Ontario Power Generation Pickering NGS Release of Licence Hold Point. Ontario Power Generation Centrale nucléaire Pickering Levée du point d arrêt

Transcription

1 UNPROTECTED/NON PROTÉGÉ ORIGINAL/ORIGINAL CMD: 14-H2 Date signed/signé le : 24 MARCH 2014 Issue Required Approval(s) for Ontario Power Generation Pickering NGS Release of Licence Hold Point Commission Public Hearing Délivrer l approbation requise pour Ontario Power Generation Centrale nucléaire Pickering Levée du point d arrêt Audience publique de la Commission Scheduled for: 7 May 2014 Prévue pour : 7 mai 2014 Submitted by: CNSC Staff Soumise par : Le personnel de la CCSN e-doc (WORD) e-doc (PDF)

2 Summary This CMD pertains to a request for a decision regarding: the removal of the regulatory hold point associated with Licence Condition 16.3 of the Pickering Nuclear Generating Station Power Reactor Operating Licence, PROL 48.00/2018. The following actions are requested of the Commission: removal of hold point associated with PROL 48.00/2018, as recommended by CNSC staff. Résumé Le présent CMD concerne une demande de décision au sujet de : levée du point d arrêt réglementaire associé à la condition de permis 16.3 du Permis d exploitation d un réacteur nucléaire, PERP 48.00/2018, pour la centrale nucléaire Pickering. La Commission pourrait considérer prendre les mesures suivantes : levée du point d arrêt associé au PERP 48.00/2018, tel que recommandé par le personnel de la CCSN. e-doc (WORD) - ii - 24 March 2014

3 14-H2 UNCLASSIFIED Signed/signe le 24 March 2014 Director General Directorate of Power Reactor Regulation Directeur general Direction de la reglementation des centrales nucleaires e-doc (WORD) - iii - 24 March 2014

4 This page was intentionally left blank. e-doc (WORD) - iv - 24 March 2014

5 TABLE OF CONTENTS EXECUTIVE SUMMARY OVERVIEW Background Highlights Overall Conclusions Overall Recommendations MATTERS FOR CONSIDERATION Fuel Channel Fitness for Service Commission Direction Related to the Hold Point Pickering A PSA Accounting of Fukushima Enhancements in the PSA Methodology for Whole-Site PSA Enhancements to Protect Containment Other Matters of Regulatory Interest Environmental Assessment Aboriginal Consultation Emergency Management Public Information Document OVERALL CONCLUSIONS AND RECOMMENDATIONS Overall Conclusions Overall Recommendations REFERENCES GLOSSARY APPENDIX A BASIS FOR THE RECOMMENDATIONS(S) A.1 REGULATORY BASIS A.2 TECHNICAL BASIS APPENDIX B PICKERING A PSA RESULTS APPENDIX C PSA RESULTS WITH FUKUSHIMA ENHANCEMENTS e-doc (WORD) - v - 24 March 2014

6 This page was intentionally left blank. e-doc (WORD) - vi - 24 March 2014

7 EXECUTIVE SUMMARY Ontario Power Generation (OPG) Inc. has requested to present information to the Commission in support of a decision to remove the Pickering hold point pursuant to Licence Condition 16.3 of the Pickering Power Reactor Operating Licence, PROL 48.00/2018. The hold point requires OPG to provide additional information on the technical basis and methodologies to support the continued operation of Pickering Nuclear Generating Station (NGS) beyond 210,000 Equivalent Full Power Hours, which is the original assumed design life of the pressure tubes. The hold point in the Pickering PROL ensures appropriate regulatory oversight of the activities and commitments required to safely manage this technical issue before the first Pickering unit exceeds the assumed design life. Through the Record of Proceedings for the Pickering NGS licence renewal, the Commission also directed OPG to provide additional information before seeking approval for removal of the hold point. This additional information includes: the revised Probabilistic Safety Assessment (PSA) for Pickering A that meets the requirements of CNSC Regulatory Standard S-294, an updated PSA for both Pickering A and Pickering B that takes into account the enhancements required under the Fukushima Action Plan, a whole-site PSA or a methodology for a whole-site PSA, specific to the Pickering NGS site, and a report on OPG s analysis and way forward for further enhancements to protect containment through its Fukushima Action Items. As described in the Record of Proceedings, the Commission did not delegate authorization for the removal of the hold point, choosing instead to consider the removal of the hold point at a Commission proceeding with public participation. This Commission Member Document (CMD) provides CNSC staff s assessment of the submissions provided by OPG in support of the removal of the hold point. Based on this assessment, CNSC staff conclude that OPG has satisfactorily met the necessary pre-requisites and additional requirements associated with Licence Condition 16.3 of PROL 48.00/2018 and recommend that the Commission remove the hold point. e-doc (WORD) March 2014

