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:
es, previously submitted to, and approved by the NRC staff, or from another alternate method of assessing an order of magnitude estimate for the contribution of the external event to the impact of the changed interval. 8. When using the methodology in EPRI Report No. 1009325, Revision 2-A to permanently extend the ILRT interval to 15 years, the licensee should submit documentation indicating that the estimated risk increase associated with extending the ILRT surveillance interval to 15 years is small. The methodology should quantitatively evaluate the risk impact of the ILRT extension. The most relevant risk metric is LERF, since the Type A test does not generally impact CDF. RG 1.174, “An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis,” (Ref. 20) provides guidance for determining the risk impact of plant-specific changes to the licensing basis. Additional risk metrics—including the increase in population dose and the increase in conditional containment failure probability— are also evaluated in EPRI Report No. 1009325, Revision 2-A to help ensure that the key safety principles in RG 1.174 are met. 9. The methodology in EPRI Report No. 1009325, Revision 2-A, is acceptable, except for the calculation of the increase in expected population dose (per year of reactor operation). To make the methodology acceptable, the average leak rate for the pre-existing containment large leak rate accident case (accident case 3b) used by the licensees should be 100 La [wt%/24-hour] instead of 35 La. 10. As part of the LAR submittal, the licensee should provide an evaluation if containment overpressure is relied upon for net positive suction head (NPSH) for emergency core cooling system (ECCS) injection 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