Document: NUREG-0800
Document ID: 215ec1da-bdbb-48d3-b871-6010c1f4bc55
Document Type: srp
Title: SEISMIC SUBSYSTEM ANALYSIS REVIEW RESPONSIBILITIES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1319/ML13198A239.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.3
CFR Part: 
CFR Title: 

Content:
ed from the time history used for the system analysis, or a minimum of 10 maximum stress cycles per earthquake may be assumed. When the OBE is defined as less than one-third the SSE (and therefore the OBE does not need to be considered in design), there may be certain structural elements which still need to be evaluated for fatigue due to the OBE induced stress cycles. In these instances, the guidance for determining the number of earthquake cycles for use in fatigue calculations should be the same as the guidance provided in Staff Requirement Memorandum (SRM) for SECY-93-087 dated July 21, 1993 for piping systems (Agencywide Document Access and Management System (ADAMS) Accession Number ML003708056). The number of earthquake cycles to consider is two SSE events with 10 maximum stress cycles per event. This is considered to be equivalent to the cyclic load basis of one SSE and five OBEs. Alternatively, 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 Institute of Electrical and Electronics Engineers (IEEE ) Standard 344-1987, Appendix D. 3. Procedures Used for Analytical Modeling. The acceptance criteria provided in SRP Section 3.7.2, Subsection II.3, are applicable. 4. Basis for Selection of Frequencies. To avoid resonance, the fundamental frequencies of components and equipment should preferably be selected to be less than one-half or more than twice the dominant frequencies of the support structure. Use of equipment frequencies within this range is acceptable if the equipment is adequately designed for the applicable loads. 5. Analysis Procedure for Damping. The acceptance criteria provided in SRP Section 3.7.2, Subsection II.13, are applicable. 3.7.3-6 Revision 4 – September 2013 6. Three Components of Design Ground Motion. The acceptance criteria provided in SRP Section 3.7.2, Subsection II.6, are