Fukushima nuclear accident (Unit 1 Reactor)

Fukushima Daiichi (Unit 1 Reactor)
Fukushima Unit 1 before its explosion.
General information
Status	Severely damaged
Type	Reactor
Location	Ōkuma and Futaba, Fukushima, Japan
Construction started	25 July 1967[1]
Completed	10 October 1970[1]
Opened	26 March 1971[1]
Closed	19 May 2011 (shutdown)[1]

External videos
24 hours live camera for Fukushima Daiichi nuclear disaster on YouTube, certified by Tokyo Electric Power Co. Inc.

The Fukushima Daiichi (Unit 1) reactor, was 1 out of 4 reactors seriously affected during the Fukushima Daiichi nuclear disaster (福島第一原子力発電所事故, Fukushima Dai-ichi) on 11 March 2011.^[2][3] Overall, the plant had 6 separate boiling water reactors originally designed by General Electric (GE), and maintained by the Tokyo Electric Power Company (TEPCO). At the time of the earthquake, Reactor 4 had been de-fueled while 5 and 6 were in cold shutdown for planned maintenance.^[4] Unit 1 was immediately shut down automatically after the earthquake, and emergency generators came online to control electronics and coolant systems. However, the tsunami following the earthquake quickly flooded the low-lying rooms in which the emergency generators were housed. The flooded generators failed, cutting power to the critical pumps that must continuously circulate coolant water through the reactor core. While the government tried pumping fresh water into the core, it was already too late due to overheat.^[5] In the hours and days that followed, Unit 1 experienced a full meltdown.^[6][7]

In the intense heat and pressure of the melting Unit 1 reactor, a reaction between the nuclear fuel metal cladding and the remaining water surrounding it produced explosive hydrogen gas. As workers struggled to cool and shut down Unit 1, it exploded the following day (12 March).^[8][9] Eventually the reactor was stabilized by switching from freshwater to seawater which was pumped into the reactor. As a whole, the Japanese government estimated that the total amount of radioactivity released into the atmosphere was approximately one-tenth as much as was released during the Chernobyl disaster.^[10] The Japanese government and TEPCO were later criticized in the foreign press for poor communication with the public and improvised cleanup efforts.^[11][12][13] It's estimated that decommissioning the reactors as a whole will take 30–40 years to complete.^[14]