Document: NUREG-0800
Document ID: f60cdc8f-3c25-45c3-a1d3-b0f530961625
Document Type: srp
Title: DETERMINING THE TECHNICAL ADEQUACY OF PROBABILISTIC RISK
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1219/ML12193A107.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.1
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CFR Title: 

Content:
For example, if the application applies the acceptance guidelines of RG 1.174, the evaluations of core damage frequency (CDF), the change in CDF (ΔCDF), large early release frequency (LERF), and the change in LERF (ΔLERF) should be performed with a full-scope PRA that includes all hazard groups and all modes of operation. In accordance with the Commission direction on PRA technical adequacy, when the risk associated with a particular hazard group or operating mode is significant to the decision being made, and a staff-endorsed PRA standard exists for that hazard group or operating mode, then the risk should be assessed using a PRA that meets that standard. For reactors, licensed under 10 CFR Part 52 the reviewer should become familiar with 10 CFR 50.71(h). As required by 10 CFR 50.71(h)(1), each COL holder shall develop a Level 1 and a Level 2 PRA no later than the scheduled date for initial loading of fuel. The PRA must cover those initiating events and modes for which NRC-endorsed consensus standards on PRA exist 1 year prior to the scheduled date for initial loading of fuel. In addition, 10 CFR 50.71(h)(3) requires that each COL holder shall upgrade the PRA required by 10 CFR 50.71(h)(1) to cover all modes and all initiating events no later than the date on which the licensee submits an application for a renewed license. With respect to this regulation, the reviewer should be aware that an all-mode, all-initiator PRA must be developed by the time a license renewal application is submitted, even if standards for such a PRA do not yet exist. It should be noted that the above regulations may have a significant impact to the decision being made for a risk-informed license amendment request. Screening and conservative analyses may be used to demonstrate that the risk contributions not addressed by a PRA model are not significant to the decision. This is discussed more fully in NUREG-1855, “Guidance on the Treatment of Uncertainties Associated with PRAs in