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:
e of an earthquake larger than the largest historic earthquakes, re-evaluating the largest historic earth quake to a significantly larger magnitude, or the occur rence of one or more moderate to large earthquakes (magnitude 5.0 or greater) in the CEUS. Geodetic measurements, particularly satellite *based networks, may provide data and interpretations of rates and styles of deformation in the CEUS that can have implications for earthquake recurrence. New hy potheses regarding present-day tectonics based on new data or reinterpretation of old data may be developed that were not considered or given high weight in the EPRI or LLNL PSHA. Any of these cases could have an impact on the estimated maximum earthquake if the result is larger than the values provided by LLNL and EPRI. E.2.3 Ground Motion Attenuation Models Alternative ground motion models may be used to determine the site-specific spectral shape as discussed in Regulatory Position 4 and Appendix F of this regula tory guide. If the ground motion models used are a ma jor departure from the original models used in the haz ard analysis and are likely to have impacts on the hazard results of many sites, a reevaluation of the reference probability may be needed using the procedure dis cussed in Appendix B. Otherwise, a periodic (e.g., every ten years) reexamination of PSHA and the associ ated data base is considered appropriate to incorporate new understanding regarding ground motion models. E.3 PROCEDURE AND EVALUATION The EPRI and LLNL studies provide a wide range of interpretations of the possible seismic sources for most regions of the CEUS, as well as a wide range of interpretations for all the key parameters of the seismic hazard model. The first step in comparing the new in formation with those interpretations is determining whether the new information is consistent with the fol lowing LLNL and EPRI parameters: (1) the range of seismogenic sources as interpreted by the seismicity experts or teams involved in