HEALTH AND SAFETY COMMISSION

Health and Safety Commission Paper
15 May 2007
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HEALTH AND SAFETY COMMISSION
HSC Coordinated programme of Nuclear Safety Research
Evaluation report for 2005/06
A Paper by Dr Peter Storey, Band 1, Nuclear Directorate 4
Board member: Dr Mike Weightman
Cleared by Justin McCracken on 24 April 2007
Issue
1.
This paper is the report on the annual evaluation of the HSC
Coordinated programme of nuclear safety research, commissioned by HSE
and the reactor licensees in 2005/06.
Timing
2.
Routine
Recommendation
3.
HSC is invited to note the evaluation of the 2005/06 programme.
Background
4.
This programme is overseen by HSE under guidelines agreed by HSC
with the DTI. The objectives of these guidelines include a balanced and
adequate programme that maximises contributions to nuclear safety, and
disseminates results appropriately. The programme should also support
independent capability, and take suitable advantage of international
collaboration.
5.
The purpose of this evaluation is to assess the efficiency, effectiveness
and benefit to nuclear safety of the Nuclear Power Reactor Programme and
the Sellafield Nuclear Chemical Plant Programme which together form part of
the HSC’s Nuclear Safety Research (NSR) Programme.
6.
HSE coordinates the programme for nuclear power reactor sites with
the nuclear licensees British Energy (BE) and Magnox Electric.
Arrangements for managing this coordination require that at the end of the
annual programme HSE and the nuclear licensees evaluate the effectiveness,
efficiency and benefit to nuclear safety of the research that was
commissioned and that HSE coordinates a report to HSC. These evaluations
are presented in detail at annexes 1-3.
7.
Although HSC does not approve the detail of the Sellafield programme,
the contents of a programme declared to HSE are determined by NII making
their safety concerns known to the Sellafield licensee, who must then develop
a programme to address them. Therefore an evaluation of the 2005/06
Sellafield programme forms part of this paper and has been attached at
Annex 4.
Argument
8.
The plan and outturn (excluding VAT and management charges) for
the nuclear power reactor sites programme are compared below.
£k
HSE
BE
Magnox
Total
Plan
858
2619
1700
5177
Outturn
888
2841
1700
5429
Outturn/plan
1.03
1.08
1.00
1.05
A summary of the HSE Levy Programme is shown in Table 1 of Annex 1 and
it may be seen that there was one more project than planned and the outturn
cost was 3.5% greater than the plan. This enhanced outturn arose from the
letting of additional new contracts in the External Hazards, Graphite and
Structural Integrity areas over the course of the year and renewal of a contract
to provide technical support to work on a Common Cause Failure database.
9.
In summarising the evaluation of the HSE levy programme (Annex 1) it
is concluded that the research was commissioned to plan and budget. For
the great majority of the research the performance of the contractors was
considered good or acceptable and 100% of the research outcomes were
made available to the nuclear licensees of which 86% (all but two projects)
was considered of safety benefit to operating nuclear power plants with 56%
of the projects yielding results that have already been applied. The Levy
research programme was consistent with the declared overall programme
strategy and is considered subjectively as having achieved the declared
objectives of maintaining capability and taking appropriate benefit of
international collaboration.
10.
During the year British Energy were able to release additional funds
than originally declared for the year. This enabled some projects deferred
from the 2004/05 programme, or omitted from the planned 2005/06
programme, to be commissioned..
11.
The Magnox Electric NRI related research programme consisted of
about 50 projects, about half of which were to be undertaken in collaboration
with British Energy. The programme was commissioned, executed and
delivered broadly in line with what was described in the Nuclear Research
Schedule for 2005-06. The few significant scope changes were discussed
and agreed with NII as part of the normal technical exchange arrangements.
The most significant changes were for graphite research in supporting the
developing needs of the Oldbury and Wylfa safety cases.
Consultation
12.
The Nuclear Safety Advisory Committee, through its sub-committee on
research (NuSAC SCR) has reviewed the three evaluation reports at its
October 2006 meeting. NDA, MOD and DTI also attended the meeting as
observers.
Presentation
13.
HSE is committed to disseminating research results that have
implications for nuclear safety, and has previously developed a strategy for
the dissemination of information through the HSE Website, that has been
agreed with Nuclear Licensees and endorsed by the NuSAC SCR.
Communications directorate has cleared the presentational aspects of this
paper.
Costs and Benefits
14.
Table 2 of Annex 1 lists the benefits to be derived from research
activities. The value of these benefits has to be balanced against the costs of
undertaking the research and is dependent upon a number of factors; the
ability of NII’s concerns to be addressed through means other than research;
the time it will take for the research to bear fruit; the time to make a judgement
on reasonable practicability. New research commissioned on the Magnox
reactors has largely ceased as the remaining two reactors are due for closure
in 2008 and 2010. Therefore any safety issues requiring research will be
undertaken through ND’s regulatory interventions.
Financial/Resource Implications for HSE
15.
The cost of the research commissioned by HSE and the programme
management charges has been recovered by levying the reactor licensees.
The costs of oversight of the Sellafield programme were recovered through
the regulatory route. There are no additional financial implications for HSE.
Other implications
16.
Not applicable.
Next Steps
17.
HSC is invited to note the evaluation of the 2005/06 programme.
