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RIC2011 MELCOR DEVELOPMENT STATUS AND CODE APPLICATIONS MELCOR Regulatory Applications

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RIC2011 MELCOR DEVELOPMENT STATUS AND CODE APPLICATIONS MELCOR Regulatory Applications
RIC2011
MELCOR DEVELOPMENT STATUS
AND CODE APPLICATIONS
Hossein Esmaili
USNRC/RES
March 9, 2011
1
MELCOR Regulatory Applications
• State of the Art Reactor Consequence Analysis
(SOARCA)
• MOX/HBU Source Term (revised NUREG-1465)
• Design Certification for New and Advanced
Reactor Designs
• BWR MSIV Leakage
L k
Analysis
A l i (RG 1.183)
1 183)
• Risk-Informed Regulation (e.g., combustible gas
control rulemaking)
• Probabilistic Risk Assessment (e.g., standardized
plant analysis risk [SPAR] models)
2
MELCOR User Community
• Strongly Influenced by Participation of Domestic Users and
International Partners through the USNRC Cooperative
Severe Accident Research Program (CSARP) and
MELCOR Code Assessment Program (MCAP)
– Development Contributions (new models)
– Applications
– Development Suggestions
3
1
MELCOR Models
4
MELCOR Nodalization
Generic
Models (no
“built-in”
nodalization)
Building block
approach (more
flexibility
=>greater user
responsibility)
5
MELCOR Development
Code life-cycle
Code Readiness
code conversion phase
code ready for applications
code not readyfor applications
code development phase
code maintenance phase
V1.8.6
F 77
YG
YH
YI
Double
Precision
V 2.0
F 95
YJ
YI
YN
YP
YR
YP
YT
Double
Precision
YT
YT
V 3.0
FY 06
• MELCOR 1.8.6
–Molten pool models
–Core Package
upgrade
–Released Fall 2005
–Code Maintenance
FY 07
• MELCOR 2.1
–FORTRAN 95
–New input
–2.0 beta version
released Sept 2006
–2.1 Release Sept
2008
FY 08
• MELCOR 3
–Current
developmental
version
6
2
MELCOR Development Focus
Code reliability
Š Validation
Š QA
Š Numerical stability
MELCOR
Code
Development
User Utilities
Š
Š
Š
Š
Code Enhancements
Converter (input)
PTFREAD (plotting)
SNAP
Uncertainty Engine
ŠNew/improved modeling
ŠCode performance
7
Accident Simulation Using SNAP
Containment
DBA
application
View Results
Sensitivity
Calculations
Severe
accident
application
Source
term DBA
application
User Control/Options
• Plant systems (SA)
• Operator actions (SA)
• Type of accident (SA)
• DBA Sources (M/E,FP)
• etc.
MELCOR Plant
Model (i.e., fixed
geometry, etc.)
Transparent to
User
Phase I
BWR
(e.g.,ABWR)
Phase II
PWR
(e.g., EPR)
Phase III
PRA
Applications
Generate MELCOR input
model
Run MELCOR
SNAP GUI Boundary
for User Access
8
MELCOR Interactive Systems
Supports communication between SNAP and MELCOR using the Read and L-Read control functions in the safety system
logic to initiate, fail, or adjust system functionality (required enhancing models and safety system details). Animation
package reads the plot data and performs display function. Simple and complex elements are used to display pertinent
information from the MELCOR run. Interactive commands are communicated from the display page to MELCOR .
9
3
EPR MELCOR Model
Steady-State
SG dryout & core relocation
Lower head failure
Core relocation to lower head
10
ABWR MELCOR Model
Short term station blackout progression
Steady-State
Core uncovery
Core Degradation
Core Heatup
Safety valves
actuation
11
HTGR FP Release and Transport
•
Develop HTGR specific fission product release and transport models for MELCOR
Use existing MELCOR
modeling framework
for fission product
transport and
deposition in the
primary system and
containment. Develop
HTGR specific models
(i
(i.e.,
lift-off,
lift ff turbulent
t b l t
deposition,
agglomeration, dust)
Implement diffusional
release models for both
intact and failed TRISO
fuel particles (also for
matrix and graphite
block)
12
4
PRA Application
•
Improve the technical basis for, and increase the consistency of, Standardized Plant Analysis
Risk (SPAR) models for selected probabilistic risk assessment (PRA) sequences of interest.
Results published as NUREG-1953 (draft report for comment).
Plant Information
Final
Safety
Analysis
A
l i
Report
MELCOR Model
Plant
Operating
Procedures
SPAR Model Confirmation or
Upgrade
Thermal Hydraulic Analysis
13
Summary
• MELCOR ongoing code development and
enhancement in response to regulatory needs
and user participation
• Code flexibility allows its use for a variety of
applications
• MELCOR/SNAP integration provides an easy to
use graphical user interface for accident
simulation and visualization
14
Acronyms
•
•
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•
•
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•
•
BWR
DBA
ECCS
FP
GUI
HTGR
LOCA
M/E
PORV
PRA
PWR
QA
RCP
SA
SG
SNAP
SPAR
SRV
Boiling water reactor
Design basis accident
Emergency core cooling system
Fission product
Graphical user interface
High temperature gas reactor
Loss of coolant accident
Mass/Energy (sources)
Power (or pilot) operated relief valve
Probabilistic risk assessment
Pressurized water reactor
Quality assurance
Reactor coolant pump
Severe accident
Steam generator
Symbolic nuclear analyzer package
Standardized plant analysis risk
Safety relief valve
15
5
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