Document: NUREG-0800
Document ID: 2d2b9404-d124-483c-971a-a8f564048299
Document Type: srp
Title: SEISMIC DESIGN PARAMETERS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0706/ML070640306.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.1
CFR Part: 
CFR Title: 

Content:
th respect to the development of the SSE. The site-specific GMRS, reviewed under SRP Section 2.5.2, are determined in the free- field on the ground surface. For sites with soil layers near the surface that will be completely excavated to expose competent material, the GMRS are specified on an outcrop or a hypothetical outcrop that will exist after excavation. Motions at this hypothetical outcrop should be developed as a free surface motion, not as an in-column motion. Competent material is defined as in-situ material having a minimum shear wave velocity of 1,000 feet/second (fps). If non-competent material is present, any excavation and/or backfilling should not alter the development or location of the GMRS. However, the soft soil or backfill material needs to be considered in the soil-structure-interaction (SSI) or other analyses. In addition, 10 CFR Part 50, Appendix S is applicable to applications for a design certification (DC) or combined license (COL) pursuant to 10 CFR Part 52 or a construction permit (CP) or operating license (OL) pursuant to 10 CFR Part 50 submitted on or after January 10, 1997. Applications subject to this appendix must: • demonstrate that the SSE ground motion in the horizontal direction in the free-field at the foundation level of the structures must be an appropriate response spectrum with a peak ground acceleration of at least 0.1g. • design SSCs to the OBE and SSE loadings. However, if the OBE is set at one-third or less of the SSE, an explicit analysis or design is not required. If the OBE is set at a value greater than one-third of the SSE, an analysis and design must be performed for the OBE to demonstrate that the applicable stress, strain, and deformation limits of the SSCs are satisfied. The magnitude of the OBE in the application is reviewed to determine whether a seismic analysis is required for this earthquake level. Throughout this SRP section, whenever the OBE is discussed, it is understood that it may not apply to the