8 1 OVERVIEW 1.1 Background Pickering Nuclear Generating Station (NGS) Power Reactor Operating Licence PROL 48.00/2018 [1], Licence Condition (LC) 16.3, requires Ontario Power Generation (OPG) to obtain the written approval of the Commission, or written consent of a person authorized by the Commission, prior to the removal of any established regulatory hold point. The hold point in the Pickering PROL ensures appropriate regulatory oversight of the activities and commitments required to safely manage the continued operation of the Pickering NGS beyond 210,000 Effective Full Power Hours (EFPH), which is the original assumed design life of the pressure tubes. The Licence Condition Handbook (LCH) [2], associated with PROL 48.00/2018, describes the eight prerequisites (release criteria) to be met before the hold point can be removed. These pre-requisites relate to additional measures and methodologies needed to demonstrate fuel channel fitness for service beyond 210,000 EFPH. Through the Record of Proceedings [3] for the Pickering NGS licence renewal, the Commission also directed OPG to provide additional information before seeking approval for removal of the hold point. This additional information includes: the revised PSA for Pickering A that meets the requirements of CNSC Regulatory Standard S-294, an updated PSA for both Pickering A and Pickering B that takes into account the enhancements required under the Fukushima Action Plan, a whole-site PSA or a methodology for a whole-site PSA, specific to the Pickering NGS site, and a report on OPG s analysis and way forward for further enhancements to protect containment through its Fukushima Action Items. As described in the Record of Proceedings, the Commission did not delegate authorization for the removal of the hold point, choosing instead to consider the removal of the hold point at a Commission proceeding with public participation. 1.2 Highlights OPG has requested to present information to the Commission in support of a decision to remove the Pickering hold point pursuant to LC 16.3 of the Pickering PROL 48.00/2018 [4]. Section 2.1 of this CMD provides information confirming that OPG has met the hold point release criteria documented in the Pickering LCH and will be able to continue to demonstrate fuel channel fitness for service beyond 210,000 EFPH. e-doc (WORD) March 2014

9 Section 2.2 of this CMD presents CNSC staff s assessment of the additional work done by OPG to meet the Commission directions detailed in the Record of Proceedings. Section 2.3 provides information on other matters of regulatory interest, including a report on OPG s progress on the production and distribution of an emergency management public information document. Although not related to the hold point, paragraphs 28 and 365 of the Record of Proceedings directed OPG to ensure the production of an emergency management public information document to be distributed to all households in the Pickering area by the end of June Overall Conclusions With respect to OPG s request to release the hold point associated with LC 16.3 of the Pickering PROL 48.00/2018, CNSC staff conclude that OPG has satisfactorily met the necessary pre-requisites and additional requirements, specifically: OPG has developed the appropriate engineering methodologies and inspection/maintenance programs to demonstrate fuel channel fitness for service beyond 210,000 EFPH and to ensure the continued safe operation of the power reactors. OPG has submitted a revised PSA for Pickering A that meets the requirements of S-294. The results indicate that risk to the public is reasonably low (to be confirmed by detailed review). OPG has submitted an updated PSA for Pickering A and B that incorporates Fukushima enhancements. OPG has submitted a concept level whole-site PSA methodology with an acceptable implementation plan. OPG s analysis and way forward for further enhancements to protect containment through its Fukushima Action Items is satisfactory to CNSC staff. 1.4 Overall Recommendations CNSC staff recommend that the Commission release the hold point associated with LC 16.3 of PROL 48.00/ MATTERS FOR CONSIDERATION 2.1 Fuel Channel Fitness for Service The hold point in PROL 48.00/2018 requires OPG to provide additional information on the technical basis and methodologies to support the continued operation of the Pickering NGS beyond 210,000 EFPH, which is the original assumed design life of the pressure tubes. The hold point in the Pickering PROL ensures appropriate regulatory oversight of the activities and commitments e-doc (WORD) March 2014

10 required to safely manage this technical issue before the first Pickering unit exceeds the assumed design life. In CMD 13-H.2A [5], published for the Day 1 Hearing of the Pickering licence renewal, CNSC staff indicated that, of all the aging and degradation mechanisms affecting the pressure tubes, it only required additional information on Deuterium uptake and its effect on fracture toughness. It is to be noted that these aging mechanisms may potentially affect the pressure tubes integrity during a very limited period of reactor operation; specifically, the power transitions between shut down state to full power state and vice versa (heat up and cool down phases). When the reactors are at power (normal operation) or shut down, the effects of the aging mechanisms are considered negligible. To track progress on the additional information requests, CNSC staff established eight pre-requisites, as shown in Table 1 below. The Pickering LCH describes these eight pre-requisites to be met before staff recommend that the hold point can be removed. TABLE 1: HOLD POINT RELEASE CRITERIA Criterion Description CNSC acceptance 1 By March 29 th 2013, OPG shall submit an update on the July 21, 2013 [6] installation of Dew-Point Rate of Rise instruments in the Annulus Gas Systems of Pickering units 5 through 8. 2 By March 29 th 2013, OPG shall submit an update on the evaluation July 21, 2013 [6] of (possible) revisions to Operating Procedures for Pickering units 1, 4 and 5-8, aimed at increasing margins in pressure tube LBB and fracture protection assessments. 3 By June 28 th 2013, OPG shall submit the technical basis for each July 21, 2013 [6] of the two-tier methods for probabilistic assessment of pressure tube LBB (Enclosure 1 of e-doc ), together with the proposed acceptance criteria. 4 By September 30 th 2013, OPG shall submit an update on progress Oct. 24, 2013 [7] in developing improved methodologies for pressure tube LBB and fracture protection assessments. 5 By September 30 th 2013, OPG shall submit an update on progress Oct. 24, 2013 [7] of revision to the pressure tube LBB and fracture protection assessments for Pickering units 1, 4 and By September 30 th 2013, OPG shall submit the status of the Rolled Oct. 24, 2013 [7] Joint Deuterium Ingress Model update (e-doc ), for application to Pickering units By September 30 th 2013, OPG shall submit an update on the status Oct. 24, 2013 [7] of hydrogen concentration sampling from the rolled joint area of pressure tubes in Pickering units Prior to the lead Pickering B unit reaching 210,000 EFPH, OPG shall submit revised pressure tube LBB and fracture protection assessments for Pickering units 1, 4 and 5-8, based on CNSCaccepted methodologies, fracture toughness value(s), and updated HTS Operating Procedures. Dec. 10, 2013 [8] e-doc (WORD) March 2014

