United States Nuclear Regulatory Commission - Protecting People and the Environment

Top event

The events across the top of the event tree, which graphically represent the systems needed to keep the plant in a safe state following an initiating event (i.e., a challenge to plant operation). A top event is the starting point of the fault tree, which identifies all of the pathways that lead to a system failure. For additional information, see Probabilistic Risk Assessment.

Page Last Reviewed/Updated Tuesday, October 28, 2014