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:
331 (Qualification by Similarity—Excitation) Section QR-A7331 states that “a conservative composite excitation may be generated by extrapolations or interpolations of data whose parameters are not identical but are justifiable. Likewise, excitation whose spectral content [is] significantly different may be used to generate lower level composite estimates, provided that an account is taken of possible multiaxis response, cross-axis coupling, or both.” The licensee or applicant should justify these statements. DG-1328, Page 16 d. Section QR-A7421 (Earthquake Experience-Based Qualification—Attributes of Equipment Class) The NRC staff will review the attributes of the equipment for establishing the inclusion rules that constitute the reference equipment class for earthquake experience, as described in Section QR-A7421, to determine the acceptability of similarity arguments to define a reference equipment class. Section QR-A7421 states the following: “Prohibited features should include any attributes that would contribute to fatigue failure from low cycle loads. The rules of this Section apply to active mechanical equipment that may undergo five OBEs or aftershocks and one SSE, resulting in 60 full-range stress cycles during facility life. If a component contains items which could experience a fatigue failure from low cycle loads (fewer than 60 full-range stress cycles), it shall be evaluated in accordance with QR-A6800.” The staff’s position on the preceding quote is that plants that do not require an evaluation of an OBE may use the alternative described in Regulatory Position C.1.2.1.i. e. Section QR-A7423 (Earthquake Experience-Based Qualification—Functionality During Earthquake) Licensees or applicants should submit detailed information about the justification used to demonstrate the functionality of the reference equipment class during and after an earthquake. f. Section QR-A7431 (Earthquake Experience-Based Qualification—Inherently Rugged Active