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:
ll 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 release probability 4 ICLERP = [(conditional LERF with the subject equipment out of service)-(baseline LERF with nominal expected equipment unavailabilities)] x (duration of single AOT under consideration). 16.1-9 Revision 1 - March 2007 (ICLERP)4 of 5.0E-8 or less is also small. Also, the ICCDP contribution should be distributed in time so any increase in conditional risk is small and within the normal operating background (risk fluctuations) of the plant (Tier 1). B. The licensee has demonstrated appropriate restrictions on dominant risk-significant configurations of the modifications (Tier 2). C. The licensee has a risk-informed plant configuration control program with procedures to utilize, maintain, and control it (Tier 3). In the context of integrated decision-making, application of the acceptance guidelines should not be overly prescriptive. They are intended to indicate, in numerical terms, what is acceptable. The numerical values are approximate and indicate changes generally acceptable. The intent in comparing PRA results to the acceptance guidelines is to demonstrate with reasonable assurance that Principle 4, addressed in the "Discussion" section of RG 1.177 (Reference 8), is met. The decision must be based on a full understanding of the contributors to the PRA results and the impacts of the uncertainties, both those explicitly considered in the results and those not. A nonquantitative assessment of risk (either alone or accompanied by quantitative assessment) may suffice to justify TS changes. The licensee is expected to use judgment on the acceptability (to support regulatory decision-making) of the risk argument, including the appropriate blend of quantitative and qualitative assessments. III. REVIEW PROCEDURES The reviewer will select material from the