nuclearsafety.gc.ca Implications of the Fukushima Daiichi Accidents for the New Builds Design Requirements in Canada

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1 Implications of the Fukushima Daiichi Accidents for the New Builds Design Requirements in Canada R.P. Rulko () IAEA Technical Meeting on Evaluation of Nuclear Power Plant Design Safety in the Aftermath of the Fukushima Daiichi Accident Vienna, Austria, August 2103 nuclearsafety.gc.ca e-docs #

2 Outline: Fukushima Feedback - Background Fukushima Feedback and New Builds Design Requirements New Builds Vendor Design Assessment Vendor Design Assessment - Fukushima Feedback Conclusions 2

3 Fukushima Feedback - Background CNSC has issued its Fukushima report posted on the CNSC website on October 28, 2011 Main emphasis on: Capability of Canadian NPPs to withstand conditions similar to those that triggered the Fukushima nuclear accident Emergency preparedness and response in Canada Effectiveness of the CNSC regulatory framework Implications for New Builds design requirements 3

4 Fukushima Feedback - Background Main Conclusion: The report makes 13 recommendations to further enhance the safety of nuclear power plants in Canada 13 recommendation were divided into TWO categories: Technical and operational recommendations: design and operational enhancements that strengthen reactor defense in depth and technical cooperation at the international level to be implemented through existing regulatory oversight operations Regulatory recommendations, which require Commission approval to amend the regulatory framework (new requirements in RD-337, Design of Nuclear Power Plants) and Commission approval and direction to enhance emergency preparedness. Implementation will be through revised priorities by CNSC staff. 4

5 Fukushima Feedback and New Builds Design Requirements REGDOC-2.5.2, Design of Reactor Facilities: Nuclear Power Plants (replaces RD-337) has been drafted to: Update requirements for the design of new water-cooled NPPs Implement findings from the Fukushima Task Force Report Provide guidance to licensees in understanding and complying with requirements Intended to assist applicants, licensees and reactor vendors in their design activities and preparations for potential construction of new NPPs, and CNSC staff with their review of applications to construct new NPPs 5

6 Fukushima Feedback and New Builds Design Requirements REGDOC implements Fukushima Recommendations: Improved requirements for spent fuel storage New requirements for portable equipment for use during emergency situations, including: Redundant connection points to provide water and electrical power in severe accident situations Setting the time for which the plant must be self-sufficient without mobile equipment More comprehensive coverage for design extension conditions (DEC) 6

7 Fukushima Feedback and New Builds Design Requirements DECs are a subset of beyond-design-basis accidents (BDBAs) that are considered in the design process of the facility Releases of radioactive material must be kept within acceptable limits A DEC is an unlikely event and may include fuel melt An extended loss of AC electrical power is an example of a DEC 7

8 Fukushima Feedback and New Builds Design Requirements DECs are a subset of BDBAs, specifically those BDBAs considered in the design In version 1 of RD-337, DECs were referred to using terminology such as selected BDBAs DECs do not extend the design basis the conservative rules that address design basis accidents continue to apply but only inside the design basis 8

9 Fukushima Feedback and New Builds Design Requirements Complementary design features are components in the design of NPPs that are necessary to address DECs: Different design requirements than those features considered for design-basis accidents (DBAs) Examples of complementary design features: Provisions to cool core debris Provisions to remain in a safe shutdown state to prevent criticality Recombiners and igniters for hydrogen control Provisions to preclude unfiltered releases In-vessel retention or core catcher to retain the core debris An alternate AC power supply or an alternative water supply Complementary design features are classified relative to their safety significance 9

10 New Builds Vendor Design Assessment Voluntary Pre-Licensing 3 step process: Phase 1: Assessment of compliance with regulatory requirements to confirm that the design intent complies with CNSC design requirements (RD-337, RD- 367), and related regulatory requirements Phase 2: Identification of potential fundamental barriers to licensing the reactor design in Canada Secondary objectives of Phase 2 review: Significant level of assurance that vendor has taken CNSC design requirements into account Attention on new design features & approaches (to ensure that adequate testing & analysis were performed or are planned) Attention on successful resolution of generic and outstanding safety issues Phase 3: Pre-construction follow-up on one or more focus areas covered in Phase 1 and 2. Vendor s anticipated goal is to avoid a detailed revisit by CNSC during the review of the construction licence application Construction License Application detailed review 10