11 CNSC staff confirm that OPG has met all eight pre-requisites to support the continued operation of the units beyond the 210,000 EFPH original assumed design life and they are in compliance with CSA standard N285.8, which provides detailed technical procedures and criteria for pressure tube fitness for service assessments. CNSC staff have accepted the new methodologies and engineering models developed by OPG through an industry joint Fuel Channel Life Management Project, which is a comprehensive research project conducted to improve mechanistic understanding of degradation mechanisms, in particular, delayed hydride cracking as a result of Deuterium uptake. Two methods are in place to prevent pressure tube rupture: Leak-Before-Break, and Fracture Protection. Leak-Before-Break ensures that if a crack develops in a pressure tube, the consequential leak can be detected in time to shut down the reactor and cool and depressurize the primary heat transport system before the pressure tube ruptures. Fracture Protection ensures that hydrides in the pressure tubes have not increased to a level which can render the pressure tubes too brittle to prevent cracks. These cracks could form at temperatures below the brittle-ductile transition temperature, while the primary heat transport system pressure is being increased to or decreased from the normal operating pressure. It is to be noted that, as required by LC 7.1, OPG must implement and maintain programs to ensure fitness for service of the pressure tubes. These programs include engineering capabilities to assess the structural integrity of the pressure tubes and in-situ inspections. CNSC staff confirm that OPG has developed more refined engineering methodologies and models to conservatively assess the fitness for service of the pressure tubes. OPG has also developed inspection and maintenance programs sufficient to ensure continued validation of the engineering assessments for the licensing period, including monitoring of the most limiting parameters such as the equivalent hydrogen concentration. The programs for inspection and maintenance include a periodic inspection program, as required by CSA standard N285.4, and Fuel Channel Life Cycle Management Plan, as required by CNSC Regulatory Document RD-334. CNSC staff will continue to follow up OPG s activities to ensure continued assurance of fitness for service of the pressure tubes at Pickering NGS. As part of the continued improvement of the engineering models, OPG has committed [9] to a plan for a continuing research and development work program on pressure tube aging effects. The purpose of the program is not to validate the current results, but rather to better understand and quantify uncertainties in the models and restrictions on the reactor operating conditions where the models are applicable. e-doc (WORD) March 2014

12 Much of the research is focused on enhancing understanding of the physical basis for the linkage between hydride formation and its effect on fracture toughness. Further burst testing of irradiated pressure tubes is planned to validate the limits of pressure which is allowed in the primary heat transport system at any particular temperature. Conclusion OPG has developed the appropriate engineering methodologies and inspection/maintenance programs to demonstrate fuel channel fitness for service beyond 210,000 EFPH and to ensure the continued safe operation of the power reactor. 2.2 Commission Direction Related to the Hold Point Through the Record of Proceedings, the Commission directed OPG to provide additional information before seeking approval for removal of the hold point. This additional information includes: the revised PSA for Pickering A that meets the requirements of CNSC Regulatory Standard S-294, an updated PSA for both Pickering A and Pickering B that takes into account the enhancements required under the Fukushima Action Plan, a whole-site PSA or a methodology for a whole-site PSA, specific to the Pickering NGS site, and a report on OPG s analysis and way forward for further enhancements to protect containment through its Fukushima Action Items. Progress on these additional items is presented in this section. Background A PSA is a comprehensive and integrated assessment that is conducted to complement traditional deterministic safety analysis in order to provide a full picture of the safety of a nuclear power plant. It considers the probability, progression and consequences of equipment failures, transient conditions, human errors, as well as internal and external hazards. Two of the outcomes of the PSA are the resulting global indicators commonly known as Core Damage Frequency (CDF) and Large Release Frequency (LRF) Safety Goals. For operating reactors, the limits are 1 in 10,000 and 1 in 100,000 years of reactor operation. There are two fundamental health effects on the public; one relating to early fatalities and the other relating to late or delayed fatalities. Early fatalities are linked to accident rates (e.g. industrial, traffic, etc.) while late fatalities are linked to cancer rates. The actual numerical safety goals, CDF and LRF, relating to the prevention and mitigation of accidents are conservative surrogates to these health effects to simplify their calculation. They were adopted by CNSC staff on the basis that the incremental contribution to public health risk from nuclear accidents should be a small fraction (<1%) of the background cancer risk. In practical e-doc (WORD) March 2014

