Location of Tōkai in Ibaraki Prefecture
|• Total||37.48 km2 (14.47 sq mi)|
|Population (1 January 2005)|
|• Density||950/km2 (2,500/sq mi)|
|Time zone||Japan Standard Time (UTC+9)|
The Japan Atomic Energy Agency along with other organizations currently operate a number of nuclear technology research facilities in the town. In particular, Tōkai Nuclear Power Plant is located in Tōkai.
- 1955 - Muramatsu-mura and Ishigami-mura merged into Tokai-mura
- 1956 - Japan Atomic Energy Research Institute was set up at Tokai-mura
JCO radiation accident
The accident occurred when seven times the allowable limit of 18.8% enriched uranium dioxide was mixed with nitric acid in order to form uranyl nitrate, and was put in a precipitation tank to homogenize. At 10:35 am, when the seventh bucket (making a total of 16.6 kg of 18.8% enriched uranium) was poured into the precipitation tank by three technicians, a blue flash of radiation occurred and the three technicians felt severe pain, nausea and had trouble breathing. The radiation alarms went off and the three technicians and their supervising technicians immediately left the building.
The criticality was stopped 20 hours later by draining the cooling water jacket around the precipitation tank and filling it with argon, and purging the tank with boric acid. The amount of neptunium and plutonium formed during the event was estimated through radiochemical analysis of the uranium solution from within the tank.
Two of the three technicians irradiated died on 22 December 1999 and 27 April 2000, respectively.
- N. Shinohara et al., Radiochimica Acta, 2001, 89, 135-138 Chemical analysis of transuranium nuclides in the uranium solution of the JCO criticality accident
Media related to Tōkai, Ibaraki at Wikimedia Commons
- Official website (Japanese)
- Report by the International Atomic Energy Agency on the nuclear accident
- Official timeline of the nuclear accident