Document: NRC Regulatory Guide
Document ID: 37f53017-d71c-4f3c-a2a4-ab67a8270066
Document Type: regulatory_guide
Title: Pre-Earthquake Planning, Shutdown, and Restart of a Nuclear Power Plant Following an Earthquake (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1826/ML18268A185.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.166
CFR Part: 
CFR Title: 

Content:
strate using appropriate risk-informed or performance-based approaches that the SSCs involved do not pose a significant seismic risk. All new or replacement equipment must meet current or amended site licensing-basis requirements. C.4 Clarification of Initial and Short-Term Evaluations in ANSI/ANS-2.23-2016, Section 6 If the seismic event resulted in a plant automatic shutdown, the licensee needs to understand the cause and evaluate the extent of the condition before plant restart to ensure that (1) operability exists for safety-related SSCs and (2) risk is managed as required by 10 CFR 50.65 for both safety- and nonsafety-related SSCs. To accomplish this, as is done after any automatic reactor shutdown, the licensee must assess the performance of both safety- and nonsafety-related SSCs to determine whether all SSCs had performed as designed, installed, and maintained. C.5 Clarification of Long-Term Evaluations in ANSI/ANS-2.23-2016, Section 9 Coincident with the long-term evaluations, as described in ANSI/ANS-2.23-2016, Section 9, the plant SSCs should be restored to match their licensing basis. C.6 Clarification Addressing Exceptions to Restoration of the Licensing Basis When using ANSI/ANS-2.23-2016, licensees or applicants should note that correction of, or operation with, degraded or nonconforming conditions related to SSCs is accomplished, as appropriate, through evaluation, restoration, modification, license amendment, or regulatory relief (e.g., notice of enforcement discretion, emergency TS amendments, exigent TS changes, exemptions, relief requests, or other relief from a regulatory requirement as granted by the Commission). Operation with SSCs that are deemed operable/functional but are degraded or nonconforming is permitted if an analysis is performed and documented and if corrective actions are completed in a manner that meets the expectations of IMC 0326. C. 7 Clarification Addressing Degraded or Inoperable Instrumentation If the seismic