ANNEX 1 EVALUATION OF HSE LEVY PROGRAMME
Introduction
1. Various descriptions of the safety benefit were considered in this
Evaluation, not mutually exclusive. They were considered to be, in
descending order of frequency of mention:
•
•
•
•
•
•
•
Maintaining knowledge and expertise in the regulator and licensees
Long term safety benefits
Providing information for new safety cases
Underpinning existing safety cases
Reducing uncertainties
Short term safety benefits
Development of safety standards / guidelines
These descriptions are fairly subjective but are consistent with what
was used in previous years, and the results are broadly similar to last
year’s. The high importance of knowledge maintenance and the
preponderance of long-term benefits tend to outweigh short-term
benefits. Research is not the only route for maintaining expertise for
the regulator, and other routes include attendance at conferences or
working groups of international agencies, and bilateral meetings with
other regulators. It could be argued that some of the projects are
aimed at informing the regulator generally rather than improving
safety directly but this distinction was not considered.
Safety benefits generally
2. There was a greater bias this year towards longer-term benefits as
opposed to immediate short-term safety gains. This may be compared
with USNRC research policy, where the aim is to have about 80%
confirmatory (short-term) research and 20% anticipatory (long-term)
research. However because of the greater degree of collaboration in
the UK research system, the industry is expected to commission the
majority of the short-term research, in order to ensure early and
effective impact. The regulator also uses the support programme for
confirmatory work. However despite the Project Officers’ responses
that more projects were of long-term benefit than of short-term benefit,
in 56% of the projects the results had already been applied.
3. 88% of the projects (all but two) were regarded as providing actual or
potential safety benefits to operating stations. However it is intrinsic in
any true research that the outcome is uncertain, and this is regarded as
an acceptable success rate.
Maintenance of expertise projects – ND access to Independent Technical
Capability
4. The projects are categorised by technical area.
Chemical Processes
•
HSE funded ITC work with consultants on both primary and secondary
side corrosion chemistry, essentially funding them to attend international
conferences. This aided our understanding of technical areas relevant to
licensees’ safety cases so we can carry out our regulatory duties more
effectively.
Graphite
•
HSE funded work at Manchester University on crack arrest in nuclear
graphite. The result was determining that the fracture toughness could not
be measured in graphite.
Conclusions on Independent Technical Capability
5. This is the subject of an annual review by HSE, last reported to NuSAC
SCR in April 2006 in paper 06/12 as being in a satisfactory state. There
are no extra conclusions arising from this evaluation.
International collaboration projects
6. The projects are categorised by the technical area.
External Events
•
HSE funded participation in an international evaluation of fire models for
nuclear power plants, organised by USNRC. This gave a greater
understanding of the behaviour of fires within compartments, and the
results can be applied in design of new plant and modification of existing
plant. USNRC will produce a NUREG report, co-authored with UK
organisations, giving accepted practice.
•
HSE funded participation in an information exchange meeting of the
organisations concerned with nuclear fire safety in 7 countries. This led
amongst other things, to a revised UK strategy for ILW retrievals.
•
HSE funded participation in an IAEA Coordinated Research Project,
benchmarking methods for ‘pushover’ non-linear analysis for the seismic
performance of concrete structures. The results will be disseminated as an
IAEA TECDOC. The method has already been proposed by licensees, but
HSE needs further validation.
Fuel
•
HSE and BNFL had funded jointly UK participation in the OECD Halden
reactor project. This provides one of the few sources of data on irradiated
fuel behaviour available. In particular, BE having proposed using new clad
material, and Halden data has been used to justify and assess this. There
is also a Man Technology Organisation side to the project, but despite
several attempts, the UK has never been convinced of the usefulness of
this.
Nuclear Physics
•
HSE administers UK membership of the OECD NEA Databank.
Commercial organisations are charged, non-commercial organisations
(universities, hospitals) are given free membership, and HSE funds the
balance of the membership through the levy. There is very little expertise
in this area in the UK now. The results (such as the NEA Databank Joint
Evaluated Fission and Fusion Nuclear Data Library) are incorporated in UK
neutronics codes.
•
HSE funded Magnox participation in the Euratom group, the European
Working Group on Reactor Dosimetry. This carries out benchmarking
exercises giving increased uniformity in standards and increasing
confidence. Participation is being continued through Serco, due to
Magnox’s divestment of technical staff to Serco, but the requirement for
Magnox reactor dosimetry will soon be at an end.
Plant Life Management (steels)
•
HSE funded 2 projects in the FP5 VOCALIST (Validation of Constraint
based assessment methodology in Structural integrity) programme. The
aim was to produce a Code of Practice, but the results were not sufficiently
advanced to produce a widely acceptable code. The main benefit was that
a large extra amount of fracture toughness data for A533B and A508
steels was produced in the course of the programme, enabling the
licensees to reduce their conservatisms if required.
Plant Modelling
•
HSE funded participation in the NEA SETH project (Senior Experts
Thermal Hydraulics). This was in two parts:
1. PKL (Primaer Kreislauf) - Tests on boron dilution in fault
sequences were done at Framatome ANP in Germany,
addressing an emergent safety issue. The results are directly
applicable to current safety assessments, and confirmed that the
existing situation is adequate.
2. PANDA – Tests at PSI in Switzerland gave information on
buoyant jets in large spaces, useful for validating CFD codes
and models, highlighting outstanding issues of numerical
accuracy and time averaging. The facility measurement
capabilities are excellent. The data is potentially applicable to
reactor new build.
•
HSE funded participation in the FP6 EURANOS project, (European
approach to nuclear and radiological emergency management and
rehabilitation strategies). However, reactor emergency arrangements are
well covered in the UK already, and the reactor licensees are not
interested in adopting the output, so direct safety benefit is very limited.
However, ND has some concerns about off-site consequence codes
industry-wide, and there are discussions with the Health Protection Agency
to address them.
Conclusions on International collaboration
7. Two thirds of the evaluated projects are international. International
collaboration is the subject of an annual review by HSE, last reported
to NuSAC SCR in April 2006 in paper 06/13. There are no extra
conclusions arising from this evaluation.
