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:
to an Earthquake.” The standard provides guidance regarding pre-earthquake planning actions; actions necessary to determine the need to shut down a nuclear power plant; and the short- and long-term processes, inspections, and tests to demonstrate that a nuclear power plant is safe for restarting after a shutdown in response to an earthquake. C. 1 Exception to Post-Earthquake Action Levels Recommended in ANSI/ANS-2.23-2016, Section 7.3 Table 1 in ANSI/ANS-2.23-2016 directs the licensee to follow Action Level 1 when the earthquake level exceeds the SSE and the observed damage level is categorized as Damage Level 0 or Damage Level 1. Action Level 1 relies on focused visual inspections and tests, but it does not require the analysis of any structures, systems, and components (SSCs) after restart. The staff’s position is that, following restart, licensees should select, on a sampling basis, components from among SSCs that were not in the scope of the focused inspections and tests, and perform analytical evaluation of selected components. These components are typically in inaccessible locations and include insulated piping. The evaluation should utilize response spectrum developed based on the time history obtained from the measured felt earthquake experienced at the facility site. The input in the evaluation should include best estimate damping values and actual material properties. The intent of the evaluation is to confirm that there are no unobserved latent or safety impacts on continued operation from components that were possibly damaged, but not inspected, as a result of the earthquake. Because plant configurations do not rapidly change, licensees should consider developing a list of these components in advance of an event. The method or logic for determining which components were selected and how the sample population was narrowed should be documented and available for NRC inspection. Any issues that are identified should be evaluated in accordance with the