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:
uch of this analysis will be used as a basis for determining the consequence of pipe failures. The review should focus on the robustness of the above models and methods in the baseline PRA, as well as appropriate use of this information to investigate the impact of the change in risk that is due to RI-ISI implementation. One acceptable approach is to investigate the change in risk due to an ISI program change is based 3.9.8-10 on developing the pipe elements’ failure potentials into probabilities, and integrating these probabilities into the existing quantitative PRA framework. The contribution to risk from each piping element may be ranked and the safety significance of the element determined. An alternative acceptable approach is based on categorizing each segment’s failure potential and the consequences of each segment’s failures. These two elements of risk, failure potential and consequences, are then systematically combined to determine the safety significance of each segment. II.2.2.4 Piping Failure Potential The determination of the degradation mechanisms present at each weld within all pipe runs included in the scope of the submittal is central to the success of the ISI application. The process used to identify the degradation mechanism at each weld should be well defined, systematic and applied to all welds within the scope. The documentation and engineering evaluations upon which the process is based should be capable of supporting the identification of all applicable degradation mechanisms. The determination of failure potential of piping segments, either as a quantitative estimate or a categorization into groups, should be based on appropriate design, operational, and inspection parameters in conjunction with the identified degradation mechanisms. The evaluation should include a determination of whether the potential failure of each segment is best characterized as a demand failure while responding to a plant transient or an operational failure