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:
ers are obtained, should be provided. The details should include the methods used to incorporate any gaps between the support systems and gaps between the fuel bundles and the guide tubes; the methods used to lump the masses of the fuel bundles and the guide tubes; the methods used to account for the effect of sloshing water on the pool walls; and the effect of submergence on the mass, the mass distribution, and the effective damping of the fuel bundle and the fuel racks. Design and analysis procedures in accordance with SRP 3.8.4, Subsection II, are acceptable. The effect of gaps, sloshing water, and increase of effective mass and damping resulting from submergence in water should be quantified. If the spent fuel racks are designed to be free standing (i.e., without connections to the pool walls/floor), then their response involves a complex combination of motions that includes sliding, rocking, and twisting and involves impacts between the fuel assemblies and the fuel cell walls, rack-to-rack, and rack-to-wall. In view of this, the seismic analysis of these fuel racks is typically performed using nonlinear dynamic time history analysis methods. For nonlinear seismic analysis of the racks, multiple time histories should be performed in accordance with the criteria for nonlinear analysis described in SRP 3.7.1, unless otherwise justified. For the free standing rack analyses, the entire range of the coefficient of friction for the rack material in water should be considered between the rack legs and the pool floor as well as the other contact surfaces (e.g., rack-to-rack impacts, rack-to-wall impacts). NUREG/CR-5912 provides further guidance on the design and analysis of free-standing fuel racks. The seismic input motion to the racks should consider the spectra at the 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