Document: NRC Regulatory Guide
Document ID: 4774af39-208c-4761-97e8-2d66c6d14794
Document Type: regulatory_guide
Title: Performance-Based Containment Leak-Test Program (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2200/ML22006A317.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.163
CFR Part: 
CFR Title: 

Content:
and a supporting plant-specific risk impact assessment. Option B also introduced a requirement for visual inspection of accessible portions of the containment before each Type A test and at a periodic interval between tests. Licensees usually satisfy this requirement through the containment inservice inspection program conducted in accordance with American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPV Code), Section XI, Subsections IWE and IWL (Ref. 8), as incorporated by reference and conditioned in 10 CFR 50.55a, “Codes and standards.” NUREG-1493 is a detailed study of the impacts, costs, and risk of the Appendix J requirements and provided the methodology used to determine the acceptability of extended testing intervals. Sensitivity analyses in NUREG-1493 and other studies show that light-water reactor accident risk is relatively insensitive to the containment leakage rate because the risk is dominated by accident sequences that result in failure or bypass of containment. Reducing the frequency of Type A tests over extended periods, including up to 15 years, was found to lead to an imperceptible increase in risk. The estimated increase in risk is very small because (1) ILRTs identify only a few potential containment leakage paths that cannot be identified by Type B and Type C testing, and (2) the leaks that have been found by Type A tests have been only marginally above existing requirements. Given the insensitivity of risk to the containment leakage rate and the small fraction of leakage paths detected solely by Type A testing, increasing the interval between ILRTs is possible with minimal impact on risk to the public. The performance-based, “Option B,” containment leak test program is characterized by three areas (1) leakage rate testing, (2) containment inspections, and (3) risk impact. The following subsections provide the technical basis for each of these focus areas. Leakage Rate Testing RG 1.163, Revision 0, (Ref. 9)