Document: NRC Regulatory Guide
Document ID: 22ccfd5e-c5d8-4615-a02c-32369aa9f533
Document Type: regulatory_guide
Title: Acceptability of Probabilistic Risk Assessment Results for Risk-Informed Activities (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1930/ML19308B636.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.200
CFR Part: 
CFR Title: 

Content:
SME/ANS RA-Sb-2013 Standard for Level 1/Large Early Release Frequency Probabilistic Risk Assessment of Nuclear Power Plant Applications,” Technical and Peer Review Requirements of a Level 1, Seismic PRA for the At-Power Operating Mode Index No Issue Position Resolution SHA-A1 through SHA-A4 -------------------- No objection -------------------- SHA-A5 Regarding supporting requirement SHA-A5 in Table 5-2.1-2, the NRC staff has discouraged use of the damage parameter cumulative absolute velocity (CAV) filter in place of a lower-bound magnitude for the PSHA. Use of CAV has often been misapplied in PSHAs to improperly filter out larger magnitude events at larger source-to- site distances. Recently completed PSHAs for Near Term Task Force (NTTF) Recommendation 2.1 and combined operating license (COL) and early site permit (ESP) applications no longer use the CAV damage parameter in place of a lower-bound magnitude. NRC staff’s related letter pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Section 50.54(f) specified use of M5 (moment magnitude 5) as an appropriate lower- bound magnitude. Clarification JUSTIFY the specified lower-bound magnitude (or probabilistically defined characterization of magnitudes based on a damage parameter) for use in the hazard analysis, such that earthquakes of magnitudes less than this value are not expected to cause significant damage to the engineered structures or equipment. SHA-A6 -------------------- No objection -------------------- Note (1), Issue 1 Note (1) of Table 5-2.1-2 states in part, “The appropriate level of the hazard analysis will depend on project- specific factors and should include Clarification The appropriate level of the hazard analysis will depend on project-specific factors and should include considerations such as the safety significance of the nuclear power plant seismicity of the plant’s location, the plant’s seismic DG-1362, Appendix B, Page B-7 Table B-1. Staff Position on ASME/ANS RA-S