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:
ivermore National Laboratory (LLNL) methodology and results (Refs. B.1 and B.2) but is also considered applicable for the Electric Power Research Institute (EPRI) study (Refs. B.3 and B.4). This refer ence probability is also to be used in conjunction with sites not in the Central and Eastern United States (CEUS) and for sites for which LLNL and EPRI meth ods and data have not been used or are not available. However, the final SSE at a higher reference probabili ty may be more appropriate and acceptable 1 for some sites considering the slope characteristics of the site hazard curves, the overall uncertainty in calculations (i.e., differences between mean and median hazard esti mates), and the knowledge of the seismic sources that contribute to the hazard. Reference B.4 includes a pro cedure to determine an alternative reference probability lThe use of a higher reference probability will be reviewed and accepted on a caseby-case basis. on the risk-based considerations; its application will also be reviewed on a case-by-case basis. B.3.1 Selection of Current Plants for Reference Probability Calculations.. Table B.1 identifies plants, along with their site characteristics, used in calculating the reference proba bility. These plants represent relatively recent designs that used Regulatory Guide 1.60, "Design Response Spectra for Seismic Design of Nuclear Power Plants" (Ref. B.5), or similar spectra as their design bases. The use of these plants should ensure an adequate level of conservatism-in determining an SSE consistent with re cent licensing decisions. B3.2 Procedure To Establish Reference Probability Step 1 Using LLNL, EPRI, or a comparable methodology that is acceptable to the NRC staff, calculate the seismic hazard results for the site for spectral responses at 5 and 10 Hz (as stated earlier, the staff used the LLNL meth odology and associated results as documented in Refs. B.1 and B.2). Step 2 Calculate the composite annual probability of ex ceeding the SSE