Document: NRC Regulatory Guide
Document ID: cfc61809-5745-460f-8a26-13c168659924
Document Type: regulatory_guide
Title: Identification and Characterization of Seismic Sources and Determination of Safe Shutdown Earthquake Ground Motion
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740084.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.165
CFR Part: 
CFR Title: 

Content:
ears), or when there is an important new finding or occurrence. An over all revision of the data base would also require a reexamination of the acceptability of the refer ence probability discussed in Appendix B and used in Step 4 below. Any significant update should follow the guidance of Reference 9. 3. For CEUS sites only, perform the LLNL or EPRI probabilistic seismic hazard analysis us ing original or updated sources as determined in Step 2. For sites in other parts of the country, perform a site-specific PSHA (Reference 9). The ground motion estimates should be made for rock conditions in the free-field or by as suming hypothetical rock conditions for a non rock site to develop the seismic hazard informa tion base discussed in Appendix C. 4. Using the reference probability (1E-5 per year) described in Appendix B, determine the 5% of critically damped median spectral ground mo tion levels for the average of 5 and 10 Hz, Sa-,510, and for the average of 1 and 2.5 Hz, Sa,1.2.5. Appendix B discusses situations in which an alternative reference probability may be more appropriate. The alternative reference probability is reviewed and accepted on a case by-case basis. Appendix B also describes a pro cedure that should be used when a general revi sion to the reference probability is needed. 5. Deaggregate the median probabilistic hazard characterization in accordance with Appendix C to determine the controlling earthquakes (i.e., magnitudes and distances). Document the hazard information base as discussed in Appendix C. 4. PROCEDURES FOR DETERMINING THE SSE After completing the PSHA (See Regulatory Posi tion 3) and determining the controlling earthquakes, the following procedure should be used to determine the SSE. Appendix F contains an additional discussion of some of the characteristics of the SSE. 1. With the controlling earthquakes determined as described in Regulatory Position 3 and by using the procedures in Revision 3 of Standard Re view Plan (SRP) Section