What is a criticality?
Cameco describes criticality in the following words: “Under certain conditions, a sufficient mass of U-235 can trigger a chain reaction called criticality’. Criticality is a sustained nuclear reaction. The products of criticality are heat and radiation.” The heat energy released by a spontaneous nuclear chain reaction (a “criticality”) is sufficient to vaporize metals and other materials. The radiation given off is an intense burst of “neutron radiation”, more penetrating and/or damaging than any other type of atomic radiation. Natural uranium cannot undergo such a spontaneous chain reaction, but the advanced fuels mentioned above (from SEU to MOX) can suffer criticality accidents if they come in contact with water. This makes the floodplain issue more significant, because if the area were inundated and Cameco was unable to keep the materials away from water, a criticality could occur.
