Document: NUREG-0800
Document ID: ac43f632-9db1-4857-9f56-bfba45965456
Document Type: srp
Title: * These are modifications to a plant’s design, operations, or other activities that require NRC approval. These modifica
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0232/ML023250195.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19
CFR Part: 
CFR Title: 

Content:
ng, installation, calibration, or operational deficiencies. CCFs are treated quantitatively by common cause failure probabilities or other dependence quantification approaches. Section A.7 of this SRP chapter presents review guidance related to CCFs. Spatial Dependencies: Multiple failures could be caused by events that fail all equipment in a defined space or area. These spatially dependent failures 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 III.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. SRP 19-A10 c. Evaluation Findings Reviewers should verify that information provided and review activities conducted support the following conclusion: 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 analysis models (fault trees). A.5 Determination of Success Criteria a. Areas of Review Guidance in the PRA policy statement and in Regulatory Guide 1.174 stipulates that realistic analysis should