Document: NUREG-0800
Document ID: b5a87a6e-5e73-493f-b8d9-5de2b5feba56
Document Type: srp
Title: SEISMIC DESIGN PARAMETERS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070317.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.1
CFR Part: 
CFR Title: 

Content:
onsistent with the properties of the soil profile. For sites composed of one or more thin soil layers overlying a competent material or in case of insufficient recorded ground-motion data, the control point is specified on an outcrop or a hypothetical outcrop at a location on the top of the competent material. The control motion specified should be consistent with the properties of the competent material. (Note: This information is reviewed under the review responsibility of SRP Section 2.5.2.) a. Design Response Spectra Design response spectra are used in the design of seismic Category I structures, systems, and components (SSCs) , and they are generally specified in the free field. The proposed 3 design response spectra for the operating basis earthquake (OBE) and safe shutdown 4 5 earthquake (SSE) (Ref. 2), as defined in Appendix A to 10 CFR 100, are reviewed 6 7 against the free-field response spectra that are reviewed and accepted under SRP Section 2.5.2. The distinction between the free-field response spectra (site specific or otherwise) reviewed in Section 2.5.2 and the design response spectra reviewed in this section is that a design response spectrum, in general, is a relatively smooth plot not exhibiting random peaks and valleys while a free-field response spectrum may exhibit random sharp peaks and valleys. The use of smooth spectra is preferred in the design and in certain situations it is needed (for example, in the design of a standard plant). The use of unsmoothed response spectra will be reviewed on a case-by-case basis. b. Design Time History For computing the response of Category I structures and equipments, acceleration time histories may be used. These time histories must be compatible with the design response spectra, site specific or otherwise, as described above. When an appropriate recorded or specified time history is not available as input motion for seismic system analysis, an artificial time history (three components) may be generated