature and Burn-up*
(Response Surface)
1
CFP Failure Rate
Fresh Fuel
0.1
1/2 Design BU
Design BU
0.01
0.001
0.00001
900
1000
1100
1200
1300
1400
Fuel Temperatu
re
* Prototypical - for illustration only
o
1500
C
1600
1700
1800
Fu
el
Bu
rn-
up
0.0001
18
Modeling Fuel Performance:
Fission Product Transport and Release
19
Fuel Fission Product Transport Modeling
Fuel element component
•
•
•
•
•
•
Kernel
Inner PyC layer
SiC layer
Outer PyC layer
Fuel matrix (pebble or compact)
Fuel graphite block (PMRs only)
20
Fuel Fission Product Transport Modeling
Fuel Element Component
Fission Prod. Source*
Kernel
IPyC
SiC
OPyC
Matrix
Graphite
Contamination
-
-
-
-
Yes
Yes
Failed SiC Layer
Yes
Yes
-
Yes
Yes
Yes
Failed Particles
Yes
-
-
-
Yes
Yes
Intact Particles
Yes
Yes
Yes
Yes
Yes
Yes
*Leach-burn-leach test provides distribution for fresh fuel
21
Fuel Effective Diffusion Coefficients*
UO2
SiC
IPyC and OPyC
Matrix
* IAEA TECDOC 978
22
Fuel Fission Product Transport Modeling
TMAP4 Code
• FP transport in a TRISO coated particle and fuel matrix
• Solves 1-D diffusion equation, with trapping (if needed) for all layers
• Intact, failed, defective SiC, and matrix contamination can be modeled
• User-specified fission product generation rate in kernel vs. time
• Calculates temperature distribution from fuel element surface to kernel
• User-specified effective diffusivities for each component
• Effective diffusion coefficients for each component calculated
• Soret diffusion in any layer (e.g., large ∆T in buffer during normal operation)
• PBR cyclic or PMR steady irradiation temperatures can be input
• Normal operation/irradiation and accident heat-up FP transport
•
Fuel temp vs. time is most important to fuel FP transport and release
23
NRC Fuel Fission Product Transport Model Development
•
Obtain TMAP4 code from INL for fuel FP transport analysis
•
Evaluate TMAP4 via code-to-code and code-to-data benchmarks
•
Conduct sensitivity studies to evaluate variations in diffusivities, etc.
•
Use TMAP4 to develop NRC fuel FP transport knowledge for the
NGNP COL review
•
Near-Term: Use available (IAEA TECDOC-978) effective diffusivities
•
Long-Term: Update TMAP4 with NGNP fuel-specific effective
diffusivities based on DOE/INL AGR test program results/data
24
NRC Fuel Fission Product Transport Model Development
•
Evaluate using TMAP4 for calculating core-wide fuel FP diffusion and release
versus fuel temperature, burn-up and time for: contamination; failed particles;
particles with failed SiC layers and; intact particles or,
•
Develop alternative simplified fuel FP diffusion and release models for calculating
core-wide fuel FP diffusion and release versus fuel temperature, burn-up and time
for: contamination; failed particles; particles with failed SiC layers and; intact
particles
•
Utilize the selected particle failure fraction response surface together with the
selected fuel FP diffusion and release models in the NRC accident analysis EM to
calculate the core-wide fuel FP transport and release vs. R, Z and time for normal
operation, transients, DBAs and BDBAs
•
Near-term: utilize available (IAEA TECDOC) fuel FP diffusion and release rate data
•
Long-term: utilize the fuel diffusion and release rate data developed by the NGNP
fuel development and qualification program
25
Fuel Fission Product Release: Effects of Water Ingress
Stored 85K Fission Gas Release as a Fraction of Kernel Inventory
Oxidants reaching exposed kernels can rapidly/significantly
increase fuel particle fission product release
•
Release fraction from exposed kernels depends on H2O
partial pressure and fuel temperature
•
If NGNP design has steam generators, SG tube failure
could significantly increase exposed kernel releases
•
NGNP designs with no high pressure, high volume water
sources, could limit/preclude increased kernel releases
•
Limited fission product release data/models for irradiated
compacts with UCO kernels and pebbles with UO2 kernels
•
Additional experimental data for NGNP fuel will be needed to
reduce model uncertainties for H2O ingress FP release
•
DOE AGR fuel technology development program may test
irradiated fuel with intact and failed particles for H2O ingress
•
NRC has access to DOE test data for developing NRC fuel
fission product release models
•
Near-term: Use available data/models (e.g., IAEA TECDOC)
with uncertainty for NGNP fuel design
H20 at 186 Pa and 770O C
Stored 85K Fission Gas Release as a Fraction of Kernel Inventory
•
H2O Partial Pressure
26
Fuel Fission Product Release: Modeling Air Ingress
•
Fuel matrix/OPyC oxidation can release FP by means other
than diffusion
•
Oxidation can fail particles by OPyC degradation and/or SiC
oxidation (SiC + O2 -> SiO or SiO2)
•
Particle failure fraction depends on extent of air supply,
particle temperature and can be much greater than heat-up
without air ingress
•
Low chemical reactivity of PMR nuclear-grade fuel blocks
(vs. PBR fuel element matrix material) provides some
protection of PMR fuel compacts and particles
•
Air ingress provides a HPB opening and motive force for FP
transport from HPB
•
Existing irradiated fuel oxidation effects data/models are not
typical of NGNP fuel design (e.g., burn-up, fluence)
•
DOE AGR fuel technology development program may
include air ingress testing of irradiated fuel
•
NRC has access to DOE test data for developing NRC fuel
fission product release models
•
Near-term: Use available data/models (e.g., IAEA TECDOC)
with uncertainty for NGNP fuel design
Oxidation of two similar fuel spheres in air.
