ML22132A299

Staff Presentation for May 17, 2022 Public Meeting

ML22132A299
Person / Time
Issue date:	05/17/2022
From:	David Heeszel, Clifford Munson, Scott Stovall, Jacqueline Thompson, Thomas Weaver NRC/NRR/DEX, NRC/NRR/DEX/EXHB, NRC/RES/DE
To:
Jenise Thompson 301-415-0381
References
Download: ML22132A299 (30)

Text

Seismic Hazard Updates Cliff Munson, David Heeszel, Jenise Thompson NRR/DEX Scott Stovall, Thomas Weaver RES/DE May 17, 2022

Contents

• Background

• Overview of Process

• Example Site Implementation

• Screening

• Project Schedule

• References

• Questions

Background

• In response to 10 CFR 50.54(f) request licensees developed updated seismic hazard curves and GMRS for each NPP

- CEUS NPP sites used CEUS-SSC and EPRI (2013) seismic models and SPID

- WUS NPP sites developed SSHAC L3 seismic models

• Most recent seismic hazard characterizations are found in NUREG/KM-017 published this year

- NRC staff re-evaluated site geology to develop updated GMRS

• Under the POANHI framework NRC staff is evaluating

- new seismic ground motion model NGA-East for the CEUS NPP sites

- Updated approaches from recent site response analyses SSHAC research project

POANHI Framework

• POANHI process outlined by NRR LIC-208

- Ongoing staff effort to collect and integrate external hazard information for operating nuclear fleet

• Currently in the aggregation and assessment phases

POANHI Seismic Hazard Update

• Reference rock seismic hazard curves using CEUS/SSC and NGA-East

• Re-evaluate site response analyses to capture SSHAC Site Response Lessons Learned

- Expand logic tree to consider wider range of epistemic uncertainty

- Consider comments on NUREG/KM-017 geologic interpretations

• Control point hazard curves and GMRS

• Seismic hazard update report with data sets available in ADAMs

• Screening evaluation

Example Site Prioritization Savannah River Test Site Reference Rock Hazard and NUREG/KM-017 Site Response Analysis GMRS

Implementation of Seismic Source and Ground Motion Models and Site Response Analysis

• Run CEUS-SSC seismic source (NUREG 2115) models

- Extend radius for source zones out to 500 km

- Include repeated large magnitude sources out to 1000 km

• Run EPRI GMM (2013)

• Run NGA-East ground motion model (PEER, 2018)

• Convolve reference rock hazard with NUREG/KM-017 site response analysis to determine control point hazard and GMRS

CEUS-SSC + NGA-East Seismotectonic Zones

CEUS-SSC + NGA-East Mmax Zones

CEUS-SSC + NGA-East Repeated Large Magnitude Earthquakes Rift Zone Sources Charleston

NUREG/KM-017 Site Response Analysis SAF GMRS Comparison Used for Prioritization

RG 1.174 Acceptance Guidelines SCDF for Test Site Calculate SCDF

1. EPRI-GMM control point hazard 50 = 0.76 = 0.4

2. NGA-East control point hazard

3. Convolve hazard with fragility curves for 1, 5 and 10 Hz

4. Average SCDF1Hz SCDF5Hz SCDF10Hz

Distribution of C50 and C Across the Fleet Using GI-199 dataset 50 = 0.55

= 0.4

SCDF For Alternative C50 Values

= 0.4

Updated Site Response Analysis and PSHA Savannah River Test Site Updated Site Response Analysis and PSHA

Implementation of Latest Site Response Analyses Models and Methods

• For each CEUS NPP site develop site response logic tree that incorporates latest methods and models from SSHAC Site Response Project

• Overall lesson learned from SSHAC Site Response Project is to carefully consider multiple alternative models and parameters

- Widen epistemic uncertainty if warranted for

• Site response methods

• Site Vs profiles

• Treatment of nonlinear response of soil and rock

• Important site parameters such as site kappa

• Final Site Adjustment Factors

Example Site Response Logic Tree

Site Adjustment Factors Development of Control Point Hazard Curves and GMRS

• Combine reference rock hazard curves with site response results to develop control point hazard curves