8. They are mainly PWR oriented. HSE policy on PWR safety research
has been largely to keep a watching brief on developments abroad and
to participate in appropriate international projects when the opportunity
arises. DTI has recently started to fund EPSRC in this area, and ND is
participating in activities such as the Eng Doc. Consistent with the
recent government Energy Review, ND is now starting to take a more
active interest in the research requirements for potential new build.
Gap filling / Punitive top-up
9. One project came into this category, reflecting the policy of obtaining
consensus as far as possible.
External events
•
HSE funded participation in a DEFRA-led joint study of the threat from
tsunamis. This confirmed the licensees’ assertion about the hazard
magnitude.
Issue closure
10. Issue closure is one of HSE’s main measures for evaluation of the
total (HSE levy and licensee commissioned NRI-related) programme.
50% of the issues related to the evaluated levy projects could be
closed, which is the same as the previous year’s figure. The levy
programme arises mainly from issues of maintenance of capability and
maintenance of contact with international activities. Depending how the
issues are written, they may be often ongoing for considerable periods
of time, and not amenable to closure by a single project, or they may
be written for a specific project that was proposed to the UK from
abroad. Therefore HSE does not regard issue closure as an important
criterion for levy projects.
Table 1 - Completed and evaluated projects classified by technical area and
research category
Technical Area
INT’L ITC Gap filling Other TOTAL
Chemical Processes
2
2
Civil Engineering
0
Control and Instrumentation
0
External Events
3
1
4
Fission Products
Fuel and Core
0
1
Graphite
1
1
1
Human Factors
Nuclear Science
0
2
2
Nuclear Systems & Equipment
Plant Life Management
Plant Modelling
0
2.5* 0.5*
3
1
1
Probabilistic Safety Assessment
0
Radiological Safety
0
Waste Management & Decommissioning
Totals
0
9.5
Notes
INT’L = International Collaboration
ERC = Essential Research Capability
ITC = Independent Technical Capability (for HSE)
* One project was put into two categories
3.5
1
0
14
Table 2 –Summary of evaluation results
05-06 Research categories (%)
International activity
ND Independent Technical Capability
Licensee Essential Research Capability
Filling gap in licensee programme
Other
67
27
0
6
0
05-06 Safety benefits to operating
stations (%)
None
Already applied
Immediately applicable
Applicable in next 5 years
Applicable in more than 5 years
When Required
04-05
61
22
17
0
10%
04-05
12
56
0
19
0
13
5
17
14
31
14
19
05-06 Safety benefits generally (%)
Maintaining knowledge and expertise in the regulator and licensees
Long term safety benefits
Providing information for new safety cases
Underpinning existing safety cases
Reducing uncertainties
Development of safety standards / guidelines
Short term safety benefits
Contractor performance (%)
93
64
50
43
36
36
29
05-06
04-05
Good Acceptable Poor Good Acceptable Poor
79
7
0 (83)
(17)
(0)
Meeting specification /
objective
Scientific quality
86
Report Standard
71
Value for money
50
Meeting budget costs
71
Meeting timescales
36
Keeping project officer
50
informed
The figures do not necessarily total 100%.
0
14
29
21
43
29
0
0
7
0
7
7
(78)
(72)
(56)
(95)
(50)
(61)
(17)
(17)
(39)
(5)
(39)
(28)
(5)
(5)
(5)
(0)
(5)
(5)
ANNEX 2 EVALUATION OF BRITISH ENERGY 2004/05 NUCLEAR
SAFETY RELATED RESEARCH PROGRAMME
INTRODUCTION
It is recognised that the benefits provided to nuclear safety are a key indicator
in assessing programme effectiveness. Although contributions to nuclear
safety are not monitored on a regular basis, examples are provided below of
where the research programme has contributed to nuclear safety.
BENEFIT TO NUCLEAR SAFETY
•
In the Chemistry area, the assessments of the Sizewell B reactor coolant
corrosion product behaviour have confirmed that this continues to be lower
than in comparable plants giving low doses to the operating staff.
•
There is an improved understanding of the behaviour of Prestressed
Concrete Pressure Vessel-type concrete at high loads and elevated
temperatures from the Civil Engineering programme. Updated and
enhanced guidance, based on the research carried out in this programme
over several years, has been provided to the Appointed Examiners to
assist them in the determination and assessment of the prestressing
tendon loads in the Prestressed Concrete Pressure Vessels.
•
Significant effort in maintaining Fault Studies and Fuel codes and
validation strengthened British Energy's in-house expertise and the tools
and methods used in support of safety critical calculations. ENIGMA
development in 2005/06 specifically benefited the production of safety
cases for the introduction of the new M5 fuel cladding at Sizewell B.
•
The Graphite projects cover all aspects of behaviour, from atomistic
studies that are providing a new understanding of the inter atomic bonding
in graphite to the material test reactor experiments and whole core
computer simulations and rigs that used to define the limits of core
operability. Significant progress is being made with understanding the
crack initiation and growth processes in pseudo brittle materials such as
graphite.
•
Three Human Factors projects were completed. The Use of Personal
Protective Equipment project has provided valuable information on the
selection and use of the gloves and flash hoods that are worn by incident
response team in site emergencies. The studies to investigate the
feasibility of assessing non-standard work pattern fatigue levels have
concluded that whilst none of the existing assessment methods are
appropriate, ongoing developments are likely to result in methods that may
be suitable for this type of application. A summary of the results from the
validity of self-checking research has been disseminated to human
performance leads at BE power stations.
•
The Structural Integrity programme is leading to increased confidence in
residual stress modelling methods for generating welding residual stress
profiles. The theoretical work on shakedown is complete and is being
developed with software tools to lead to more accurate creep-fatigue life
estimates. A modelling code and a guidance document on guided wave
inspection have been produced, aiding the choice of inspection method on
plant.
