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).
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Last modified 14 September 2005.
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