Document: NUREG-0800
Document ID: 129133a3-2833-4da5-a564-052efbadbeb2
Document Type: srp
Title: but as applied to Category I subsystems.
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070319.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.2
CFR Part: 
CFR Title: 

Content:
FR 100 Appendix A requirement that all safety-related structures, systems, and components be designed to remain functional and within applicable stress and deformation limits when subjected to an OBE. This exemption was based on the licensees' alternative analyses performed for the SSE and procedural requirements to perform an inspection of the plant following an earthquake at or above 3.7.3-9 DRAFT Rev. 3 - April 1996 one-third the SSE. The licensees' alternative analyses met one or both of the following approaches in determining the number of earthquake cycles to be used in the fatigue analysis of piping systems: a. use two SSE events with 10 maximum stress cycles per event (20 full cycles of the maximum SSE stress range), or alternatively, b. the number of fractional vibratory cycles equivalent to that of 20 full SSE vibratory cycles may be used (but with an amplitude not less than one third of the maximum SSE amplitude) when derived in accordance with Appendix D to IEEE Std 344-1987 (Reference 7). These alternative analyses accomplish the design objectives of the OBE design analyses and meet the Commission-approved staff recommendations in SECY 93-087 (Reference 3).26 3. Procedures Used for Analytical Modeling The criteria and procedures used for modeling for the seismic subsystem analysis are reviewed to determine that these are in accordance with the acceptance criteria of SRP Section 3.7.2, subsection II.3. 4. Basis for Selection of Frequencies As applicable, criteria or procedures used to separate fundamental frequencies of components and equipment from the forcing frequencies of the support structure are reviewed to determine compliance with the acceptance criteria of subsection II.4 of this SRP section. 5. Analysis Procedure for Damping The analysis procedure to account for damping in different elements of the model of a coupled system is reviewed to determine that it is in accordance with the acceptance criteria of SRP Section 3.7.2, subsection II.13. 6.