Document: NUREG-0800
Document ID: 5dc31795-dfdc-4ed0-a4c2-e6a13e4997ab
Document Type: srp
Title: SEISMIC AND DYNAMIC QUALIFICATION OF MECHANICAL AND ELECTRICAL
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1608/ML16088A101.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.10
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Content:
ed boiling-water reactor (ABWR) and System 80+ DC final safety evaluation reports (SERs), the staff accepted an exemption from the requirement in Appendix A to 10 CFR Part 100, “Seismic and Geologic Siting Criteria for Nuclear Power Plants,” that all safety-related SSCs 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 one-third the SSE (see Appendix S to 10 CFR Part 50). The staff concluded in SECY 93-087, “Policy, Technical, and Licensing Issues Pertaining to Evolutionary and Advanced Light-Water Reactor (ALWR) Designs,” that the effect of eliminating the OBE from equipment qualification by analysis should be negligible. Mechanical equipment is generally seismically rugged when properly anchored, and its tolerance limits are controlled by the SSE rather than the OBE. However, some electrical equipment qualified by seismic analysis requires five OBE events followed by one SSE event. With the elimination of OBE, analysis checks for fatigue effects can be performed at a fraction of the SSE. The NRC concluded in Staff Requirement Memorandum on SECY-93-087 that electrical equipment should be qualified with five one-half SSE events followed by one full SSE event. Or alternatively, a number of fractional peak cycles equivalent to the maximum peak cycle for five one-half SSE events may be used in accordance with Appendix D to IEEE Std. 344-1987 when followed by one full SSE, even if the OBE of the plant is defined to be one-third of SSE or less. For other reactors, the staff will review the seismic qualification based on the OBE level, in accordance with the licensing basis. 4. For review of a DC application, the reviewer should follow the above procedures to verify that the design, including requirements and