ANNEX 3 EVALUATION OF THE MAGNOX GENERATION 2005/6
NUCLEAR SAFETY RELATED RESEARCH PROGRAMME
INTRODUCTION
1.
It is recognised that the benefits provided to nuclear safety are a key
indicator in assessing the programme’s effectiveness. In order to help
evaluate the outcome of the 2005/6 research programme and to provide some
further detail of the type of work undertaken, some examples of the projects
are provided below together with their actual or potential application in
improving nuclear safety.
BENEFIT TO NUCLEAR SAFETY
Control and Instrumentation
2.
Magnox Electric Ltd. contributes to funding of a wide range of research
work in the area of Control and Instrumentation Engineering, including safetyrelated software.
3.
The whole of this programme of research work is carried out
collaboratively with British Energy (BEG) and British Nuclear Group Sellafield
Ltd. in a programme of work which is now also supported by the Atomic
Weapons Establishment (AWE). As BEG is the major player and major
financial contributor to the joint programme, most of the individual projects are
managed contractually by BEG. The highly collaborative approach is efficient
and provides very real benefits to all participants, including financially by
‘gearing’ the value of the benefits in relation to the individual contribution, and
also by allowing efficient use of the scarce specialist resource within the
industry members, in development and management of the work programme.
It also facilitates free exchange of information and ideas, and a common
knowledge base across the nuclear industry sector contributors.
4.
The programme of work is directed and reviewed via the C&I Nuclear
Industry Forum (CINIF), which is a technical forum which has taken up the
role formerly played by the IMC Technical Working Group for C&I. The CINIF
includes membership from BEG, British Nuclear Group Sellafield, Magnox
Electric, NII and AWE. Quarterly meetings are held in order to review the
direction of the work, work progress and to review and agree proposals for
future work. Given the complex pattern of work, this arrangement is essential
and has been found to work extremely well.
5.
During 2005/06, Magnox Electric has contributed to work on the
following projects:
•
Software Diversity (DISPO4), at City University
•
•
•
•
•
•
•
•
•
Software Diversity - Quantification (New DISPO2 phase 3), at Bristol
University
Statistical Systems Testing (New DDT2-3), at Bristol University
Safety Implications for the use of PCs in Low SIL Systems, at Adelard
Ltd.
Further Investigations into Legacy Code Analysis (ILCA), at Advantage
Ltd.
Further Assessment of Smart Sensor Software (FEAST), at Adelard
Ltd.
Goal-based assessment of COTS products for safety related systems
(COGS), at Adelard Ltd.
Generic Component Vendor-Based documents (EMPHASIS) and case
study, at Moore Industries Ltd.
Safety implications of using PLCs in Low SIL Applications, at
Advantage Ltd.
Use of Formal Methods in specification of high integrity safety systems,
at York University
In addition we have supported the following Key Teams:
•
•
Nucleonics equipment Key Team, Canberra Harwell Ltd. (Now Ultra
Electronics)
Reactor Protection Equipment Key Team, Alstec Ltd. (Now Babcock
International Group plc)
6.
Work on all of the software projects (above) has been progressed
during the year and many reports have been issued. Currently a high priority
within the industry is to establish an agreed licensing route for use of SMART
instruments at SIL1 and SIL2, and several of the projects have delivered
results which contribute substantially to this aim. This includes completion of
the ‘EMPHASIS’ tool, for use in assessment of potential suppliers (against
IEC61508 etc. requirements), also case studies have been carried out on
assessment of typical SMART devices (‘FEAST’), and to apply test methods
to sample SMART devices (‘New DDT’). Techniques developed in these
projects will be used in future substantiation of SMART devices. Other
projects on use of PCs and also on use of PLCs in low SIL applications have
produced guidelines covering the likely integrity claimable and how supporting
arguments can be structured. The work on software diversity (DISPO)
remains more theoretical, but is providing powerful insights into the nature of
diversity claims and how to substantiate them.
7.
The nucleonics key team has carried out an agreed programme of
work and has issued reports on several different topics. Notably this has
included collation and review of detector site test data, a review of detector
spares holdings and associated test regimes, and further work on review and
development of the highly specialised mineral insulated cables used with
several detector types. In addition, support was provided to BE and Magnox
to support current safety case issues, including for problems associated with
breakthrough current of DC12A detectors at AGR stations, and regarding low
sensitivity of some detectors, found at Wylfa power station.
8.
The Reactor Protection Equipment Key Team has addressed and
issued reports on several different topics, including component obsolescence
issues, component ageing issues, and a comparison of the design process
with recent standards (IEC 61508). An expert review (York University), aimed
at reviewing the value and opportunities for introducing formality into the
design process has also been supported. An extensive investigation of ‘noise’
problems on trip setpoint potentiometers has led to possible solutions to this
troublesome operational issue.
9.
The work covers a broad spectrum, and has ranged from relatively
‘blue skies’ theoretical investigation of software issues (such as aspects of
diversity) to much more applied software assessment techniques (such as the
work on the EMPHASIS software assessment tool). Pleasingly, we are now in
a position to build on work done in several projects over several years, and
the recent and current work programme is now able use the knowledge
gained in order to be much more focussed on development of practical
guidance, and techniques and methods which are capable of practical
application in order to support software integrity claims made in safety cases.
10.
Within the Key Teams, the work is largely focused on applied aspects
such as expert investigations of technical issues to support operational
problems (equipment failures, obsolescence issues, technical advice to
support modifications etc.) as well as investigation of potential improvements
to add formality to the design process for high integrity hardware. The majority
of this work therefore has a direct role in supporting current safety cases and
in contributing to understanding of failure modes of safety equipment, so as to
maintain a good technical understanding and to facilitate optimal support for
operation of existing equipment and modifications.
11.
During the past year, both of the specialist contractors who are
supported under the Key Teams, have been taken over by other companies.
