ML18263A152
| ML18263A152 | |
| Person / Time | |
|---|---|
| Site: | Nuclear Energy Institute |
| Issue date: | 09/14/2018 |
| From: | Kapitz J Nuclear Energy Institute |
| To: | Ed Miller Special Projects and Process Branch |
| References | |
| Download: ML18263A152 (23) | |
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1 NRR-DMPSPEm Resource From:
KAPITZ, Jon <jkk@nei.org>
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Friday, September 14, 2018 10:23 AM To:
Rosenberg, Stacey; Miller, Ed Cc:
Richards, John
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[External_Sender] Slides for Monday Attachments:
50.69 Seismic Criteria Meeting Presentation.pdf JON KAPITZ, PE l Sr Project Manager, Risk & Technical Support 1201 F Street, NW, Suite 1100 l Washington, DC 20004 P: 612.330.5893 (Minneapolis)
P: 202.739.8077 (Wash, DC)
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© NEI 2018. All rights reserved.
Alternate Methods to Account for Seismic Risk in 50.69 Applications John Richards, EPRI Jon Kapitz, NEI September 17, 2018
© NEI 2018. All rights reserved.
Introductions and Meeting Goals
- Review technical criteria for alternate methods to account for seismic risk in 50.69 applications
- Achieve agreement on near term follow-on plant LARs and technical review process 2
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Example Application of Risk Informed Decision Making Risk Informed Decision Making (RIDM) is a top regulatory priority
- SECY-17-0112, Plans for Increasing Staff Capabilities to Use Risk Information in Decision-making Activities
- SECY-18-0060, Achieving Modern Risk Informed Regulation The application of a seismic alternative approach to inform the 50.69 categorization process is an example of RIDM
- The incorporation of insights from contemporary seismic PRAs provide a perspective on the seismic risk contribution to the 50.69 categorization decision making process
- A graded approach based on site seismic hazard is employed to highlight consideration of potential unique seismic insights using existing PRA models
© NEI 2018. All rights reserved.
Application of RIDM The application of seismic insights from the categorization process provides a perspective that the direct use of the existing methodology does not warrant detailed development of seismic equipment lists Use of this approach is consistent with the a recommendation of SECY-18-0060
- expanding the use of qualitative and quantitative risk insights to scale the scope and depth of licensing reviews depending on the safety and security significance of the matter being reviewed Within the context of the 50.69 application this approach highlights the need to consider the risk informed application as an integrated approach (framework - implementation - feedback) rather than solely as a license submittal
© NEI 2018. All rights reserved.
Lead Plant Identification and Schedule
- Tier 1 plant and schedule
- Calvert Cliffs (Exelon)
- Pre-Submittal meeting October 4th
- Submittal end of Oct/ Beginning of Nov
- Tier 2 plant and schedule
- Selecting plant
- Pre-Submittal meeting and submittal 1st Quarter 2019
© NEI 2018. All rights reserved.
Follow-on Plant Submittal Process
- They will follow similar criteria for applying the alternate seismic criteria
- Review of the non-seismic portions of those submittal would be expected to continue
© NEI 2018. All rights reserved.
Alternate Seismic Approach - EPRI 3002012988, July 2018 A graded approach based on site seismic hazard is employed to highlight consideration of potential unique seismic insights using existing PRA models Extensive existing seismic reviews provide inputs for understanding seismic conditions at sites Plant walkdowns performed to validate design basis compliance Additional confirmation of IPEEE seismic resolution implementation New site-specific seismic hazard estimates Recent SPRAs at selected sites Even for high seismic hazard plants, there are limited unique component level insights for 50.69 categorization Trial case studies show SPRAs produce few (if any) unique HSS components Expected insights for low and medium seismic hazard plants would be even more limited 50.69 Integral Importance Assessment makes it even less likely that seismic unique components would be HSS at lower seismic hazard sites
© NEI 2018. All rights reserved.
50.69 Seismic Categorization Trial Studies
- Determined how many and what kinds of SSCs would be categorized as HSS due to different hazard PRA models
- Study four plants with seismic hazards significantly above the original design basis and new SPRAs
- Identify HSS components based on importance measures for model types using Internal Events, Fire, and Seismic PRA models
- Compared risk-significant (HSS) seismic components to those derived from internal events and/or fire models
© NEI 2018. All rights reserved.
© NEI 2018. All rights reserved. For use by NEI members only.
50.69 Categorization - Trial Studies Results from Plants A and B were presented at the October 23, 2017 meeting Results from Plant C were presented at the January 18, 2018 meeting Results from Plant D are consistent with the previous 3 results Plant A Plant B Plant C Plant D Plant A Plant B Plant C Plant D
© NEI 2018. All rights reserved.
