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:
ngs, and research and analysis results relevant to the proposed change. Plant-specific experience with inspection program results is reviewed and characterization relative to the effectiveness of past inspections of the piping and the flaws that have been observed is reviewed. 3.9.8-3 I.2 Element 2: Engineering Analysis As part of the second element, the staff will review the licensee’s engineering analysis of the proposed changes. The purpose of the review is to determine whether defense in depth is maintained, sufficient safety margins are maintained, and that proposed increases in risk, and their cumulative effect, are small and do not cause the safety goals in the NRC Safety Goals Policy Statement to be exceeded. Regulatory Guide 1.174 and Regulatory Guide 1.178 provide guidance for the performance of this evaluation. I.2.1 Traditional Analysis The engineering analyses are reviewed to determine whether the impact of the proposed ISI changes is consistent with the principles that defense in depth and adequate safety margins are maintained. The primary regulations governing ISI of piping are 10 CFR 50.55a and Appendix A to 10 CFR Part 50. The regulations reference other codes and requirements that define the elements of defense in depth and safety margins to ensure that structural integrity of piping is maintained. The staff reviews the licensee’s assessment of whether the proposed changes meet the regulations. The ASME Boiler and Pressure Vessel Code (B&PVC), Section XI, is referenced in 10 CFR 50.55a for the detailed requirements regarding piping ISI. Inspections required by ASME B&PVC Section XI are performed on a sample basis with additional inspections, in terms of locations as well as frequency, mandated in response to the detection of flaws. The objective of ISI is to identify conditions, such as flaw indications, that are precursors to leaks and ruptures in pressure boundaries that may impact plant safety. The staff reviews the licensee’s bases for