Document: NRC Regulatory Guide
Document ID: c7a40fcc-fc9d-4eb2-ad86-f9f5b0f04c82
Document Type: regulatory_guide
Title: Plant-Specific, Risk-Informed Decisionmaking:  Technical Specifications (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1920/ML19206A489.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.177
CFR Part: 
CFR Title: 

Content:
e taken to change this term within the common-cause contribution. The common cause of failing multiple components resulting from human error following a test is not a function of the SF, but it may be affected by the test strategy used. When different test strategies are being evaluated, the human error term should be evaluated. Specific assumptions that were used in quantifying the human error common-cause term should be identified and checked if they apply to the test strategy being analyzed. For example, if the term was developed assuming a sequential test strategy, but a staggered test strategy is being analyzed, the term should be modified to reflect this change. The failure probability from a common-cause human error for a staggered test strategy is expected to be significantly lower than that for the sequential test strategy. A-1.3.1.4 Using Minimal Cutsets To Calculate Test-Limited Risks The test-limited risk for a component or a set of components also can be determined by identifying those minimal cutsets that contain one or more of the SF contributions. The sum of the relevant minimal cutset contributions is then equal to the test-limited risk. To evaluate changes in the test-limited risks for changes in the SFs, the difference between the minimal cutset contributions with and without the SF changes will be the difference between the test-limited risks. In using the minimal cutsets, the SF contributions should all be included in the set of minimal cutsets used. Even though use of the minimal cutsets gives the same results, the above basic description of methods for obtaining the test-limited risks is useful because it shows the basic contributing factors to the SF risk. DG-1287, Appendix A, Page A-5 A-1.3.1.5 Specific Considerations for Evaluating Multiple Test-Limited Risks When multiple SFs are modified or defined, the total test-limited risk from the multiple SF changes or definitions should be properly evaluated. Instead of using the PRA to evaluate