Date: 21 May 1946

Location: Los Alamos Scientific Laboratory, New Mexico, USA

Type of event: criticality accident with plutonium metal assembly

Description:

An experimenter was demonstrating techniques to a group using a plutonium assembly. The assembly comprised two hemispheres of plutonium metal, total mass 6.2 kg (just short of bare critical mass). The experimenter had the two hemispheres together, separated by a screwdriver supporting the top hemisphere, when the assembly became supercritical. He separated the assembly within 0.5 seconds. The experimenter received a dose of 2100 rem, from which he died 9 days later. The other individuals in the room received doses of 360, 250, 160, 110, 65, 47, and 37 rem. The individual receiving the second highest dose, a woman, was the only other individual to develop radiation sickness.

Consequences: 1 fatality (2100 rem) and 1 injury (360 rem).

References:

• McLaughlin, Thomas P., Shean P. Monahan, Norman L. Pruvost, Vladimir V. Frolov, Boris G. Ryazanov, and Victor I. Sviridov, May 2000, A Review of Criticality Accidents, 2000 Revision, Los Alamos National Laboratory (Los Alamos, NM), on line at CSRIC [http://www.csirc.net/docs/reports/la-13638.pdf].
• Messerschmidt, Otfried, 1990, "Medical aspects of radiation accidents," in Radiation Exposure and Occupational Risks, ed. by Eberhard Scherer, Christian Streffer, and Klaus-Rudiger Trott, Springer-Verlag (Berlin, Germany), pp. 75-95.

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