This indicates the potential vulnerability of these residual specialist teams and
underlines the importance of supporting the core capability via the Key
Teams.
Graphite
12.
A large programme of research investigating various aspects of
graphite ageing and the development of new material testing techniques for
graphite at high weight losses continued during 2005/6. The projects
generally continue into 2006/7. Significant developments included
•
A revised methodology for predicting how graphite weight loss progresses
with increased irradiation.
•
A revised methodology for estimating the strength of graphite based upon
a large database of samples taken from the Magnox reactor fleet.
•
The development of a new test technique for determining the Young’s
Modulus of aged irradiated graphite samples.
Waste and Decommissioning
13.
The Waste and Decommissioning section of the NRS formed by
far the largest component of the research portfolio consisting of about 40% of
the cost. Three examples of projects progressed during 2005/6 are provided
below.
Long-Term Integrity of Packaged Waste
14.
The majority of the work under this general area is covered by
three projects jointly funded with British Energy. These have been on-going
at AEA Technology (Winfrith) for several years.
a)
b)
c)
Long-term monitoring of cemented simulated waste samples.
Gamma-irradiation of samples of cemented wastes.
Corrosion assessment of containers of cemented stimulant wastes.
15.
The results of (a) have demonstrated the long-term integrity of samples
of many simulated wasteforms produced with a variety of cement formulations
and stored for many years within an environment of controlled relative
humidity and temperature.
16.
The results of (b) have demonstrated the integrity of samples of many
simulated wasteforms produced with a variety of cement formulations and
irradiated in all cases up to a dose of 9 MGy. In addition several polymer
encapsulated materials have been tested to in excess of 9 MGy.
17.
The results of (c) have demonstrated the corrosion integrity of the
internal surface of stainless steel containers with a variety of cemented
simulated wasteforms for periods of time well in excess of that required to
meet the current timescale for backfilling of the repository.
18.
The monitoring work is crucial in demonstrating the integrity of waste
packages for the anticipated periods from encapsulation through interim
storage, transport to the repository, emplacement and the early post-closure
period prior to backfilling. The work underpins the Letters of Compliance
required by Nirex for disposal of radioactive wastes as the repository safety
case is predicated on a cementitious environment. Failure of the
“cementation strategy” would require the nuclear industry to re-examine other
options for waste disposal, such as polymer encapsulation, high temperature
treatment etc.
Code of Practice for Venting of Reactor Vessels and the Establishment of
Flow Measuring Requirements for Decommissioning.
19.
Several of the Magnox reactors in the UK are entering a
decommissioning phase, where the vessels will be stored, without fuel, for a
period of years prior to dismantling. During this storage period arrangements
must be made such that the vessels remain sufficiently intact to retain any
activity within them. Further constraints may be made by regulatory bodies,
regarding the amount and location of any gaseous discharges.
20.
This report addresses these issues as part of the Nuclear Research
Schedule, specifically to determine the effect of various methods of venting
the internal atmosphere of the vessel. Six power station reactors on three
sites have been studied and these have covered the three most obvious
passive venting modes of a (i) a low-resistance open vent, (ii) an open vent
with a one-way (outward flow) valve and (iii) closed vessel. This report
provides a flow chart to select a venting strategy within the constraints of the
stakeholders and a method of monitoring gas exchange with the exterior that
is universally applicable.
Strategy for Dealing with Archive Samples of Magnox Reactor Materials.
21.
The work considered the requirements for retaining archive specimens
of materials which are of relevance to Magnox reactor safety-related issues
and the reduction of hazards on reactor sites. It identified the key materials
which need to be retained and the requirements for retention in the remaining
phases of Magnox operations from generation through to decommissioning
and final site clearance.
22.
The conclusions are summarised briefly below.
•
Many facilities used to house Magnox materials in experimental
programmes have closed.
•
The obtaining of irradiated core graphite and steel specimens will
become much more difficult after de-fuelling and pile cap dismantling.
•
Very few experts remain within the industry with detailed knowledge of
these materials and associated properties.
•
Cessation of generation has removed the need to retain specimens
useful for structural integrity purposes.
•
Mandatory guidance is required to stop potentially useful archive
materials from being discarded.
•
Requirements for Waste and Decommissioning purposes will need to
be more fully defined.
•
Early final site clearance may alter the strategy for retention of
materials.
•
Additional requirements for the retention of irradiated and nonirradiated material may emerge for measurements of radionuclide
inventory.
•
Specifically, it may be necessary to obtain boiler tube samples from
Oldbury and Wylfa.
23.
Recommendation have been made covering the disposal of Magnox
reactor materials, retention of specialised tools, retention of records, setting
up of a working group, potential locations for storing archive materials and
specific critical materials such as ion exchange resins.
24,
It can be seen from these examples that the output of the research
programme is being, or will be, used to enhance nuclear safety, as intended.
TECHNICAL EXCHANGES
25.
The continuing adequacy of the technical exchange arrangements is
reviewed on an ongoing basis by the licensee Research Co-ordinators and
ND. No problems have emerged and the arrangements continue to operate
to the satisfaction of all parties.
ANNEX 4 EVALUATION OF THE BNFL SELLAFIELD 2005/06 NUCLEAR SAFETY
RESEARCH RELATED PROGRAMME
INTRODUCTION
1. This Evaluation identifies progress made in topics identified in the NRS for
each technical area. In accordance with the Arrangements, appropriate
contact has been maintained throughout the year between BNGSL and HSE
technical personnel to communicate and monitor progress. The reviews below
illustrate the success of the arrangements in 2005/06 in increasing the
visibility and transparency of key Sellafield research to HSE and NuSAC SCR.
TECHNICAL AREA REVIEWS
2. The progress on key research topics/issues identified in the 2005/06
Sellafield Research Schedule is summarised below.
