Document: NUREG-0800
Document ID: 7916b088-fb90-4163-84fe-027bd315bcc5
Document Type: srp
Title: REVIEW OF RISK INFORMATION USED TO SUPPORT PERMANENT PLANT-
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0717/ML071700658.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.2
CFR Part: 
CFR Title: 

Content:
ct the PRA in a fundamental way. 19.2-74 June 2007 APPENDIX C Categorization of Plant Elements with Respect to Safety Significance For several proposed applications in risk-informed regulation, one of the principal activities is the categorization of SSCs and human actions with respect to their safety-significance. This appendix discusses how to review approaches that may be used in this categorization process. The first review consideration is the definition of safety-significance as it applies to SSCs and human actions for a specific application. A related, but not identical concept, is that of risk significance. For example, an individual SSC can be identified as being risk-significant if it can be demonstrated that its failure or unavailability contributes significantly to the measures of risk (e.g., CDF and LERF). Safety significance, on the other hand, can be thought of as being related to the role the SSC or human action plays in preventing the occurrence of the undesired end state. Thus, the SSCs and human actions considered when constructing the PRA model have the potential to be safety significant, since they play a role in preventing core damage or large early release. These SSCs and human actions may include those that do not necessarily appear in the final quantified model because they have initially been screened, are assumed to be inherently reliable, or have been truncated from the solution of the model. In addition, there may be SSCs or human actions not modeled in the PRA that have the potential to be safety significant because they play a role in preventing core damage or large early release. In reviewing the categorization, it is important to recognize its underlying purpose. Categorization is generally intended to sort the SSCs or human actions into two general groups: those for which some change is proposed, and those for which no change is proposed. It is the potential impact of the application on the particular SSCs and human actions and on