Reliability and Probabilistic Safety Assessment in Multi-Unit Nuclear Power Plants

Front cover
Half title
Title
Copyright
Dedication
Contents
About the Author
Preface
Chapter 1 Reliability modeling
1.1 Reliability mathematics
1.1.1 Set theory
1.1.2 Fundamentals of Boolean algebra
1.2 Probability theory
1.2.1 Conditional probability
1.2.2 Bayes theorem
1.3 Probability distributions
1.3.1 Discrete probability distribution
1.3.2 Continuous probability distribution
1.4 System reliability
Further readings
Chapter 2 Introduction to probabilistic safety assessment
2.1 Safety approach in NPPs—defense-in-depth
2.2 Need for PSA
2.3 Regulatory decision making with PSA insights
2.3.1 Probabilistic safety goals/criteria
2.4 Approaches for regulatory decisions
2.4.1 Risk-informed approach
2.4.2 Risk-based approach
2.4.3 Risk-informed, performance-based approach
2.5 Quality assurance
2.5.1 Management of QA activities
2.5.2 Structure of QA program
2.6 Standardization of PSA
2.7 PSA methodology
2.7.1 Data
2.7.2 Failure mode selection
2.7.3 External events
2.7.4 Computer code
2.7.5 A graded approach to risk evaluation
2.7.6 Level-1 PSA
2.7.7 Level-2 PSA
2.7.8 Level-3 PSA
2.8 Initiating event frequency
2.9 Component data
2.9.1 Component reliability models
2.10 Human reliability
2.11 Dependence analysis
2.11.1 Complete dependency
2.11.2 High dependency
2.11.3 Moderate dependency
2.11.4 Low dependency
2.11.5 Zero dependency
2.12 Passive systems
2.12.1 Category A
2.12.2 Category B
2.12.3 Category C
2.12.4 Category D
2.13 Software reliability
2.13.1 Black-box reliability models
2.13.2 White-box reliability models
2.14 Uncertainty analysis
2.15 Sensitivity analysis
2.16 Importance measures
2.16.1 Risk achievement worth
2.16.2 Risk reduction worth
2.16.3 Birnbaum importance
2.17 Applications of PSA
2.17.1 Design of NPPs
2.17.2 Operation of NPPs
Further readings
Chapter 3 Risk assessment
3.1 Background
3.2 Objective and scope
3.2.1 Definition
3.3 Qualitative and quantitative methods of risk assessment
3.3.1 Risk assessment methods for individual units
3.3.2 Importance of multiunit PSA
3.3.3 Screening in multiunit PSA
3.3.4 Internal and external hazards
3.3.5 Correlated hazards
3.3.6 Shared connections
3.3.7 Human dependencies
3.3.8 Common cause failures
3.3.9 Combination of initiating events
Further readings
Chapter 4 Site safety goals
4.1 Multi-unit considerations
4.2 Site safety goals
4.3 Site safety goals—international scenario
4.4 Multi-criteria analysis for risk metrics
4.5 Communication of risk information to public and their perception
Further readings
Chapter 5 Challenges in risk assessment of multiunit site
5.1 Key issues
5.1.1 Shared systems or connections
5.1.2 Identical components
5.1.3 Human dependencies
5.1.4 Proximity dependencies
5.1.5 Modeling site level response
5.2 Methods for integrated risk assessment
5.2.1 Identification of multiunit initiating events
5.2.2 Hazard categorization method
5.2.3 Event sequence MUPSA method
5.2.4 Master event tree method
5.3 Seismic PSA for multiunit site
5.3.1 Site-specific seismic hazard assessment
5.3.2 Safety analysis
5.3.3 Component fragility
5.3.4 Plant fragility
5.3.5 Seismic core damage frequency
5.4 MUPSA for Level 2
5.5 MUPSA for Level 3
Further readings
Chapter 6 Risk aggregation
6.1 Unit level
6.2 Site level
6.3 Aspects to be considered in risk aggregation
6.3.1 Heterogeneity
6.3.2 Aging
6.3.3 Multi-facility site
6.3.4 Combination of hazards and uncertainties in external hazards
6.3.5 Human, organizational, and technological factors
6.3.6 Risk importance and sensitivity measures
6.4 Risk aggregation and its effect on risk metric
6.5 Mathematical aspects of risk aggregation
6.6 Interpretation of results
6.7 Risk aggregation for risk-informed decisions
Further readings
Chapter 7 Human reliability
7.1 Introduction
7.2 Types of human errors
7.3 Human error in nuclear power plants
7.4 Human reliability models
7.4.1 Technique for human error rate prediction
7.4.2 Accident sequence evaluation program
7.4.3 Success likelihood index methodology
7.4.4 Human cognitive reliability model
7.4.5 Standardized plant analysis risk-HRA model
7.5 HRA generations
7.5.1 First-generation HRA models
7.5.2 Second-generation HRA models
7.5.3 Third-generation HRA models
7.5.4 Cognitive architecture models
7.6 Human cognitive architecture
7.7 HRA in the context of multiunit PSA
Further readings
Chapter 8 Common cause failures and dependency modeling in single and multiunit NPP sites
8.1 Dependent failures
8.2 Common cause failures
8.3 CCF models
8.3.1 Beta factor model
8.3.2 Multiple Greek letter model
8.3.3 Alpha factor model
8.4 Impact vector method to estimate the alpha factors
8.4.1 Mapping techniques
8.4.2 Estimation of impact vectors
8.4.3 Estimation of alpha factors from impact vectors
8.5 Approach for interunit CCF in multiunit sites
Further readings
Chapter 9 International studies related to multiunit PSA: A review
9.1 Seabrook PSA
9.2 Byron and Braidwood PSA
9.3 Research work at Maryland University, United States
9.4 Korea Atomic Energy Research Institute
9.4.1 MUPSA software
9.5 CANDU Owners Group
9.5.1 Proposed site safety goals
9.5.2 Site CDF
9.5.3 Large off-site release safety goal
9.6 Multiunit PSA studies at EDF France
9.7 Fukushima Daiichi experience
9.8 MUPSA research in India
9.9 MUPSA approach in the United Kingdom
9.10 Site risk model development in Hungary
9.11 Other countries
9.12 Summary of international experience on MUPSA
Further readings
Chapter 10 Multiunit risk assessment for small modular reactors
10.1 Introduction
10.2 Small modular reactors
10.2.1 Regulators concern for SMRs
10.2.2 Multiunit risk assessment for SMRs
10.3 Multiunit risk in chemical industries
10.3.1 Safety culture
Further readings
Chapter 11 Summary
11.1 Case study and conclusions
11.2 Different approaches for MUPSA
11.3 Application of MUPSA methodology
11.3.1 Loss of offsite power
11.3.2 System analysis
11.3.3 Results
11.4 Insights and lessons learnt in MUPSA
11.5 Closure
Further readings
Index
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