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Civil Engineering
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Ageing and Degradation Mechanisms-A number of reports were
completed addressing topics including B211 Roof Assessment,
Nitric Acid effects on THORP Feed Clarification Cell: Structural
steelwork corrosion tests (subjected to immersion & vapour)
complete NS6471, external/internal survey of SETP tanks and B30
Satisfactory performance of aged Asbestos Cement cladding &
fasteners. CS&A LFE in-house forums were held bi-monthly
throughout 05/06 and in house electronic access was provided for
Key Civil Engineering CS&A documents. A cathodic protection is
being installed to extend the life of the Sea Line Pipe Bridge its
effectiveness will be monitored & reported.
Pond Containment with particular reference to leakage
processes, leakage rates and leak detection mechanisms-B30
Studies on water bars were completed and reports provide
confidence for continued safe operation. Empirical methodology for
estimating leakage proved to be inconclusive. B30 are to undertake
study on implications of water bar / joint layout details and concrete
makeup (i.e. cements, additives, water content etc. B30 is now
developing strategies to identify and mitigate for any degradation
leading to leakage (of any scale) and subsequent incorporation into
emergency instructions for all ponds. B38 is also now undertaking 6
monthly Radscan surveys for future comparisons.
Application of current design codes for design and
assessment of nuclear structures-Existing design Guides &
Standards are being maintained to provide for current project
requirements and in the main use British Standards as the basis for
their criteria. Eurocodes: staff in house training continues with
sessions covering EN1990 & EN 1991 with EN 1992 training
arranged. Champions have been nominated for specific codes and
names posted on internal department web site.
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Long life Structures-A CS&A Guide: Design for Concrete
Durability in New Structures was completed (ref RP/DESCAP/CSA/00051-A). The CS&A Generic (template) specification
includes details of high performance concrete for 100 year
performance for new structures. Further work on the CS&A
specification is needed to comply with EU rules.
Maintenance and Repair techniques for use in the nuclear
industry-A Report “Maintenance and Repair Techniques for use in
the Nuclear Industry “ Proj No 0/103583 was issued to the NII
Subsequent discussions have taken place.
Non destructive testing-Non destructive testing work was
undertaken for example that described in the issue related to
Ageing and Degradation addressing the B211 roof assessment. A
number of techniques have been considered for example
consideration of acoustic monitoring to aged pre-stressed roof
beams.
External Hazards
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Development of Seismic ALARP Methodology- A high level
guide was produced and published as a BNFL standard on the
application of seismic ALARP to existing structures for continued
operation, modification, POCO and decommissioning.
Application of Seismic Probabilistic Safety Assessment (PSA)No significant progress on 04/05 in this area due to prioritisation of
funds.
Climate Change- Watching brief was maintained, primarily through
the United Kingdom Climate Impact Programme.
Seismic Hazard techniques - No significant progress on 04/05 in
this area due to prioritisation of funds. Plans were made for
research on a smaller scale to be carried out in the Seismic,
Extreme Hazards and Geotechnical Centre of Expertise.
Extreme Wind Loadings in a closely spaced plant area - No
significant progress on 04/05 in this area due to prioritisation of
funds.
“Beyond Design Basis Events” Assessment TechniquesSpecific research on non-linear cracking of concrete structures
cancelled due to lack of Direct Portfolio funding. Similar techniques
were promoted on a specific project to evaluate the changes to the
response of masonry panels as they cracked under seismic loading
and their ability to provide continued structural stability. This is
currently being implemented on the project and the generic lessons
will be captured and reported. Revised design criteria were
published and are now in use.
Review Modern Standards-Transition towards the Eurocodes in
general was promoted through CS&A Eurocode nominees, of which
the Technical Representative in this area covers EC0, EC1
(loading) and EC8 (seismic). Discussions held with NII and BRE on
benefits and pitfalls of Eurocode implementation. New criteria for
seismic design of BNGSL structures were published.
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Human Factors
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Root Causes-It was decided to address this issue by including it
within the scope of the main research project (discussed below).
That project was completed on schedule at the end of March 2006
by independent Human Factors consultants. It concluded that the
amended WANO causal coding system is appropriate for the
Sellafield OEF process.
Clarify the characteristics of an effective and best practice
OEF system for nuclear chemical plant and to determine the
extent to which current MSS arrangements meet these- The
research specification was completed, potential contractors were
identified and research contract was placed on November
2005.The research was completed and the final report issued on
30 March 2006.
Monitoring of other licensees programmes - Work was reviewed
in May 2005. A number of new research areas were identified.
These and the ongoing research areas are being monitored as the
research areas are addressed, through liaison with Human Factors
specialists in British Energy and British Nuclear Group Reactor
Sites.
Internal Events/Fire
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Inclusion of data on number of people evacuated and the
duration- Expected to be complete before end of 2006.
Inclusion of data on damage caused by fire- Expected to be
complete before end of 2006.
Roll out of Fire Call database- Data bases have been identified
that can all be interrogated for fire related events and analysis is to
be carried out by BNGSL /S&RM Fire Engineering Group. The
databases identified are PROSAFE, Safety Culture Database
CBOS (behavioural observations) and decommissioning learning
library.
Promulgation of best practice in fire assessment and
management across sites- Proactive membership continues to be
a priority of the BNGSL /S&RM Fire Engineering Group and many
mutually beneficial topics are debated.
Best practices in industries other than nuclear facilitiesBNGSL/ S&RM Fire Engineering Group have joined the joint Oil
and Industry Fire Forum
Understanding design challenges to ventilation systems used
on nuclear chemical plant caused by fire- Preliminary
discussions have taken place between BNGSL /S&RM Fire
Engineering Group and ventilation design authority with the view to
a joint project to determine suitable means of taking account of fire
growth in treatment of contamination control ventilation systems.
