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:
e scope of piping included in the proposed RI-ISI program is reviewed. The current ISI requirements for nuclear power plant piping are specified in 10 CFR 50.55a, which incorporates, by reference, the requirements of ASME B&PVC Section XI. The extent to which the RI-ISI program 3.9.8-4 scope incorporates ASME Class 1, 2 and 3 piping systems currently included in ASME B&PVC Section XI program and any balance of plant piping is reviewed. The process to select the scope of piping, justification for the scope, and the specific choice of piping selected is reviewed. I.2.2.2 Piping Segments The procedure for defining piping segments within the piping systems for the purpose of modeling a run of a pipe in a PRA or to define its ISI requirements is reviewed. The methods by which the failure consequences, such as an initiating event, loss of a train, loss of a system, or a combination thereof, are incorporated in the definition of segments are reviewed. In addition to the failure consequences, the procedure and criteria used to identify and document the degradation mechanisms that can be present in piping within the selected systems boundaries are reviewed. The procedure by which the location of the piping in the plant, and whether inside or outside the containment, is taken into account in defining piping segments is reviewed. The selection of piping segments within the piping system boundaries is an iterative process that may be affected by degradation as well as consequence evaluation, which is not completed at the time of initial selection of piping segments within the selected piping systems. The procedure by which degradation mechanisms and consequences of piping segment failures are incorporated in the iterative process is reviewed. I.2.2.3 Evaluating Pipe Failures with PRA Pipe ruptures are traditionally modeled as initiators, and the failure of individual pipe segments or structural elements is not modeled in PRAs. The manner in which PRA, or the PRA results, is