Document: NUREG-0800
Document ID: 40e10196-ca2f-4e1c-804d-a8ccd1b7e332
Document Type: srp
Title: Safe Shutdown Earthauake Ground Motion. In this subsection, the
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0529/ML052910327.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.5.2.6
CFR Part: 
CFR Title: 

Content:
staff reviews the applicant's procedure to determine the SSE, including the procedure used to derive spectral shape from the controlling earthquakes as describ6d in Reference 9. As a part of the review of the adequacy of the SSE proposed by the applicant, the staff performs an independent evaluation of ground motion estimates, as required. The following procedures (in descending order of preference) should be used to develop the site-specific spectral shapes for controlling earthquakes. These procedures are also used to make ground motion estimates when the probabilistic methods are not used. In the following procedures, 84th percentile response spectra are used for both spectral shape and ground motion amplitude estimates. 1. Both horizontal and vertical component site-specific response spectra should be developed statistically from response spectra of recorded strong motion records that are selected because they have similar sources, propagation paths, and recording site properties as the controlling earthquakes. It must be ensured that the recorded motions represent free-field conditions and are free of or corrected for any soil-structure interaction effects that may be present because of locations or housing of recording instruments. Important source properties include magnitude and, if possible, fault type and tectonic environment. Propagation path properties include distance, depth, and attenuation. Relevant site properties include shear wave velocity profile and other factors that affect the amplitude of waves at different frequencies. A sufficiently large number of site-specific time-histories or response spectra or both should be used to obtain an adequate broadband spectrum to encompass the uncertainties in these parameters. An 84th percentile response spectrum for the records should be presented for each damping value of interest (e.g., Refs. 22--25). The staff considers direct estimates of spectral ordinates preferable to scaling of spectra to peak