It has been mutually agreed between BNGSL and NII that the area
of internal hazards need no longer sit within the current research
arrangements between BNGSL and NII. Issues in these areas will
be addressed in future through the Process Technology section.
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Plant Materials
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Confirmation of inspection procedures for Plutonium nitrate
evaporation plant- Inspection procedures confirmed with NII,
Magnox plant inspected, results were transmitted to NII.
HAL clarification of effects of oxidising species- Demonstrated
that some nitrosyl complexes are corrosion accelerators and some
are not. Speciation studies underway to identify those existing in
plant liquors
Assessment of impact of temperature on pitting propagation in
HA systems- Work completed. Relatively little effect of temperature
could be discerned within background variation
Assessment of pit propagation models- Discussions are ongoing
with the alliance. Modeling studies for SCC have been proposed by
alliance but no pitting corrosion studies have been agreed.
Development of inspection options for HAE - Push systems
have been developed and successfully rig tested. However, when
deployed in plant it was found that the pipe work was more
restrictive to movement than anticipated from the drawings and full
deployment was not pursued. The programme is being reassessed.
Initial appraisal of under tank inspection options did not reveal any
applicable new technology. The success of an ultrasonic inspection
would be dependent of sludge levels in the water system.
Procedures for localised corrosion inspection- Work completed.
A document defining the recommended procedure has been issued.
The principal methods have been assessed. Further refinement of
the methods is being considered.
Assessment of AGR storage options- No research work is
ongoing pending the results of BNG internal policy discussions
Co-ordination of ILW inspection with MGBG- Discussions have
been held with MGBG. A targeted autumn meeting is planned to
involve the various interested NDA sites.
Assessment of environmental conditions to induce SCC on
ILW drums- Delayed due to six month absence of student. Study
now resumed. Report due in autumn.
Development of NDE methods for crack /corrosion detectionAcoustic emission study underway. Assessment of corrosion
processes planned for next year. Programme started and a report
due at end of the year. Progress made on focussing waves along
welds. Nuclear test pieces supplied. Initial programme coming to
completion. Detection of pits demonstrated in stainless steel plant
specimens. Proposal for development of plant instrument being
considered. Studies commenced in April at Warwick. Eddy current
report issued considering the use of eddy currents in various plant
areas including WVP. Report being considered internally. Eddy
currents being considered for application in THORP plant.
Process Technology
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Probabilistic Safety Assessment
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Flammable Gases-The specialist working group continues to work
within BNGSL. The HWP held 7 meetings 05/06; Several sections
of Hydrogen Technical Guide were updated to reflect
developments. Two papers on hydrogen research were presented
to IChemE Major Hazards Symposium. Links were established
with UK Hydrogen Association, to ensure BNGSL is aware of best
practice. Hydrogen Forum (pan-nuclear forum) held March
2005.Follow up meeting of Hydrogen Forum was delayed to
November 2006 because of industry re-structuring
Unstable By-Products- Work undertaken in 2005 in support of
High Active Evaporation was reported in March. Further work
programme planned 06/07.
Two Phase Mixtures of Solids in Saturated Solutions -Thermal modelling
work completed, future work being considered. Experimental
investigations of evaporation and crystallisation phenomena are
underway in accordance with the programme of work in support of
the High Level Waste Plants. Evaporation reviews and experiments
underway, Magnox work completed, oxide/blended work
continuing. Gamma irradiation studies on hold pending clarification
of sample and facilities availability.
Volatile Radionuclides- Experimental work to support a Safety
Case for known stocks of material committed for reprocessing has
been completed.
Consequence Analysis - Appropriateness of current
resuspension and deposition factors for decommissioning
activities - Report produced and issued. No further work is
planned.
Consequence Analysis - Validation of in-house codes - Report
issued - No further work planned
Consequence Analysis - To carry out a phased review of the
adequacy of the current release fraction and decontamination
factor data, to seek new sources of relevant data, and to
produce new experimental data in specific areas. - A Review of
a number of RFDB sheets is being carried out for the NII by HSL
labs at Buxton. When this review is complete any issues raised will
allow a strategy of to be produced for future research if required.
Consequence Analysis - Seek out new data sources for highrisk areas and decommissioning - Investigations are ongoing to
confirm releases caused by cutting operations. Any other issues
that are identified as problems will also be reviewed as required.
Human Action Representation – A detailed Technical Guide on the
subject of Human Dependency and Human Performance Limiting
Values is expected to be issued this year.
Nuclear Physics
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ILW Methodology-Methodology development and consensus
building with industry and regulators was continued through the
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Working Party on Criticality (WPC) sub-group (attended by NII).
Topics under discussion have included the setting up of a banding
scheme in order to aggregate similar waste streams into categories;
decision processes for evaluating the optimum (with respect to
safety and risk) packaging/assay arrangements for waste streams;
methods of making off-site transport criticality cases for fissile
bearing wastes. A draft S&RM Technical Guide has been produced
to provide guidance on the methodology and how to apply it. The
specific issue has been closed. This area of development will
continue in FY2006/7 via continued participation in the WPC subgroup. This activity will continue to be subject to ongoing review via
SSRA until the methodology is suitably developed.
Low Risk Methodology-Overview being maintained of ongoing
work in area of PCM methodology. Methodology in low risk
decommissioning operations continues to be developed. The issue
was closed.
Criticality ALARP Methodology-Formal criticality ALARP training
course was addressed and a course is being developed (scheduled
to be run in February 2007). Issue was closed.
