criticality

Syllable breakdown

Dictionary meaning

The state of a nuclear fission chain reaction in which exactly one neutron from each fission event causes exactly one subsequent fission, sustaining a steady-state reaction; the design target for operating nuclear reactors; 'supercriticality' (more than one chain per event) causes exponential power increase

History and origin

From critical (Greek kritikos, able to judge) applied to the neutron chain reaction threshold; the term became standard in reactor physics during the Manhattan Project

Examples

• Achieving criticality for the first time in the Chicago Pile-1 reactor on 2 December 1942 was a historic milestone.
• Criticality accidents can release lethal doses of radiation within seconds.

Synonyms: critical state, self-sustaining chain reaction