Document Details

Potential Hazards of Criticality Accidents
Document Location:
DOE INFORMATION CENTER 1 Way, Oak Ridge, TN 37831; Eva Butler; Phone: 865-241-4780; Toll-Free: 800-382-6938, Option 6; FAX: 865-574-3521; Email:
Document Categories:
Specific Material\Fission Products; Health, Safety and Environment\Worker Health and Safety
Document Type:
Publication Date:
1952 Aug 05
Declassification Date:
1957 Feb 11
Declassification Status:
Document Pages:
Accession Number:
Document Number(s):
Originating Research Org.:
Carbide and Carbon Chemicals Corporation
OpenNet Entry Date:
1998 Jun 16
This report discusses accidental accumulations of super-critical masses of fissionable materials resulting in radiation bursts ranging from a little less than 0.1 megawatt to more than 15 megawatts. The lethal radii for bursts of 0.1 megawatt, 3 and 15 megawatts are calculated to be approximately 1-1/2, 9-1/2 and 22 feet, respectively. These calculations are based on the assumption that 400 roentgens of gamma or gamma equivalent radiation is lethal to 50 percent of the population. Although the residual radiation from the fission fragments is large, operating personnel outside of the lethal circle can remain in the contaminated area for as long as 20 to 30 seconds without adding significantly to their over-all exposure. For an accident of about 0.1 megawatt, probably less than 7 additional roentgens will be received by remaining in the contaminated area for 20 seconds. The additional radiation would be proportionally higher for bursts of from 3 to 15 megawatts. These do not include the health hazard of ingested beta and alpha-active contaminants, which might be present in the air after a burst. Figures and a bibliography are included in this report. Also included is a discussion of the first known accidental and unscheduled nuclear chain reaction that occurred on June 16, 1958, in an industrial process facility which was Union Carbide Nuclear Company Y-12 facility for the recovery of enriched uranium from fuel fabrication scrap and other salvage. The hazard of first concern in an incident of this type is the lethal radiation that accompanies the incident, and the second concern, to those who must combat the hazard, is the radiation after-effects. This discussion intends to generally describe the conditions encountered during the course of the Y-12 incident and the Health Physics measures taken to evaluate and regain control of the area. Figures are also included.

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