Tōkai, Ibaraki

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Flag of Tōkai
Location of Tōkai in Ibaraki Prefecture
Location of Tōkai in Ibaraki Prefecture
Tōkai is located in Japan
Location in Japan
Coordinates: 36°28′N 140°34′E / 36.467°N 140.567°E / 36.467; 140.567Coordinates: 36°28′N 140°34′E / 36.467°N 140.567°E / 36.467; 140.567
Country Japan
Region Kantō
Prefecture Ibaraki Prefecture
District Naka
 • Total 37.48 km2 (14.47 sq mi)
Population (1 January 2005)
 • Total 35,467
 • Density 950/km2 (2,500/sq mi)
Time zone Japan Standard Time (UTC+9)
Website www.vill.tokai.ibaraki.jp
Tōkai Station, west side

Tōkai (東海村 Tōkai-mura?) is a village located in Naka District, Ibaraki Prefecture, 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 population density of 946.29 persons per km². The total area is 37.48 km².

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.

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

JCO radiation accident[edit]

Tokai was the scene of a nuclear criticality accident which occurred at the JCO nuclear reprocessing plant on 30 September 1999, which killed two people.

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.[1]

Two of the three technicians irradiated died on 22 December 1999 and 27 April 2000, respectively.


Tōkai is served by Tōkai Station which is located on the Jōban Line. There is suburban service to Mito Station and Iwaki Station, as well as service to Ueno Station in Tokyo.

Sister City[edit]

Tōkai, Ibaraki has a sister city, as designated by Sister Cities International

See also[edit]


External links[edit]

Media related to Tōkai, Ibaraki at Wikimedia Commons