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:
interpretations of seismologi- cal parameters. A PSHA also provides an evaluation of the likelihood of SSE recurrence during the design lifetime of a given facility, given the recurrence inter val and recurrence pattern of earthquakes in pertinent seismic sources. Within the framework of a probabil istic analysis, uncertainties in the characterization of seismic sources and ground motions are identified and incorporated in the procedure at each step of the process for estimating the SSE. The role of geologi cal, seismological, and geophysical investigations is to develop geosciences information about the site for use in the detailed design analysis of the facility, as well as to ensure that the seismic hazard analysis is based on up-to-date information. Experience in performing seismic hazard evalua tions in active plate-margin regions in the Western United States (for example, the San Gregorio-Hosgri fault zone and the Cascadia Subduction Zone) has also identified uncertainties associatedwith the char acterization of seismic sources (Refs. 1-3). Sources of uncertainty include fault geometry, rupture seg mentation, rupture extent, seismic-activity rate, ground motion, and earthquake occurrence model ing. As is the case for sites in the CEUS, alternative hypotheses and parameters must be considered to ac count for these uncertainties. Uncertainties associated with the identification and characterization of seismic sources in tectonic en vironments in both the CEUS and the Western United States should be evaluated. Therefore, the same basic approach can be applied to determine the SSE. APPROACH The general process to determine the SSE at a site includes: 1. Site- and region-specific geological, seismo logical, geophysical, and geotechnical inves tigations and 2. A probabilistic seismic hazard assessment. CENTRAL AND EASTERN UNITED STATES The CEUS is considered to be that part of the United States east of the Rocky Mountain front, or east of Longitude 1050 West (Refs.