13 terms, it means that the additional latent fatality risk to the most exposed member of the public should be less than 1 in 10,000 per site per year. The likelihood of prolonged relocation of members living in the vicinity of the site would be less than 1 in 100,000 years of reactor operation. It is to be noted that the CNSC has adopted, as per international practice, ten times more stringent health objectives for new nuclear power plants (recommended in the Basis of Design Requirements document for new nuclear power plants). The US-NRC established the same safety goals as surrogates of two quantitative health objectives: The risk to an average individual in the vicinity of a nuclear power plant (1 mile) of prompt fatalities that might result from reactor accidents should not exceed 0.1 per cent of the sum of prompt fatality risks resulting from other accidents to which members of the US population are generally exposed. The risk to the population in the area near a nuclear power plant (10 miles) of cancer fatalities that might result from nuclear power plant operation should not exceed 0.1 per cent of the sum of cancer fatality risks resulting from all other causes. The main difference in these approaches is related to the relative risk contribution considered as acceptable; 0.1% in the US and 1% in Canada. It results from the definition of public, which in the Canadian context, is defined as the average member of the critical group most at risk. Most at risk refers to location and generally refers to an individual resident at the site boundary. Furthermore, the societal effects of nuclear accidents (prolonged relocation) are explicitly considered. As a result, the Canadian approach is more stringent than the American approach. It is important to note that the Safety Goals are not the primary means by which nuclear facilities are regulated. The Safety Goals are formulated in addition to the deterministic design requirements (such as, redundancy, diversity, physical separation and reliability) and the dose acceptance criteria (0.5 msv for Anticipated Operating Occurrences and 20 msv for Design Basis Accidents), so that the risk to the public that originates from accidents outside the design basis is considered, and adequate protection of the public health and safety is provided. Effectively, the Safety Goals extend the plant design envelope to include not only the capabilities of the plant to successfully cope with various plant accident states, but also practical measures to halt the progression of severe accidents. More specifically, the CNSC uses the Safety Goals as a clear statement of the desired level of safety which the regulatory process aims to deliver. The Safety Goals are also considered along with other key elements of the risk informed decision approach, [10], such as the defence-in-depth principle, the safety margin, and the regulatory requirements, in order to make informed decisions Pickering A PSA OPG has submitted the complete updated Pickering A PSA, which includes both internal events (events occurring within the plant systems) and external events e-doc (WORD) March 2014

14 (seismic, high winds, internal fires, internal floods and other hazards) to align with the requirements in CNSC Regulatory Document S-294 Probabilistic Safety Assessment (PSA) for Nuclear Power Plants. OPG and Bruce have jointly developed a Phase 1 methodology for incorporating the Emergency Mitigation Equipment (EME) into the PSA. Phase 1 consists of crediting the EME benefits before the core damage, during which the operator actions are well established. This is done by using self-powered pumps to add inventory to the Steam Generators, the Heat Transport System and the Calandria. CNSC staff performed a high level review of the Pickering A PSAs and concluded that the Pickering A PSA reports are consistent with the accepted methodologies and meet S-294 requirements (a detailed review to confirm their conclusion is in progress). For Pickering A, CNSC staff confirm that the overall PSA results indicate that risk to the public is reasonably low. The dominant contributors to CDF and LRF are the fire and high wind events. CNSC staff recognize that this is primarily due to the overly conservative assumptions made as part of the analysis and the less advanced state of development of the methodologies. For instance, for the fire analysis, it was assumed that all structures, systems and components in a given fire zone will fail following the initiation of a fire in that particular zone. For illustrative purposes, CNSC staff aggregated all event frequencies for a single unit in accordance with the IAEA definition of CDF and LRF Safety Goals (also in CNSC Regulatory Document RD-337 Design of New Nuclear Power Plants ). However, the aggregation of internal events and external events by simple summation should be performed only once the bias, due to the uncertainties and conservative assumptions associated with the methodology for external events, is removed. Furthermore, it has to be recognized that the aggregation of all event frequencies is not representative of the actual risk, since many risk contributors cannot happen concurrently. The final numbers are often used as one of the inputs to the risk-informed decision making, to simply indicate the need for and potential areas for improvements, but are not considered as the sole source for regulatory decisions. The Pickering A PSA results are provided in Appendix B. The results show that: CDF and LRF calculated individually for internal events and for each external event meet the safety goal limits (established by OPG and accepted by CNSC staff) per reactor year of 1 in 10,000 years and 1 in 100,000 years respectively. The dominant contributor to CDF and LRF is the Fire events PSA. This is primarily due to the over conservative assumptions made as part of the analysis which assumes that all structures, systems and components in a given fire zone will fail following the initiation of a fire in that particular zone. Overall the PSA aggregated results indicate that risk to the public is reasonably low. e-doc (WORD) March 2014

15 As per standard practice, CNSC staff will perform a detailed review of the submission to further confirm, by way of sampling, the models and the input utilized by OPG. As part of this review, CNSC staff requested Natural Resources Canada and Environment Canada for their expert input to validate the postulated extreme conditions for seismic and high wind analysis. CNSC staff expect to complete the detailed review of the PSAs by June 30, Accounting of Fukushima Enhancements in the PSA In addition to the S-294 requirements discussed above, OPG has also submitted an updated Pickering A and Pickering B PSA that incorporates, to the extent practicable, the additional Fukushima Action Items (FAIs) in terms of PSA risk reduction. Due to the lack of appropriate models, OPG has not yet incorporated in the PSA all the Fukushima enhancements, for example severe accident management guidelines (SAMG) and other emergency actions, especially in Level 2 PSA. The updated PSAs also incorporate improvements in PSA modeling and operational changes being made at the site. The Operational changes include online refueling of the Auxiliary Power System and make-up to the Pickering A steam generators from the emergency boiler water system in the event of a loss of class 4 power at Pickering B. Pickering A PSA FAI update The Pickering A PSA results with and without the EME credit are provided in Appendix C (Table C.1). The results show that: The CDF calculated individually for internal events and for each external event meets the safety goal limit (established by OPG and accepted by CNSC staff). The aggregated CDF, calculated by simple summation from the contribution of both internal and external events, also meets the OPG safety goal limit. The LRF calculated individually for internal events and for each external event meets the OPG safety goal limit. The aggregated LRF, calculated by simple summation from for Pickering A is slightly above OPG safety goal limit. This is primarily due to the overly conservative assumptions and simplified methods in the Fire PSA. Overall, based on the aggregation of all risk contributors, the Fukushima enhancements credits in the Pickering A PSA show the following reduction factors: CDF reduction factor is 1.5 LRF reduction factor is 2.1 Further reduction will be achieved once all post-fukushima enhancements have been credited in the PSA. e-doc (WORD) March 2014

