criticality

Syllable breakdown

Dictionary meaning

the condition of a nuclear fission chain reaction in which each fission event produces exactly one neutron that goes on to cause another fission event, sustaining a steady-state reaction; a subcritical system produces fewer than one fission per fission, causing the chain reaction to diminish and stop; a supercritical system produces more than one fission per fission, causing exponential growth in the reaction rate; nuclear power reactors operate at criticality under controlled conditions to produce steady thermal power; criticality accidents, in which fissile material is inadvertently assembled into a supercritical configuration outside a reactor, have caused fatalities at nuclear fuel processing facilities and represent a key concern in the handling and storage of enriched uranium and plutonium