Top: 9% FIMA; Bottom: 8.8% FIMA (IAEA TECDOC-978)
27
Fuel Fission Product Release: Modeling Reactivity Accidents
•
Large/rapid power pulse can release kernel FP and
melt kernel, potentially over-pressurizing/failing CFPs
•
CFP failure rate depends on energy deposition,
deposition rate and fuel kernel transient temp rise
•
Severity of reactivity accidents depends on core
excess reactivity
•
Concurrent HPB failure (CR ejection) would provide a
motive force for fuel FP transport outside the HPB
•
Limited reactivity insertion test data/models exist for
irradiated fuel and is not typical of NGNP fuel design
•
Reactor type (PBR or PMR) and limiting RIA event
selection will determine whether NGNP fuel-specific
reactivity accident testing is needed
•
Near-term: Use available data/models (e.g., IAEA
TECDOC) with uncertainty for NGNP fuel design
Particle failure rate vs. pulse energy deposition (IAEA TECDOC-978)
28
Background
“Manufacturing and inspecting of the
fuel are critical steps in assuring the
performance necessary for the
success of the reactor system.”1
1
DOE-HTGR -90257
29
Fuel Fabrication
30
U.S. and German Fuel Performance Experience
1.00E-03
Range of
Old (NPR)
US Fuel
Irradiation
Data
1.00E-04
1.00E-05
1.00E-06
GF-4
SSL-2
R2-K13
HRB-15A
NPR1
NPR1A
NPR2
HRB21
FSV
P13S Cell 2
P13R Cell 6
P13S Cell 5
1.00E-07
1.00E-08
1.00E-09
1.00E-10
0.00E+00
2.00E+00
4.00E+00
6.00E+00
8.00E+00
Range of
New (AGR1)
US Fuel
Irradiation
Data
1.00E+01
Range of
German Fuel
Irradiation
Data
Fast Fluence (* 10^25 n/m^2)
31
NRC Fuel Manufacture
Quality Assurance Oversight Strategy
Develop an NRC inspection protocol for HTGR production fuel fabrication
facilities addressing:
– Conformance with fuel product and process specifications to consistently meet fuel
quality and performance requirements
– Fabrication process equipment and process parameters for fuel quality and
performance
– Fuel characterization methods to ensure fuel product specifications are being met
– Needed calibration testing equipment and calibration inspection procedures for
critical product and process parameters
– Maintenance procedures for fuel fabrication process equipment
– Sampling and Q/C statistical analysis methods
– Process equipment maintenance procedures, calibration and testing
– Procedures, training and qualification of fuel fabrication facility staff
– Automation of process controls and fuel characterizations methods
32
Summary
•
CFP integrity and FP retention is the key to the HTGR safety case
•
Fuel behavior and FP release depends on fuel fabrication, operating
history and accident conditions
•
NRC is developing analytical tools, data and expertise to assess CFP
behavior and fuel fission product diffusion and release
•
CFP behavior performance and fuel fission product release models are
being evaluated for integration into the NRC accident evaluation model
to predict the core-wide event-specific accident source term
•
The contribution of matrix dust to the accident source term must be
assessed and addressed
•
NRC will extensively utilize the DOE AGR fuel development and
qualification program work products to meet HTGR fuels R&D needs
•
Cooperative research will also be used to supplement and assess DOE
data, models and tools, as appropriate
•
NRC is developing the basis for inspecting HTGR fuel production
facilities
33
Advanced Reactor Research Plan
Human Performance
J.J. Persensky, Ph.D.
Valerie E. Barnes, Ph.D.
Office of Nuclear Regulatory Research
January 14, 2009
1
Human Performance
R&D Objectives
• Establish the bases for new methods and tools for
evaluation of human performance issues at
advanced reactors
• Anticipate paradigm shifts in human performance
issues because of new concepts of operations.
• Identify new, or any needed, changes to review
guidance
2
Safety and Licensing Issues
in the Human Performance
Technical Area
Safety issues
– Potential for human error
– Reduction of situation awareness
– Availability of adequate qualified plant staff
Licensing issues
– Accommodation of rapidly changing technology
in the current regulatory framework
– Training and development of NRC staff
3
How HSIs at advanced control
rooms may differ
Current LWR
Advanced Reactors
Large expansive control rooms
Centralization of HSIs into compact
workstations and overview displays
Crew interaction with plant
systems and components
Interaction through computer
systems
Physical HSIs
Virtual HSIs
Parallel access to HSIs
Serial access to HSIs through
view ports (keyholes)
Fixed HSIs
Flexible HSIs
Limited functionality
Expanding functionality of HSIs
4
Control Room
at Beznau
5
PBMR simulator in South
Africa
6
Human Performance
Plan Activities
• Basis document
– “Human Factors Considerations with Respect to
Emerging Technology in Nuclear Power Plants”
(NUREG/CR-6947)
– Ongoing research
• Operations under degraded I&C conditions
• Human factors methods and tools
• Roles of personnel and automation
7
Human Performance
Plan Activities (Cont.)
