Methods for Safety Assessment of Geological Disposal Facilities for Radioactive Waste [electronic resource]: Outcomes of the NEA MeSA Initiative /
Organisation for Economic Co-operation and Development.
Organisation for Economic Co-operation and DevelopmentContributor
Organisation for Economic Co-operation and DevelopmentContent Provider
Paris : OECD Publishing,
2012.
Safety assessment is an interdisciplinary approach that focuses on the scientific understanding and performance assessment of safety functions as well as the hazards associated with a geological disposal facility. It forms a central part of the safety case, and the results of the safety assessments provide evidence to support decision making. The goals of the NEA project on "Methods for Safety Assessment for Geological Disposal Facilities for Radioactive Waste" (MeSA) were to examine and document methods used in safety assessment for radioactive waste disposal facilities, to generate collective views based on the methods' similarities and differences, and to identify future work. The project reviewed a number of approaches used by various national and international organisations. Following the comprehensive review, a generic safety case with a safety assessment flowchart was developed and is presented herein. The elaboration of the safety concept, the use of safety functions, the implication of uncertainties and the formulation of scenarios are also discussed.
Executive summary 9 PART I. BACKGROUND  1. Introduction 17 2. Overall regulatory perspective 19 3. Safety assessment in the context of the safety case 21 -3.1 Definitions 21 -3.2 The safety case as context for safety assessment 22 -3.3 Scope of safety assessment 23 -3.4 Importance of the assessment basis 24 -3.5 Handling uncertainties 24 -3.6 Evolution of the safety assessment and the safety case over time 24 -3.7 Feedback and links with site characterisation, testing, engineering, design 25 -3.8 Safety assessment results and communication 25 -3.9 Regulatory perspective 26 4. Safety assessment and safety case flowcharts 27 -4.1 Development of assessment strategy flowcharts 27 -4.2 Generic assessment strategy flowchart 28 -4.3 Regulatory perspective 32 5. System description and scenarios 33 -5.1 Scenarios in safety assessment 33 -5.2 System description: initial state and evolution 33 -5.3 Derivation of scenarios 35 -5.4 Structuring scientific knowledge and identifying safety-relevant phenomena and uncertainties 36 -5.5 Scenario probabilities 37 -5.6 Regulatory perspective 39 6. Modelling strategy 43 -6.1 General 43 -6.2 Process-level models 43 -6.3 Integrated or system-level modelling 44 -6.4 Computer power and software 46 -6.5 Data gathering and management 46 -6.6 Model qualification 47 -6.7 Regulatory perspective 48 7. Indicators for safety assessment 51 -7.1 General 51 -7.2 Classification of indicators 51 -7.3 Safety indicators 52 -7.4 Performance indicators 53 -7.5 Safety function indicators 53 -7.6 Reference values 54 -7.7 Timescales 55 -7.8 Transferability 55 -7.9 Regulatory perspective 56 8. Treatment of uncertainties 59 -8.1 Classification of uncertainty 59 -8.2 Strategies for treating uncertainty 60 -8.3 Mathematical techniques 61 -8.4 Regulatory perspectives 61 9. Conclusions and recommendations 63 10. References 65 PART II. ISSUE PAPERS 11. Safety assessment in the context of the safety case - Issue Paper No. 1  69 -11.1 Introduction and definitions 69 -11.2 The safety case as context for safety assessment 71 -11.3 The scope and basis of safety assessment 75 -11.4 The safety assessment and safety case in repository development 77 -11.5 Interpretation and presentation of safety assessment results  80 -11.6 Conclusions 81 -11.7 References 82 12. Safety assessment and safety case flowcharts - Issue Paper No. 2  85 -12.1 Introduction 86 -12.2 Methodology 86 -12.3 Conclusions 101 -12.4 References 102 13. System description and scenarios - Issue Paper No. 3 115 -13.1 Introduction 115 -13.2 History and recent developments 116 -13.3 Place and purpose of system description and scenario development in the safety strategy and safety case 120 -13.4 System description: Initial state and evolution 123 -13.5 Derivation of scenarios 129 -13.6 The regulator's perspective 141 -13.7 Conclusions 143 -13.8 References 145 14. Modelling strategy - Issue Paper No. 4 149 -14.1 Introduction 149 -14.2 Methodology 150 -14.3 Types of models and modelling strategy 151 -14.4 Process-level modelling 153 -14.5 Integrated or system-level modelling 154 -14.6 Advances in tools 156 -14.7 Data selection 158 -14.8 Model qualification 160 -14.9 Conclusions 162 -14.10 References 163 15. Indicators for safety assessment - Issue Paper No. 5 165 -15.1 Introduction 166  -15.2 Methodology 166 -15.3 Conclusions 185 -15.4 References 186  16. Treatment of uncertainties - Issue Paper No. 6 195 -16.1 Introduction 195 -16.2 Sources and classification of uncertainties 199 -16.3 Safety relevance of uncertainties 202 -16.4 Description and quantification of uncertainties 202 -16.5 Impacts of uncertainties 205 -16.6 Mathematical techniques 208 -16.7 Conclusions 210 -16.8 References 212 17. Regulatory issues - Issue Paper No. 7 221 -17.1 Introduction 221 -17.2 Context of the safety assessment 223 -17.3 Safety concept 223 -17.4 Assessment strategy 224 -17.5 Indicators and criteria 227 -17.6 System description 229 -17.7 System evolution and scenarios 230 -17.8 Modelling strategy 234 -17.9 Conclusions 236 -17.10 References 236   
Safety assessment is an interdisciplinary approach that focuses on the scientific understanding and performance assessment of safety functions as well as the hazards associated with a geological disposal facility. It forms a central part of the safety case, and the results of the safety assessments provide evidence to support decision making. The goals of the NEA project on "Methods for Safety Assessment for Geological Disposal Facilities for Radioactive Waste" (MeSA) were to examine and document methods used in safety assessment for radioactive waste disposal facilities, to generate collective views based on the methods' similarities and differences, and to identify future work. The project reviewed a number of approaches used by various national and international organisations. Following the comprehensive review, a generic safety case with a safety assessment flowchart was developed and is presented herein. The elaboration of the safety concept, the use of safety functions, the implication of uncertainties and the formulation of scenarios are also discussed.
Bibliographic Level Mode of Issuance: Monograph
Nuclear Energy
Civil & Environmental Engineering
Engineering & Applied Sciences
Environmental Engineering