A primer on criticality safety

Criticality is the state of a nuclear chain reacting medium when the chain reaction is just self-sustaining (or critical). Criticality is dependent on nine interrelated parameters. Criticality safety controls are designed to constrain these parameters to minimize fissions and maximize neutron leakage and absorption in other materials, which makes criticality more difficult or impossible to achieve. In this paper, the consequences of criticality accidents are discussed, the nine interrelated parameters that combine to affect criticality are described, and criticality safety controls used to minimize the likelihood of a criticality accident are presented.