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

Siberian Chemical Combine criticality accident, 1961

compiled by Wm. Robert Johnston
last modified 14 September 2005

Date: 14 July 1961

Location: Siberian Chemical Combine, Russia, USSR

Type of event: criticality accident with uranium


An accumulation of uranium hexaflouride (with uranium enriched to 23.3% U-235) in a vacuum pump oil reservior caused a criticality excursion and set off radiation alarms. Operators failed to identify the cause of the radiation readings and resumed operations. An operator turned on the vacuum pump again, producing a criticality excursion accompanied by a flash of light; the operator turned off the pump and went to a telephone to alert a supervisor. He developed mild radiation sickness from a dose of 200 rad. The oil reservior was finally drained 18-19 July.

Consequences: 1 injury (200 rem).


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