• Related Activities
– Develop long-term guidance for “Highly-Integrated
Control Room - Human Factors” plan (TWG #5 of the
Digital I&C Steering Committee)
– Participate in the OECD Halden Reactor Project
– Participate in the NEA/CSNI/Working Group on Human
and Organizational Factors to implement the Technical
Opinion Paper (TOP) on an integrated human factors
research program for advanced reactors
8
Human Performance
Planned R&D Areas
in ARRP
•
•
•
•
•
•
•
•
•
New concepts of operation
Operational designs and operator functions and tasks
Function allocation - Automation
Process complexity and opacity
Workload variations, transitions, and staffing
Teamwork and communication
Computer-based procedures and intelligent automation
Alarm management
HFE methods and tools
9
Human Performance R&D
to be started in
FY 09 & FY 10
Project Title
FY09
FY10
Degraded I&C and
computerized procedures
X
X
Update NUREGs-0711 &
- 0711
X
X
Halden Reactor Program
X
X
Distributed decision-making
X
Operator modeling
X
Support HF standards
X
EPRI collaboration
X
10
Applications of Human
Performance R & D
• Clear expectations for the evaluation of
advanced control rooms with a well-defined path
for advanced reactor licensing
• Identify the need for safety enhancements and
regulatory action
• Technical basis and criteria for design
acceptability reviews (e.g., input for regulatory
guides, SRP enhancements, NUREGs, or
inspection guidance)
11
Human Performance R & D
Conclusions
• Good match between the NRC ARRP and the
internationally recognized CSNI-TOP
• Opportunities for international collaboration –
Leveraging and efficiency
• The Halden program will incorporate efforts
related to the CSNI report
• The CSNI program could encourage the
development of new research facilities and
opportunities for field studies
12
Advanced Reactor
Control Room?
13
Advanced Reactor Research Plan
for Hydrogen and Process Plant
Analysis
Nathan Hudson
Office of Nuclear Regulatory Research
January 14-15, 2009
1
Hydrogen and Process Plant R&D Objectives
• To develop independent expertise, tools,
and capabilities to support staff review of
the safety implications on the VHTR posed
by the NGNP hydrogen production facility.
• Tools & methods to be implemented
should be accurate to the extent that they
are not unnecessarily overly-conservative.
2
Hydrogen and Process Plant Analysis
3
Hydrogen and Process Plant Performance
Safety issues
Chemical Releases:
• Ground hugging heavy gas release (e.g., oxygen,
suffocants, and toxic gases)
• Hydrogen gas detonation from H2 plant
• Combustion of another flammable gas or liquid
Process Heat Transport System:
• Transients in chemical plant that lead to reactor trip
or component failures
• IHX tube failures, PHX tube failures, piping failures
VHTR Events that Effect Hydrogen Plant
• Tritium transport
4
Hydrogen and Process Plant R&D Plans
• Develop an Evaluation Model (EM) to predict
response of VHTR to transients undertaken in
the hydrogen production plant and vice versa.
– to be accomplished by extending the developing
VHTR core EM to include the connecting heat
exchangers and piping
– will be necessary to couple this extended EM to
existing chemical process software through a
software interface.
5
• Develop detailed fluid flow and solid stress
models for the connecting process heat
exchangers and piping using existing tools.
• Develop EM for hydrogen deflagration &
detonation events.
– Hydrogen deserves a special treatment due to its
highly buoyant & diffusive properties
– EM to implement already existing analytical tools,
correlations, or software.
– EM to be able to predict the incident blast overpressure loading on the reactor containment as a
function of the separation distance between the
containment and the hydrogen plant.
6
• Assess hydrogen EM against historical
experimental data
• Develop EM for general deflagration and
combustion events, excluding hydrogen
at the hydrogen plant.
– should be able to approximate radiative &
convective heat flux projected upon the
reactor building(s)
– blast over-pressure & impulse shape from
combustion event.
7
• Develop EM to approximate
concentrations of a heavy gas release at
specified distances from the reactor
building(s)
• Establish a measurable regulatory activity
of tritium to be detected in the
intermediate coolant loop, through use of
a radiation detector submerged within the
gas during NGNP operations.
8
Advanced Reactor Research
for
Nuclear Analysis
Anthony Ulses
Office of Nuclear Regulatory Research
January 14th, 2009
1
Introduction
•
•
•
•
Objectives
Summary of Current Status
Review PIRT Findings
Research Plans
2
Objective
• “…to establish and qualify the
independent nuclear analysis
capabilities and insights that may be
needed to support the licensing
evaluation of reactor safety analyses
for PBR and PMR designs.”
