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:
ncluded, and the NRC agreed, that the use of experience data was feasible to verify the seismic adequacy of equipment in the older USI A-46 plants. The staff does not accept the use of SQUG guidelines for the seismic qualification of equipment in non-USI A-46 plants licensed under 10 CFR Part 50 or in plants licensed under 10 CFR Part 52. Large uncertainties exist in the seismic qualification of equipment, as a class, on the basis of earthquake experience data, because (1) it is difficult to compile a credible earthquake experience database (e.g., estimation of ground and floor earthquake excitations used in the earthquake experience database), (2) the inclusion and exclusion rules (termed “prohibited features” in IEEE Std 344-2013) of equipment in the database might be incomplete, (3) the similarity between equipment in fossil or petrochemical plants in the database and the equipment in NPPs is difficult to establish, and (4) the earthquake experience database does not have sufficient credible information to provide assurance that certain active electrical equipment will function properly during earthquakes. In using the test experience data for the seismic qualification of electrical equipment, quantifying the damage potential of equipment under testing should capture the combination of input motion and the equipment item that is exhibiting a particular malfunction. Because the resonant frequency for items of equipment of the same class might differ significantly, multiple malfunction mechanisms for components and subcomponents should be considered in comparing the test response spectra (TRS) and the required response spectra (RRS). As a result of the more prevalent use of digital rather than analog instrumentation and control components, the technology and design of certain electrical components (such as certain types of relays and microprocessor-based components) have undergone significant changes since the NRC issued RG 1.100, Revision 2 (Ref. 14), in June