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

Mayak Enterprise criticality accident, 1957

compiled by Wm. Robert Johnston
last modified 21 September 2007

Date: 21 April 1957

Location: Mayak Enterprise, Russia, USSR

Type of event: criticality accident with uranium solution


The accident occurred in a glovebox assembly within which uranium solution was precipitated into vessels. For several reasons, an unexpectedly large amount of uranium precipitate accumulated in a filter receiving vessel. The operator at the glovebox observed the filter vessel to bulge prior to ejection of gas and some solution and precipitate from the vessel within the glovebox. The operator gathered some precipitate by (gloved) hand and returned it to the vessel; within seconds she began to feel ill. It was not recognized that a criticality excursion had occurred until the radiation control officer made measurements 15-20 minutes later. The female operator received a whole body dose of 3,000 rad or 4,600 rad, developed nausea, vomiting, headache, and fatigue within 20-30 minutes, and died 12 days later. The other five operators in the room at the time received doses over 300 rad, and five other individuals sustained doses up to 100 rad; the five operators developed radiation sickness (one report suggests all ten did). All ten (3 male, 7 female) recovered.

Consequences: 1 fatality (3,000-4,600 rad), 10 injuries (100-300 rad).


© 2004-2005, 2007 by Wm. Robert Johnston.
Last modified 21 September 2007.
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