Overview of IAEA's Projects on Safety Goals and Integrated Risk Informed Decision Making

Transcription

1 Overview of IAEA's Projects on Safety Goals and Integrated Risk Informed Decision Making Presented by: Irina Kuzmina, PhD, Safety Officer Safety Assessment Section/ Division of Nuclear Installation Safety/ Department of Nuclear Safety 1st Consultants Meeting on the INPRO Collaborative Project: Review of Innovative Reactor Concepts for Prevention of Severe Accidents and Mitigation of their Consequences (RISC) 31 March 2 April 2014, IAEA, Vienna, Austria

2 HIGHLIGHTS Safety Goals Background, status, high-level overview of the contents Integrated Risk Informed Decision Making (IRIDM) Background, status, high-level overview of the contents IAEA-TECDOC publication series 2of 44

3 Safety Goals 3of 44

4 WHAT DO WE MEANT BY SAFETY GOALS? Safety Goals for nuclear installations: characteristics aimed to assist in answering the fundamental question: How safe is safe enough? Generally, Safety Goals provide a measure of sufficiency/adequacy of safety provisions embedded in the design of a nuclear installation and its operational process 4of 44

5 CHARACTERIZATION OF SAFETY GOALS SAFETY GOALS QUALITATIVE QUANTITATIVE Safety Margins Defense-in-Depth Multiple barriers and levels of protection Diversity and redundancy within and between safety systems Single failure criterion Postulated initiating events, etc. 1.0E E E E E E E E E E E+00 Limits for respective RISK METRICS - frequencies of undesirable consequences (events/time unit) 5of 44

6 SAFETY GOALS Safety Provisions Safety Assessment 6of 44

7 SAFETY FUNDAMENTALS (1/2) The Fundamental Safety Objective is to protect people and the environment from harmful effects of ionizing radiation Safety means the protection of people and the environment against radiation risks Ten safety principleshave been formulated, on the basis of which safety requirements are developed and safety measures are to be implemented in order to achieve the fundamental safety objective 7of 44

8 SAFETY FUNDAMENTALS (2/2) Principle 6: Limitation of risks to individuals Measures for controlling radiation risks must ensure that no individual bears an unacceptable risk of harm Implications: 1) Riskassociated with nuclear installations needs to be assessed 2)Guidance (criteria) for unacceptable risk need to be established SAFETY GOALS 3) Relevant measures(design features and procedures) provided 8of 44

9 INSAG-12 Basic Safety Principles for Nuclear Power Plants, 75-INSAG-3 Rev.1, INSAG-12, A report by the International Nuclear Safety Advisory Group, IAEA, Vienna, 1999 Revision of the original 75-INSAG-3 (1988) Qualitative safety concepts, Defense-in-Depth emphasized Current reference IAEA publication for probabilistic safety goals 9of 44

10 ILLUSTRATION OF THE CONCEPT OF NUMERICAL SAFETY GOALS CONSIDERED IN INSAG-12 & NS-G-1.2* Core Damage Frequency (CDF) Large Release Frequency (LRF) 1.0E E-05 CDF for operating NPPs 1.0E E-06 LRF for operating NPPs 8.0E E E E-06 1/y 6.0E E-05 1/y 6.0E E E E E E E E+00 CDF for new NPPs 3.0E E E E+00 Practical elimination of accident sequences that could lead to large early radioactive releases for new NPPs (NS-G-1.2)* *Comment: NS-G-1.2 is superseded by SSG-2, where the consideration is not included 10of 44

11 11of 44 CITATION FROM INSAG-12 ON SAFETY GOALS 25. For future NPPs, consideration of multiple failures and severe accidents will be achieved in a more systematic and complete way from the design stage. This will include improving accident prevention (for example, reduced common mode failures, reduced complexity, increased inspectability and maintainability, extended use of passive features, optimized human machine interface, extended use of information technology) and further reducing the possibilities and consequences of off-site radioactive releases. 26. In the safety technology of nuclear power, overall riskis obtained by considering the entire set of potential events and their respective probabilities and consequences. The technical safety objective for accidents is to apply accident prevention, management and mitigation measures in such a way that overall risk is very low and no accident sequence, whether it is of low probability or high probability, contributes to risk in a way that is excessive in comparison with other sequences. 27. The target for existing NPPs L is a frequency of occurrence of severe core damage that is below about 10 4 events per plant operating year. Severe accident management and mitigation measures could reduce by a factor of at least ten the probability of large off-site releasesrequiring short term off-site response. Application of all safety principles and the objectives (of para. 25) to future plants could lead to the achievement of an improved goal of not more than 10 5 severe core damage events per plant operating year. Another objective for these future plants is the practical elimination of accident sequences that could lead to large early radioactive releases, whereas severe accidents that could imply late containment failure would be considered in the design process with realistic assumptions and best estimate analyses so that their consequences would necessitate only protective measures limited in area and in time.

