CNSC Evaluation of Plant-Specific SAMG

CNSC Evaluation of Plant-Specific SAMG Quanmin Lei IAEA Technical Meeting on Verification and Validation of SAMG Vienna, Austria December 12-14, 2016 e-docs # 5104918 nuclearsafety.gc.ca

Outline Summarize CNSC experience with severe accident management guidance (SAMG) evaluation Cover Regulatory basis and requirements Approach to and insights from recent SAMG evaluation Focus of ongoing work on severe accident management (SAM) 2

Post Fukushima Actions related to SAMG Implement key SAM provisions at each station by 2015 Expand scope of SAMG to include accidents triggered by multi-unit events and irradiated fuel bay events Completed for all NPPs in Canada Integrate Emergency Mitigating Equipment (EME) into overall SAM (e.g., EMEG/SAMG) Validate SAMG (e.g., through exercises and drills) to demonstrate their adequacy Regular activity 3

REGDOC-2.3.2 Accident Management Sets requirements and guidance for licensees to develop, implement and evaluate integrated accident management Includes management of accidents in design basis Focuses on beyond design basis accidents, in particular, requiring SAM International guidance used IAEA NS-G-2.15, SRS-32, SSS-9 NEA Task Group on Accident Management WANO criteria for SAM Input from recognized experts Connects to emergency response 4

Verification and Validation (V&V) of SAMG (1) REGDOC-2.3.2 V2 requires licensees (3.2) identify and implement reactor-specific accident management measures to ensure that adequate capabilities are maintained to cope with scenarios ranging from AOOs to severe accidents (3.4) develop, verify and validate accident management procedures and guidelines, including EOPs, emergency mitigating equipment guidelines (EMEGs) and SAMGs as applicable Integrated accident management helps ensure that personnel is trained and have necessary information, guidelines and resources 5

Verification and Validation (V&V) of SAMG (2) REGDOC-2.3.2 V2 provides guidance for SAMG V&V The objectives of the verification and validation of accident management procedures and guidelines are to: demonstrate that procedures and guidelines achieve the goals for which they were developed confirm their usability (in terms of being easily understood and followed by their users) verify technical accuracy (meaning identification of the correct equipment and line-ups) assure completeness of scope (that is, to provide adequate guidance for expected activities) confirm that specified actions consider possible challenges and threats to the personnel and identify alternatives, where appropriate 6

Means to Increase SAMG V&V Tabletop exercises Plant walk-through Simulator training Plant drills, exercises, field rounds Independent peer review (e.g., WANO, IAEA) Analytical simulations Regulatory evaluation One method alone may be insufficient to assess SAMG effectiveness 7

Ongoing Improvement Regular exercises and drills feed back to strengthen ability to respond to accidents effectively and efficiently Regulatory (CNSC) evaluation of SAMG Single-unit CANDU-6 NPP in 2013-2014. Involved independent experts with recent international experience In 2015, CNSC completed an evaluation of SAMG at a multi-unit NPP Intent to undertake similar evaluations at other NPPs 8

Objectives of Regulatory Evaluation Assess technical basis including station-specific aspects Assess adequacy of station-specific SAMG implementation, including Station-specific guidance Enhancements arising from Fukushima lessons Plan for SAMG drills and exercises Completeness of documentation Integration with other procedures/guidelines Personnel readiness 9

Scope and Overall Approach 10

Not in the scope, yet Past evaluations did not include Still ongoing SAMG updates to include multi-unit and irradiated fuel bay events PSA SAMG inter-influence Instrument and equipment survivability Performed assessment but Facility habitability assessment separately 11

Criteria Used Detailed review criteria developed from requirements Reflect CNSC staff experience obtained from the SAMG evaluations conducted to date Incorporate key insights from international publications Examples given below 12

Examples of Criteria For each of SAM goals: Is there adequate operational guidance to personnel involved in SAM? Are there sufficient design provisions and equipment to accomplish SAM actions? Is personnel prepared to perform actions identified in SAM? Are procedures and equipment adequate to deal with prolonged station blackout, SGTR, LOCA, etc. Are entry and exit conditions for different guidelines defined? 13

Examples of Evaluation Outcome The review of EMEG and its integration with other procedures and guidelines were undertaken through observation of EME storage and deployment locations, connection points, EME drills and a full-scale plant severe accident exercise during which EME was used. The review team also interviewed the site staff responsible for EME deployment. As a result, the review team concluded that The EME scope and deployment processes are well established. The licensee s emergency response team is well trained and qualified. Based on drill results, the team has demonstrated its capability to deploy the necessary EME as required. 14

Examples of Evaluation Outcome Interviews with site staff were found to be an effective means to gain insights into the strengths of SAM team. Examples of observations: The interviewees showed station personnel understanding of roles and responsibilities and their competence in fulfilling them. The interviews indicated a strong leadership within the technical support group (TSG). However, there appeared to be only one highly qualified TSG lead. It was not clear how the licensee would maintain leadership within the TSG if the specific expert is unavailable. 15

Examples of Evaluation Outcome A multi-unit drill was carried out involving: two (A &B) stations, two different reactor core designs, two groups of staff, and two sets of manuals, procedures, and guidelines. During the drill, there were two authorized nuclear operators (ANOs) with the TSG. The ANOs presence was not a requirement. It was observed that their presence added detailed knowledge of plant configuration and operation, and also helped speak the same language as the control room staff, thus enhancing communication. Therefore, participation of ANO in TSG was considered as a commendable practice. 16

Examples of Evaluation Outcome A number of technical questions arose during review of documentation What is the impact of an earlier or later initiation of the action that has been selected from the SAMG by the TSG for implementation? What are the environmental conditions at the time of an action? What are the potential positive and negative consequences resulting from SAMG-specified actions? CNSC staff undertook limited analyses to gain insights in accident progression and impact from SAM actions, and concluded: Simulations of SAMG actions allowed improved understanding of the temporal constraints and environmental conditions under which actions may be carried out and thus helped with evaluation of SAMG feasibility and efficiency 17

Focus of Ongoing Work on SAM Accident management in case of external events Earthquakes, tornado, flooding, fire, man-made events Irradiated fuel bay (long time available for make-up) Multi-unit Hydrogen control and mitigation Containment venting strategies 18

Examples of Design Enhancement for SAM Point Lepreau emergency filtered vent stack Containment cooling enhancement through repowering Containment Air Coolers Hydrogen Control and Mitigation Licensees have enhanced hydrogen control through installation of PARs. 19

Conclusions CNSC evaluation to date has identified strengths of the SAM program as well as several opportunities for improvement Station-specific SAM programs have been developed based on the generic CANDU SAMG with consideration of factors specific to the plant design SAM programs have been implemented at all sites. The organizational structure of SAM program with the roles and responsibilities of all participants clearly established Tabletop exercises and plant drills have been conducted to validate the plant-specific SAMG, including EMEG, and demonstrate their effectiveness CNSC will continue to evaluate the SAM programs for other NPPs 20