16 Pickering B PSA FAI Update The Pickering B results with and without the credits for EMEs are provided in Appendix C (Table C.2). These results show that: The CDF and LRF calculated individually for internal events and for each external event meet the safety goal limit (established by OPG and accepted by CNSC staff). The aggregated CDF, calculated by simple summation from the contribution of both internal and external events, also meets the OPG safety goal limit. The aggregated LRF, calculated by simple summation from for Pickering B for both internal and external events, meets the OPG safety goal limit. Overall, based on the aggregation of all risk contributors, the Fukushima enhancements credits in the Pickering B PSA show the following reduction factors: CDF reduction factor is 3.8 LRF reduction factor is 9.3 As in the case of Pickering A, further reduction will be achieved once all post- Fukushima enhancements have been credited in the PSA. Conclusion The results show that the Fukushima enhancement improves the safety in terms of mitigating some very rare events which were not considered in the design of nuclear power plants before. CNSC staff are satisfied with the development of the updated PSA to incorporate Fukushima enhancement and lessons learned and confirmed that the PSA reports are consistent with the accepted methodology [11], as well as applicable Quality Assurance requirements. CNSC staff expect to complete the detailed review of the PSAs by June 30, Methodology for Whole-Site PSA Unlike the safety goals for a single unit, the safety goals for whole-site PSA are still under development. It is recognized that site safety goals should follow a hierarchical structure that starts with the high level qualitative concepts in accordance with the Nuclear Safety and Control Act (NSCA) to prevent unreasonable risk to the environment and to the health and safety of persons. With the goal of meeting the Commission directions, the first stage consists of the development, by OPG, of a methodology for multi-unit sites. It is expected that more work will be carried out after the release of the hold point to develop a more detailed methodology. e-doc (WORD) March 2014

17 In accordance with the Commission directions, OPG has submitted the following: an outline of strategies to develop methodology for achieving a whole-site PSA, a concept-level methodology (not required to be S-294 compliant), and an estimated timeline for detailed methodology and the whole-site PSA. OPG s concept level whole-site PSA methodology was submitted in March 2014 [12]. It was developed following an industry workshop which included members of the Canadian nuclear industry as well as international experts (IAEA, EPRI, WENRA-ENREG, US industry, US NRC Commissioner, and the CNSC). The methodology includes the following elements: the definition of site-based safety goals, risk aggregation, and the concept level whole-site PSA methodology with the description of the subsequent steps as part of the implementation plan. The submitted implementation plan consists of a phased approach to further develop the detailed whole-site PSA. This includes the following phases: Phase A (duration 1 year from start date): Development of a site based Safety Goal Framework, Phase B (duration 1.5 years from start date): Risk aggregation, Phase C (duration 1 year after completion of Phase A): Pickering NGS wholesite PSA, Phase D (duration TBD): Complementary Risk Assessment. CNSC staff find the general methodology for a whole-site PSA acceptable. The submission suggests applying a range of the identified options to gain experience with the process and to identify the most appropriate option. The submission also suggests supplementing the PSA by complementary approaches to risk assessment to address the residual risk. CNSC Initiatives CNSC staff also undertook initiatives for multi-unit PSA. This includes the establishment of a working group on safety goals to identify and select site risk metrics. Staff is also organizing an international workshop on multi-unit PSA coorganized with IAEA, US NRC, and NEA/OECD, for November Regarding the PSA results aggregation, the simple summation of internal events and external events at the unit level will provide an extremely conservative result. Aggregation at the site level by simply multiplying the unit metric by the number of units at the site will result in double or multiple counting some of the accident sequences, given that the effects of the adjacent units (for instance, steam line break) on the representative unit are already factored in the calculation of the unit CDF and LRF as they are counted as initiating events. In addition, the calculated e-doc (WORD) March 2014