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13 IAEA TECHNICAL MEETING ON SAFETY GOALS IN APPLICATION TO NUCLEAR INSTALLATIONS TM Objective Provide international forum for presentations and discussions on the current practices in establishing and use of Safety Goals for nuclear installations To contribute to outlining the way forward TM Summary Some 40attendees from 23countries and 5 international organizations - regulators, operators, designers, consultants, and TSOs 30 presentations and papers Two working groups: WG1: General Framework for Safety Goals and Methodologies/Processes for Compliance Assessment WG2: Process of Derivation of Low-Tier Quantitative Safety Goals and Qualitative and Quantitative Safety Goals Specification Questionnaire on national framework for Safety Goals with 20 responses 13of 44

14 OUTPUT A formal TM report has been produced Outputs of WGs Questionnaires responded Papers Conclusions and recommendations for IAEA activities Producing guidance on establishing and use of Safety Goals recommended 14of 44

15 OBSERVATIONS Surveys show that there is a variety of approaches relating to establishment and use of Safety Goals in Member States, which often include qualitative considerations and quantitative risk metrics Recent international projects on Safety Goals being pursued by different expert groups [e.g. MDEP, WENRA, Nordic PSA Group (NPSAG)] produced recommendations Growing importance of establishing a technically consistent holistic framework for Safety Goals for NPPs and other nuclear installations on the basis of synergetic consideration of qualitative concepts and quantitative risk metrics Hierarchical structure 15of 44

16 RECOMMENDATIONS Five areaswere recommended by the TM where IAEA should consider producing guidance (the formal TM report): 1. Develop a hierarchical approach for Safety Goals 2.Clarify interfacesbetween the Fundamental Safety Objectives, Safety Principles, Safety Requirements and the proposed framework for Safety Goals 3.Develop a methodology to derive lower-tier goalsin a consistent and coherent manner 4.Develop guidanceon methods and approachesto assess the degree of compliancewith the full spectrum of Safety Goals and a comprehensive review methodology 5. Develop an approach to using Safety Goals 16of 44

17 CONTINUED WORK AFTER TM APRIL 2011 A series of consultant meetings ( ) to develop a draft TECDOC - Development and Application of a Safety Goals Framework for Nuclear Installations Overall Objective: to promote a greater harmonization of the use of Safety Goals in Member States Specific Objectives: to provide guidance for establishing a formal framework for Safety Goals and compliance assessment Drafting TECDOC - CM participants: Irina Kuzmina (IAEA) Andy Ashworth (AECL, Canada) Heinz Peter Berg (BfS, Germany) Nigel Buttery (EdF Energy, UK) Michael Knochenhauer (Lloyd s Register Scandpower, Sweden) Geoff Vaughan (ONR, UK) See-Meng Wong (NRC, USA) 17of 44

18 OUTLINE (1/2) 1. INTRODUCTION 2. DISCUSSION ON THE BACKGROUND AND BENEFITS OF A SAFETY GOALS FRAMEWORK Safety Goals Definition A Framework for Safety Goals Relationship to IAEA Safety Standards Global Harmonisation Public Understanding and Communication Use of Safety Goals by Stakeholders Safety Goals Framework and Safety Performance Indicators 3. CHARACTERISTICS AND ASPECTS OF A SAFETY GOALS FRAMEWORK Considerations from the Technical Meeting, April 2011 Safety Goals and IAEA Safety Standards Framework Safety Goals Framework Characteristics Aspects to be Considered in Developing a Safety Goals Framework Communication 18of 44

19 OUTLINE (2/2) 4. A GENERAL FRAMEWORK FOR SAFETY GOALS Basic Types of Safety Goals Hierarchical Approach to Safety Goals 5. DERIVATION OF SAFETY GOALS The Roles of Stakeholders Involved in the Definition of Safety Goals Safety Goals within the Framework Organising the Safety Goals defined within the Framework 6. APPLICATIONS OF A SAFETY GOALS FRAMEWORK Compliance Assessment Regulatory and Licensee Applications Use of the Safety Goals Framework in Integrated Risk Informed Decision Making 7. CONCLUDING REMARKS APPENDIX 1 GLOSSARY APPENDIX 2 SPECIFIC EXAMPLES OF SAFETY GOALS FRAMEWORK 19of 44

