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:
sented. Because engineering solu tions cannot always be satisfactorily demonstrated for the effects of permanent ground displacement, it is pru dent to avoid a site that has a potential for surface or near-surface deformation. Such sites normally will re quire extensive additional investigations. 1.5 For the site and for the area surrounding the site, the lithologic, stratigraphic, hydrologic, and structural geologic conditions should be character ized. The investigations should include the measure ment of the static and dynamic engineering proper ties of the materials underlying the site and an evaluation of physical evidence concerning the be havior during prior earthquakes of the surficial mate rials and the substrata underlying the site. The prop erties needed to assess the behavior of the underlying material during earthquakes, including the potential for liquefaction, and the characteristics of the under lying material in transmitting earthquake ground mo tions to the foundations of the plant (such as seismic wave velocities, density, water content, porosity, elastic moduli, and strength) should be measured. 2. SEISMIC SOURCES SIGNIFICANT TO THE SITE SEISMIC HAZARD 2.1 For sites in the CEUS, when the EPRI or LLNL PSHA methodologies and data bases are used to determine the SSE, it still may be necessary to investi gate and characterize potential seismic sources that were previously unknown or uncharacterized and to perform sensitivity analyses to assess their significance to the seismic hazard estimate. The results of investiga tions discussed in Regulatory Position 1 should be used, in accordance with Appendix E, to determine whether the LLNL or EPRI seismic sources and their characterization should be updated. The guidance in Regulatory Positions 2.2 and 2.3 below and in Appen dix D of this guide may be used if additional seismic sources are to be developed as a result of investigations. 2.2 When the LLNL and EPRI methods are not used or are not applicable,