Summary of the 6th Technical Advisory Committee (TAC) Meeting
Date:
Place:

November 7 – 11, 2016
Nuclear Risk Research Center (NRRC), Central ResearchInstitute of Electric Power Industry

Participants:
TAC:
Mr. Stetkar (Chair), Mr. Afzali, Dr. Chokshi, Mr. Miraucourt,
Prof. Takada, Prof. Yamaguchi
NRRC:
Dr. Apostolakis (Head), Experts of the Nuclear Risk ResearchCenterIndustry:
Experts of Tokyo EPCO, TEPCO SYSTEMS, Shikoku EPCO
for respective topics
Proceedings
All topics were discussed in full committee. In addition, two lectures weredelivered by Mr. Stetkar and Mr. Afzali to share information on the current
practice of Risk-Informed Decision Making (RIDM) in the US.
November 7 (Mon.)
Topic 1: Overview of Research Plan for FY2017• NRRC presented an overview of the research plan for FY2017.
• TAC members commented as follows:- As R&D activities of NRRC progress, it will be crucial that the R&D
results be put to applications by the utilities. We, the TAC, hope todiscuss not only R&D but also practical applications.
（Handouts）
1-1-0. NRRC’s Research Plan for FY2017
1-1-1. R&D plan for FY 2017 - Risk Assessment 1-1-2. R&D plan for FY 2017 - External Natural Events Topic 2: External Natural Event Research NRRC presented the current R&D status of the “Senior Seismic Hazard
Analysis Committee (SSHAC) Project”, “Tsunami PRA”, “Volcanic PRA”,“Fault Displacement PRA” and “Superposed Seismic and TsunamiHazards”.
 TAC members commented as follows:- It is important that commonly applicable insights are identified and1

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extracted from the Ikata SSHAC project for later application at otherNPP sites so that the PSHA in Japan will be improved through theSSHAC process.
Use of the tsunami mean exceedance frequency for screening
purposes may not provide the appropriate graded analyses. The teamshould reconsider how the screening criteria are applied.
The evaluation of superposed seismic and tsunami hazards is not aneasy challenge and is a state-of-the-art R&D project internationally.
It can provide additional important insights into the safety
improvement of the NPP sites along the Pacific Ocean, where theJapan Trench and the Nankai Trough are located.
Analyses of seismically-induced tsunamis should not try to accountfor relative timing of the seismic event and the tsunami arrival. Thatissue is difficult to model, and it has very large uncertainties.
Treatment of the timing should be considered only if it is importantto site-specific risk.

（Handouts）
2-1. PSHA enhancement in Japan based on Ikata SSHAC level 3 project2-2. Strategy of development of tsunami PRA
2-3. R&D related to Volcanic PRA
2-4. Fault displacement evaluation
2-5. Development of PRA Methodology for Superposed Seismic and Tsunami Hazards
November 8 (Tue.)
Topic 3: Risk-Informed Decision Making (RIDM) Promotion Team and Pilot
Projects
 NRRC presented the organization/mission/role of the RIDM Promotion
Team established in July of this year. Also, it presented the plan for theexpert team review of the pilot projects and how the results will bepresented to TAC for review.
 TEPCO and TEPCO SYSTEMS presented the current status of theKashiwazaki-Kariwa (KK) 6/7 pilot project. Shikoku EPCO presented
the current status of the Ikata 3 pilot project.
 TAC members commented as follows:- As to the KK 6/7 project, the PRA models for internal events andother hazards, such as internal fires, should not be developed
separately, but should use the same model.
2(Handouts)
3-1. Introduction of RIDM promotion team
3-2. Overview of KK-6 and -7 PRA pilot project plan and current status
3-3. Ikata Unit3 Project Status Update
November 9 (Wed.)
Topic 4: Risk Assessment Research• NRRC presented the current R&D status of “Level-1 PRA R&D” (Data for
the Frequency and Duration of Loss of Offsite Power Events, Treatment of CCF
for Initiating Events, Human Reliability Database) and “HRA Guide” andalso presented the research plans of “Level-2 PRA R&D” (Fission ProductBehavior in Severe Accidents, Containment Vessel Temperature Evaluation under
Severe Accidents), “Thermally Induced SG Tube Rupture” and “Fire PRAGuide”.
• TAC members commented as follows:- Separate data should be developed for the frequency and duration ofswitchyard-related, grid-related, and weather-related offsite power
failures. Switchyard-related data should also be developed separatelyfor plant power operation and shutdown.
- The HRA guidance should include evaluation of uncertainties in thetime available and time required to perform an action. The guidanceshould also describe how those timing uncertainties contribute to theoverall human error probability.
- As to the HRA guide, NRRC should be aware that, if the methodology
requires a massive effort by PRA practitioners at NPP sites, it will
never be used.
（Handouts）
4-1. Data for the Frequency and Recovery Time of Loss of Offsite Power (LOOP) Events
4-2. “Treatment of Common Cause Failures for Plant-Specific Initiating Events” ResearchPlan
4-3. Current status on human reliability database
4-4. Research plan on Upgrading of Knowledge about Fission Product behavior in Severe
Accident
4-5. Research plan on the containment vessel temperature evaluation under severe
accident
4-6. Research Plan for Thermally Induced-SGTR
34-7. Development of Fire PRA Guide (Implementation Plan)
4-8. NRRC HRA Guide Combining the Narrative Approach and the EPRI HRA Calculator

November 10 (Thu.)
Topic 5: Other Topics
 NRRC presented on the direction of the research on “ComprehensiveFragility Evaluation”.
 NRRC presented its progress on “White Paper on RIDM”.
(Handouts)
5-1. Direction of comprehensive fragility evaluation
5-2. Progress on White Paper on RI-DM
Topic 6: Current Practice of Risk Management in the US Mr. Stetkar delivered a lecture titled “Selected Topics in Risk-Informed
Decision Making”. Mr. Afzali delivered a lecture titled “Risk-InformedDecision Making in Plant Operations”.
(Handouts)
Selected Topics in Risk-Informed Decision Making
Risk-Informed Decision Making in Plant Operations
Topic 7: Exit Meeting
TAC and NRRC had an open discussion on the role of TAC and how toorganize future meetings.
November 11 (Fri.)
Committee internal meeting.

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