Contribution of Risk from Human Failures in PRA Models

Large industrial facilities, such as commercial nuclear power plants, still require human operators to respond to abnormal conditions. Failures of these operators to perform the appropriate actions can lead to significant consequences. Human failure events (HFEs) are modeled in probabilistic risk assessment (PRA) models for these plants to consider the consequences of these failed actions. These PRA models explicitly consider various types of failures, including failures to align equipment prior to an event, which leaves that equipment unavailable to respond, and failures of human actions after the abnormal event that are designed to mitigate the event.