Onagawa Nuclear Power Plant

Onagawa Nuclear Power Plant
The Onagawa Nuclear Power Plant
Location of Onagawa Nuclear Power Plant
Country	Japan
Coordinates	38°24′04″N 141°29′59″E / 38.40111°N 141.49972°E / 38.40111; 141.49972Coordinates: 38°24′04″N 141°29′59″E / 38.40111°N 141.49972°E / 38.40111; 141.49972
Construction began	July 8, 1980 (1980-07-08)
Commission date	June 1, 1984 (1984-06-01)
Operator(s)	Tohoku Electric Power Company
Reactor information
Reactors operational	1 x 524 MW 2 x 825 MW
Power generation information
Annual generation	5,283 GW·h
Net generation	157,545 GW·h
Website Japanese version, English version
As of July 25, 2007

The Onagawa Nuclear Power Plant (女川原子力発電所, Onagawa ( pronunciation) genshiryoku hatsudensho^?, Onagawa NPP) is a nuclear power plant located on a 1,730,000 m² (432 acres) site^[1] in Onagawa in the Oshika District and Ishinomaki city, Miyagi Prefecture, Japan. It is managed by the Tohoku Electric Power Company. It was the most quickly constructed nuclear power plant in the world.^{[citation needed]}

The Onagawa-3 unit was used as a prototype for the Higashidori Nuclear Power Plant.^{[citation needed]}

The plant conforms fully to ISO 14001, a set of international environmental management standards. The plant's waste heat water leaves 7 degrees Celsius higher than it came in and is released 10 meters under the surface of the water, in order to reduce adverse effects on the environment^[2] All the reactors were constructed by Toshiba.^[3]

Reactors on Site

Unit	Type	Start of Operation	Electric Power
Onagawa - 1	BWR	June 1, 1984	524 MW
Onagawa - 2	BWR	July 28, 1995	825 MW
Onagawa - 3	BWR	January 30, 2002	825 MW

Unit 1

Shut down manually on 25 February 2005 because it was determined that the reactor containment leaked small amounts of nitrogen. The unit was restarted once Nuclear and Industrial Safety Agency was satisfied that the countermeasures taken by the plant operator to prevent a reoccurrence were adequate.^[4]

Unit 2

• May 2006 it was confirmed that a pipe was leaking due to debris damage.
• June 7, 2006 Difficulties with pressure control prompted further inspections.
• July 7, 2006 METI and the Nuclear and Industrial Safety Agency determined that the plant's performance was not satisfactory.^{[citation needed]}

Unit 3

• July 7, 2006 Due to pipe integrity concerns the reactor was shut down.
• November 25, 2006 Following repairs the reactor was restarted.
• March 11, 2011 2011 Tōhoku earthquake damaged the turbines after a fire broke out and was shut down.

Incidents

2001

Small fire in the administrative offices. Did not affect functioning of the plant.

2005

The Onagawa Nuclear Power Plant was affected by the 2005 Miyagi earthquake and recorded vibrations above what the plant was designed for. Analysis after the event, however, found no damage to the reactor systems. Some people reported seeing smoke come from the plant after the earthquake and reported it, thinking that it indicated an accident, but the smoke was actually produced by the backup diesel generators.^{[citation needed]}

2011

On April 8, 2011, a leak of radioactive water spilled from pools holding spent nuclear fuel rods following the 2011 Tōhoku earthquake , the nuclear safety agency said, was reported by Kyodo News [1]

A fire from the turbine section of the plant following the 2011 Tōhoku earthquake was reported by Kyodo News.^[5]

On March 13, 2011, levels of radiation on site reached 21μSv/hour, a level at which Tohoku Electric Power Company were mandated to declare state of emergency, and they did so at 12:50, declaring the lowest-level such state. Within 10 minutes the level had dropped to 10μSv/hour.^[6][7][8] The Japanese authorities assume the temporarily heightened values were due to radiation from the Fukushima I nuclear accidents and not from the plant itself.^[9][10] On March 13 20:45 UTC, the IAEA announced that radiation levels at the Onagawa plant had returned to normal background levels.^[9]

