Document: NUREG-0800
Document ID: b07c8dd1-23f6-41f1-a3ba-aa378f9ea59a
Document Type: srp
Title: RISK-INFORMED INSERVICE INSPECTION
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0325/ML032510135.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.9.8
CFR Part: 
CFR Title: 

Content:
nges to the current licensing basis can be found in SRP Chapter 19 in Section III.2.2.5, “Evaluation of Risk Impact.” The methods used to determine the piping failure potential, the piping failure consequence, and the impact of the change in the number of inspections should together provide confidence that any increase in CDF or risk is small and acceptable in accordance with Regulatory Guide 1.174 guidelines and consistent with the intent of the Commission's Safety Goal Policy Statement. Increase in risk caused by changes in the ISI program could arise from a decrease in the number of welds inspected, reduced efficiency from simplified weld inspections, or both. Decreases in risk could arise from inspecting welds not currently being inspected in the program, improved weld inspections, or both. The greater the potential risk increase that is due to the proposed change in the ISI program (e.g., the larger the reduction in the number of welds to be inspected and of replacements of detailed inspections with simplified inspections), the more rigorous and detailed the risk analyses needed. The licensee should demonstrate that principle four in Regulatory Guide 1.174 and Regulatory Guide 1.178 is met. Principle four states that proposed increases in CDF and risk should be small and consistent with the intent of the Commission’s Safety Goal Policy Statement. A direct evaluation of the fulfillment of principle four may be based on:  Risk importance measures or bounding estimates capable of characterizing plant specific pipe element failure potential and consequences categories,  A systematic process to combine failure potential and consequence to determine pipe element safety significance,  Pipe segmentation and element inspection selection process that provides for changes in the ISI program based on the safety significance of the pipe element, and  A discussion and evaluation of the aggregate risk impact of the set of changes requested in the ISI program,