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:
ressure coolant injection mode) SRP 19-A8 Reviewers should look for evidence that the licensee properly considered the above types of dependencies in the evaluation of the change. In most cases, these dependencies should be explicitly included in the fault tree or event tree logic models; however, in some cases, a qualitative evaluation process may be sufficient. Human Interaction Dependencies: These dependencies could become important contributors to risk if operator error can result in multiple component failures. Past PRAs show that the following plant conditions could lead to human interaction dependencies that can become important: * tests or maintenance that require multiple components to be reconfigured • multiple calibrations performed by the same personnel post-accident manual initiation (or backup initiation) of components that require the operator to interact with multiple components Reviewers should verify that the licensee's evaluation of risk from proposed changes to plant procedures or changes to operator training included a process to identify these (or similar) activities, and that the licensee evaluated the activities that could be risk contributors. Component Hardware Failure Dependencies: These dependencies, usually referred to as common cause failures (CCFs), cover the failures of usually identical components which may be caused by design, manufacturing, 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