The Fukushima I Nuclear Power Plant is a nuclear power plant located in the town of Okuma in the Futaba District of Fukushima Prefecture. With 8 separate units located on site, Fukushima I is one of the largest nuclear plants in the world. Fukushima I is the first nuclear plant to be constructed and run entirely by the The Tokyo Electric Power Company.

Unit	Type	First Criticality	Electric Power
Fukushima I - 1	BWR	March 26, 1971	460 MW
Fukushima I - 2	BWR	July 18, 1974	784 MW
Fukushima I - 3	BWR	March 27, 1976	784 MW
Fukushima I - 4	BWR	October 12, 1978	784 MW
Fukushima I - 5	BWR	April 18, 1978	784 MW
Fukushima I - 6	BWR	October 24, 1979	1100 MW
Fukushima I - 7 (planned)	ABWR	October, 2013	1380 MW
Fukushima I - 8 (planned)	ABWR	October, 2014	1380 MW

Fukushima I Nuclear Power Plant
The Fukushima 1 NPP
Data
Country	Japan
Operator	Tokyo Electric Power Company
Built	1966
Start of commercial operation	March 26, 1971
Reactors
Reactors active	6 (4,696 MW)
Reactors planned	2 (2,760 MW)
Power
Total power generation in 2006	25,806 GW·h
Average annual generation (last 5 yrs)	21,436 GW·h
Net generation	781,594 GW·h

Fukushima I Nuclear Power Plant after Earthquake 2011

The company also said monitoring data suggested the air pressure level has also soared inside the container of the reactor.

Under Japanese law, a nuclear emergency must be declared if there is a release of radiation, if there is a dangerous level of water in the reactor, or if the cooling mechanisms fail. Japan declared a state of atomic power emergency instructing around 3,000 residents near a reactor in Fukushima Prefecture to evacuate. The evacuation advisory was issued for people living within a 3-kilometer radius of the plant, affecting approximately 5800 residents living near the power plant, while those living within a 10 kilometers radius were requested to stay home.

At 16:30 JST (7:30 GMT) on March 12, there was an explosion at the Fukushima I plant.

Early on March 13, an official of the Japan Nuclear and Industrial Safety Agency told a news conference that the emergency cooling system of Unit 3 had failed, spurring an urgent search for a means to supply cooling water to the reactor vessel in order to prevent a meltdown of its reactor core.

At 7:30 JST, TEPCO prepared to release radioactive steam, indicating that "the amount of radiation to be released would be small and not of a level that would affect human health".

At 12:33 JST on March 13, it was reported that Secretary Edano said "it was 'highly possible' a partial meltdown was underway" in Unit 3. The six other active Fukushima 1 and 2 reactors would be venting radioactive gas to reduce pressure. The Post blamed the hydrogen explosion in Unit 1 on the lack of electrical power to the plant, which disabled a safety device that ignites hydrogen gas before it builds to a dangerous level.

Radiation at the Fukushima No. 1 plant has risen to 882 micro sievert, compared with the legal limit of 500, said Tokyo Electric Power Co.(TEPOC), operator and owner of the Fukushima plants, on Sunday.

At an emergency press conference, Chief Cabinet Secretary Yukio Edano said that the radiation has briefly jumped to 1,204 micro sievert at the plant.

He said that fresh water has been injected into No. 3 reactor of the plant and radiation at the reactor was small and under control.

Earlier in the day, the TEPOC reported the reactor lost its ability to cool the reactor core.

It was the sixth reactor that lost the function after No. 1 and No. 2 reactors at the No. 1 plant and No.1, No.2 and No.4 at the No.2 plant had suffered the same trouble.

Fukushima I Nuclear Reactor Accidents