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:
n for certain accident sequences. If the plant relies on containment overpressure for NPSH for ECCS injection for certain accident sequences, the plant may experience an increase in CDF as a result of the proposed change in the ILRT interval. For these plants, the ILRT evaluation should consider the impacts on both CDF and LERF and compare them with the risk acceptance guidelines in RG 1.174. RG 1.174 gives guidance for determining the risk impact of plant-specific changes to the licensing basis. EPRI Report No. 1009325, DG-1391, Page 10 Revision 2-A, provides that in the case where containment overpressure may be a consideration, that licensees should (1) examine their NPSH requirements to determine whether containment overpressure is required (and assumed to be available) in various accident scenarios and (2) adjust the PRA model to account for this requirement if accident scenarios could be impacted by a large containment failure that eliminates the necessary containment overpressure. The combined impacts on CDF and LERF will be considered by the NRC staff in the ILRT evaluation and compared with the risk acceptance guidelines in RG 1.174. 11. The post-outage report described in NEI 94-01, Revision 3-A should include the margin between the LLRT leakage rate summation and its regulatory limit. If there are adverse trends in the Type B and Type C leakage rate summation, the licensee should include a statement in the LAR indicating that it will develop corrective actions to restore the margin to an acceptable level. 12. Use of the 9-month extension specified in NEI 94-01, Revision 3-A, Section 10.1, for eligible Type C valves should only be used for nonroutine emergent conditions. It should not be used for valves categorically restricted, those valves with a history of leakage, or any valves held to either a less than maximum interval or to the base refueling cycle interval. 13. The licensee should provide in the post-outage report a conservative estimate of the