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
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include those caused by internal flooding, fires, seismic events, missiles (e.g., turbine missiles), or any of the other external event initiators. In cases where these events could affect the results of the change evaluation, and where these events are not modeled in the PRA, the dependencies resulting from the unmodeled initiators should be evaluated qualitatively as part of the integrated decisionmaking process. Section 111.2.2 of this SRP chapter discusses the required scope of the PRA in more detail. In addition, the change request should include the licensee's consideration of the common influences on component operation such as adverse environment (including excessive temperature, humidity, radiation), inadequate space, inadvertent or spurious sprinkler operation, or routine equipment travel near major components. Reviewers should verify that the change request has used a systematic process to identify potential spatial challenges that could result in multiple failures of SSCs. c. Evaluation Findings Reviewers should verify that information provided and review activities conducted support the following conclusion: SRP 19-A9 Dependencies between system and operator interactions have been properly accounted for in the evaluation of the proposed change. Where appropriate, these dependencies have been included in the accident progression models (event trees) and the system inalysis models (fault trees). A.5 Determination of Success Criteria a. Areas of Review Guidance in the PRA policy statement and in RG 1.174 stipulates that realistic analysis should be used in PRA implementation. The following discussion is intended to sort out what is meant by "realistic" analysis of success criteria by reference to SAR analysis. In order to fulfill its intended purpose, SAR analysis is ordinarily based on a set of assumptions containing :significant embedded conservatisms. SAR analysis also reflects a postulated single active failure, in addition to whatever event initiated