18 unit CDF and LRF also include some multi-unit events as a result of common mode events (e.g., loss of off-site power, loss of service water, seismic, high winds, etc.). One of the approaches considered as the appropriate way to calculate the multiunit CDF and LRF is to: divide the calculated unit CDF and LRF into single unit events and multiunit events; and then multiply single unit events by the number of units at the site. A first-approximation calculation, performed by CNSC staff, indicates that this approach may reduce the whole-site Safety Goals by approximately 60%, in comparison to simple multiplication of the unit safety metrics by the number of units at a site. The specific numbers may differ depending on the details of the plant design and site characteristics. Conclusion CNSC staff are generally satisfied with the development to date of the conceptlevel whole-site PSA methodology carried out by OPG, considering that this is an area in the early stages of development. The CNSC and Canadian Industry are making intensive effort in international forums to move this topic forward. CNSC staff consider the proposed timetable for the refining and implementation of the methodologies to be reasonable, but will be conditional on the achievement of international consensus on the approaches to adopt, and a decision by CNSC staff of the acceptable safety goals Enhancements to Protect Containment An update on OPG s plans to ensure containment integrity as a result of the Fukushima event was provided to CNSC staff on January 31, 2014, in the most recent scheduled progress report [13]. OPG operates the Pickering station under their Standard Operating Procedures and Abnormal Incidents Manuals to handle incidents as they arise. If these procedures are not sufficient to arrest progression of the event, the operators revert to the Emergency Operating Procedures, which brings on additional standby supplies of water for cooling, power to operate equipment and other safety systems and components. If this does not arrest the event progression, then Emergency Mitigating Equipment Guidelines and Severe Accident Management Guidelines are implemented in turn, which brings in further measures to stop progression of the event. Venting from containment may be required during severe accidents to prevent damage to containment due to overpressure. In this regard, OPG considered two types of Containment Filtered Venting System available from vendors, each of which has its advantages and disadvantages due to the characteristics of the Pickering containment design. They chose not to implement either, as neither captures radioactive noble gases or addresses the risk of a hydrogen explosion. e-doc (WORD) March 2014

19 Instead, OPG has chosen to enhance the reliability of existing systems by adding additional sources of cooling water and electrical power to tackle an event as early as possible, preventing its escalation to a severe accident. CNSC staff reviewed the submission and concur with the strategy and the proposed implementation [14]. In the event of a severe accident, overpressure of containment would be caused by overheated fuel bundles discharging their heat and fission products into the water in containment, causing steam to build pressure inside the reactor building. This would automatically trigger the opening of the pressure relief duct for the vacuum building to capture the radioactive particles and condense the steam, lowering the pressure in the affected reactor building. In severe cases, the heat and radiation could cause water to disassociate into hydrogen and oxygen, resulting in a potentially explosive atmosphere. Measures to address this issue are the Hydrogen Igniters and Passive Autocatalytic Recombiners. If these measures are insufficient to reduce the overpressure, the Containment Air Cooling Units would circulate water to remove the heat and reduce the pressure. If this is insufficient, the existing Filtered Air Discharge System (FADS) can filter radioactive particles, aerosols and iodines before venting to the atmosphere. If the capacity of the FADS is insufficient, then additional venting is possible through the Containment Exhaust Stacks, which are monitored, but not filtered. It would be preferable to vent a known amount of radioactivity under favourable circumstances (wind direction) rather than compromise the integrity of an intact containment and lose control of venting. Conclusion The update confirms that OPG has committed to enhance the protection of containment provided by several installed systems to prevent severe accident conditions. CNSC staff are satisfied with the strategy and the proposed implementation. The implementation of this strategy will be followed up through the Fukushima project. 2.3 Other Matters of Regulatory Interest Environmental Assessment An Environmental Assessment under the NSCA and its regulations was conducted for this application. Environmental protection-related information was considered in the conclusions drawn in sections 2.1 and 2.2 of the CMD. Conclusion Based on the review of OPG s submissions related to this CMD, CNSC staff conclude that the licensee will make adequate provision for the protection of the environment and the health and safety of persons Aboriginal Consultation The CNSC undertakes consultation activities in recognition of the importance of building relationships and consulting with Canada s Aboriginal peoples, and to e-doc (WORD) March 2014

20 ensure that all licensing decisions under the NSCA uphold the honour of the Crown and consider Aboriginal peoples potential or established Aboriginal and/or treaty rights pursuant to section 35 of the Constitution Act, Prior to the May 2013 Commission public hearing on OPG s licence renewal application, CNSC staff identified and informed fourteen Aboriginal groups of OPG s application and encouraged the groups to participate in the Commission s May 2013 public hearing. The same groups were sent letters on OPG s hold-point release request on February 19, 2014 [15]. The letters included information on OPG s request, participating in the regulatory review process, submitting a written intervention for the Commission s public hearing, subscribing to the CNSC website, and CNSC contact information. Follow-up phone calls were made in March 2014 to ensure the groups had received the letters of information and to answer any questions. Conclusion Based on the information received and reviewed to date, CNSC staff conclude that the release of the hold point and continued operation of the Pickering NGS is unlikely to cause adverse impacts to any potential or established Aboriginal and/or treaty rights. First Nations and Métis groups have been informed of the opportunity to participate in the Commission s public hearing to inform the Commission of any outstanding issues or related interests regarding OPG s request Emergency Management Public Information Document In paragraphs 28 and 365 of the Record of Proceedings, the Commission directed OPG to ensure the production of an emergency management public information document to be distributed to all households in the Pickering area summarizing the integrated emergency response plan of all involved organizations, including all key roles and responsibilities. The document should include information of potassium iodide (KI) tablet distribution and information included in CSA standard N1600. The document is expected to be produced by the end of June This Commission direction is not related to the hold point, however, a report on OPG s progress is provided here for the Commission s information. OPG is producing a public information brochure which will be distributed the first week of May, to coincide with national Emergency Preparedness Week. In developing the brochure, OPG held focus groups with primary zone residents from Pickering and Darlington to determine the existing levels of Emergency Preparedness awareness and to gather information on what and how much information the public wants. Regular meetings were held between OPG and Provincial and Municipal stakeholders to review the focus group findings and to discuss design concepts. Additional focus group sessions were held in March to review contending brochure designs. At the time of writing, CNSC staff have not seen the draft brochure. However, OPG has provided regular status updates to e-doc (WORD) March 2014

