Document: NRC Regulatory Guide
Document ID: 22ccfd5e-c5d8-4615-a02c-32369aa9f533
Document Type: regulatory_guide
Title: Acceptability of Probabilistic Risk Assessment Results for Risk-Informed Activities (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1930/ML19308B636.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.200
CFR Part: 
CFR Title: 

Content:
, the ASME/ANS Level 1/LERF PRA standard and NEI 17-07, Revision 2, addresses a Level 1 and limited Level 2 PRA analysis for all hazards (i.e., internal events, internal flood, internal fire, seismic, high wind, external flood, and other hazards), with respect to at-power operations. DG-1362, Page 48 3.2 Identification of the Parts of a PRA Used to Support the Application Based on an understanding of how the PRA model is to be used to achieve the desired results, the licensee should have identified the portions of the PRA for each hazard group required to support a specific application. This includes the following two categories of items: (1) the PRA logic model elements onto which the cause-effect relationships are mapped (i.e., those directly affected by the application), and (2) all the events with mapped cause-effect relationships that appear in the accident sequences. For some applications, this may be some subset of all items in the base PRA, but for others (e.g., risk-informing the scope of special treatment requirements), all portions of the PRA model may be relevant. 3.3 Demonstration of PRA Acceptability There are two aspects to demonstrating the acceptability of the portions of the PRA used to support an application. The first aspect is the assurance that the portions of the PRA used in the application have been developed and performed in a technically correct manner. The second aspect is the assurance that the assumptions and approximations used in developing the PRA are appropriate. For the first aspect, assurance that the portions of the PRA used in the application have been developed and performed in a technically correct manner indicates that (1) the PRA model, or those portions of the model required to support the application, represents the as-designed or as-built and as- operated plant, which, in turn, indicates that the PRA reflects the current design and operating practices and experience, where appropriate; (2) the PRA logic model has been