Document: NUREG-0800
Document ID: 73dc4705-6dff-4f44-87ee-2a6f76cc6536
Document Type: srp
Title: OTHER SEISMIC CATEGORY I STRUCTURES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1319/ML13198A258.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.8.4
CFR Part: 
CFR Title: 

Content:
e rack base and the wall of the spent fuel pool that typically is obtained from the overall seismic building SSI analysis. It is acceptable to envelop the seismic motion at these two locations for the input loading to the racks. This approach is also applicable to free standing racks because seismic inertial loading can be transferred from the pool walls through the water in the pool to the racks. Alternative methods that may be used should be provided and reviewed on a case-by-case basis. When pool walls are used to provide lateral restraint at higher elevations, the applicant should provide a determination of the flexibility of the pool walls and the capability of the walls to sustain such loads. If the pool walls are flexible (having a fundamental frequency less than 33 hertz), the floor response spectra corresponding to the lateral restraint point at the higher elevation are likely to be greater than those at the base of the pool. To use the response spectrum approach in such a case, the following two separate analyses should be performed: 3.8.4-34 Revision 4 – September 2013 A. A spectrum analysis of the rack system using response spectra corresponding to the highest support elevation provided that there is not significant peak frequency shift between the response spectra at the lower and higher elevations B. A static analysis of the rack system by subjecting it to the maximum relative support displacement The resulting stresses from the two analyses above should be combined by the absolute sum method. To determine the flexibility of the pool wall, it is acceptable for the applicant to use equivalent mass and stiffness properties obtained from calculations similar to those described in “Introduction to Structural Dynamics,” McGraw-Hill Book Co., New York, 1964, by Biggs, John M. Should the fundamental frequency of the pool wall model be higher than or equal to 33 hertz, it may be assumed that the response of the pool wall and the corresponding lateral