Genkai Nuclear Power Plant

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Genkai Nuclear Power Plant
Genkai Nuclear Power Plant (in the distance)
Coordinates33°30′56″N 129°50′14″E / 33.51556°N 129.83722°E / 33.51556; 129.83722Coordinates: 33°30′56″N 129°50′14″E / 33.51556°N 129.83722°E / 33.51556; 129.83722
Construction beganSeptember 15, 1971 (1971-09-15)
Commission dateOctober 15, 1975 (1975-10-15)
Owner(s)Kyūshū Electric Power Company
Operator(s)Kyushu Electric Power Company
Nuclear power station
Reactor typePWR
Cooling sourceKorea Strait
Power generation
Units operational1 x 559 MW
2 x 1180 MW
Units decommissioned1 x 559 MW
Nameplate capacity2,919 MW
Capacity factor82.1%
Annual net output21,000 GW·h
External links
CommonsRelated media on Commons

The Genkai Nuclear Power Plant (玄海原子力発電所, Genkai genshiryoku hatsudensho, Genkai NPP) is located in the town of Genkai in the Higashimatsuura District in the Saga Prefecture in Japan. It is owned and operated by the Kyūshū Electric Power Company.

The reactors were all built by Mitsubishi Heavy Industries and are of the 2 and 4-loop M type pressurized water reactor.[1] Unit 3 has been selected as a special Plutonium fuel test case.[clarification needed] The plant is on a site with a total of 0.87 square kilometers.[2] Saga does not lie on a fault line and receives the fewest earthquakes in Japan.[citation needed]


2011 restart, controversy and reclosure[edit]

In early 2011, Units 2 and 3 were suspended for routine maintenance. Following the Tohoku earthquake, Kyushu Electric voluntarily sought reapproval with the town of Genkai and Saga prefecture to make sure that there would be no objection to turning the reactors back on. Negotiations extended several months past the normal restart time.[3] Because Units 2 and 3 were not restarted for the summer, Kyushu was expected to have an electricity shortage and only be able to meet 85% of normal summer needs.[4]

After the mayor of Genkai extended his approval, the larger consensus of Saga prefecture was sought. A meeting was organized to inform the people in the district and to get permission to restart the reactors. The meeting was broadcast live on TV and the internet, and viewers were invited to submit their opinions by e-mail or fax. Later, the Japanese Communist Party paper Akahata learned that the board of the Kyushu Electric Power Company had requested employees of the plant to send emails to this meeting encouraging the restart. Later it was admitted that not only employees of the utility but the workers of 4 affiliated firms too, more than 1,500 people in total, received such requests.[5]

At the same time as this crisis broke, Prime Minister Naoto Kan unexpectedly requested more stress tests of the reactor. This seemed to imply, despite the earlier assurances of the national government, that the routine maintenance and additional post-earthquake tests had not been sufficient to clear the reactors for restart, and that the mayor of Genkai had therefore approved the restart without complete information about the reactors' safety. As a result, the mayor rescinded his approval.[6] The governor of Saga, who had not yet given his approval, also expressed surprise.[7] Chief Cabinet Secretary Yukio Edano flew to Saga prefecture immediately to apologize to the governor in person.[8] On July 9, Kan also apologized.[9]

On 2 November 2011 the No. 4 reactor, the newest model, was restarted. The reactor was the first in Japan to resume operations after the March accident at Fukushima Daiichi nuclear plant. In December the reactor was stopped again for a regular inspection.[10][11]

On 9 December 2011 a leak was discovered in the cooling system of reactor No. 3. An alarm was triggered when the temperature rose to over 80C at the base of one of the pumps, but this alarm did not indicate the leakage of 1.8 cubic meters of radioactive water, because the water did not go outside the purification system. After the leak was discovered Kyushu Electric failed to report the troubles in full to the local government. Only the failure of the pumps in the system for the No. 3 reactor were mentioned.[12]

As of September 2012, Saga prefecture was aiming to have the Genkai reactors permanently retired after 40 years of operation, meaning that reactor 1 would close in 2015.[13] A citizens' group sued to have the reactors shut down immediately, but the state argued that there is no process in Japanese law that could cause an industry's operations to cease through a civil, rather than criminal, action.[14]

In February 2019 the Kyūshū Electric Power Company announced that unit 2 would be decommissioned ahead of its 40-year end of life in 2021, alongside the already agreed decommissioning of unit 1. Neither unit had operated since 2011.[15]

Units 3 and 4 restart[edit]

