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:
mission success (e.g., water sources, air, fuel oil, etc.). When applicable, licensees should factor these dependencies into the analysis of the change. When proposed changes deal with proceduralized test and maintenance actions or applicable technical specification conditions, the modeling of test and maintenance unavailabilities and the modeling of restoration errors for the affected systems/components should be reviewed. Changes to the frequency of each test or maintenance activity, its approximate duration, the components repositioned for the action, the verification activities post test and maintenance, and the availability of the system during the test procedure should have been factored into the change analysis. Operational history (i.e., plant-specific operational experience) should be considered in the review of the system models and especially in the review of how the proposed change will affect system operation. Considerations like recurring check valve problems (e.g., back-leakages), water hammer events, or flow blockages by sludge or debris should also be considered in the analysis. The potential for common cause failures including those potentially resulting from the change should have been evaluated and modeled where appropriate. Review guidance for the evaluation of common cause failures is provided in Section A.7 of this SRP chapter. SRP 19-A6 * The function of the modeled system should remain consistent with that required in the event tree models. Success criteria and event sequence conditions should be correctly modeled and consistent with the definition in the event trees. When fault tree solutions in the form of function cutsets are available, an efficient way to review for the logic in system models is to study the cutsets produced by the solution of the linked fault trees (i.e., the fault tree formed by linking the support system fault trees to the system fault tree). In performing this visual inspection, reviewers should compare the results