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:
pectrum 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 accelerations. If the data for site-specific response spectra were not obtained under geologic conditions similar to those at the site, corrections for site effects should be included in the development of the site-specific spectra. 2. Where a large enough ensemble of strong-motion records is not available, response spectra may be approximated by scaling that ensemble of strong- motion data that represent the best estimate of source, propagation path, and site properties (e.g., Ref. 26). Sensitivity studies should show the effects of scaling. 3. If strong-motion records are not available, site-specific peak ground acceleration, velocity, and displacement (if necessary) should be deter- mined for appropriate magnitude, distance, and foundation conditions. Then response spectra may be determined by scaling the acceleration, velocity, and displacement values by appropriate amplification factors (e.g., Ref. 27). For each controlling earthquake, the peak ground motions should be determined using current relations between 2.5.2-8 Rev. 3 - March 1997 acceleration, velocity, and, if necessary, displacement, earthquake size (magnitude or intensity), and source distance. Peak ground motion should be determined from state-of-the-art relationships. Relationships between magnitude and ground motion are found, for example, in References 13 and 28. Because of the limited data for high intensities greater than MMI VIII, the available empirical relationships between intensity and peak ground motion may not be suitable for determining the appropriate reference acceleration for seismic design. 4. Spectra developed by theoretical-empirical modeling of ground motion may be used to supplement site-specific spectra if the input parameters and the appropriateness of the model are thoroughly