(Workshop on Level 2 PSA and Severe Accident Management, March 2004 )
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International WorkshopInternational WorkshopOnOn
Level 2 PSA and Severe Accident ManagementLevel 2 PSA and Severe Accident Management Hosted by: Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) mbh, Hosted by: Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) mbh, Köln, GermanyKöln, Germany
29th to the 31st of March 200429th to the 31st of March 2004
Barry Kaufer, Deputy Head, Regulation
Nuclear Safety Division
Le Seine St.-Germain
12, boulevard des Iles
92130 Issy-les-Moulineaux, France
(Workshop on Level 2 PSA and Severe Accident Management, March 2004 )
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Table of contentsTable of contents
Safety and Regulation at OECD/NEA Committee on the Safety of Nuclear
Installations (CSNI) Working Group on Risk Assessment
(WGRisk) – Level 2 PSA– 1997 State-of-the-Art Report– 2004 Programme of Work
Summary
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COMMITTEE ON THE SAFETY OF NUCLEAR INSTALLATIONS (CSNI)CHAIRMAN: A. THADANI - SECRETARY: J. REIG
BUREAU: G. LOWENHIELM, L. HAHN, K. ABE, J.C. NIEL, K. VALTONEN
CSNI PROGRAMME REVIEW GROUP (PRG) CHAIRMAN: T. KING - SECRETARY: M. HREHOR
FUEL CYCLE SAFETY
(FCS)
CHAIR: J. M. LANORE
SECRETARY: B. KAUFER
JOINT CSNI/CNRATASK ON PLANT SAFETY
PERFORMANCE
INDICATORS
CO-ORDINATED
PROGRAMME SERENA
WORKING GROUPS
RISK
ASSESSMENT
(WGRISK)
SPECIAL EXPERT GROUPS
ANALYSIS AND
MANAGEMENT OF
ACCIDENTS
(GAMA)
INTEGRITY AND
AGEING OF
COMPONENTS AND
STRUCTURES
(IAGE)
OPERATING
EXPERIENCE
(WGOE)
SEISMIC BEHAVIOUR OF
STRUCTURES
CONCRETE STRUCTURES
AGEING
INTEGRITY OF METAL
COMPONENTS &
STRUCTURES
CHAIR: M. DURIN
SECRETARY: J. ROYEN
CHAIR: N. CHOKSHI
SECRETARY: E. MATHET
CHAIR: A. VANDEWALLE
SECRETARY: P. PYY
CHAIR: A. FRISCHKNECHT
SECRETARY: P. PYY
CHAIR: W. WIESENACK
SECRETARY: M. HREHOR
HUMAN &
ORGANISATIONAL
FACTORS
(SEGHOF)
FUEL SAFETY
MARGINS
(SEGFSM)
SESAR/SFEAR GROUP
SECRETARY: C. VITANZA
SAFETY MARGINS ACTION PLAN
CHAIR: O. SANDVERAG
SECRETARY: J. ROYEN
January 2004
HALDENCABRI WATER
LOOP
MASCA II
SETH
MCCI ICDE
OECD-FIRE
PSB-VVER
OPDEOECD PROJECTS
SECRETARIES: C. VITANZA
E.MATHET, P. PYY
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COMMITTEE ON NUCLEAR REGULATORY ACTIVITIES (CNRA)CHAIRMAN: J. LAAKSONEN - SECRETARY: J. REIG
CNRA BUREAU: S. COLLINS, C. VIKTORSSON, J. FURNESS/M. WEIGHTMAN, A. SCHMITT, K. ABE, J.J. VAN BINNEBEEK
JOINT CSNI/CNRATASK ON PLANT SAFETY
PERFORMANCE INDICATORS
SECRETARY: P. PYY
REGULATORY EFFECTIVENESS
INDICATOR INFORMATION EXCHANGE
(PILOT CONTINUATION)
SECRETARY: B. KAUFER
WORKING GROUP ON
INSPECTION PRACTICES
(WGIP)
CHAIRMAN: H. KLONK
SECRETARY: B. KAUFER
WORKING GROUP ON PUBLIC
COMMUNICATION (WGPC)
CHAIRMAN: A JÖRLE
SECRETARY: J. ROYEN
NEA/WANO/IAEANUCLEAR EVENTS BASED WEB
SYSTEM (NEWS)
SECRETARY: B. KAUFER
TASK GROUP ON
REGULATORY DECISION
MAKING
CHAIRMAN: U. SCHMOCKER
SECRETARY: B. KAUFER
WORKING GROUPS TASK GROUPS JOINT ACTIVITIES
NEA REGULATOR/INDUSTRY FORUM (RIF2004)
SECRETARY: B. KAUFER
January 2004
RADIOACTIVE WASTE MANAGEMENT COMMITTEE
REGULATORS’ FORUM (RWMC-RF)
ANNUAL REPORT ON REGULATORY RELATED
ISSUES
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WGRiskWGRisk Over the past 24 years, PWG5 and now WGRisk have looked at the
technology and methods used for identifying contributors to risk and assessing their importance. Work during the early part of this period was concentrated on Level 1 PSA methodology, but in recent years, the focus has shifted into specific PSA methodologies modelling issues and risk informed applications. During this long period WGRisk has produced over 40 technical reports, held over 25 international workshops and has issued several important consensus statements and opinion papers on specific aspects of PSA.
