|Hamaoka Nuclear Power Plant|
The Hamaoka NPP from the viewing platform at the plant museum
|Status||Out of service for 8 years, 8 months|
|Construction began||June 10, 1971|
|Commission date||March 17, 1976|
|Operator(s)||Chubu Electric Power Company|
|Nuclear power station|
|Cooling source||Ensh?-nada Sea|
|Units operational||1 × 1100 MW|
1 × 1137 MW
1 × 1267 MW
|Units decommissioned||1 × 540 MW|
1 × 840 MW
|Nameplate capacity||3504 MW|
|Annual net output||0 GW·h|
|Commons||Related media on Commons|
The Hamaoka Nuclear Power Plant (, Hamaoka Genshiryoku Hatsudensho, Hamaoka NPP) is a nuclear power plant in the city of Omaezaki in Shizuoka Prefecture, on Japan's east coast, 200 km south-west of Tokyo. It is managed by the Chubu Electric Power Company. There are five units contained at a single site with a net area of 1.6 km2 (395 acres). A sixth unit began construction on December 22, 2008. On January 30, 2009, Hamaoka-1 and Hamaoka-2 were permanently shut down.
On 6 May 2011, Prime Minister Naoto Kan requested the plant be shut down as an earthquake of magnitude 8.0 or higher was estimated 87% likely to hit the area within the following 30 years. Kan wanted to avoid a possible repeat of the Fukushima nuclear disaster. On 9 May 2011, Chubu Electric decided to comply with the government request. In July 2011, a mayor in Shizuoka Prefecture and a group of residents filed a lawsuit seeking the decommissioning of the reactors at the Hamaoka nuclear power plant permanently.
Hamaoka is built directly over the subduction zone near the junction of two tectonic plates, and a major T?kai earthquake is said to be overdue. The possibility of such a shallow magnitude 8.0 earthquake in the Tokai region was pointed out by Kiyoo Mogi in 1969, 7 months before permission to construct the Hamaoka plant was sought, and by the Coordinating Committee for Earthquake Prediction (CCEP) in 1970, prior to the permission being granted on December 10, 1970. As a consequence, Professor Katsuhiko Ishibashi, a former member of a government panel on nuclear reactor safety, claimed in 2004 that Hamaoka was 'considered to be the most dangerous nuclear power plant in Japan' with the potential to create a genpatsu-shinsai (domino-effect nuclear power plant earthquake disaster). In 2007, following the 2007 Ch?etsu offshore earthquake, Dr Mogi, by then chair of Japan's Coordinating Committee for Earthquake Prediction, called for the immediate closure of the plant.
On 6 May 2011, Japanese prime minister Naoto Kan asked Chubu Electric Power Company, which operates the Hamaoka plant, to halt reactors No. 4 and No. 5, and not to restart reactor No. 3 which was then offline for regular inspection. Kan said that a science ministry panel on earthquake research has projected an 87% possibility of a magnitude-8-class earthquake hitting the region within 30 years. He said that considering the unique location of the Hamaoka plant, the operator must draw up and implement mid-to-long-term plans to ensure the reactors can withstand the projected T?kai earthquake and any triggered tsunami. Kan also said that until such plans are implemented, all the reactors should remain out of operation. Chubu Electric has decided to comply with the government request on 9 May 2011. The Yomiuri Shimbun, one of Japan's largest newspapers, criticized Kan and his request, calling it "abrupt" and noting the difficulty towards Chubu Electric's shareholders and further stated Kan "should seriously reflect on the way he made his request".Yomiuri followed up with an article that wondered how dangerous Hamaoka really was and claimed the request was "a political judgment that went beyond technological worthiness". The next day damage to the pipes inside the condenser were discovered following a leak of seawater into the reactor.
The plant has been designed to withstand an earthquake of magnitude 8.5. Sand hills of up to 15 metres (49 ft) height provide defence against a tsunami of up to 8 metres (26 ft) high, but Hamaoka currently lacks a concrete sea barrier.
On 22 July 2011 plans were unfolded to build an 18-meter-high embankment by December 2012 to prevent tsunami damage to the facility. This would protect the reactors against waves higher than the waves that occurred in the Fukushima Daiichi nuclear power plant on 11 March 2011. The barrier would also be 10 meters taller than the highest waves expected in the area in the event of 3 major earthquakes occurring at the same time. Plans were studied to build a new embankment 1.5 kilometers along the coast by the plant. Next to this a waterproof building was planned to house a backup-pump and also the wall around the reactors was extended. Overall costs of the plans: 1.3 billion dollars.
|Unit||Reactor Type||Net Capacity||Gross Capacity||Construction Start||Grid Connection||Commercial Operation||Status|
|Hamaoka-1||BWR||515 MW||540 MW||June 10, 1971||August 13, 1974||March 17, 1976||Shutdown|
January 30, 2009
|Hamaoka-2||BWR||806 MW||840 MW||June 14, 1974||May 4, 1978||November 29, 1978||Shutdown|
January 30, 2009
|Hamaoka-3||BWR-5||1056 MW||1100 MW||April 18, 1983||January 20, 1987||August 28, 1987||Shutdown|
|Hamaoka-4||BWR-5||1092 MW||1137 MW||October 13, 1989||January 27, 1993||September 3, 1993||Shutdown|
|Hamaoka-5||ABWR||1212 MW||1267 MW||July 12, 2000||April 26, 2004||January 18, 2005||Shutdown|
The plant showed stellar performance through the 1990s, however, problems that caused Unit 1 to be shut down from 2001 to present, and Unit 2 from 2005 to present significantly hurt the capacity factor figures in the recent history of the plant.
On November 7, 2001, a valve in the HPCI system of Unit 1 ruptured during a Periodical-manual-startup-test. Since this is considered a part of the ECCS, the implications reach further than the event itself, and drew into question the reliability of the emergency safety system. Unit 2 was also shut down for the purpose of investigating similar structures.
Too recent to cover the entire relevant time frame in the data above, on June 15, 2006 Unit 5 was shut down due to excessive turbine vibrations. It was discovered that a number of turbine vanes had actually completely broken off. In the turbine that failed, nearly all vanes showed fractures or cracking while the majority of the vanes of the other two low pressure turbines also showed problems. Fault for the problems was placed on Hitachi, the NSSS supplier.
In Omaezaki city, restarting or decommissioning the Hamaoka nuclear power plant became a big issue in campaigning for the 15 April 2012 mayoral election. Of three candidates, the sitting mayor Shigeo Ishihara was willing to grant a restart, after consultation with the city residents and taking into account the "lessons learned form the Fukushima crisis", if he were re-elected for a third term. Haruhisa Muramatsu, a travel agent and member of the Japanese communist party, said that the plant should be decommissioned, and the third candidate Katsuhisa Mizuno, a former city councilor, promised that the power plant would not be taken into service, if he should win the election. Ishihara was re-elected.