Wood River, R.I. criticality accident, 1964
On July 24,1964, a nuclear criticality accident took place at a United Nuclear Corp commercial processing facility at Wood River, Rhode Island, USA. The plant was involved in reprocessing for recovery highly enriched uranium in scrap material from fuel element production. A sodium carbonate solution and uranium (93% U-235) was being mixed by a machine. A worker, intending to add a bottle of trichloroethane to remove organics, erroneously added a bottle of uranium solution to the tank, producing a criticality excursion accompanied by a flash of light and the splashing of about 20% of the tank's contents (about 10 liters out of 40-50 liters, including the bottle contents) out of the tank. The worker fled to the site's emergency building. Two plant administrators returned to the building; one turned off the agitator, producing a lesser criticality excursion that was not recognized until their dosimeters were examined. The administrators incurred doses of 100 rads and 60 rads. The worker absorbed about 10,000 rads and died 49 hours after the accident.
Excellent Yankee Magazine on the incident: