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:
ion 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 particular licensing application being reviewed depending on the magnitude of the OBE as defined above. A. Design Response Spectra. Design response spectra are used in the design of seismic Category I SSCs, and they are generally specified at the top of the ground surface in the free-field or at the top of the first layer of competent material as outcrop motion if soil layers near the surface will be completely excavated to the competent material. The proposed design response spectra for the OBE and SSE, are reviewed against the free-field site-specific GMRS that are reviewed and accepted under SRP Section 2.5.2. The design response spectra, in general, are relatively smooth plots not exhibiting random peaks and valleys. The use of smooth spectra is preferred in the design and is needed for generic site seismic hazard evaluation, as in the design of a standard plant. The use of unsmoothed design response spectra to develop the input ground motion (design time history) will be reviewed on a case-by-case basis. 3.7.1-3 Revision 3 - March 2007 A review is also made of the approach used to demonstrate that the horizontal component of the SSE ground motion in the free-field at the foundation level of seismic Category I structures is an appropriate response spectrum with a peak ground acceleration of at least 0.1 g, as required by Appendix S to 10 CFR Part 50. B. Design Time Histories. Acceleration time histories for computing the response of seismic Category I SSCs, are reviewed. The extent to which these time histories are compatible with the design response spectra are reviewed. When an appropriate recorded or specified time history is not available as input ground motion for seismic system analysis, the three spatial components of artificial time histories may be