11 New Builds Vendor Design Assessment # Focus Topic 1 General NPP Description, Defense-in-Depth, Safety Goals, Dose Acceptance Criteria 2 Classification of Structures, Systems & Components 3 Nuclear Design of Reactor Core 4 Fuel Design & Qualification 5 Control Systems & Facilities 6 Means of Reactor Shutdown 7 Emergency Core Cooling & Emergency Heat Removal Systems 8 Containment & Civil Structures Important to Safety High-Priority Topic 9 BDBAs & Severe Accident Prevention & Mitigation 10 Safety Analysis 11 11

12 New Builds Vendor Design Assessment # Focus Topic 11 Pressure Boundary 12 Fire Protection 13 Radiation Protection 14 Out-of-Core Criticality 15 Robustness & Seismic Issues 16 Safeguards & Security 17 Vendor R&D Programs 18 Management System of Design Process & Quality Assurance in Design & Safety Analysis 19 Human Factors 20 Incorporation of Decommissioning Design Considerations 12 12

13 Vendor Design Assessment - Fukushima Feedback Three vendor design pre-project reviews carried out to date: EC6 (Phase 3), AP1000 (Phase 2) and ATMEA (Phase 1) CNSC added an extra special topic on Fukushima lessons learnt to the standard set of 20 review topics CNSC provided to vendors the CNSC Fukushima Task Force report CNSC Fukushima Task Force report conclusions have been added to the new version of RD-337 regulatory doc on design requirements for new NPPs REGDOC CNSC review of all three designs features relevant to the Fukushima Task Force report conclusions is positive at the level of reviews 13

14 Vendor Design Assessment - Fukushima Feedback Scope of verification of design provisions: Relief capability for degasser condenser (CANDU specific) Relief capability for calandria vessel (CANDU specific) Protection of containment and prevention of unfiltered releases Provision of passive autocatalytic recombiners (PAR) Provision of Hydrogen mitigation for spent fuel pool Assessment of spent fuel bay integrity Evaluation of make-up: boilers, reactor, spent fuel bay Survivability of equipment for severe accident Habitability of control facilities Electrical power supplies: batteries, additional generators Emergency equipment 14

15 Vendor Design Assessment - Fukushima Feedback Scope of evaluation of external hazards, Sever Accident Management (SAM) and modeling: External hazards design provisions for severe events (e.g. seismically induced fires and floods, robustness of spent fuel pools under seismic events, external floods, tornados, extreme weather, industrial accidents) Provision of Severe Accident Management Guidelines for spent fuel pool and multi-unit NPPs Provision of severe accident modelling capability for multi-unit sites 15

16 Vendor Design Assessment - Fukushima Feedback Scope of evaluation of equipment for emergency situations: Provision of portable equipment Provision of makeup water pumps (SG, calandria, shield tanks, spent fuel pools, vault coolers) Provision of portable generators/batteries to power critical equipment Provision of hoses, cables, manifolds Verification that plant design facilitates multiple connections Provision of storage facilities Deployment procedures and practices Maintenance and testing programs 16

17 Vendor Design Assessment - Fukushima Feedback Scope of evaluation of design provisions for protecting containment: Hydrogen hazards (provision of PAR, provision of igniters at multi-unit plants) Venting (dedicated venting for severe accident conditions) Cooling (provision of cooling water to air-coolers) Modelling (multi-unit containment model) 17

18 Vendor Design Assessment - Fukushima Feedback Scope of evaluation of design provisions for spent fuel pools: Confirmation of structural strength thermal stress analysis (boiling of water) seismic robustness (Review Level Earthquake of 10,000 y) Consideration of need to install PAR Provision of SAM to events in spent fuel pool 18

19 Conclusions Canada has analyzed in-depth the Fukushima accident and determined its implications not only for the operating but also the New Builds The existing regulatory framework was updated to include the new design requirement for the New Builds draft REGDOC Recently conducted pre-project vendor design reviews of the three technologies (EC-6, AP1000, ATMEA) included the special review topic of the Fukushima and assessed the proposed designs according to the updated requirements 19