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:
ce on the evaluation of proposed STI changes is in the following subsections. (iii) Risk Evaluation for All TS Changes. The scope and the level of PRA necessary for the evaluation of a TS change fully depend on the type of TS change sought; however, in some cases, a PRA of sufficient scope may not be available and qualitative arguments, bounding analyses, or compensatory measures must compensate for this lack. (1) Breadth and Depth of PRA Review. The breadth and depth of the PRA review should be addressed in the review for TS changes. The breadth and depth of the review depend on several factors: (a) The emphasis placed on traditional analysis as opposed to PRA in the basis for the TS change. If the justification for the change is based on well founded traditional arguments easily supported by PRA insights, only a limited PRA review may be warranted; however, if a TS change is supported primarily by complex PRA arguments with limited traditional bases, the breadth and depth of the PRA review are substantially greater. (b) The safety significance of the SSC under consideration. The level of redundancy, diversity, and need for operator recovery actions will impact the safety significance of any proposed TS change. The reliance on operator actions for safety functions under high-stress conditions requires greater scrutiny of the human reliability than of the automatic systems analysis. (c) The validity of the PRA. An initial evaluation of the PRA is needed for confidence in the PRA validity. The confidence necessary depends on the application. PRA validity for the decision-making process can be established by evaluating: • Consistency of the PRA methodology with acceptable methods and practices. • Robustness of the results through sensitivity studies. 16.1-14 Revision 1 - March 2007 • Consistency of the PRA findings as to the plant's design and operational characteristics. • Modeling detail and scope necessary to support the decision-making activity. •