Safety Goals for Nuclear Installations a Status Overview

Transcription

1 Safety Goals for Nuclear Installations a Status Overview Michael Knochenhauer Vice President, R&D Director Lloyd s Register Scandpower POWER-GEN Vienna Austria, 4-6 June 2013

2 Overview Safety Goals what are they and why are they needed? Examples of Safety Goals An overview of current status based on current activities at the IAEA

3 Safety Goals typical examples: Core damage frequency < 10-5 /year Large (early) release frequency < 10-7 /year

4 Safety Goals what are they and why are they needed? What are Safety Goals? A Safety Goal is a set of necessary characteristics which, if achieved, assure that an acceptable level of safety is provided Safety Goals can be both qualitative and quantitative. Safety Goals should also help in answering the questions how safe is safe enough? has the required level of safety been achieved in practice? Why Safety Goals? Promote a harmonised view on safety Guidance for new nuclear countries Justification of safety levels how safe is safe enough? Basis for rational decisions in design and operation Risk informed applications require consistent method for judgment

5 Background There has been a lot of activity in the area of safety goals in recent years, both on national and international level Some examples of international activities MDEP Multinational Design Evaluation Programme NPSAG Nordic PSA Group OECD/NEA OECD Nuclear Energy Agency WENRA Western European Nuclear Regulators Association IAEA International Atomic Energy Agency Lloyd s Register Scandpower is involved in several of these activities

6 Defining and Applying Safety Goals The total picture is quite complex What is meant by core? What is meant by damage? What happens on exceedance? What frequency level? Who defines the criteria? When are the criteria applied? Core damage frequency < 10-5 /year What is the connection between these levels? Large (early) release frequency < 10-7 /year How is the frequency calculated? How is the frequency calculated? What is meant by large? What is meant by early? What is meant by release? What frequency level? What happens on exceedance?

7 IAEA position 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, etc.) 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

8 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 principles have 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

9 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 In order to control radiation risks: 1) Risk associated 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

10 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-04 9,0E-05 8,0E-05 7,0E-05 6,0E-05 5,0E-05 4,0E-05 3,0E-05 2,0E-05 1,0E-05 0,0E+00 Limits for respective RISK METRICS frequencies of undesirable consequences (events/time unit)

11 ILLUSTRATION OF THE CONCEPT OF NUMERICAL SAFETY GOALS CONSIDERED IN INSAG-12 Core Damage Frequency (CDF) Large Release Frequency (LRF) 1,0E-04 9,0E-05 CDF for operating NPPs 1,0E-05 9,0E-06 LRF for operating NPPs 8,0E-05 8,0E-06 7,0E-05 7,0E-06 6,0E-05 6,0E-06 1/y 5,0E-05 4,0E-05 3,0E-05 1/y 5,0E-06 4,0E-06 3,0E-06 2,0E-05 1,0E-05 0,0E+00 CDF for new NPPs 2,0E-06 1,0E-06 0,0E+00 Practical elimination of accident sequences that could lead to large early radioactive releases for new NPPs (NS G 1.2) INSAG-12 does not provide a detailed explicit consideration of qualitative and quantitative goals on health effects (early and latent cancer fatalities) and impact to the environment

12 ONGOING IAEA WORK A Technical Meeting in 2011 recommended five areas were where IAEA should consider producing guidance: 1. Develop a hierarchical approach for safety goals 2. Clarify interfaces between the Fundamental Safety Objectives, Safety Principles, Safety Requirements and the proposed framework for Safety Goals 3. Develop a methodology to derive lower-tier goals in a consistent and coherent manner 4. Develop guidance on methods and approaches to assess the degree of compliance with the full spectrum of safety goals and a comprehensive review methodology 5. Develop an approach to using safety goals

13 Outline of draft TECDOC Development and Application of a Safety Goals Framework for Nuclear Installations INTRODUCTION OBJECTIVES AND BENEFITS OF INTRODUCING A SAFETY GOALS FRAMEWORK GENERAL CONCEPTS FOR THE SAFETY GOALS FRAMEWORK A GENERAL FRAMEWORK FOR SAFETY GOALS DERIVATION OF SAFETY GOALS WITHIN THE HIERARCHY APPLICATION OF THE SAFETY GOAL STRUCTURE AND COMPLIANCE ASSESSMENT CONCLUSIONS NB! The IAEA TECDOC is still a draft, i.e., the information presented is preliminary, and may change during the finalisation of the TECDOC

14 Basic types of Safety Goals

15 Suggested Hierarchy of Safety Goals

16 Suggested Hierarchy of Safety Goals Level Top Level Primary Safety Goal Description Primary safety goal as set out in SF-1 and society level safety goals as defined in national legislation or regulations.

17 Suggested Hierarchy of Safety Goals Level Upper Level Adequate Protection Description Interpretation of the top level safety goal in risk terms. This is often done by comparison with the levels of risks coming from other involuntary sources of risk.

18 Suggested Hierarchy of Safety Goals Level Intermediate Level General Safety Provisions Description Proven approaches and good practices to achieve the higher level safety goals as well as definition of general requirements on site level.

19 Suggested Hierarchy of Safety Goals Level Low Level Specific Safety Provisions Description Technology and facility specific safety goals aimed at assuring the nuclear installation meets the higher level safety goals.

20 SUMMARY High level of activity in recent years both nationally and internationally Important to create a harmonised view on safety and how it is to be achieved A hierarchical framework is suggested, linking high level requirements (society) with gradually more detailed lower (technical) levels The framework and hierarchy allows consistent definition and application of safety goals

21 For more information, please contact: Michael Knochenhauer Vice President, R&D Director Scandpower Group T E mkn@scandpower.com W w