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
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Content:
edures, including changes to the system design or alignments, system performance characteristics, support system dependencies, and operational procedures or operational philosophies. Where applicable, these changes are appropriately included in the PRA system models. A.4 Dependent Failure Analysis a. Areas of Review 19.2-47 June 2007 Accident progression models and system models should correctly account for dependencies between systems and operator actions needed for accident mitigation. Proposed changes to the plant's design or operations could affect these dependencies; therefore, the evaluation of the risk change should also consider system-operator dependencies. However, since the modeling of these dependencies requires detailed knowledge of the plant systems and procedures, it will not be practical (nor is it intended) for reviewers to verify that all dependencies have been included in the change evaluation. Instead, reviewers should verify that the evaluation used a comprehensive and systematic process to look for these dependencies. Reviewers should rely on their experience with similar change analyses (when applicable) or with PRAs of similar plants, but should be aware that dependencies are in many cases plant-specific and will depend on plant-specific system capabilities and interactions, procedural guidance, and timing of potential accident sequences. b. Review Guidance and Procedures Review guidance in this section consists of a discussion of the dependencies that could be important and that could be affected by changes to the plant’s design or operations. Although most changes will not alter the original PRA dependent failure analysis, some design or procedure changes could introduce new dependencies or affect existing ones. Therefore, reviewers should be cognizant with regard to the following types of dependencies that could exist and could affect the results of the change analysis: Functional Dependencies: These dependencies occur because the