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TEPCO Fukushima Daiichi Nuclear Power Station accident in 2011

2019年4月19日更新 Update

Status

The Great East Japan Earthquake occurred on 11 March, 2011. A massive earthquake triggered tsunami which damaged the coastal areas of the Tohoku District, including Fukushima Prefecture.

Damage at the Power Station

Earthquake　Damage

The Earthquake triggered the emergency stop of the operating reactors(1 - 3)
Emergency power supplies were triggered, starting fuel cooling operations for reactors 1-6

Tsunami　Damage

Tsunami caused flooding of the emergency power supplies including batteries, which lead to a loss of power for reactors 1-5
Fuel melted in reactors 1-3 and radioactive substances were released into the air
Hydrogen explosions caused damage to the buildings containing reactors 1, 3, and 4.
Cooling function was lost for the spent fuel pools of reactors 1-6.

Photo:Power Station struck by tsunami
Power Station struck by tsunami

Damage Response

Fuel in Reactors 1-3 were cooled using water injection, and reached a stable condition
Reactor 5 resumed cooling operations using the emergency power facilities of Reactor 6.
Cooling of the spent fuel pools was resumed using pumping vehicles and other temporary equipment.

Fukushima Daiichi NPS - Situation after Tsunami Disaster

Reactor No.	Operational Condition	Reactor fuel （Unit：rod）	Fuel in Pool （Unit:rod）	ACPower Source	DC Power Source	Emergency AC Power Source
1	Operating	400	392	Unusable	Unusable	Unusable
2	Operating	548	615	Unusable	Unusable	Unusable
3	Operating	548	566	Unusable	Partially usable	Unusable
4	Suspended	0	1,535	Unusable	Unusable	Unusable
5	Suspended	548	994	Unusable	Usable	Unusable
6	Suspended	764	940	Unusable	Usable	Usable

The site shortly after the accident

Fukushima Daiichi NPS　（March　２０１１）

Current situation of units

No　３

Reactor decommissioning operations are currently underway for Units 1-6 at the Fukushima Diichi NPS
(As of September 2017)

Temperatures inside containment vessel air conditioners

Reactor temperatures are stable at below 45℃

Real-time data : 　Parameters related to the plants at Fukushima Daiichi Nuclear Power Station (TEPCO webwite)

Temperatures of reactors

Amount of radio cesium per hour dispersed from nuclesr reactor buildings

Concentrations of radioactive substances are being monitored and no signs of recriticality have been observed.

radioactive cesium

Current Situation（2017）of the site of Fukushima Daiichi NPS

1F site

Marine monitoring

TEPCO is conducting marine monitoring in order to confirm the impact on the environment caused by the radioactive substances released from the F1NPS. There are also many measures in place for the processing and reduction of contaminated water.

TEPCO is making efforts to confirm the environmental impact of radioactive substances released from the F1NPS

Radiation levels inside and outside the power station are being measured.
In spite of the leak of contaminated water, no significant increase in radiation levels has been observed outside the port.
Radiation levels of sea water are well below standards for drinking water set by WHO.

Image : Marine monitoring 1