3
NRC Code Suite
4
NRC Spectrum Analysis
Capability
•
TRISO
– 1- D CE Transport
Theory for Detailed
Spectrum
•
Fuel Sphere (or compact)
– Uses TRISO averaged
xsecs
– 1-D CE Transport for
Spectrum
•
Assembly (or multiple
pebbles)
– Uses Sphere or Compact
averaged xsecs
– Multi-dimensional MG
Transport Theory
•
Makes Extensive use of
pre-existing methods
5
Summary of Current Status
• SCALE has working Double Heterogeneity Model
Implemented
– Uses layered continuous energy CENTRM calculations
for self shielding
• Calculated kernel specific disadvantage factors
• Does not rely on Dancoff Factors
– Initial Assessment is Promising
– Applicable to both pebble and prismatic systems
• SCALE has general quadrature capable of
modeling non-orthogonal boundaries
• Depletion and Branching of Double Het.
Configurations implemented
– Not extensively tested
6
HTR-10 Validation Model
Development
• Full model developed based on
available specifications from IRPhEP
Specifications
• Provides a validation case to support
pebble-bed methods development.
• Used SCALE ENDF/B-VII cross section
libraries, double-het capability and
KENO Monte Carlo Code
• Benchmark configurations available for:
– Initial criticality
– Control rod worth
• Comparison of criticality at initial critical
pebble height (123.06 cm)
– SCALE keff = 1.0004±0.0007
• Control-rod worth calculations
underway
DeHart, et .al., “Status Report on the
Validation of the SCALE Code System for
High-Temperature Gas-Cooled Reactor
Analysis,” July 30, 2008.
7
HTTR Validation Model
•
•
•
•
Full model developed based on IAEA
CRP5 Documents.
Provides a validation model for prismatic
core methods
Data Available for:
– Critical configurations with differing
number of fuel columns
– Control rod worth and scram reactivity
– Crticiality vs isothermal temperature
(temperature coef)
Full SCALE model developed (cross
section processing/KENO)
Critical Control Rod Location (300K)
Critical Control Location (418K)
Control Rod Excess Reactivity
Control Rod SCRAM Reactivity
HTTR Experiment
1775 ± 5 mm
1903 ± 5 mm
12.1 % k/k
-46.3 % k/k
SCALE Model
1771 mm
1899 mm
11.9 % k/k
-45.9 % k/k
Ames, et. al. “BENCHMARK EFFORTS TO SUPPORT STUDIES OF VHTRs WITH TRUs,”
HTR2008, Washington D.C., October 1, 2008.
8
NRC Reactor Analysis
Capability
• GenPMAXS
– Currently handles TRITON generated
cross sections
• PARCS
– Cylindrical coordinate solver
implemented
– N-group capability with upscattering
9
PBMR-400 Benchmark
Slow Control Bank Withdrawal
Reitsma, et. al., “OECD 400 MW PBMR BENCHMARK: TRANSIENT CASE 5a COMPARISON
RESULTS,” PHYSOR 2008, Interlaken, Switzerland, 2008.
10
Review of PIRT Conclusions
• Nuclear Phenomena Ranked High or
of Low or Medium Knowledge Level
– Flux and Power Profiles
– Decay Heat
– Temperature Dependent Reactivity
Feedback
– Reactivity Insertion from Moisture
Ingress
– Spatial Xenon Stability
11
Research Plans Flux and Power Profiles
•
We need to develop a fundamental understanding of
system behavior
– TSUNAMI methods will be used to better understand
uncertainties
•
Multi-tiered approach envisioned
– Small scale studies
• Kernel and pebble (or compact) level
– Study available measured data
• HTTR, HTR-10, PROTEUS, etc.
– Prepare detailed models of NGNP system for sensitivity and
parametric studies
– Identify focus areas
•
Prepare PARCS interface
– Research homogenization / de-homogenization techniques
•
Prepare Interface for Fission Product Release Calculations
12
Current Expectations
• Pebble systems more complex than
prismatic
– Stochastic nature of burnup
– Homogenization / de-homogenization effects
– Validating predictions difficult
• Method to measure kernel (and pebble) power
unavailable
• Common Challenges
– Neutron scattering and streaming
– Enrichment
– Multi layered heterogeneity
13
Research Plans Decay Heat
• Stay involved with standards work
• Point depletion models such as
ORIGEN should be valid
– Properly weighted cross sections
– Good predictions of power distribution
• Some applicable calorimetric data
needed for validation
14
Research Plans Spatial Xenon Instability
• Should be able to disposition
analytically
– Assuming good prediction of core
isotopics
• Confirm as part of startup physics
program
15
Research Plans Reactivity Coefficients
• Require fundamental understanding of
phenomena
– Will require measured data
• Ideally, we will have separate effects data
• SCALE to PARCS interface will strongly
influence reactivity predictions
• Recent work by Dagan suggests problem
with processing of scattering resonances
– CENTRM will be modified to assess impact
– High temperature data will be needed to
complete assessment
• TSUNAMI will be used to assess
uncertainties
16
Validation of Physics Methods
• ORNL has performed an initial review of
available experimental data that can be used for
validation of our physics methods
• Validation needed for:
–
–
–
–
–
–
Criticality
Power distribution
Reactivity control worth
Reactivity coefficients (fuel/moderator temperature)
Decay heat
Radionuclide source terms
• Initial focus on establishing a pebble-bed and
prismatic core model to assess current methods
and use for testing during methods development
• Take advantage of large amount of international
data.