20 DEVELOPMENTS BY MULTINATIONAL DESIGN EVALUATION PROJECT - MDEP Within MDEP, a group was tasked with considering how to harmonise Safety Goals The MDEP work attempted to set out a hierarchical approach Top level = Fundamental Safety Objective of the IAEA of protecting people from radiation risks Second tier is based partly on the basic defence-in-depth approach, probably still to some extent technology independent From the upper levels the intention is to develop lower-level goals, eventually technology specific Top Level Safety Goal High Level Safety Goals (DiD and Risk Goals) Lower Level Safety Goals and Targets (Deterministic and probabilistic) Technology Specific Safety Targets 20of 44

21 HIERARCHY SUGGESTED IN NORDIC PSA GROUP PROJECT - NPSAG As part of the NPSAG project on probabilistic Safety Goals, a hierarchy was suggested There are four levels : Society level (legislation expressing high-level requirements) Intermediate level (interpretation of legal requirements in a way that allows quantification) Technical level (quantitative requirements) High level (corresponding to PSA Level 1, 2 and 3) Low level (corresponding to safety systems and functions) 21of 44

22 SUGGESTED HIERARCHY OF SAFETY GOALS 22of 44

23 HIERARCHICAL LEVELS OF SAFETY GOALS (1/4) Level Formulation Notes Top Level Primary Safety Goal Protecting people and the environment from harmful effect of ionizing radiation Primary safety goal as set out in SF-1 (or society level safety goals as defined in national legislation or regulations) 23of 44

24 HIERARCHICAL LEVELS OF SAFETY GOALS (2/4) Level Formulation Notes Upper Level Adequate Protection Ensuring adequate protection in all operational modes of all facilities and installations at the site Qualitative safety goals interpreting what is needed to ensure adequate protection Includes interpretation of the top level safety goal in risk terms for accident conditions. This is often done by comparison with the levels of risks coming from other involuntary sources of risk 24of 44

25 HIERARCHICAL LEVELS OF SAFETY GOALS (3/4) Level Formulation Notes Intermediate Level General Safety Provisions Providing necessary safety provisions including technical and organizational measures based on proven approaches and good practices to ensure adequate protection Technologyneutral site-wide safety goals based on proven approaches and good practices to achieve the upper level safety goals (e.g. definition of general requirements at site level) 25of 44

26 HIERARCHICAL LEVELS OF SAFETY GOALS (4/4) Level Formulation Notes Low Level Specific Safety Provisions Providing necessary specific safety provisions for all facilities and installations at the site Technology and facility specific safety goals aimed at assuring that all nuclear installations/ facilities at the jointly meet the respective intermediate level safety goals 26of 44

27 BASIC TYPES OF SAFETY GOALS 27of 44

28 An Example of Hierarchy of Safety Goals for Nuclear Installations O1 To protect workers, the public and the environment TOP LEVEL PRIMARY SAFETY GOAL: To protect people and the environment from harmful effects of ionizing radiation UPPER LEVEL SAFETY GOALS: Ensuring adequate protection in all operational modes of all facilities and installations at the site Operational states O2 To provide design features for security O3 To minimize radioactive waste O4 To provide design features to facilitate decommissioning A1 Risk to life and health of people from the facilities and installations located at the site should be low comparing with risk from other sources to which an individual is generally exposed Accident conditions A2 Large off-site releases leading to land interdiction should be practically eliminated A3 Safety-security interface should be addressed A4 Emergency response should be provided Society-wide Society & site-wide Technologyneutral INTERMEDIATE LEVEL SAFETY GOALS: Providing necessary safety provisions including technical and organizational measures based on proven approaches and good practices to ensure adequate protection Qualitative O1-Q1 Management, leadership and safety culture Deterministic quantitative O1-D1 To meet ICRP criteria for workers by providing adequate radiation protection measures K K K L Qualitative A1-Q1 Maintaining effective defence-in-depth Deterministic quantitative A1-D1 Maintaining allowed doses for workers in DBAs Probabilistic quantitative A1-P1 Overall L(E)RF for the site for all events and hazards Qualitative A2-Q1 Providing effective SAM design features and SAMG at the site level Probabilistic quantitative A2-P1 Probabilistic interpretation of practically eliminated for land, site-level A3-Q1 Vital area identification at the site level A4-Q1 Detailed emergency plan Site-wide Technologyneutral O1-D2 To meet ICRP criteria for discharges to the environment by providing adequate measures for controlling the discharges A1-Q2 Maintaining sufficient safety margins A1-D2 Maintaining allowed discharges to the environment in DBAs A1-P2 Frequencies of external hazards/ magnitudes for design of site protective features A2-P2 Food ban radioactivity levels and accepted frequency A4-D1 Food ban levels A1-Q3 Providing sufficient redundancy and diversity to comply with single failure criterion A1-D3 Containment withstanding the crash of a specified size aircraft A2-P3 Habitation radioactivity levels and accepted frequency A4-D2 Habitation radioactivity levels LOW LEVEL SAFETY GOALS: Providing necessary specific safety provisions for all facilities and installations at the site K K K K Deterministic quantitative A1-Q2-INST1(D1) max fuel clad temp. for INST1 A1-Q2-INST1(D2) K for INST A1-Q2-INST2(D1) max fuel clad temp. for INST2 A1-Q2-INST2(D2) K for INST2 Probabilistic quantitative LERF for each installation: A1-P1-INST1(LERF), A1-P1-INST2(LERF), Supplemental goals on CDF as applicable: A1-P1-INST1(CDF ), Qualitative A2-Q1- INST1(SAMG) A2-Q1- INST2(SAMG) Providing effective SAM design measures and SAMG at the facility level A3-Q1-INST1 A3-Q1-INST12 K Vital area identification at facility level Technologyspecific Facility and installationspecific 28of 44

