Document: NRC Regulatory Guide
Document ID: 921f4c90-482e-4f9e-a835-28839c357dcb
Document Type: regulatory_guide
Title: Flexible Mitigation Strategies for Beyond-Design-Basis Events + HISTORY - HISTORY 11/2015 – DG-1301 , Proposed Revision 0
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1316/ML13168A031.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.226
CFR Part: 
CFR Title: 

Content:
lable by the reevaluated seismic hazard. 6.1.2.1. Case 1: Demonstration of Reasonable Protection Based upon the Individual Plant Examination of External Events Licensees completed the Individual Plant Examination of External Events (IPEEE) in the 1990s under Generic Letter (GL) 88-20 Supplements 4 (Ref. 29) and 5 (Ref. 30) using the guidance of NUREG-1407, “Procedural and Submittal Guidance for the Individual Plant Examination of External Events (IPEEE) for Severe Accident Vulnerabilities,” (Ref. 31). Acceptable approaches to perform the IPEEE included the NRC seismic margin assessment (SMA) method, the EPRI SMA method described in EPRI NP-6041-SL, Rev. 1, “A Methodology for Assessment of Nuclear Plant Seismic Margin,” (Ref. 32) or a seismic probabilistic risk assessment (SPRA). For each approach, a seismic equipment list (SEL) was developed that included multiple redundant safe shutdown success paths and/or accident sequences. Under NUREG-1407, plants performed the seismic portion of the IPEEE in three categories, reduced scope, focused scope and full scope. The seismic IPEEEs were generally performed using input motions based on the following: a. Median-centered response spectrum using the shape from NUREG/CR-0098, “Development of Criteria for Seismic Review of Selected Nuclear Power Plants,” (Ref. 33) anchored to 0.3g peak ground acceleration (PGA). b. For SPRAs, plants generally used the mean uniform hazard response spectra and hazard curves developed by Lawrence Livermore National Laboratory (LLNL) in NUREG- 1488, “Revised Livermore Seismic Hazard Estimates for Sixty-Nine Nuclear Power Plant Sites East of the Rocky Mountains,” (Ref. 34), and/or the EPRI in the EPRI NP-6395-D, “Probabilistic Seismic Hazard Evaluations at Nuclear Plant Sites in the Central and Eastern US: Resolution of the Charleston Earthquake Issue” (Ref. 35). c. In some cases, past SPRAs were submitted for IPEEE closure that used input motions and hazard curves that