17
HTGR Physics and Fuels
Sources of Experimental Data Current Facilities
• High Temperature Test Reactor (HTTR)
– 30MW prismatic reactor, JAEA, Japan
– Currently operational
– Well-documented startup experiments (IAEA CRP)
• High Temperature Gas-Cooled Reactor (HTR-10)
– 10MWt pebble-bed reactor Tsinghua University, China
– Currently operation
– Well-documented startup experiments (IAEA CRP,
OECD/NEA IRPHeP)
• ASTRA Critical Facility
– Zero-power critical facility, RRC-Kurchatov Institute,
Russia
– Pebble-bed configuration supporting PBMR
– Critical states available in evaluated experiment
description
HTGR Physics and Fuels
18
Sources of Experimental Data Historical Facilities
•
HTR-PROTEUS Critical Experiments
– Zero-power critical experiments performed at PSI,
Switzerland, in early 1990s
– Pebble-bed configuration
– Excellent documentation
•
Very High Temperature Reactor Critical Assembly
(VHTRC)
– Critical assembly to support HTTR
– Pin-in-block design
– Documentation available
•
DRAGON Reactor Experiment
– 20MWt Experimental Reactor for OECD High Temperature
Reactor Project, 1960s-1970s
– Over 1000 archived reports available
– Large amount of data to sort through and evaluate, some LEU
experiments
HTGR Physics and Fuels
19
Sources of Experimental Data Prototype facilities
• Prototype facilities can provide useful
information, but fuel enrichment (HEU) and type
(U/Th) limits usefulness
• Prismatic cores:
– Peach Bottom-1 (1967-1974)
– Fort Saint Vrain (1977-1989)
• Pebble-bed cores:
– AVR (1967-1988)
– THTR (1983-1989)
HTGR Physics and Fuels
20
Neutron Scattering in Graphite
• Recent NCSU work has raised some
concerns about the adequacy of current
scattering models
– “Impact of Simple Carbon Interstitial
Formations on Thermal Neutron Scattering in
Graphite, ” Hawari, A. I., A. I. , Al-Qasir, I. I,
and Ougouag, A. M, Nucl. Sci. Eng. 155, 449462 (2007)
• Further work is planned
– RES will continue to follow these
developments and make code modifications
as necessary
21
Near Term Actions (within the
next several months)
• Develop OECD Standard Problem for
Pebble Burnup
– For presentation at February WPRS meeting
– Intended to guide our assessment and
development of burnup capability
• Refine list of data needs
• Continue scoping studies
• Begin detailed model development
– Based on currently available HTR-10 and
HTTR information
22
Expected work Scope for next
Several Years
• Complete detailed assessment studies
–
–
–
–
–
–
Criticality
Power distribution
Reactivity control worth
Reactivity coefficients (fuel/moderator temperature)
Decay heat
Radionuclide source terms
• Update TSUNAMI as needed
• SCALE execution speed
– It is expected that complex models will be needed as
part of licensing
• Complete SCALE to PARCS interface
– How to parameterize cross sections
– Homogenization / de-homogenization
23
Summary
•
Supports the NRC Evaluation Model development by developing,
validating, and utilizing HTGR nuclear analysis models and
methods
– Nuclear analysis interface for fission product release calculations
– Flux and power profiles, effects of burnup and isotopic distribution
– Insights to support safety and licensing reviews
•
Key Nuclear Analysis Challenges
–
–
–
–
–
•
Temperature-dependent reactivity feedback
Stochastic nature of burnup, homogenization/de-homogenization effects
Multilayered heterogeneity
Reactivity insertion from moisture ingress
Reliable prediction of fuel isotopics
Ongoing and Planned R&D
– Phased approach to SCALE and PARCS development for HTGRs
– MELCOR-PARCS interface
– Code assessment and validation
– Neutron scattering properties of graphite
24
Advanced Reactor Research Plan
for
Reactor-Plant Systems Analysis
J. M. Kelly
Office of Nuclear Regulatory Research
New and Advanced Reactors Branch
1
Reactor Plant Systems Analysis
• Presentation Roadmap
– Overview of NRC Evaluation Model (this
presentation)
– Details of support for NRC Evaluation Model
development by technical area:
•
•
•
•
•
Fuels Analysis: Stuart Rubin
Nuclear Analysis: Anthony Ulses
Thermal-Fluids Analysis: Stephen Bajorek
Accident Analysis: Allen Notafrancesco
Consequence Analysis: Jocelyn Mitchell
2
Reactor Plant Systems Analysis
• Contents
– Evaluation Model: Scope & Requirements
– NRC Evaluation Models for NGNP
– Role of CFD Analysis
• Example of ongoing studies (time permitting)
3
Reactor Plant Systems Analysis
• Evaluation Model
– Regulatory Guide (RG) 1.203:
• ‘An evaluation model (EM) is the calculational
framework for evaluating the behavior of the reactor
system during a postulated transient or design-basis
accident. As such, the EM may include one or more
computer programs, special models, and all other
information needed to apply the calculational
framework to a specific event.’
4
Reactor Plant Systems Analysis
• Scope
– Reactor/Plant System Analysis
• FP Release from Confinement/Containment
–
–
–
–
Nuclear Analysis
Thermo-Fluids
Fuel Performance
Fission Product Transport
– Applies to PBR and PMR designs
– Consists of three EM’s
• Normal Operations (Pre-Break)
• Initial FP Release
• Delayed FP Release
5
Reactor Plant Systems Analysis
• Evaluation Models
– Normal Operations
• Determines the source term for the initial release.