50.69 Seismic Categorization Trial Studies Trial studies at sites with seismic hazards well above the design basis show limited unique component insights
- HSS SSCs identified in the Seismic PRAs are also identified as risk significant in the IE PRA and/or Fire PRA
- In certain limited cases, correlated failures in the Seismic PRA can lead to some components being candidate HSS due to seismic
- Would expect only a handful of such unique components
- Unique seismic HSS components expected to be even fewer at low and medium seismic hazard plants s
d
© NEI 2018. All rights reserved.
50.69 Seismic Categorization Proposed Tiers and Criteria Tier 1 - Low Seismic Hazard / High Margin Sites
- GMRS peak acceleration is at or below ~0.2g or ZKHUHWKH*056a66( -10 Hz)
Tier 2 - Medium Seismic Hazard / Moderate Margin Sites
- GMRS to SSE comparison is greater than Tier 1 (1-10 Hz) but not high enough to be treated as Tier 3 Tier 3 - High Seismic Hazard / Low Margin Sites
- GMRS to SSE comparison is high enough that the NRC required the plant to perform an SPRA to respond to the Fukushima 50.54(f) letter
© NEI 2018. All rights reserved.
Tier 1 - Low Seismic Hazard / High Margin Sites
- Sites with low seismic hazard relative to their design basis are not expected to have unique seismic HSS SSCs
- HSS SSCs identified by IE PRA and Fire PRA and other NEI 00-04 criteria adequately address seismic risks
- Seismic not a driving risk in the integrated importance review
- Low seismic sites unlikely to identify unique seismic insights
- No explicit seismic assessment necessary as part of the categorization process
© NEI 2018. All rights reserved.
Tier 2 - Medium Seismic Hazard / Moderate Margin Sites Tier 2 sites perform an assessment to determine if seismic correlated failures would contribute HSS insights
- Start with SSCs in system
- Screen selected SSCs that dont need to be considered in seismic evaluation
- Use a walkdown to identify conditions that would meet criteria for seismic-correlated fragilities and/or seismic interactions
- Use IE PRA common cause failure modeling approach to identify the system components to be considered HSS
© NEI 2018. All rights reserved.
Tier 2 - Medium Seismic Hazard / Moderate Margin Sites SSCs in a system to be categorized Identify SSCs in the system to be categorized Group SSCs by seismic equipment class Screen selected SSCs that do not need to be considered in the evaluation Screen out inherently rugged SSCs (would not be modeled in an SPRA)
Screen out SSCs not used in functions that mitigate core damage or functions related to containment performance (do not contribute to CDF or LERF)
Screen out SSCs that are already HSS in other 50.69 categorization evaluations (no need for further consideration)
© NEI 2018. All rights reserved.
Tier 2 - Medium Seismic Hazard / Moderate Margin Sites Perform evaluations to identify SSCs that could experience seismic correlated failures or common interaction failures
- Review plant documentation and perform walkdown to identify correlation and interaction conditions
- Identify SSCs considered seismically correlated in SPRA
- Identify SSCs subject to common seismic interaction failures
- Consider plant-specific seismic capacity screening for items unlikely to be dominant risk contributors
© NEI 2018. All rights reserved.
Tier 2 - Medium Seismic Hazard / Moderate Margin Sites Perform Common Cause type evaluation to identify HSS SSCs For seismically correlated SSCs or those subject to common interaction failures, create seismic surrogate events in the FPIE PRA Quantify LOOP and SLOCA events to determine F-V and RAW importance measures SSCs with F-V or RAW values above thresholds designated as HSS This is a pseudo-deterministic evaluation (similar to using IPEEE SMA), therefore HSS designations should not be subject to IDP reconsideration
© NEI 2018. All rights reserved.
Tier 3 - High Seismic Hazard / Low Margin Sites
- At sites with high seismic hazard relative to their design basis, unique seismic insights are expected to be limited but difficult to exclude
© NEI 2018. All rights reserved.
Path Forward For Submittals
- Tier 1 Lead Plant
- GMRS to SSE comparison for Calvert Cliffs demonstrating plant fits into Tier 1
- HSS insights from other evaluations are acceptable without explicit additional seismic evaluations
- PRA Technical adequacy previously demonstrated - TSTF-505 SE approval
- Calvert Cliffs 50.69 LAR same as approved LAR for Limerick, with exception of seismic
- Should allow focus on seismic approach
© NEI 2018. All rights reserved.
Path Forward For Submittals
- Tier 2 Lead Plant
- GMRS to SSE comparison demonstrating the plant fits into Tier 2
- HSS insights from other evaluations are acceptable coupled with a commitment to employ the Tier 2 Correlated Failure Assessment process to identify potential unique seismic insights
© NEI 2018. All rights reserved.
Summary
- Agreement on path forward
- lead plants
- early follow-on plants
- Agreement on schedule
- Action items
- Follow-up on Desired / Expected Outcome
© NEI 2018. All rights reserved.
© NEI 2018. All rights reserved. For use by NEI members only.
QUESTIONS?