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.

Chain reaction

A reaction that initiates its own repetition. In a fission chain reaction, a fissionable nucleus absorbs a neutron and fissions spontaneously, releasing additional neutrons. These, in turn, can be absorbed by other fissionable nuclei, releasing still more neutrons. A fission chain reaction is self-sustaining when the number of neutrons released in a given time equals or exceeds the number of neutrons lost by absorption in nonfissionable material or by escape from the system.

Page Last Reviewed/Updated Tuesday, March 09, 2021