Database of radiological incidents and related events--Johnston's Archive

Hanford criticality accident, 1962

compiled by Wm. Robert Johnston
last modified 14 September 2005

Date: 7 April 1962

Location: Hanford Works, Hanford, Washington, USA

Type of event: criticality accident with plutonium solution


An accident at a plutonium processing plant resulted in a criticality accident. Plutonium solution was spilled onto the floor of a solvent extraction hood. Improper operation of valves allowed a mixture of plutonium solutions in a tank that became supercritical, prompting criticality alarms to sound and subsequent evacuation of the building. Exact details of the accident could not be reconstructed. The excursion continued at low power levels for 37.5 hours, during which a remotely controlled robot was used to check conditions and operate valves. Criticality was probably terminated by precipitation of plutonium in the tank to a non-critical state. Three people had significant radiation exposures (110, 43, and 19 rem).

Consequences: 2 injuries.


© 2004, 2005 by Wm. Robert Johnston.
Last modified 14 September 2005.
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