29 An Example of Hierarchy of Safety Goals for Nuclear Installations TOP LEVEL PRIMARY SAFETY GOAL: To protect people and the environment from harmful effects of ionizing radiation UPPER LEVEL SAFETY GOALS: Ensuring adequate protection in all operational modes of all facilities and installations at the site Operational states Accident conditions Society-wide Site-wide Technologyneutral O1 To protect workers, the public and the environment O2 To provide design features for security O3 To minimize radioactive waste O4 To provide design features to facilitate decommissioning A1 Risk to life and health of people from the facilities and installations located at the site should be low comparing with risk from other sources to which an individual is generally exposed A2 Large off-site releases leading to land interdiction should be practically eliminated A3 Safety-security interface should be addressed A4 Emergency response should be provided INTERMEDIATE LEVEL SAFETY GOALS: Providing necessary safety provisions including technical and organizational measures based on proven approaches and good practices to ensure adequate protection Qualitative O1-Q1 Management, leadership and safety culture Deterministic quantitative O1-D1 To meet ICRP criteria for workers by providing adequate radiation protection measures K K K L Qualitative A1-Q1 Maintaining effective defence-in-depth Deterministic quantitative A1-D1 Maintaining allowed doses for workers in DBAs Probabilistic quantitative A1-P1 Overall L(E)RF for the site for all events and hazards Qualitative A2-Q1 Providing effective SAM design features and SAMG at the site level Probabilistic quantitative A2-P1 Probabilistic interpretation of practically eliminated for land, site-level A3-Q1 Vital area identification at the site level A4-Q1 Detailed emergency plan Site-wide Technologyneutral O1-D2 To meet ICRP criteria for discharges to the environment by providing adequate measures for controlling the discharges A1-Q2 Maintaining sufficient safety margins A1-D2 Maintaining allowed discharges to the environment in DBAs A1-P2 Frequencies of external hazards/ magnitudes for design of site protective features A2-P2 Food ban radioactivity levels and accepted frequency A4-D1 Food ban levels A1-Q3 Providing sufficient redundancy and diversity to comply with single failure criterion A1-D3 Containment withstanding the crash of a specified size aircraft A2-P3 Habitation radioactivity levels and accepted frequency A4-D2 Habitation radioactivity levels LOW LEVEL SAFETY GOALS: Providing necessary specific safety provisions for all facilities and installations at the site K K K K Deterministic quantitative A1-Q2-INST1(D1) max fuel clad temp. for INST1 A1-Q2-INST1(D2) K for INST A1-Q2-INST2(D1) max fuel clad temp. for INST2 A1-Q2-INST2(D2) K for INST2 Probabilistic quantitative LERF for each installation: A1-P1-INST1(LERF), A1-P1-INST2(LERF), Supplemental goals on CDF as applicable: A1-P1-INST1(CDF ), Qualitative A2-Q1- INST1(SAMG) A2-Q1- INST2(SAMG) Providing effective SAM design measures and SAMG at the facility level A3-Q1-INST1 A3-Q1-INST12 K Vital area identification at facility level Technologyspecific Facility and installationspecific 29of 44