The main mission of the Working Group on Risk Assessment (WGRisk) is to advance the understanding and utilisation of Probabilistic Safety Assessment (PSA) in ensuring continued safety of nuclear installations and in improving the effectiveness of regulatory practices in Member countries. In pursuing this goal, the Working Group shall recognise the different methodologies for identifying contributors to risk and assessing their importance. While the Working Group shall continue to focus on the more mature PSA methodologies for Level 1, Level 2, internal, external, shutdown, etc. It shall also consider the applicability and maturity of PSA methods for considering evolving issues such as human reliability, software reliability, ageing issues, etc., as appropriate.
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WGRisk Classification of Probabilistic Safety Assessment Topics
Risk Informed Regulation and Safety Management
Level 1 PSA Level 2 PSA and Severe Accident Management
Level 3 PSA Living PSA
Integrated Methods for PSA Methodologies
Non-reactor nuclear facilities Exchange of Information PSA Standards
Human Reliability Seismic Risk Fire Assessment Other External
Events Low Power &
Shutdown Events PSA Topic Specific Methods Development
Modelling Ageing Issues in PSA
Software Reliability Reliability of Passive
Systems Uncertainty Analysis
PSA Applications Risk Monitors Event Analysis
(PSAEA) Plant Modifications
PSA for Operation (Tech. Specs., ISI,
IST, etc.)
PSA for Power Upgrades, Life Extensions, etc.
PSA Related Information Collection
Common Cause Failures (ICDE)
Software (COMPSIS) Piping (OPDE) Fire (OECD-FIRE) Human Reliability
Other PSA Issues Alternative approaches
Dynamic PSA PSA Comparison PSA for Advanced
Reactors Public Perception of
Risks
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Pri
orit
y
Importance
Hig
h
HighLow
Med
ium
Low
Medium
Level 1 PSA
Exchange of InformationHuman Reliability
Fire AssessmentLevel 2 PSA
Low Power/ShutdownEvent Analysis
ICDEOECD-FIRE
HRAD
Level 3 PSANon-reactor Nuclear
FacilitiesPSA Comparison
Advanced Reactors
Living PSASeismic Risk
PSA for OperationOPDE
PSA Standards
Other External EventsAgeing Issues
Software ReliabilityCOMPSIS
PSA for Power Upgrades,Life Extension, etc.
Passive SystemsPublic Perception
Uncertainty Analysis,Plant Modifications
Risk Monitors
AlternativeApproaches
Dynamic PSA
Figure 1 Prioritisation of PSA Topics
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WGRisk – Level 2 PSA Discussion OutcomesWGRisk – Level 2 PSA Discussion Outcomes
[1996]– In the early 1990’s, with the advent of increasing use of PSAs, a proposal was made
at the 1993 PWG5 Annual meeting for future work in the area of Level 2 PSA. The main objective of the proposed task was to perform a state-of-the-art review of the methods available for performing level 2 PSAs and severe accident/source term uncertainty analyses for use in the regulatory process and the evaluation/implementation of severe accident management strategies.
[2002]– The reports from the experts and discussions within WGRisk show it is clear that if
one were to use NUREG 1150 as a basis, experimental evidence over the past 10 years or more indicates that the perceptions of risk in Level 2 PSA has changed what may be considered significant. While it is not clear how the results would specifically change, the body of information that has been compiled would change the distributions that were used in NUREG 1150. Additionally, based on the national reports presented at WGRisk meetings many countries (Germany, Korea, Finland, France, Hungary, Czech Republic, Switzerland and Japan) are actively working on Level 2 PSA. Therefore the proposed workshop is considered is seen as beneficial to getting a better understanding of the current state-of-the-art.
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WGRisk WGRisk State-of-the-Art Report, 1997State-of-the-Art Report, 1997
The report (Level 2 PSA Methodology and Severe Accident Management NEA/CSNI/R(1997)11) reviews and evaluates Level 2 PSA results and methodologies with respect to plant type specific and general insights
The report also looks at approaches and practices for using PSA results in the regulatory context and for supporting severe accident management programmes by input from Level 2 PSAs are examined.
– The report is based on information contained in: PSA procedure guides, PSA review guides and regulatory guides for the use of PSA
results in risk-informed decision making, and
Plant specific PSAs and PSA related literature exemplifying specific procedures, methods analytical models, relevant input data and important results, use of computer codes and results of code calculations. The PSAs are evaluated with respect to results and insights.
Review of Report was performed in 2002 (next presentation)
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Chapter 1Chapter 11. TASK DESCRIPTION AND WORKING
METHODOLOGY– 1.1 Background
– 1.2 Objective and Scope
– 1.3 Level 2 PSA methodologies
– 1.4 Accident management
– 1.5 OECD/NEA activities on accident management
– 1.6 OECD/NEA activities on severe accident phenomena
– 1.7 Structure of the report.