Non-intrusive assay of moderator content- Review performed of
existing and potential new measurement techniques. Concluded
that no safety driver or business case identified for undertaking
development/ procurement of additional moderator investigation
techniques. A watching brief will be kept of technology available in
the area. Work was performed (as part of SIRP project) to better
understand the physical/ chemical mechanisms for moisture uptake
in PuO2. This information has been used in safety cases to provide
a better understanding of the margins of safety present. Information
reviewed at a meeting with NII in January 2006. It was agreed that
further investigation in the area is not necessary and the issue
should be closed.
NDA measurements validation-Several meetings were held
involving representatives from relevant key areas (e.g. Waste
Treatment Plants, CE&I, BIL Solutions, Criticality Technical
Manager for Waste Management and Decommissioning) to discuss
the issue. A meeting, led by Waste Treatment Plants (WTP), was
held with NII in January 2006 to discuss the issue (reported in more
detail in the 2005/06 research schedule). Actions were placed on
WTP to investigate the feasibility of chemical dissolution and
calorimetry. This issue was closed in the 2006/7 research strategy.
Radiological Protection
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Validation of in-house codes and data used for radiological
assessments - Passed to the Risk Analysis programme
Resuspension and deposition factors in dispersion modelling
calculations- Passed to the Risk Analysis programme
Restriction of the spread of activity - Issue was closed following
the issue of formal guidance (MSS/RPDS/05, Sub-change room
requirements for new plant, (formerly NF0082/5) and SSP 1.06.03
Radiological Clearance)
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Good practice ALARP- Issue was closed following issue of
MSS/RPDS/12, Design Considerations for Prevention of
Radiological (Pu) Contaminated Wounds. Workshop on the subject
was held by the WPC with one planned by the Shielding Forum for
2006
Performance indicators for radiological protection- Removed
from SSRA as decided it was better dealt with through other
channels.
Subsidiary guidance on the principles for the protection of
employees following a radiation accident- Draft guidance
received from HPA and been discussed internally
Waste and Decommissioning
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Ion exchange and filtration-Progress in 05/06 has been in terms
of continuing informal technical exchange between experts on a
one-to-one basis. Technical exchanges have been by video
conference, site visits and at least 1 formal meeting. The technical
learning has provided valuable input into improving filtration and ion
exchange in SIXEP and water treatment at the Magnox reactor
ponds
Treatment of waste oils- The forward plan for waste oils was
developed within the Orphan Wastes project. The value in
developing a cross-industry approach was fully recognised within
the project although much of the focus centred on improved
understanding of the nature of the wastes and the volumes
involved.
Collaboration with MAGNOX Reactor Sites- The principal
mechanisms for collaboration with Magnox Reactor Sites has been
via attendance and participation in the Reactor Waste &
Decommissioning Technical Group (RWDTG) and Reactor Waste &
Decommissioning Industry Group (RWDIG). Sellafield has
contributed to the RWDTG's development programme for 2006/7.
Summaries of work on the Sellafield Site Remediation Innovation
programme have also been shared with RWDIG attendees, and
have included detailed discussions on areas such as long
wavelength ultrasound for pipe inspection. Additional mechanisms
for building on areas such as these included setting up of a
‘Technology Collaboration’ Group in 2005/6.
Collaboration with UKAEA- UKAEA’s attendance at the Reactor
Waste Decommissioning Industry Group has provided a useful
mechanism for BNGSL/UKAEA personnel to explore common
issues. Additionally, BNGSL have worked together with UKAEA to
develop approaches/ propose common solutions/ understand
emerging issues at Regulatory workshops and University Research
Alliance (URA) meetings. For these reasons it has been decided
not to pursue setting up a separate bilateral exchange with UKAEA
at this stage.
Clarify how MSS will interact with the NDA Direct Portfolio
Programme - BNGSL has had strong interactions with the NDA on
the direct portfolio programme. BNGSL has participated in a series
of consultation exercises, for example: ‘ILW Treatment and
Storage’ and ‘Graphite Waste’ and was an active part in additional
gate meetings. BNGSL was responsive to requests to provide
advice , along with other SLC’s , on the content and relevance of
such projects and is committed to continued interaction.
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Control and Instrumentation
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The majority of the CE&I Nuclear Research Issues are addressed
in collaboration with British Energy and British Nuclear Group
Reactor Sites through the C&I Nuclear Industry Forum (CINIF).
This collaborative approach not only brings benefits in terms of
shared costs, but it also facilitates interaction between licencees
whilst addressing the NRI issues, thereby bringing a consistency to
the solutions to similar problems.
A significant number of issues were addressed through the
production and delivery of reports and guidelines. These covered
issues in Software diversity , Statistical systems testing, Safety
implications from use of PCs in low safety integrity level
systems, Development of an Approach to the Assurance of
SMART Sensor Software, Goal Based Assessment of COTS
Products for safety related Systems, Evaluation International
subscription and Further Investigations into Legacy Code
Analysis
Complex safety related measurement and data processing
systems-Continuous review maintained through out the year
Cost Effective Modernisation of Systems Import to Safety
(CEMSIS)- British Energy have maintained contact with the
Framework 6 process and are involved in the ‘MAGIC’ project –
Management of Ageing of I&C Components. Funding is not being
provided by CINIF or BNGSL for this project as it is wholly funded
by EU. CINIF consortium has however been declared as an
interested party and will receive deliverables. NRI issue was closed
out.
Guidelines for Assessment of SMART Instruments Suppliers
(EMPHASIS)- Tool was delivered to allow assessment.
Safety Implications of Using PLCs in Low SIL ApplicationsReport delivered and issue closed out
Statistical systems testing guidance note- Guideline were
delivered
Vendor assessment of SMART Instruments- Assessments for
Yokogawa EJX and ABB 2600T pressure transmitters delivered.
Dissemination of information- Relevant Centres of Expertise,
Safety Systems Forum and Nuclear Industry Smart Instruments
Working Group briefed on relevant results.