Alert

The NRC is shutdown due to the lapse in appropriations. Exempted activities to maintain critical health and safety activities and progress on critical activities, including activities outlined in Executive Order 14300, as described in the OMB Approved NRC Lapse Plan will continue.

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, March 09, 2021