- Use Approach 3 PSHA to convolve rock hazard curves with site adjustment factors

• Develop mean Uniform Hazard Response Spectra and then GMRS

• Prepare seismic hazard update and publish in ADAMS

- Description of site geology, site response analysis, and PSHA

- Tables of rock hazard curves, site adjustment factors, control point hazard, and GMRS

Screening Evaluation Screening Evaluation

• Changes in hazard with respect to previous GMRS

• Other factors such as plant SSE and overall hazard level between 1 and 10 Hz

• Delta risk with respect to previous plant risk assessments

• Further risk considerations

GMRS Comparisons Further Considerations in Screening Review

• Licensing basis for approved risk-informed applications

• Insights from SPRAs submitted in response to NRCs post-Fukushima efforts

• Principles of risk-informed decision making (embodies Be riskSMART framework)

• 10 CFR 50.109 and Management Directive 8.4 (Backfitting), as applicable

References NRC, 2005, Screening Analysis for GI-199, Implications of Updated Probabilistic Seismic Hazard Estimates in Central and Eastern United States on Existing Plants, ADAMS Accession No. ML073400504.

• NRC, 2012. Central and Eastern United States Seismic Source Characterization for Nuclear Facilities, NUREG-2115, ADAMS Accession No. ML12048A776.

• NRC, 2018. An Approach for Using Probabilistic Risk Assessment in Rik-Informed Decisions on Plant-Specific Changes of the Licensing Basis, Regulatory Guide (RG) 1.174, ML17317A256.

• NRC, 2019. Management of Backfitting, Forward Fitting, Issue Finality, and Information Requests, Management Directive (MD) 8.4, ADAMS Accession No. ML18093B087.

• NRC, 2019. Process for the Ongoing Assessment of Natural Hazard Information, NRR LIC-208, ADAMS Accession No. ML19210C288.

• NRC, 2021. Be riskSMART, Guidance for Integrating Risk Insights into NRC Decisions, NUREG/KM-0016, ADAMS Accession No. ML21071A238

• NRC, 2021. Documentation Report for SSHAC Level 2: Site Response, RIL 2021-15, ADAMS Accession No. ML21323A056

• NRC, 2021. Seismic Hazard Evaluations for U.S. Nuclear Power Plants: Near-Term Task Force Recommendation 2.1 Results, NUREG/KM-0017, ADAMS Accession No. ML21344A126.

• Pacific Earthquake Engineering Research Center, 2018. PEER Report No. 2018/08 Central and Eastern North America Ground-Motion Characterization - NGA-East Final Report.

• EPRI, 2012. EPRI Report 1025287 Seismic Evaluation Guidance, Screening , Prioritization and Implementation Details (SPID) for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic November 27, 2012, ADAMS Accesion No.

ML12333A170.

• EPRI, 2013. EPRI Ground Motion Model Review Final Report, June 3, 2013, ADAMS Accession No. ML13155A553.

Project Schedule Task Initial Milestone Revised Milestone NRC development and verification of seismic analyses Q1FY22 Completed 3/31/22 computer code

• Run NRC computer codes for operating plants in CEUS Q2FY22 Ongoing (8/50 sites completed

• Screen Prioritize hazard updates using NUREG/KM- 3 more running) 0017 results Q4FY22 Public Meeting - stakeholder interaction Q2FY22 5/17/22

• Run advanced site response analyses for screened all Q3FY22 Ongoing sites Q1FY23

• Screen updated site seismic hazard GMRS relative to previous results

• Develop seismic hazard update report for each site Public Meeting - stakeholder interaction Q3FY22 Q4FY22 Assessment of screened sites for risk significance Q4FY22 Q1FY23 Public Meeting - stakeholder interaction Q4FY22 Q1FY23

Sharing comments and information

• Staff will create a resource email to accept comments and information

• Staff will consider public comments and new information submitted through this email

• POANHI annual report will summarize comments received on POANHI projects

Questions