The three units remain in cold shutdown since the earthquake of 11 March. Two hundred people who lost their homes to the tsunami took refuge in the plant.^[11] The April 7th aftershock damaged 2 of the 3 external power lines to the plant but cooling was maintained through the third line.^[12]

See also

	Japan portal
	Nuclear technology portal
	Energy portal

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

References

1. ^ Tohoku Power. The Onagawa Plant (information).
2. ^ Tohoku Power. Onagawa Nuclear Power Station.
3. ^ Toshiba. Nuclear List of Delivered Units.
4. ^ http://www2.jnes.go.jp/atom-db/en/trouble/individ/power/e/e20050225/index.html Manual Shutdown of Onagawa NPP Unit-1
5. ^ "Fire at Tohoku Elec Onagawa nuclear plant". Kyodo | Reuters. Reuters. 2011. http://www.reuters.com/article/2011/03/11/quake-japan-nuclear-idUSLHE7E801E20110311. Retrieved March 13, 2011. 
6. ^ "Contamination checks on evacuated residents". world-nuclear-news.org. 2011. http://www.world-nuclear-news.org/RS-Contamination_found_on_evacuated_residents-1303114.html. Retrieved March 13, 2011. "A technical emergency was declared at 12.50 pm today at the Onagawa nuclear power plant after radiation levels in the plant site reached 21 microSieverts per hour. At this level plant, owner Tohoku Electric Power Company is legally obligated to inform government of the fact. Within just ten minutes, however, the level had dropped to 10 microSieverts per hour." 
7. ^ "IAEA update on Japan Earthquake". iaea.org. March 13, 2011. http://www.iaea.org/newscenter/news/tsunamiupdate01.html. Retrieved March 13, 2011. "Japanese authorities have also informed the IAEA that the first (i.e., lowest) state of emergency at the Onagawa nuclear power plant has been reported by Tohoku Electric Power Company. The authorities have informed the IAEA that the three reactor units at the Onagawa nuclear power plant are under control. As defined in Article 10 of Japan's Act on Special Measures Concerning Nuclear Emergency Preparedness, the alert was declared as a consequence of radioactivity readings exceeding allowed levels in the area surrounding the plant. Japanese authorities are investigating the source of radiation." 
8. ^ Chico Harlan, Steven Mufson: Japanese nuclear plants' operator scrambles to avert meltdowns. The Washington Post, March 11, 2011
9. ^ ^{a b} "Fukushima Nuclear Accident Update Log - Updates of 13 March 2011". iaea.org. 2011. http://www.iaea.org/newscenter/news/2011/fukushima130311.html. Retrieved March 13, 2011. 
10. ^ "Sea water injected into troubled Fukushima power plant | The Manila Bulletin Newspaper Online". mb.com.ph. 2011 [last update]. http://www.mb.com.ph/articles/309172/sea-water-injected-troubled-fukushima-power-plant. Retrieved March 13, 2011. "Meanwhile, radiation monitored at the Onagawa nuclear power plant in Miyagi Prefecture on the Pacific coast shot up on Sunday, Tohoku Electric Power Co. said, adding that it was likely caused by radioactive substances let out at the troubled Fukushima No. 1 nuclear power plant in Fukushima Prefecture." 
11. ^ Ito, Shingo (Agence France-Presse/Jiji Press), "Neighbors of Miyagi reactor mull getting out", Japan Times, 1 April 2011, p. 3.
12. ^ Japan earthquake today: Tsunami warning lifted, but Fukushima evacuated, Christian Science Monitor, Gavin Blair, April 7, 2011

External links

• Onagawa Nuclear Power Plant site c/o Tohoku Electric Co. 東北電力・女川原子力発電所
• IAEA Alert Log