Document: NUREG-0800
Document ID: e32f0820-4e33-476e-aa36-4ca8c2c64af0
Document Type: srp
Title: Use of Probabilistic Risk Assessment in Plant-Specific, Risk-Informed Decisionmaking:
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0119/ML011940192.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.0
CFR Part: 
CFR Title: 

Content:
he eventual occurrence of a PRA initiating event. SRP 19-C6 The SSC is not a part of a system that acts as a barrier to fission product release during severe accidents. The failure of the SSC will not result in unintentional releases of radioactive material even in the absence of severe accident conditions. If any of the above conditions apply, or if SSC performance is difficult to quantify, the licensee should have used a qualitative evaluation process to determine the impact of relaxing requirements on equipment reliability and performance. This evaluation should include identifying those failure modes for which the failure rate may increase, and those for which detection could become more difficult. Reviewers should then verify that the licensee provided one or more of the following (or similar) justifications: * a qualitative discussion on how the change is consistent with the defense-in-depth philosophy and how the change maintains sufficient safety margins * a qualitative discussion and historical evidence why these failure modes may be unlikely to occur 0 a qualitative engineering discussion on how such failure modes could be detected in a timely fashion a a discussion on what other requirements may be useful to control such failure rate increases * a qualitative engineering discussion on why relaxing the requirements may have minimal impact on the failure rate increase c. Evaluation Findings The SER should incorporate language equivalent to the following, and exceptions (if any) should be noted and explained: The categorization of the SSCs or human actions has adequately captured their significance to safety, and has been performed in such a way that the potential impact of the proposed application results in at most a small increase in the risk to the health and safety of the public. The input to the integrated decisionmaking process derived from importance measures has been utilized, taking into account the known limitations of importance calculations, and