Document: NUREG-0800
Document ID: e32f0820-4e33-476e-aa36-4ca8c2c64af0
Document Type: srp
Title: Use of Probabilistic Risk Assessment in Plant-Specific, Risk-Informed Decisionmaking:
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0119/ML011940192.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.0
CFR Part: 
CFR Title: 

Content:
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 utilized 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. SRP 19-A7 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 coulcl exist and could affect the results of the change analysis: Functional Dependencies: These dependencies occur because the function of one system or component depends on that of another system or component. Functional dependencies include interactions whic-h can occur when the change in the function of a system or component causes a physical change in the environment which results in the failure of another system or component. Functional dependencies include the following examples: shared componert dependencies (e.g., systems or system trains that depend on a common intake or discharge valve) actuation requirement dependencies (e.g., systems that depend on common actuation signals, common actuation circuitry, or common support systems like AC or DC power or instrument air for initiation or actuation) and conditions needed for actuation (e.g., low RPV water level). isolation requirement