Canadian Regulatory Perspective on Safety Challenges for New NPP

Transcription

1 Canadian Regulatory Perspective on Safety Challenges for New NPP A. Viktorov, Canadian Nuclear Safety Commission IAEA Technical Meeting June 22-26,

2 How this presentation works.. 1. CNSC outline 2. Preparation for new build in Canada 3. Canadian requirements related to the TM scope 4. Special case small reactors 2

3 1. Canadian Nuclear Safety Commission Established May 2000, under the Nuclear Safety and Control Act Replaced the AECB, established in 1946, under the Atomic Energy Control Act The CNSC regulates all nuclearrelated facilities and activities 3

4 1. Our Mission To protect the health, safety and security of persons and the environment; and to implement Canada s international commitments on the peaceful use of nuclear energy To disseminate objective scientific, technical and regulatory information to the public concerning the activities of the Commission and the effects on the environment and on the health and safety of persons 4

5 1. CNSC Core Activities Develop regulatory framework Carry out licensing and certification Assess baseline compliance Support Canada's international obligations Engage stakeholders through public hearings and consultations Commitment to continuous improvement 5

6 2. Preparation for New Build Site preparation licence issued in August 2012 for Darlington B Technology not specified But several specific reactor designs considered Decision is contested in courts 6

7 2. Mature regulatory framework for new NPP Most of regulatory documents for nuclear power reactors updated recently Coherent approach for all nuclear facilities Requirements must meet Enabling Legislation Act Regulations Licences, Certificates, Licence Conditions and Orders Requirements Guidance 7

8 2. CNSC Licensing Process Five stages in the lifecycle of a nuclear facility Site preparation under Licence to Prepare Site Construction under Licence to Construct Operation under Licence to Operate Decommissioning under Licence to Decommission Release from licensing under Licence to Abandon 8 8

9 2. Licensing process independent of reactor technology or size Estimated licensing time ~ 9 years from the initial trigger to the operating licence In addition to design and operational requirements, guides explain the licensing process in Canada Page - 9 9

10 2. Vendor Design Review - test of readiness VDR is a high level review of design to evaluate whether there are fundamental barriers to licensing in Canada Tool to determine whether the vendor is ready for potential deployment in Canada Standardized process Requires design to be essentially complete Outcomes help the vendor have discussions with potential customers and the regulator on the path forward Vendor Design Review is optional and not part of licensing 10

11 2. Vendor Design Review outcomes Several designs have gone through the all or some stages of review ACR, EC6, AP1000, EPR, ATMEA No fundamental barriers for licensing of considered designs in Canada That is, no safety challenges that could not be resolved based on the current knowledge and technology 11

12 2. VDR examples of potential challenges Reflection of lessons learned from the Fukushima Daiichi accident Beyond Design Basis Accidents (BDBA) and Severe Accidents (SA) prevention and mitigation Classification of Structures, Systems and Components Application of Single Failure Criteria Containment Leak Rate and Filtered Venting provisions Robustness against malevolent acts, physical and cyber security Digital control systems, sharing of instrumentation and measurements 12

13 2. Being prepared for safety challenges New reactors would not be licensed for construction with any substantive safety issues outstanding Substantive issues are those which may require multi-year effort to achieve satisfactory resolution Regulatory requirements and acceptance criteria should be developed in anticipation of substantive issues or safety challenges Need to identify potential safety challenges 13 13

14 2. Where challenges lie The reactors in Canada are re-licensed every 5 years based on the outcomes of regulatory assessments Reactors are safe to operate safety challenges are understood Safety requirements are in place for new NPP at least, for the traditional technologies Largest challenges for new NPP are not related to safety but Economics Public acceptance Regulatory readiness, for novel technologies 14

15 3. Emerging safety challenges Some safety challenges are relatively novel Malevolent acts Cyber security Counterfeit, fraudulent or suspect items Digitalization of plant control Loss of know-how in countries with established programs Acquiring expertise, in countries starting to develop nuclear energy Not the focus of this discussion 15

16 3. Focus on Defence in Depth CNSC perspective on Principle of DiD and Assessment of DiD Design Extension Conditions Emergency Mitigating Equipment Engagement with IAEA 16

17 IAEA Summary Report on Fukushima Daiichi Accident The defence in depth concept remains valid, but implementation of the concept needs to be strengthened at all levels by adequate independence, redundancy, diversity and protection against internal and external hazards. There is a need to focus not only on accident prevention, but also on improving mitigation measures. 17

18 3. Three key messages CNSC takes away Re-balancing capability for prevention and for mitigation Design features to deal with DEC SAMG Increased understanding of safety margins in DEC Attention to external hazards Quantification of site specific hazards PSA Refinement of regulatory requirements 18

19 3. CNSC requirements for DiD REGDOC-2.5.2, Design of Reactor Facilities: Nuclear Power Plants This documents sets requirements for New NPP Used as guidance in conduct of Periodic Safety Reviews Based on IAEA NS-R-2 and SSR-2/1 and reflects Canadian best practices The concept of defence in depth shall be applied to all organizational, behavioural, and design-related safety and security activities to ensure they are subject to overlapping provisions. The levels of defence in depth shall be independent to the extent practicable. 19

