Document: NUREG-0800
Document ID: 73747cf4-ff95-449b-b6b0-53dc0755b9e0
Document Type: srp
Title: OTHER SEISMIC CATEGORY I STRUCTURES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1235/ML12353A382.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.8.4
CFR Part: 
CFR Title: 

Content:
sign basis. As an alternate, the seismic analysis of spent fuel pool racks may be conducted using an updated plant seismic design basis developed using the criteria described in SRP Section 3.7. . For free-standing spent fuel pool racks, which are potentially subject to sliding, uplift, and impact between racks and with the pool walls, time-varying seismic excitation along three orthogonal directions (2 horizontal and vertical) should be imposed simultaneously. For fully supported spent fuel pool racks, the response spectra analysis (RSA) method is acceptable. The peak response from each direction is combined in accordance with RG 1.92. If response spectra are available for a vertical and horizontal direction only, the same horizontal response spectra may be applied along the other horizontal direction. The effects of submergence in water need to be addressed in the spent fuel rack structural analysis. The effects of submergence are evaluated by the staff on case-by- case basis. Because of gaps between fuel assemblies and the walls of the guide tubes, additional loads will be generated by the impact of fuel assemblies during a postulated seismic excitation. Additional loads resulting from this impact effect may be determined by estimating the kinetic energy of the fuel assembly. The maximum velocity of the fuel assembly may be estimated to be the spectral velocity associated with the natural frequency of the submerged fuel assembly. Loads thus generated should be considered for local as well as overall effects on the walls of the rack and the supporting framework. It should be demonstrated that the consequent loads on the fuel assembly do not lead to damage of the fuel. Damage of the fuel refers to structural elements of a fuel assembly (including the fuel rod cladding) which are stressed beyond the material allowable limits 3.8.4-31 Draft Revision 4 – December 2012 (established in terms of either strength or strain limits) such that the fuel rods are no longer