On 19 January 2017, units 3 and 4 received from NRA the confirmation of meeting the new regulatory standards.[16] In February the town council voted in favor of re-running. In March, the Mayor, Tohru Kishimoto confirmed at a press conference approval to restart. The Mayor asked that storage of spent nuclear fuel in the same nuclear plant would be limited in time as possible. The Mayor stated that the restart is expected in summer as the early date.[17]

On 23 March 2018 unit 3 was restarted after seven years out of production. The reactor was briefly shut down again only a week later, due to a steam leakage. According to the owner Kyushu Electric Power of the reactor there had been no radioactive pollution emitted.[18] The reactor was restarted again on April 18.[19] Unit 4 was restarted in June 2018.[20]

Reactors on site[edit]

All reactors at the Genkai plant use low enriched (3-4%) Uranium dioxide fuel. Genkai 1 belongs to the first generation of PWR built by Mitsubishi, based on imported technology. Genkai 2 is the first reactor of the second generation of Mitsubishi's PWR, fully using its own technology. Genkai 3 and 4 represent the third generation of Mitsubishi's PWR, with further improvements.[1]

Name Reactor Type First Criticality Power Rating Thermal Power Core Tonnage # of Fuel Assemblies Capital Costs
(billion yen)
Genkai - 1 PWR 1975/02/14 559 MW 1650 MW 48 tons 121 54.5
Genkai - 2 PWR 1980/06/03 559 MW 1650 MW 48 tons 121 123.6
Genkai - 3 PWR 1993/06/15 1180 MW 3423 MW 89 tons 193 399.3
Genkai - 4 PWR 1996/11/12 1180 MW 3423 MW 89 tons 193 324.4

See also[edit]


  1. ^ a b "Our History - MNES". Retrieved 7 February 2017.
  2. ^ Kyuden (Japanese). Genkai Plant Outline.
  3. ^ "Archived copy". Archived from the original on 2011-06-09. Retrieved 2011-06-23.CS1 maint: archived copy as title (link)
  4. ^ "Kyushu Elec warns of summer power shortage as 2 reactors shut". Reuters. 19 May 2011. Archived from the original on 15 September 2017. Retrieved 15 September 2017.
  5. ^ NHK-world (8 July 2011) Systematic involvement suspected in Genkai scandal Archived 2011-08-10 at the Wayback Machine
  6. ^ Ito, Masami (8 July 2011). "Genkai mayor withdraws OK for two reactors' restart". The Japan Times. Archived from the original on 15 September 2017. Retrieved 15 September 2017.
  7. ^ "Genkai mayor retracts approval of reactor restarts after 'surprise' stress tests". Archived from the original on 2011-07-12.
  8. ^ "Mayor nixes Japan plant reactivation". The Yomiuri Shimbun. 8 July 2011. Retrieved 15 September 2017 – via asiaone.
  9. ^ "Kan apologizes for confusion over restart of reactors". Kyodo News. 9 July 2011. Retrieved 15 September 2017.
  10. ^ NHK-world (2 November 2011) Genkai reactor resumes power generation
  11. ^ JAIF (2 November 2011) Earthquake-report 253 Archived 2013-05-21 at the Wayback Machine
  12. ^ The Daily Mainichi News (10 December 2011)Radioactive water leaks at Kyushu Electric's Genkai reactor
  13. ^ 佐賀知事が廃炉容認、玄海1号機運転40年で
  14. ^ 「史上最悪の公害事件」 玄海原発操業停止訴訟
  15. ^ "Genkai 2 to be decommissioned". World Nuclear News. 13 February 2019. Retrieved 15 February 2019.
  16. ^ "Kyushu gets approval for Genkai upgrade plans". World Nuclear Association. 20 January 2017. Retrieved 25 January 2017.
  17. ^ "地元町長が再稼働に同意=玄海原発、九電社長に電話で-佐賀 - Local town mayor agrees to restart of Genkai nuclear power plant, call to president Ku Den - Saga". (in Japanese). Jiji Press. 7 March 2017. Archived from the original on 19 March 2017. Retrieved 17 March 2017.
  18. ^ "Steam leak found at Genkai nuclear power plant- News - NHK WORLD - English". NHK WORLD. Archived from the original on 4 April 2018. Retrieved 4 April 2018.
  19. ^ "OE Information related to Genkai Unit 3 restart". Retrieved 1 May 2018.
  20. ^ "Genkai unit 4 supplying power again". Retrieved 22 June 2018.

External links[edit]