– i.e., the generation and distribution of FPs, magnitude and distribution of
plate-out & absorbed FPs within He pressure boundary, circulating
activity, coolant contaminant & erosion activation products, and dust-born
radionuclides.
– Initial Release
• Models the release of circulating activity including dust mobilization
and plate out lift-off; large/rapid reactivity events that result in CFP
failures.
– Delayed Release
• Models the release of FPs from intact & failed CFPs during core heat
up and with or without air or steam ingress; models FP hold-up and
retention within the helium pressure boundary and the confinement.
6
Reactor Plant Systems Analysis
• Examples of Transients to be Analyzed
– Pressurized loss-of-forced circulation (P-LOFC)
• Temperature in upper vessel & associated components.
– Depressurized loss-of-forced circulation (D-LOFC)
• Peak fuel temperature; keff and RCCS performance.
– Air Ingress following a D-LOFC
• Graphite oxidation, integrity of core & support, CFP
damage, release of fission products from graphite.
– Reactivity Events, including ATWS
• Control rod withdrawal, pebble-bed compaction, etc.
– Water ingress
• Reactivity insertion & chemical attack.
7
NGNP Evaluation Model
• By Function
• Code Specific
8
NGNP Evaluation Model
• Development Tasks
– Code & Model Development
– Code Integration
• Automated workflow for EM code suite
– Uncertainty Analysis Methodology
• Implementation of statistical approach
– e.g., Wilks’ method
• Incorporation of model bias & uncertainty
factors into codes
– PIRT Based Code Assessment
– Code Applicability Report
9
NGNP EM: Codes
•
MELCOR - U.S. NRC Severe Accident Code
– Solves 2D flow, heat transfer & fission product transport.
•
•
•
•
•
Core heat transfer & flow models: PBR & PMR
Graphite oxidation models
Extend aerosol models to graphite dust transport
Fission product release models for coated fuel particles
SCALE/AMPX - U.S. NRC Nuclear Analysis Code Suite
– AMPX processes ENDF nuclear data into code usable libraries
– SCALE provides lattice physics and depletion capabilities to generate
few-group cross-sections, decay heat and FP inventory.
•
PARFUME/TMAP4 - INL Mechanistic CFP Performance Codes
– CFP failure rate vs. fuel temperature and BU from NGNP-specific CFP
failure rate test data & PARFUME sensitivity studies
– FP transport in a CFP, fuel matrix, and prismatic fuel block (TMAP4)
•
MACCS2 - U.S. NRC Accident Consequences Code
– Estimates off-site consequences
– Input source term, health, and site parameters
10
NGNP EM: Codes
•
PARCS - U.S. NRC Advanced Reactor Core Neutronics Simulator
– Solves 3D, Time Dependent Core Flux/Power Equations
– Solves 3D Flux in both Cylindrical (PBR) and Hexagonal (PMR)
– Benchmarked for PBR with OECD PBMR-400 Benchmark
•
AGREE
-
Advanced Gas REactor Evaluation
– 3D, two-temperature porous medium (PBR) approach based on the
legacy THERMIX/DIREKT codes.
– Coupled to PARCS to provide coupled time-dependent neutronicsthermo-fluid solution for gas reactors
– Benchmarked with Julich SANA Test Experimental Data and OECD
PBMR-400 Benchmark
– Will be extended to model prismatic core.
•
GENPMAXS - GENerates PMAXS cross section files for PARCS
– Reads SCALE/TRITON output at all burnup and temperature/fluid
conditions and provides cross section library for PARCS
11
NGNP Evaluation Model
• Schedule
– Code Development
• Initial Model Development:
• Model Improvement
– Based on Assessment Results:
Sept. 2010
May 2013
– Develop New Data:
– Validation:
Sept. 2012
• Existing Data:
• New Data:
Sept. 2012
May 2013
– Code Adequacy Report:
Dec. 2013
12
Role of CFD Analysis
• Not part of NRC EM, but used to
– Provide benchmarks
– Develop & select models for system level codes
• Examples of Potential Applications:
– Lower Plenum:
• Graphite oxidation during air ingress event.
– Dust deposition and lift-off.
– Reactor Cavity Cooling System:
• Provide benchmark for MELCOR model: combined radiation &
natural convection heat transfer.
• Investigate effect of graphite dust on radiation heat transfer.
– PMR & PBR Core
• Bypass flow due to gaps between fuel/reflector blocks.
13
Role of CFD: Examples
of Ongoing Studies
• Time & interest permitting
14
Role of CFD: Examples
of Ongoing Studies
• Core Heat Transfer
– Pebble-Bed Reactors
• Micro-Scale Model:
– Fuel kernel temperature distribution
– Effect of CFP clustering (hot spot factor)
• CFD Modeling:
– Pressure Loss & Pebble-Gas Heat Transfer
» Randomly packed bed far from wall
» Randomly packed bed next to wall (reflector)
– Core Effective Thermal Conductivity
– Pebble Multi-Batch Modeling
– Whole Core Porous Body Model
» Provide benchmarks for MELCOR
15
Role of CFD: Examples
of Ongoing Studies
• Core Heat Transfer
– Prismatic Core Reactors
• Meso-Scale Heat Transfer Model
– Temperature distribution within a fuel element
» Fuel compact surface & centerline temperatures
» Moderator (graphite block) temperature
» Coolant channel wall temperature
• Macro-Scale Heat Transfer Model
– Effective thermal conductivity for heat transfer
between fuel assemblies.