30 RECENT ACTIVITIES SecondTechnical Meeting to review the preliminary draft TECDOC July 2013, Vienna, Austria A formal report produced The suggested structure is seen adequate + recommendations Helpful for developing countries (holistic view) & benchmarking the existing safety goals frameworks Wider informing the international community is useful CMs: July 15-19, December 2-6, 2013 Addressing recommendations of the 2 d TM Updated final draft soon 30of 44

31 ISSUES NEEDING FURTHER CONSIDERATION Practically eliminated: The possibility of certain conditions occurring is considered to have been practically eliminated if it is physically impossible for the conditions to occur or if the conditions can be considered with a high level of confidence to be extremely unlikely to arise. Quantification is asked by Member States for the terms : - Extremely unlikely - High level of confidence What should be the basis for these? 31of 44

32 Integrated Risk Informed Decision Making INSAG-25 Guidance (TECDOC) 32of 44

33 IRIDM PROCESS The Integrated Risk Informed Decision Making (IRIDM) process is a structured process in which all the insights and requirements relating to an operational, safety or a regulatory issue are considered in reaching a balanced and optimized decision The main goal of IRIDM is to ensure that any decision which might affect nuclear safety is optimized without unduly limitingthe conduct of safe operation of the nuclear power plant 33of 44

34 EXAMPLES OF IRIDM APPLICATIONS An integrated approach can be applied to making decisions on operational and safety issues of a nuclear power plant These typically include Hardware Modifications & Procedural Changes Plant modifications and backfittings Emergency operating procedures Accident management measures, etc. Changes to Tech Specs (Operation Limits and Conditions) Optimization of on-line maintenance practices Changes to allowed outage times Optimization of testing intervals & arrangements Plant configuration management, etc. Exemptions from Tech Specs, etc. 34of 44

35 INSAG-25 INSAG-25 published in 2011 Identifies the basic framework Sets out the principles for application Define the key elements of IRIDM 35of 44

36 IRIDM FRAMEWORK (INSAG-25) Logical, reproducible, verifiable, uncertainties addressed 36of 44

37 IRIDM BENEFITS Improved safety By taking each factor influencing safety into account in a decision and its implementation Increased installation performance, operational flexibility, cost effectiveness of operations Reduced radiation exposure By focusing maintenance on more risk-significant areas and reducing unnecessary activities in high radiation areas Etc. 37of 44

38 TECDOC IRIDM GUIDANCE Objective: to suggest approaches to integrate the results of DSA and PSA as well as other important aspects to make sound, optimum, and safe decisions Follows the main principles presented in INSAG-25 Provides detailed information/guidance on the key elements of IRIDM and their integration Provides examples illustrating how the decisions can be made or have been made using a structured IRIDM process Explain issues not elaborated in the INSAG-25 Establishment of the IRIDM process Integration of inputs Treatment of uncertainties, etc. IAEA technical lead A.Lyubarskiy, SAS/NSNI (A.Lyubarskiy@iaea.org) 38of 44

39 IRIDM FRAMEWORK (NEW TECDOC) Examples (annexes) Discussion on uncertainty 39of 44

40 IRIDM FRAMEWORK (NEW TECDOC) Examples (annexes) Discussion on unceratinty 40of 44

41 STRUCTURE OF THE TECDOC 1. INTRODUCTION 2. GENERAL OVERVIEW OF THE IRIDM PROCESS 3. DESCRIPTION OF THE IRIDM WORK FLOW 4. PREPARATION FOR THE ASSESSMENT OF THE INPUTS 5. ASSESSMENT, INTEGRATION AND DOCUMENTATION 6. APPROVAL, IMPLEMENTATION AND QUALITY ASSURANCE 7. SETTING UP A FORMAL IRIDM CAPABILITY 8. REFERENCES ANNEXES 1 to 8 EXAMPLES & DETAILED GUIDANCE 41of 44

42 SECTION 7: SETTING UP FORMAL IRIDM CAPABILITY 42of 44

43 SUMMARY SAS/NSNI is currently developing two publications in the IAEA-TECDOC series: 1. Development and Application of a Safety Goals Framework for Nuclear Installations and 2. Integrated Risk Informed Decision Making Guidance Provide a structured, comprehensive and logical framework and a process to promote making more transparent and justifiable decisions to achieve adequate protection of people and the environment against radiation risks Advanced development stage (publishing ~ end 2014) 43of 44

44 THANK YOU FOR YOUR ATTENTION 44of 44