Document: NRC Regulatory Guide
Document ID: cdc706d5-60ed-40a4-b55a-9771904107a7
Document Type: regulatory_guide
Title: Seismic Qualification of Electric and Mechanical Equipment for Nuclear Power Plants (Rev. 4)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1809/ML18093A675.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.100
CFR Part: 
CFR Title: 

Content:
qualification programs with higher frequency content based on the high-frequency ground motion. Based on IEEE Std 344-2004, previous qualification programs traditionally used a cutoff frequency of 33 hertz (Hz). In current practice, cutoff frequency is generally between 33 Hz and 50 Hz for a building structure subjected to an earthquake, with the exception of the hard rock regions in the Central and Eastern U.S., which may experience energy content up to 100 Hz. IEEE has included a reference to RG 1.92, “Combining Modal Responses and Spatial Components in Seismic Response Analysis” (Ref. 10), to Clause 7 of IEEE Std 344-2013 to provide guidance for addressing the missing mass and combination of modal responses. The update to Clause 7 also discusses rigid and flexible equipment and clarifies the differences between static, static coefficient, and dynamic (response spectrum and time history) analysis methods. In addition, IEEE expanded IEEE Std 344-2013, Annex C, to provide guidance in determining equipment fragility levels, and rearranged the text in the Annex in a logical order. Clause 10 and relevant parts of Clause 11 of IEEE Std 344-2013 describe the use of experience data as a method for the seismic qualification of nuclear plant equipment. Experience data include earthquake experience data and test experience data. Nonmandatory Appendix QR-A, “Seismic Qualification of Active Mechanical Equipment,” to ASME QME-1-2017 also includes the use of experience data as a method for the seismic qualification of active mechanical equipment. The use of earthquake experience data for the seismic qualification of electrical and mechanical equipment has its origin in the NRC research program associated with Unresolved Safety Issue (USI) A-46, “Seismic Qualification of Mechanical and Electrical Equipment in Operating Nuclear Power Plants.” In 1980, the NRC staff raised a safety concern that licensees had not conducted the seismic qualification of electrical and