Document: NUREG-0800
Document ID: 7916b088-fb90-4163-84fe-027bd315bcc5
Document Type: srp
Title: REVIEW OF RISK INFORMATION USED TO SUPPORT PERMANENT PLANT-
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0717/ML071700658.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.2
CFR Part: 
CFR Title: 

Content:
f the system into ones that are not currently modeled, the revised fault trees should be one focus of the review. Other considerations of which reviewers should be aware in the area of system analysis are whether the application can impact support functions in such a way as to alter the dependencies in the model, and whether the application can impact system performance to an extent that would require changes to the fault tree logic or modeling assumptions. b. Review Guidance and Procedures When the review of one or more of the system logic models becomes necessary, this review should include a study of the appropriate system notebooks from the base PRA to understand the modeling characteristics that may be affected by the change. It should also include an evaluation of the licensee’s process for modeling the system change as well as a spot-check of the revised system models and results. Reviewers should verify that, in modeling the change, the licensee appropriately modified the system logic models to reflect changes in the plant’s configuration, including changes to the system design, system performance characteristics, system alignments, operational procedures, and operational philosophies. In particular, reviewers should address the following considerations: • The analysis of the change should account for the effects of the change on the definition of system success. That is, if the proposed application affects component configurations, expected operability conditions, failure modes and their effects, and alternative success and potential failure paths, these should be taken into account. In addition, the licensee should show that the justification used in the original analysis to exclude components, component failure modes, or flow diversion paths, etc., remain valid in light of the proposed change. The analysis should also identify and account for changes that could affect environmental conditions that could cause system failure (e.g., room temperature,