• NOTE: meso-scale results have been used to
develop a simplified model for MELCOR.
16
Role of CFD: Examples
of Ongoing Studies
• Sample Results
– Meshing of a random packed pebble bed.
• Remote from reflector wall (infinite medium)
17
Role of CFD: Examples
of Ongoing Studies
• Sample Results: near reflector wall
• Pressure Drop
• Pebble-Gas HTC.
18
HTGR Thermal-Fluids Research
Stephen M. Bajorek, Ph.D.
Office of Nuclear Regulatory Research
Presentation to the Advisory Committee on Reactor Safeguards
Subcommittee on Future Plant Designs
January 14, 2009
1
Introduction & Background
• Thermal-Fluids R&D Objectives
• Major HTGR Thermal-Fluid Issues
– Thermal-Fluids PIRT Rankings
– Approach
– Products & Relation to EM Development
• Experimental Data & Facilities
– Safety Significant Data Needs
– Sources
2
Thermal-Fluids R&D Objectives
• Support the NRC Evaluation Model
development by:
– Obtain and/or generate integral and
separate effects data suitable for code
assessment & model development.
• DOE & Applicant Data
• Collaboration with international organizations.
• Conduct independent experiments:
– Thermal-Hydraulic Institute (THI)
– OSU/TAMU/PU Cooperative Agreement
– Develop or identify correlations for HTGR
processes as necessary.
3
PIRT Identified Processes of
Significant Interest
( Importance = H
and
Knowledge Level = M or L )
• Core & Vessel Thermal-Fluids
– Core effective thermal conductivity (PBR)
– Thermal properties
• Vessel, Core Barrel & Reflector emissivities
• Gas mixture properties
– Bypass and coolant flow distribution
– Heat transfer correlations
• Mixed convection
• Coolant property variation (viscosity, mixture effects)
• Air Ingress
– Duct exchange flow
– Molecular diffusion
– Oxidation of core and supports
4
PIRT Identified Processes of
Significant Interest
• RCCS Performance
– Cavity air circulation & heat transfer
– Thermal radiation
• RCCS panel and vessel emissivities
• Participating media (.i.e. “gray gas” effect)
– RCCS failure assumptions
• Failure of 1 of 2 channel (asymmetry)
• Failure of both channels (concrete thermal response)
– RCCS internal side heat transfer
• Parallel channel interactions
• Forced-natural circulation transitions
• Boiling and two-phase phenomena
5
PIRT Identified Processes of
Significant Interest
• Graphite “Dust” Phenomena
– Hydrodynamic conditions for dust suspension.
• Coolant velocity for liftoff
• Suspension & carryover
– Dust effect on coolant properties and flow.
– Cavity filtering performance
Note: Graphite “Dust” is an issue primarily for
PBR and with D-LOFC scenarios.
Note: Generation rate, FP content, size and
shape distribution of graphite particles are also
issues, but not specified in TF PIRT.
6
Introduction to Thermal-Fluid
Technical Challenges
Centre Reflector
Conduction
Pebble Bed
Side Reflector
Core Barrel
RPV
RCCS
Citadel
Radiation
Conduction
Conduction
Convection
Radiation
Convection
Conduction
Conduction
Radiation
Radiation
Convection
Conduction
Convection
Convection
Radiation
•Combined Mode Heat Transfer
•Bypass Flow
•Maximum Fuel Temperatures
•Local Temperature Variations
7
Core & Vessel Thermal-Fluids
• Issues:
– Limited convective heat transfer data exists at
flow rates and temperatures expected in PBR
or PMRs with helium as the coolant.
– Properties of helium show large variations with
temperature. Some uncertainty in properties
for gas mixtures at high temperature.
– Limited data to validate models for effective
core thermal conductivity in PBR.
– Bypass flows; flow along the reflectors (PBR)
or through gaps in graphite (PMR), can
account for a significant fraction of core flow.
8
Core & Vessel Thermal-Fluids
• Approach
– Project initiated to review existing correlations for
core effective thermal conductivity and use CFD to
examine sensitivities (PBR).
- - - in progress
– Gas mixture properties reviewed, improved model
recommended for MELCOR. - - - in progress
– Make use of existing and/or applicant data (such as
SANA or tests planned by PBMR, Inc.) to evaluate
models for core convective heat transfer & bypass.
– Conduct NRC sponsored SETs, if necessary.
9
Core Convective Heat Transfer
• Current Progress:
– Assessing the several correlations for effective thermal
conductivity and are attempting to validate CFD models.
– Have examined effect of porosity (near- and far wall) on heat
transfer and pressure drop.
10
Air Ingress
• Issues:
– “Lock Exchange” Flow refers to the counter-flow of fluids
with different densities past one another. Initial view
was that air ingress was diffusion limited - which is
incorrect for most break orientations of interest. Difficult
process to calculate.
– Data for natural circulation in a scaled facility is lacking.
