Document: NUREG-0800
Document ID: 32179098-f78d-4852-9c29-1e5e3abb2705
Document Type: srp
Title: RISK-INFORMED DECISION MAKING:  TECHNICAL SPECIFICATIONS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0703/ML070380228.pdf
Revision Date: 2023-06
Chapter: 16
Section ID: 16.1
CFR Part: 
CFR Title: 

Content:
al guidelines ensure that the risk increase is small and provide a quantitative basis for the risk increase according to modeled or quantified aspects of the TS change. The numerical guidelines for an acceptable TS change are taken into account along with other traditional considerations, operating experience, lessons learned from previous changes, and practical considerations for test and maintenance practices. The final acceptability of the proposed change should be based on all of these considerations and not solely on PRA-informed results compared to numerical acceptance guidelines. The numerical guidelines ensure that any increased risk is within acceptable limits; traditional considerations ensure that the change meets rules and regulations in effect; practical considerations judge the acceptability of the change; and lessons learned from past experience ensure that mistakes are not repeated. Using the risk measures addressed in RG 1.177, the change in risk should be calculated for the TS changes and compared against the numeric guidelines referenced in this section. In calculating the risk impact of the change, additional changes from the change can be credited (e.g., for an STI change, if the test strategy also is changed, the effect should be incorporated in the risk evaluation). However, this SRP and RGs 1.177 and 1.174, apply only to permanent (as opposed to temporary or "one-time") changes to TS requirements. TS AOT changes are permanent but, because AOTs are entered infrequently and are temporary by their very nature, the following TS acceptance guidelines for AOT changes evaluate the risk of the revised AOT additionally to the evaluation by the RG 1.174 acceptance guidelines. A. The licensee has demonstrated that the TS AOT modification has only a small quantitative impact on plant risk. An incremental conditional core damage probability (ICCDP)2 of less than 5.0E-73 is small for a single TS AOT modification. An incremental conditional large early