Document: NUREG-0800
Document ID: 4e1d86bd-74a5-4678-8bc0-ffce3ba28ea0
Document Type: srp
Title: RISK-INFORMED INSERVICE TESTING
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0428/ML042880272.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.9.7
CFR Part: 
CFR Title: 

Content:
n part on results from importance/risk rankings from a PRA. Since importance measures are only applicable to components taken one at a time, these measures are not an adequate measure of the change in total risk for changes that involve more than one component. Therefore, reviewers should confirm that the overall impact from an IST change is calculated, and that if risk increases are proposed, these increases are small and consistent with the intent of the Commission's Safety Goal Policy Statement. Section 111.2.2 of SRP Chapter 19 contains guidance on the review of the overall risk impact. Although the categorization process and the assessment of risk impact requires that all plant operating modes and initiating events be addressed, it is not necessary in RI-IST that licensees submit PRAs that treat all plant operating modes and all initiating events. Instead, when full- 3.9.7-23 Rev. 0 - August 1998 scope PRAs are not available, reviewers should ensure that the submitted findings are supportable on the basis of available risk insights, traditional engineering analyses or other plant operational information addressing modes and initiators not analyzed in the base PRA. Section 111.2.2 of SRP Chapter 19 provides review guidance on this topic. When relaxations in IST strategy are offset by alternative measures (e.g., additional monitoring, different tests, procedures, training, etc.), the licensee should identify, and quantify to the extent practicable, the effects of these alternative measures. Similarly, if there are benefits associated with proposed relaxations (e.g., reduction in initiating event frequency, reduction in system misalignment, reduction in radiation exposure), the licensee should identify, and quantify to the extent practicable, the effects of these benefits. As a general rule, the alternative measures and benefits should be directly linked to the systems or components associated with proposed relaxations. However, on a case by case basis, the staff