21 CNSC staff and staff are satisfied that OPG is on track to meeting this request by the Commission. The specific requirements regarding the responsibilities for KI procurement and distribution are being addressed in two upcoming publications: CSA standard N General Requirements for Nuclear Emergency Management Programs and CNSC REGDOC Nuclear Emergency Preparedness and Response. Both of these documents have undergone public comment and are in the process of final revisions and preparation for publication. The CSA N1600 standard is scheduled to be published in June 2014 and the CNSC Regulatory Document is expected to be presented to the Commission in August OVERALL CONCLUSIONS AND RECOMMENDATIONS 3.1 Overall Conclusions With respect to OPG s request to release the hold point associated with LC 16.3 of the Pickering PROL 48.00/2018, CNSC staff conclude that OPG has satisfactorily met the necessary pre-requisites and additional requirements, specifically: OPG has developed the appropriate engineering methodologies and inspection/maintenance programs to demonstrate fuel channel fitness for service beyond 210,000 EFPH and to ensure the continued safe operation of the power reactor. OPG has submitted a revised PSA for Pickering A that meets the requirements of S-294. The results indicate that risk to the public is reasonably low (to be confirmed by detailed review). OPG has submitted an updated PSA for Pickering A and B that incorporates Fukushima enhancements. OPG has submitted a concept level whole-site PSA methodology with an acceptable implementation plan. OPG s analysis and way forward for further enhancements to protect containment through its Fukushima Action Items is satisfactory to CNSC staff. 3.2 Overall Recommendations CNSC staff recommend that the Commission release the hold point associated with LC 16.3 of PROL 48.00/2018. e-doc (WORD) March 2014

22 REFERENCES 1. Nuclear Power Reactor Operating Licence, Pickering Nuclear Generating Station, PROL 48.00/2018, e-doc # Pickering Licence Condition Handbook, LCH-PNGS-R000, associated with PROL 28.00/2018, September 1, e-doc # CNSC Record of Proceedings, Including Reasons for Decision, Ontario Power Generation Inc. Application to Renew the Power Reactor Operating Licence for the Pickering Nuclear Generating Station, Public Hearing Dates: February 20 and May 29 to 31, 2013, e-doc # OPG letter, Bryce Phillips to Marc Leblanc, Request to be Placed on the May 7/8, 2014 Commission Hearing Agenda Pickering Operating Licence Condition 16.3 Hold Point, February 3, CD# P-CORR , e-doc # CNSC Commission Member Document (CMD) 13-H.2A, Ontario Power Generation Inc. Pickering Nuclear Generating Station Public Hearing Day 1 Scheduled for 20 February 2013, e-doc # CNSC letter, Miguel Santini to Glenn Jager, Status Update of Work to Address Expected Changes in Pressure Tube Facture Toughness at Pickering NGS, July 12, 2013, e-doc # CNSC letter, Miguel Santini to Glenn Jager, Pickering Units 1 to 8: Closure of Prerequisite Release Criteria 4, 5, 6 and 7 of the Regulatory Hold Point Licence Conditions Handbook Section 16.3, October 24, 2013, e-doc # CNSC letter, Miguel Santini to Bryce Phillips, Pickering Units 1 to 8: Closure of Pre-requisite Release Criterion #8 of the Regulatory Hold Point Licence Conditions Handbook Section 16.3, December 10, 2013, e-doc # OPG letter, P. Spekkens to R. Lojk, Submission of Continuing Research and Development Work Plan to Enhance Pressure Tube Fracture Toughness Models, March 17, 2014, CD# N-CORR , e-doc # CNSC Procedure Document, Make a Risk Informed Regulatory Decision, January 2011, e-doc # OPG letter, W.M. Elliott to M. Santini and F. Rinfret, Submission of the Human Reliability Analysis Methodology for Deployment of the Emergency Mitigation Equipment (EME) for CNSC Acceptance, February 6, 2014, CD# N-CORR , e-doc # CANDU Owners Group document, Development of a Whole Site PSA Methodology, COG R0, February 2014, e-doc # OPG letter, W.M. Elliott to M. Santini and F. Rinfret, OPG Progress Report No.4 on CNSC Action Plan - Fukushima Action Items, January 31, CD# N- CORR , e-doc # e-doc (WORD) March 2014

23 14. CNSC report, DAA Review of Industry Fukushima Action Item Update #4, March 6, 2014, e-doc # CNSC letter, Notice of Public Hearing Regaring Ontario Power Generation s Request to Remove Regulatory Hold Point on the Nuclear Power Reactor Operating Licence for the Pickering Nuclear Generating Station, February 19, 2014, e-doc # e-doc (WORD) March 2014

24 GLOSSARY CDF CMD CNSC CSA EME EPRI FAI IAEA LC LCH LRF NEA/OECD NGS OPG PROL PSA SAMG US NRC Core Damage Frequency Commission Member Document Canadian Nuclear Safety Commission Canadian Standards Association Emergency Mitigation Equipment Electric Power Research Institute Fukushima Action Item International Atomic Energy Agency Licence Condition Licence Conditions Handbook Large Release Frequency Nuclear Energy Agency/Organization for Economic Cooperation and Development Nuclear Generating Station Ontario Power Generation Power Reactor Operating Licence Probabilistic Safety Assessment Severe Accident Management Guidelines United States Nuclear Regulatory Commission WENRA-ENREG Western European Nuclear Regulators Association - European Safety Regulators Group e-doc (WORD) March 2014

