Document: NUREG-0800
Document ID: 8b8173c5-5bd5-417d-bda1-023ee9c7ef5e
Document Type: srp
Title: Ground Motion Response Spectra.  In this subsection, the staff reviews the
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1230/ML12301A010.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.5.2.6
CFR Part: 
CFR Title: 

Content:
tcrop or a hypothetical outcrop that will exist after excavation. Motions at the hypothetical outcrop should be developed as a free surface motion, not as an in- column motion. Although the definition of competent material is not mandated by regulation, a number of reactor designs have specified a shear wave velocity of 1000 fps (305 m/s) as the definition of competent material. When the GMRS are determined as free-field outcrop motions on the uppermost in-situ competent material, only the effects of the materials below this elevation are included in the site response analysis. However, as discussed in Subsection II.2.5.2.5 of this SRP, the site response analysis needs to capture the effects of the overburden soils on the soil properties to be included in the definition of the site profiles. The time duration and number of cycles of strong ground motion are required for analysis and design of many plant components. The adequacy of the time history for structural analysis is reviewed under SRP Section 3.7.1. For evaluation of the liquefaction potential at the site, the time duration and number of cycles of strong ground motion are critical parameters and require additional consideration. If the controlling earthquakes for the site have magnitudes of less than 6, the time history selected for the evaluation of liquefaction potential should have a duration and number of strong motion cycles corresponding to at least an event of magnitude 6. 2.5.2-14 Draft Revision 5 – 2013 Technical Rationale The technical rationale for application of these acceptance criteria to the areas of review addressed by this SRP section is discussed in the following paragraphs: GDC 2, or 10 CFR 52.17(a)(1)(vi) for ESP applications, require consideration of the most severe of the natural phenomena. 10 CFR 100.23(c) requires that the geologic and seismic characteristics of the site and its environs be investigated in sufficient scope and detail to permit an adequate evaluation of the proposed