20 3. Assessment of DiD Guidance on performing a systematic assessment of DiD is given in IAEA safety reports series No. 46, Assessment of Defence in Depth for Nuclear Power Plants Logical and comprehensive approach Very cumbersome in application Effort to strengthen DiD principle should be accompanied by effort to develop an approach for evaluation CNSC currently undertakes a project to develop a simplified assessment approach 20

21 3. Design Extension Conditions High level requirements in REGDOC-2.5.2, Design of Reactor Facilities: Nuclear Power Plants The design authority shall identify the set of design-extension conditions (DECs)... These DECs shall be used to further improve the safety of the NPP by enhancing the plant's capabilities to withstand accidents that are more severe than DBAs Standard CSA N will provide more specific requirements related to BDBA 21

22 3. Canadian standard N (in development) Sets Canadian requirements for both existing and new reactors Clarifies terminology (for example BDBA versus DEC ) Based on the Plant State diagram next slide Describes functional requirements for different types of systems used in BDBA Defines objectives and requirements for analysis and management of BDBA 22

23 3. Plant states, according to CNSC 23

24 3. Design principles for DEC Design basis not to be compromised Features necessary for accident management to be provided Containment performance requirements to be specified for DEC Complementary design features, fixed and portable 24

25 3. Design principles for DEC Interfaces / connection points to be designed to the highest safety class of interfacing systems Portable SSC shall have an approved design process and specific criteria Includes inspection, testing and maintenance requirements DEC SSC to be assessed for survivability and habitability Reasonable confidence in functionality of SSC under harsh conditions 25

26 3. Assessment principles for DEC and BDBA Objective evaluate design ability to withstand challenges posed by DEC, to reasonable degree of confidence Use of best estimate method and integration with PSA PSA main, but not the only, source for identification of DEC Uncertainties to be considered Ongoing hazard assessment, recognizing that site hazard change over time, especially man-made 26

27 3. Emergency mitigating (portable) equipment Additional features to supplement fixed SSC if needed EME is currently provided at, or close to, NPP sites 27

28 3. Emergency Mitigating Equipment Design requirements for EME to be developed, supported and documented Could be commercial grade New NPP could employ the concept of additional mobile equipment to strengthen independence of safety provisions 28

29 3. CNSC engagement in refinement of DID concept NEA/CNRA STG Green booklet on DiD final stages of preparation IAEA SSR-2/1 and TECDOC Considerations on the Application of the IAEA Safety Requirements for Design of Nuclear Power Plants Active Canadian participation Few notable differences in interpretation of high level requirements 29

30 3. DiD aspects where differences persist Definition of Design Basis and cascading effects on interpretation of Design Basis Accidents, Safety Systems, design and analysis rules, etc Splitting of Level 3 of DiD (and/or sometimes Level 4) Place of DEC relative to the Design Basis Scope of events included in DEC 30

31 3. Design Basis vs Design Extension In Canadian framework, DB and DEC are distinct part of the overall Plant Design Envelope Different rules apply less conservative for DEC Bringing some DEC (no significant core damage) into level 3 DiD creates confusion by having different rules within same level Having DEC in levels 3a and 4 requires independent two sets of independent equipment for DEC Consideration of DEC as part of Design Basis along with DBA leads to confusion in terminology 31

32 4. Small Modular Reactors Stress-test of the regulatory framework, including identification and resolution of safety challenges 32

33 4. What makes SMR different Large variety of technologies Loop-based, integrated or pool-type LWR Sodium, lead, gas cooled Novel features Factory fuelled Remote operation Features may challenge existing licensing approaches Page

34 4. SMR safety requirements Requirements should be founded on well-understood, technology neutral scientific bases Risk-informing specific requirements is inevitable given the wide variety of SMR Graded application of requirements under different circumstances and risk scenarios becomes essential Page

35 4. Example: autonomous operation of reactors Technology allows remote operatoin of a facility, but needed: better understand the state of the art and its safety case examine public acceptability (i.e. develop a position and plan to show how confidence will be developed) review existing requirements, codes and standards for applicability assess whether any additional requirements (i.e., security, human factors, emergency response, etc) needed understand sensitivity to external hazards 35

36 5. To sum up Canada is actively involved with IAEA in development of requirements and guides Canada cooperates with several international frameworks examining challenges that future NPP will face MDEP SMR regulatory forum INPRO Gen IV Forum Early identification of potential challenges and common approach helps resolution 36

37 5. To sum up readiness for New NPP Canadian regulatory framework has been updated and ready to face challenges posed by new nuclear construction Level of safety already achieved by the current NPP is high but opportunities exist for safety improvements Safety is not the biggest challenge New technologies are likely to bring novel challenges 37

38 Questions are welcome nuclearsafety.gc.ca 38