Document: NRC Regulatory Guide
Document ID: 6f84e3bf-9ff3-49fb-a16a-0de3b89e6bc6
Document Type: regulatory_guide
Title: An Approach for Plant-Specific Risk-Informed Decisionmaking for Inservice Inspection of Piping (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2103/ML21036A105.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.178
CFR Part: 
CFR Title: 

Content:
on (FAC) in the balance of plant for both PWRs and BWRs (NRC Generic Letter 89-08, “Erosion/Corrosion-Induced Pipe Wall Thinning,” issued May 1989 (Ref. 21)) Augmented programs have generally been developed to address observed degradation, and the inspections tend to be targeted at locations where the most severe effects are expected. A licensee may incorporate selected augmented programs, or parts of the programs, into its RI-ISI program, provided that it identifies, and the NRC staff approves, the specific programs and program changes. This guide addresses risk-informed methods to develop, monitor, and update more efficient ISI programs for piping at a nuclear power facility. It does not preclude other approaches for incorporating risk insights into the ISI programs. Licensees may propose other approaches for NRC consideration. The staff intends that the methods presented in this guide be regarded as examples of acceptable practices; licensees should have some flexibility in satisfying the regulations on the basis of their accumulated plant experience and knowledge. This guide addresses risk-informed approaches that are consistent with the basic elements identified in RG 1.174. In addition, it provides guidance on the issues described below for the purposes of RI-ISI. • estimating the probability of a leak that prevents the system from performing its function (disabling leak), and a rupture for piping segments • identifying the structural elements for which ISI can be modified (reduced or increased), based on factors such as risk insights, defense in depth, and reduction of unnecessary radiation exposure to personnel • determining the risk impact of changes to ISI programs • capturing deterministic considerations in the revised ISI program RG 1.178, Page 7 • developing an inspection program that monitors the performance of the piping elements for consistency with the conclusions from the risk assessment This guide only addresses changes to the ISI