Document: NRC Regulatory Guide
Document ID: d9f4b714-eb98-48e4-a663-7a7dd874b2db
Document Type: regulatory_guide
Title: A Performance-Based Approach to Define the Site-Specific Earthquake Ground Motion (Rev. 0)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1928/ML19288A181.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.208
CFR Part: 
CFR Title: 

Content:
should also incorporate staff experience from the reviews of early site permit (ESP) and combined license (COL) applications conducted since 2007 as well as the lessons learned from the seismic hazard re-assessments conducted as part of the Fukushima Near Term Task Force activities. To date, the staff has identified several site response-related revisions needed in the RG. Appendix E “Seismic Wave Transmission Analysis” of the RG refers to the different approaches for developing a site-specific GMRS presented in NUREG/CR-6728. These approaches vary in complexity from simple deterministic amplification of probabilistically- derived rock response spectra (Approaches 1, 2A, and 2B) to rigorous treatment of soil amplification within the probabilistic seismic hazard analysis (Approaches 3, 3A, 3B, and 4). However, the RG needs to be updated to provide guidance on selecting the appropriate site response approach for a particular site. In addition, guidance related to the following areas should be added to the RG: 1) Selection of kappa and representation of epistemic uncertainty; 2) Development of input motions for time domain methods or random vibration theory (RVT) methods; 3) Development of probabilistic site-specific soil hazard curves (Approaches 3 or 4); and 5) Use of appropriate shear modulus reduction and damping curves and/or low strain damping values for materials in the site response model that are below the depth range where materials can be retrieved for testing. In addition, Section C.3 “Evaluation of New Information Obtained from Site-specific Investigations” needs to be updated in the context of new SSHAC guidelines (e.g. NUREG-2213, “Updated Implementation Guidelines for SSHAC Hazard Studies”) and the new ground motion models, such as the recently published NGA East ground motion models. 2. What is the impact on internal and external stakeholders of not updating the RG for the known issues, in terms of anticipated numbers of licensing and