Tōkai (東海村; -mura) is a village located in Naka District, Ibaraki, Japan. It is approximately 120 km north of Tokyo, Japan on the Pacific coast.

As of 1 January 2005, the village has an estimated population of 35,467 and a density of 946.29 persons per km². The total area is 37.48 km².

Aside from nuclear facilities, Tokai has lovely beaches. Tokai is the sister city of Idaho Falls, Idaho, another town associated with nuclear energy.

JCO reactivity accident

Tokai is best known for a nuclear accident that occurred on September 30, 1999, which killed two people. The accident was a criticality accident.

The Tokaimura nuclear accident happened at the JCO reconversion plant.

The accident was caused 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 kg of enriched uranium) was poured into the precipitation tank by two technicians, a blue flash of radiation occurred and the two technicians felt severe pain, nausea and had trouble breathing. The radiation alarms went off and the two 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.

Due to the radiation they received, the two technicians died on December 22, 1999, and April 27, 2000, respectively.

External links

• Tokai official website in Japanese
• ^* Report by the IAEA on the event.
• ^* A report on Soviet criticality events.
• ^* A review of criticality accidents, Warning it is a big file.

See also

• Nuclear fuel reprocessing plant
• List of nuclear accidents
• 5 yen coin

Villages in Ibaraki Prefecture | Radioactive waste | Nuclear reprocessing | Nuclear accidents

Tōkai (Ibaraki) | Tokaimura | 도카이 촌 | 東海村