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Chapter 2Chapter 2
2 RESULTS AND INSIGHTS FROM RECENT LEVEL 2 PSA– 2.1 Examined PSAs and considered aspects
– 2.2 Objectives and scope of recent level-2 PSAs.
– 2.3 Plant characteristics influencing severe accident progression
– 2.4 Level 2 methodology and codes
– 2.5 Principal results, insights on containment failure modes and releases.
– 2.6 References
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Chapter 3Chapter 3
3 KEY SEVERE ACCIDENT ISSUES
– 3.1 Key Severe Accident Phenomena.
– 3.2 Review of severe accident computer codes
– 3.3 Documentation of the Use of Severe Accident Computer Codes in Selected Level 2 PSAs for Nuclear
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Chapter 4Chapter 4
4 SEVERE ACCIDENT MANAGEMENT– 4.1 Background and Objectives
– 4.2 Evolution of an accident from the operators perspective
– 4.3 Safety objectives for the development of SAM Guidance
– 4.4 Examples of implemented provisions for mitigative SAM (level 2) and of their effectiveness
– 4.5 Identification of Recovery and SAM Actions in the Level 1 Domain that can influence SAM in the Level 2 Domain. Some Examples
– 4.6 References
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Chapters 5 and 6Chapters 5 and 6
5 AVAILABLE METHODOLOGY FOR QUALITATIVE LEVEL 2 ANALYSIS– 5.1 Level 1/2 Interface
– 5.2 Accident progression Event Trees
– 5.3 Modelling of human intervention
6 EVALUATION OF LEVEL 2 PSA MODELS AND QUANTIFICATION– 6.1 Brief description of Methods
– 6.2 Use of Expert Judgement
– 6.3 Uncertainty Issue Quantification Technique
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Chapter 7Chapter 7 7 INTEGRATED AND PSA INFORMED APPROACH
TO DECISION MAKING– 7.1 Introduction
– 7.2 Recent activities and publications related to risk informed decision making
– 7.3 Quality requirements for PSAs
– 7.4 National Positions on risk informed decision making.
– 7.5 Treatment of Uncertainties
– 7.6 Examples of risk informed decisions in the level 2 domain
– 7.7 Conclusions
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AppendicesAppendicesAPPENDIX A: SEVERE ACCIDENT COMPUTER
CODES– A.1 Fully Integrated Plant Simulation Codes– A.2 Separate Phenomena Codes– A.3 Parametric Codes
APPENDIX B:– B.1 EVNTRE– B.2 SOLOMON– B.3 RISKMAN– B.4 SPSA
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2004 WGRisk Programme of Work (1)2004 WGRisk Programme of Work (1)
International Workshop on Level 2 PSA and Severe Accident Management.– The main objectives are:
To provide a forum to discuss recent developments in the state-of-the-art of Level 2 PSA and Severe Accident Management.
The information gathered will be used to produce an addendum to the 1997 WGRisk report,
Will provide input into the joint workshop planned by WGAMA, IAGE and WGRisk on Evaluation of Uncertainties in relation to Severe Accident and Level 2 Probabilistic Safety Analysis (to be held in the Fall of 2004), and
Will be used to develop future tasks by WGRisk.
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2004 WGRisk Programme of Work (2)2004 WGRisk Programme of Work (2)
The Use and Development of PSA in NEA Member Countries [NEA/CSNI/R(2002)18]– This report provides descriptions of the current status of PSA
programmes in 17 Member countries including basic background information, guidelines, various PSA applications, major results in recent studies, PSA based plant modifications and research and development topics. While the compilation is a not complete compilation it provides a “snapshot” of the current situation in the Member countries and hence it provides reference information and various insights to both the PSA practicien and others involved in the nuclear industry.
– The report forms the basis for a yearly round table discussion at WGRisk meetings and will be updated every 3 to 4 years.
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2004 WGRisk Programme of Work (3)2004 WGRisk Programme of Work (3)
Use of PSA in Emergency Planning [Task 2004-3]– The aim is to identify the approaches being used in the
member countries to define the emergency planning zones round nuclear facilities and how this relates to the information provided by the Level 2 PSA. The various approaches would be compared to identify similarities and differences. Consideration would also be given on whether it would be possible to define a common approach to using the Level 2 PSA information for this purpose.
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2004 WGRisk Programme of Work (4)2004 WGRisk Programme of Work (4)
GAMA/WGRISK/IAGE Workshop on Evaluation of Uncertainties in Relation to Severe Accidents and Level 2 PSA– The objectives are:
To transfer information among Working Groups on an important cross-cutting issue.
To develop a coherent approach/understanding regarding uncertainties. The product will be proceedings, and conclusions/recommendations
addressed to CSNI and the Working Groups.
– Tentative Date: Spring 2005
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SummarySummary
WGRisk State-of-the-Art report provided first in-depth look at Level 2 PSA Methodology in the Member Countries
WGRisk has an active programme in the area of Level 2 PSA and Severe Accident Management
WGRisk works (and will continue to work) with other working groups (e.g., GAMA) and other organisations (e.g., IAEA) to co-ordinate it work on this issue.