25 APPENDIX A BASIS FOR THE RECOMMENDATIONS(S) A.1 Regulatory Basis The regulatory basis for the recommendations presented in this CMD is as follows: Nuclear Power Reactor Operating Licence, Pickering Nuclear Generating Station, PROL48.00/2018. Pickering Licence Condition Handbook, LCH-PNGS-R000, associated with PROL 28.00/2018, September 1, CNSC Record of Proceedings, Including Reasons for Decision, Ontario Power Generation Inc. Application to Renew the Power Reactor Operating Licence for the Pickering Nuclear Generating Station, Public Hearing Dates: February 20 and May 29-31, Fuel Channel Fitness for Service CSA N Periodic Inspection of CANDU Nuclear Power Plant Components. CSA N Technical Requirements for in-service Evaluation of Zirconium Alloy Pressure Tubes in CANDU Reactors. Probabilistic Safety Assessment CNSC Regulatory Document S-294 Probabilistic Safety Assessment (PSA) for Nuclear Power Plants. A.2 Technical Basis The technical basis for the recommendations presented in this CMD relevant to PSA are based on the following: IAEA SSG-3, Development and Application of Level 1 Probabilistic Safety Assessment for Nuclear Power Plants. IAEA SSG-4, Development and Application of Level 2 Probabilistic Safety Assessment for Nuclear Power Plants. USNRC NUREG/CR-2300, PRA Procedures Guide A Guide to the Performance of Probabilistic Risk Assessments for Nuclear Power Plants, Final Report. ASME/ANS RA-Sa-2009, Addenda to ASME/ANS RA-S-2008 Standard for Level 1/Large Early Release Frequency Probabilistic Risk Assessment for Nuclear Power Plant Applications, ASME/ANS RA-S 2008, EPRI, TR Guidelines for Performance of Internal Flooding Probabilistic Risk Assessment. IAEA-TECDOC-1135, Regulatory review of probabilistic safety assessment (PSA) Level 1. IAEA-TECDOC-1229, Regulatory review of probabilistic safety assessment (PSA) Level 2. e-doc (WORD) March 2014

26 IAEA Safety Guide No. NS-G-2.13 Evaluation of Seismic Safety for Existing Nuclear Installations. IAEA-TECDOC-1511, Determining the quality of probabilistic safety assessment (PSA) for application in nuclear power plants. Ontario Ministry of Natural Resources, Water Resources Section: River & Stream Systems: Flooding Hazard Limit. Technical Guide, IAEA, Specific Safety Guide SSG-18: Meteorological and Hydrological Hazards in Site Evaluation for Nuclear Installations, IAEA, Vienna NEI External Hazards PRA Peer Review Process Guidelines, August Regulatory Guide 4.2, Preparation of Environmental Reports for Nuclear Power Stations, U.S. Nuclear Regulatory Commission, Washington, DC. U.S. Department of Energy, STD , Accident Analysis for Aircraft Crash into Hazardous Facilities, Washington, DC, March US NRC Standard Review Plan, NUREG-0800, Section Aircraft Hazards, Revision 4, March 2010, ML Regulatory Guide 1.91, Evaluations of Explosions Postulated to Occur on Transportation Routes Near Nuclear Power Plants. Section of NUREG-0800: Accidents at present or projected nearby industrial, military, and transportation facilities may affect the safety of a nuclear power station. ML , Revision 3, March Regulatory Guide 4.2, Preparation of Environmental Reports for Nuclear Power Stations, U.S. Nuclear Regulatory Commission, Washington, DC. e-doc (WORD) March 2014

27 APPENDIX B PICKERING A PSA RESULTS This Appendix provides the results of the updated Pickering A PSA that align with the requirements in CNSC Regulatory Document S-294 Probabilistic Safety Assessment (PSA) for Nuclear Power Plants. The Pickering B PSA results are shown for comparison only. The simple summation is the aggregation of the PSA results from the internal events, seismic event, internal fire, internal flood, and high winds. This simple summation provides a biased result because of the uncertainties and conservative assumptions in the external PSA results. TABLE B.1: PICKERING A PSA RESULTS Model Operational State CDF LRF (1E-4/reactor year) (1E-5/ reactor year) Internal Events At power Shutdown 0.07* N/A** Internal Fires At power 0.47* 0.84* Shutdown N/A** N/A** Internal Floods At power Shutdown Seismic Events At power Shutdown High Winds At power 0.27* 0.80* Shutdown 0.01* 0.02* Simple Summation *These S-294 results include credits for Phase 1 of the Emergency Mitigating Equipment. **Bounded by the at-power state. TABLE B.2: PICKERING B PSA RESULTS Model Operational State CDF LRF (1E-4/reactor year) (1E-5/ reactor year) Internal Events At power Shutdown 0.01 N/A* Internal Fires At power Shutdown N/A* N/A* Internal Floods At power Shutdown N/A* N/A* Seismic Events At power 0.01 <0.01 Shutdown N/A* N/A* High Winds At power Shutdown N/A* N/A* Simple Summation *Bounded by the at-power state. e-doc (WORD) March 2014