Confinement to reactor cavity air ingress data also
lacking.
– Graphite oxidation:
• Where in core oxidation takes place
• Oxidation kinetics, including graphite irradiation and O2 content
11
Air Ingress
• Approach:
– Identified existing graphite oxidation rate models to be
added to MELCOR. (Use existing models where
applicable and evaluate on receipt of applicant data.)
– Make use of existing and/or applicant data to evaluate
modeling of air ingress and natural circulation in
vessel.
– NRC intends to conduct separate effects, and possibly
integral effects tests to assist in model development
and code assessment.
12
Air Ingress
• Current Progress:
– Separate effects test currently being planned and test
apparatus being designed. Data to provide air
ingress flow rates for variety of break sizes,
orientations, and geometries.
– Exploratory CFD calculations made to confirm air
ingress for top vessel breaks.
– Plans for a small integral multi-purpose test rig to be
considered. Intent would be a test loop to investigate
natural circulation, air ingress, and particulate
transport.
13
Air Ingress
Air ingress through vessel top break:
Blue = He / Red = Air
14
RCCS Performance
• Issues
– Lack of prototypic data for vessel cavity air circulation
& heat transfer. Difficult to benchmark codes for
finding local hot spots.
– Modeling of thermal radiation (including surface
emissivities) and radiation-convention interactions.
– Lack of data / modeling guidelines for RCCS
performance with various failures. Asymmetric
conditions may exist, affecting flows and heat transfer
to cavity walls.
– In-tube single phase and boiling heat transfer crucial to
function. May be parallel channel interactions. Test
data a major need.
15
RCCS Performance
• Approach:
– RCCS performance is viewed as crucial in
evaluation of a HTGR and licensing.
– NRC will participate in experiments using the
Natural Convection Shutdown Heat Removal
Test Facility (NSTF) at ANL to investigate
RCCS performance.
– NRC would sponsor independent RCCS tests
if necessary to meet schedule.
16
RCCS Performance
• Current Progress:
– Preliminary CFD calculations initiated to
explore modeling of “gray gas” in reactor
cavity.
– Experimental plans not started yet. Design
information currently insufficient.
17
Graphite “Dust” Transport
• Issues
– During normal operation, abrasion & vibration may
generate graphite particles which can carry FP.
These FP can escape the vessel through a break
very early in an event.
– Very little data available on graphite particle
size/shape distribution, fluid conditions for lift-off,
suspension and transport.
– Graphite particles may impact heat transfer
through effect on circulation and thermal radiation.
18
Graphite “Dust” Transport
• Approach:
– Perform literature survey of graphite
“dust” and its issues & identify existing
applicable data.
– NRC may need to conduct separate
effects test(s) to develop models for
MELCOR for graphite particle lift-off,
transport, and deposition.
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Graphite “Dust” Issues
• Current Progress
– Completed a literature survey on
graphite dust issues; generation, size
characterization, oxidation, etc.
– New issue that may be of concern is
detonation.
– Test planning not started yet.
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Experimental Database
• An extensive experimental database, including
both integral and separate effects data is
considered vital towards development.
• In preparation for EM development, NRC has
compiled a survey of gas cooled reactor
facilities that may be applicable to PBR or PMR.
• Participating in international (CSNI) activity
(TAREF = Task on Advance Reactor
Experimental Facilities) .
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Experimental Database
Facility
Type
Status
Operator
Issue
HTTR
30 MW
prismatic,
nuclear core
Operating
JAERI
IET
HTR
10 MW, pebble
bed, nuclear
core
Operating
China
IET
HTTTR
Not specified.
Proposed
UT/GA
IET
NSTF
SET, non-nucl
Operating
ANL
RCCS
INWA
SET, non-nucl
Operating
Germany
RCCS
RCCS Fac.
SET, non-nucl
Planned
S.Korea
RCCS
Air Ingress
SET, non-nucl
Operating
JAERI
Air ingress
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Experimental Database
Facility
Type
Status
Operator
Issue
NACOK
SET, non-nucl
Operating
Germany
Air ingress,
natural circ.
SANA
SET, non-nucl
Operating
Germany
Pebble bed core
heat transfer
MIR
SET, non-nucl
Operating
INL
LP streaking,
turbulent mixing
AVR
pebble bed,
nuclear core
Shutdown
Germany
IET
HTF
SET, non-nucl
Planned
PBMR, Inc.
Aux systems,
misc.
PBMM
SET, non-nucl
Complete
PBMR, Inc.
Brayton cycle
tests
HTTF
SET, non-nucl
Planned
PBMR, Inc.
Core TF
HELITE
He Loop
Operating
CEA
IHX, Component
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Outlook on Infrastructure Needs
• Separate effects data exist for many of the HTGR TF
processes. However, most of these data are currently
unavailable to the staff. Cooperative agreements & access
to existing data is crucial.
• The staff may need independent SET data for new model
development where only Proprietary info will exist.
• The staff will need access to a well scaled integral effects
facility for any design licensed in order to investigate
multiple system failures and safety system performance.
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Thermal-Fluids Research
Summary
• Thermal-Fluids research has been initiated,
with the intent to provide data for the staff’s
EM development and assessment.
• CFD is being used to help guide decisions
on EM development and well as in
identification of necessary test programs.
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