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:
in 10 CFR 100.23 as a means to de termine the SSE and account for uncertainties in the seismological and geological evaluations. The rule fur ther recognizes that the nature of uncertainty and the ap propriate approach to account for it depend on the tec tonic regime and parameters such as the knowledge of seismic sources, the existence of historical and re corded data, and the level of understanding of the tec tonics. Therefore, methods other than probabilistic methods such as sensitivity analyses may be adequate for some sites to account for uncertainties. -Appendix A, "Seismic and Geologic Siting Crite ria for Nuclear Power Plants," to 10 CFR Part 100 is primarily based on a deterministic methodology. Past licensing experience in applying Appendix A has dem onstrated the need to formulate procedures that quanti tatively incorporate uncertainty (including alternative scientific interpretations) in the evaluation of seismic hazards. A single deterministic representation of seis mic sources and ground motions at a site may not explicitly provide a quantitative representation of the uncertainties in geological, seismological, and geo physical data and alternative scientific interpretations. Probabilistic procedures were developed during the past 10 to 15 years specifically for nuclear power plant seismic hazard assessments in the Central and Eastern United States (CEUS) (the area east of the Rocky Mountains), also referred to as the Stable Con tinent Region (SCR). These procedures provide a structured approach for decisionmaking with respect to the SSE when performed together with site-specif ic investigations. A PSHA provides a framework to address the uncertainties associated with the identifi cation and characterization of seismic sources by in corporating multiple 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