Fukushima Daiichi Nuclear Power Plant
|Fukushima Daiichi Nuclear Power Plant|
The Fukushima Daiichi Nuclear Power Plant in 2002
The Fukushima Daiichi Nuclear Power Plant (福島第一原子力発電所 Fukushima
First commissioned in 1971, the plant consists of six
The March 2011 disaster disabled the reactor cooling systems, leading to releases of radioactivity and triggering a 30 km evacuation zone surrounding the plant; the releases continue to this day. On April 20, 2011, the Japanese authorities declared the 20 km evacuation zone a no-go area which may only be entered under government supervision.
In April 2012, Units 1-4 were decommissioned. Units 2-4 were decommissioned on April 19, while Unit 1 was the last of these four units to be decommissioned on April 20 at midnight.[
The sister nuclear plant
The reactors for Units 1, 2, and 6 were supplied by
Unit 1 is a 460 MW
Unit 1 was designed for a
The reactor's emergency diesel generators and DC batteries, crucial components in helping keep the reactors cool in the event of a power loss, were located in the basements of the reactor turbine buildings. The reactor design plans provided by General Electric specified placing the generators and batteries in that location, but mid-level engineers working on the construction of the plant were concerned that this made the backup power systems vulnerable to flooding. TEPCO elected to strictly follow General Electric's design in the construction of the reactors.
The plant is on a bluff which was originally 35 meters above sea level. During construction, however, TEPCO lowered the height of the bluff by 25 meters. One reason for lowering the bluff was to allow the base of the reactors to be constructed on solid bedrock in order to mitigate the threat posed by earthquakes. Another reason was the lowered height would keep the running costs of the seawater pumps low. TEPCO's analysis of the tsunami risk when planning the site's construction determined that the lower elevation was safe because the sea wall would provide adequate protection for the maximum tsunami assumed by the design basis. However, the lower site elevation did increase the vulnerability for a tsunami larger than anticipated in design.
The Fukushima Daiichi site is divided into two reactor groups, the leftmost group - when viewing from the ocean - contains units 4, 3, 2 and 1 going from left to right. The rightmost group - when viewing from the ocean - contains the newer units 5 and 6, respectively, the positions from left to right. A set of seawalls protrude into the ocean, with the water intake in the middle and water discharge outlets on either side.
Units 7 and 8 were planned to start construction in April 2012 and 2013 and to come into operation in October 2016 and 2017 respectively. The project was formally canceled by TEPCO in April 2011 after local authorities questioned the fact that they were still included in the supply plan for 2011, released in March 2011, after the accidents. The company stated that the plan had been drafted before the earthquake.
|Net power||Start construction||First criticality||Commercial operation||Shutdown||NSSS||Builder|
|439 MW||July 25, 1967||October 10, 1970||March 26, 1971||May 19, 2011|
|760 MW||June 9, 1969||May 10, 1973||July 18, 1974||May 19, 2011||General Electric||Ebasco||Kajima|
|760 MW||December 28, 1970||September 6, 1974||March 27, 1976||May 19, 2011||Toshiba||Kajima|
|760 MW||February 12, 1973||January 28, 1978||October 12, 1978||May 19, 2011||Hitachi||Kajima|
|760 MW||May 22, 1972||August 26, 1977||April 18, 1978||December 17, 2013||Toshiba||Toshiba||Kajima|
|1067 MW||October 26, 1973||March 9, 1979||October 24, 1979||December 17, 2013||General Electric||Ebasco||Kajima|
|7 (planned)||1380 MW||Canceled 04/2011||Planned 10/2016|
|8 (planned)||ABWR||1380 MW||Canceled 04/2011||Planned 10/2017|
The Fukushima Daiichi plant is connected to the power grid by four lines, the 500 kV Futaba Line (双葉線), the two 275 kV Ōkuma Lines (大熊線) and the 66 kV Yonomori Line (夜の森線) to the Shin-Fukushima (New Fukushima) substation.
The Shin-Fukushima substation also connects to the Fukushima Daini plant by the Tomioka Line (富岡線). Its major connection to the north is the Iwaki Line (いわき幹線), which is owned by
The plant reactors came online one at a time beginning in 1970 and the last in 1979. From the end of 2002 through 2005, the reactors were among those shut down for a time for safety checks due to the
On April 5, 2011, TEPCO vice president Takashi Fujimoto announced that the company was canceling plans to build Reactors No. 7 and 8. On May 20 TEPCO's board of directors' officially voted to decommission Units 1 through 4 of the Fukushima Daiichi nuclear power plant and to cancel plans to build units 7 and 8. It refused however to make a decision regarding units 5 and 6 of the station or units 1 to 4 of the Fukushima Daini nuclear power station until a detailed investigation is made. In December 2013 TEPCO decided to decommission the undamaged units 5 and 6; they may be used to test remote clean-up methods before use on the damaged reactors.