Tōkai Nuclear Power Plant

Tōkai Nuclear Power Plant
Tōkai I (right) and Tōkai II (left)
Country	Japan
Coordinates	36°27′59″N 140°36′24″E
Status	Operational
Construction began	March 1, 1961 (1961-03-01)
Commission date	July 25, 1966 (1966-07-25)
Operator	Japan Atomic Power Company
Power generation
Nameplate capacity	1,100 MW
External links
Website	www.japc.co.jp/tokai/english/plant_guide/tokai02.html
Commons	Related media on Commons

The Tōkai Nuclear Power Plant (東海原子力発電所, Tōkai genshi-ryoku hatsuden-sho, Tōkai NPP) was Japan's first nuclear power plant. It was built in the early 1960s to the British Magnox design, and generated power from 1966 until it was decommissioned in 1998. A second nuclear plant, built at the site in the 1970s, was the first in Japan to produce over 1000 MW of electricity.

Following the 2011 Tōhoku earthquake and tsunami the number 2 reactor was shut down automatically. It has been suggested that the reactor should not be restarted and should be decommissioned.

Location

The site is located in Tokai in the Naka District in Ibaraki Prefecture, Japan and is operated by the Japan Atomic Power Company. The total site area amounts to 0.76 km² (188 acres) with 0.33 km², or 43% of it, being green area that the company is working to preserve.

Reactors on site

Unit	Type	Average electric power	Capacity	Construction started	First criticality	Commercial operation	Closure
Tōkai I	Magnox (GCR)	159 MW	166 MW	March 1, 1961	November 10, 1965	July 25, 1966	March 31, 1998
Tōkai II	BWR/5	1060 MW	1100 MW	October 3, 1973	March 13, 1978	November 28, 1978	Shutdown since March 2011

Unit 1

Tōkai I

This reactor was built based on British developed Magnox technology. Unit 1 will be the first nuclear reactor to be decommissioned in Japan. The experience in decommissioning this plant is expected to be of use in the future when more Japanese plants are decommissioned. Below is a brief time-line of the process.

• March 31, 1998: operations cease
• March 2001: last of the nuclear fuel moved off-site
• October 4, 2001: decommissioning plan announced
• December 2001: decommissioning begins, spent fuel pool is cleaned
• 2003: turbine room and electric generator taken down
• Late 2004: fuel moving crane dismantled
• 2011: the reactor itself is dismantled

Unit 2

This Boiling Water Reactor was the first nuclear reactor built in Japan to produce over 1,000 MW of electricity. By some formalities in the paperwork, the unit is technically separate from the rest of the nuclear facilities at Tokai-mura, but it is managed with the rest of them and even shares the same front gate.

Incidents

Following the 2011 Tōhoku earthquake and tsunami the number 2 reactor was one of eleven nuclear reactors nationwide to be shut down automatically. It was reported on 14 March that a cooling system pump for the number 2 reactor had stopped working. Japan Atomic Power Company stated that there was a second operational pump and cooling was working, but that two of three diesel generators used to power the cooling system were out of order.

In 2007, Ibaraki Prefecture assumed possible attack tsunami height 5.7 metre, and additional seawall construction to immune to 6.1 metre tsunami height had been conducted and completed 2 days before 2011 Tōhoku earthquake and tsunami, 9 March 2011. The height of 5.4 metre tsunami attacked on 11 March to the plant. These fact are disclose to news media at the time of plant inspection by government on 13 February 2012.

During the earthquake of 11 March 2011, the Tokai-power plant suffered external power-loss, just like it happened in Fukushima. Thanks to extra and voluntarily measurements taken by the Japan Atomic Power, the reactors could still be cooled safely, and another major accident was prevented. In 2002 was concluded, based on an evaluation technology adopted by the Japan Society of Civil Engineers, that at this place tsunami waves could be expected as high as 4.86 meters. After the government of the prefecture Ibaraki in October 2007 their own calculations published, and estimated that these waves could be as high as 6 to 7 meters. Japan Atomic Power changed its wave level assumption to 5.7 meters. The reconstruction works were started in July 2009 to raise the height of the 4.9-meter protection around the plant to 6.1 meters, in order to protect the seawater pumps designed to cool an emergency diesel generator. Although most of the works were completed by September 2010, cable holes in the levee were still not fully covered. This work was scheduled to take place before around May 2011. When the tsunami did hit the Tokai plant in March, the waves were 5.3 to 5.4 meters in height, even higher than earlier estimations but still 30 to 40 centimeters lower than the last assumption. The Tokai plant suffered a loss of external power-supply like it happened in Fukushima. Even the levee was overrun in Tokai, but only one of three seawater pumps did fail, and the reactors could be kept stable and safe in cold shutdown with the emergency diesel generator cooled by the two remaining seawater pumps.

After the disaster in Fukushima a stress-test was ordered by the Japanese government, after investigations the electrical installations of the Tokai Daini reactor did not meet the earthquake-resistance standards set by the government.

Public opinion

On 11 October 2011 Tatsuya Murakami, the mayor of the village Tokai, said in a meeting with minister Goshi Hosono, that the Tokai Daini reactor situated at 110 kilometer from Tokyo should be decommissioned, because the reactor was more than 30 years old, and the people had lost confidence in the nuclear safety commission of the government.

In 2011 and 2012, about 100,000 signatures against the resumption of the plant's operation, halted since last year, were submitted to Ibaraki Gov. Masaru Hashimoto. The petition urges the prefectural government not to allow the Tokai power station to resume operation, saying, "We should not allow a recurrence of the irretrievable sacrifice and loss as experienced in the Fukushima Daiichi nuclear power plant accident".

See also

• 2011 Japanese nuclear accidents
• List of boiling water reactors
• Lists of nuclear disasters and radioactive incidents
• Tokaimura nuclear accident

External links

Media related to Tōkai Nuclear Power Plant at Wikimedia Commons