Document: NUREG-0800
Document ID: 7f6b0af0-d79e-4704-9eac-aa03109a7731
Document Type: srp
Title: RISK-INFORMED DECISIONMAKING: TECHNICAL SPECIFICATIONS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0425/ML042520260.pdf
Revision Date: 2023-06
Chapter: 16
Section ID: 16.1
CFR Part: 
CFR Title: 

Content:
osals for TS modifications will be done in a manner consistent with the fundamental principle that changes to TS result in small increases in the risk to the health and safety of the public (Principle 4, as described in the "Discussion" section of Regulatory Guide 1 .177) (Ref. 8). General guidance for evaluating the risk impact from TS and other types of changes can be found in SRP Chapter 19, Section II. TS change evaluations may involve some small increase in risk as quantified by PRA models. Usually, it is argued that such a small increase is offset by the many beneficial effects of the change that are not modeled by the PRA. The role of numerical guidelines is to ensure that the increase in risk is small, and to provide a quantitative basis for the risk increase based on aspects of the TS change that are modeled or quantified. The numerical guidelines used to decide an acceptable TS change are taken into account along with other traditional considerations, operating experience, lessons learned from previous changes, and practical considerations associated with test and maintenance practices. The final acceptability of the proposed change should be based on all of these considerations and not solely on the use of PRA-informed results compared to numerical acceptance guidelines. As discussed previously, the numerical guidelines are used to ensure that any increase in risk is within acceptable limits; traditional considerations are used to ensure that the change satisfies rules and regulations that are in effect; practical considerations judge the acceptability of implementing the change; and lessons learned from past experience ensure that mistakes are not repeated. Using the risk measures discussed in Regulatory Guide 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 changed case, additional changes to be implemented as part of the