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:
motion levels, as determined from a probabilistic seismic hazard analysis (PSHA), are used to scale a response spectrum shape. A site specific response spectrum shape is determined for the controlling earthquakes and local site conditions. Reg ulatory Position 4 and Appendix F to this regulatory guide describe a procedure 'to determine the SSE using the controlling earthquakes and results from the PSHA. C.2 PROCEDURE TO DETERMINE CONTROLLING EARTHQUAKES The following is an approach acceptable to the NRC staff for determining the controlling earthquakes and developing a seismic hazard information base. This procedure is based on a de-aggregation of the probabi -listic seismic hazard in terms of earthquake magnitudes and distances. Once the 'controlling earthquakes have been obtained, the SSE response spectrum can be deter- mined according to the procedure described in Appen dix F to this regulatory guide. Step I Perform a site-specific PSHA using the Lawrence Livermore National Laboratory (LLNL) or.Electric Power Research Institute (EPRI) methodologies for Central and Eastern United States (CEUS) sites or per form a site-specific PSHA for sites not in the CEUS or for sites for which LLNL or EPRI methods and data are not applicable, for actual or assumed rock conditions. The hazard assessment (mean, median, 85th percentile, and 15th percentile) should be performed for spectral accelerations at 1, 2.5, 5, 10, and 25 Hz, and the peak ground acceleration. A lower-bound magnitude of 5.0 'is recommended. Step 2 (a) Using the reference probability (1E-5/yr) as de fined in Appendix B to this regulatory guide, determine the ground motion levels for the spectral accelerations at 1, 2.5, 5, and 10 Hz from the total median hazard ob tained in Step 1. (b) Calculate the average of the ground motion lev el for the I and 2.5 Hz and the 5 and 10 Hz spectral ac celeration pairs. Step 3 Perform a complete probabilistic seismic hazard analysis for each of the magnitude-distance bins