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:
n 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 1988. Some solid-state relays and microprocessor-based components might be sensitive to earthquake excitations. Therefore, the use of test experience data from the older electrical components may not be appropriate for the seismic qualification of the new generation of such electrical components. Furthermore, a number of original manufacturers of electrical or active mechanical equipment are no longer in business, and the use of the test experience of old equipment made by these manufacturers for the seismic qualification of modern equipment designs made by different manufacturers may not be appropriate. Recent studies related to applications for early site permits at certain hard rock-based sites along the east coast of the United States indicate that the site-specific spectra might exceed the certified design spectra of those proposed new plant sites in the high-frequency range (20 hertz and above). This exceedance cannot always be eliminated even with incoherency added to the soil-structure interaction analyses. As a result of the high-frequency ground motion, the seismic input to SSCs might also contain high-frequency excitations. For operating boiling-water reactor (BWR) plants, the seismic qualifications of some safety-related electrical and active mechanical equipment were performed using IEEE Std 344- type tests with intentional high-frequency content to account for concurrent BWR hydrodynamic loads. DG-1328, Page 6 However, most existing seismic qualification tests used input frequencies up to only 33 hertz, although the TRS might have shown a zero-period acceleration (nonamplified frequency range) up to 100 hertz. Ball joints and kinematics linkages of the shake tables likely generated these high frequencies inadvertently, without both the proper frequency