Diablo Canyon Nuclear Power Plant: The WikiBook/Fukushima Daini Nuclear Power Plant

The nihongo|Fukushima II Nuclear Power Plant|福島第二原子力発電所|Fukushima Dai-Ni Genshiryoku Hatsudensho|extra=Fukushima II NPP, 2F}}, or Fukushima Dai-ni (dai-ni means "number two"), is a nuclear power plant located on a 1,500,000acre site Tepco site in Fukushima Prefecture, Japan. The Tokyo Electric Power Company (TEPCO) runs the plant.

After the 2011 Tōhoku earthquake and tsunami, the four reactors at Fukushima II scrammed (automatically shut down).

Japan's worst nuclear accident occurred at TEPCO's Fukushima I Nuclear Power Plant, or Fukushima Dai-ichi, an 11.5|km boundary to boundary road journey to the north, after the same March 11 earthquake.

Description
All reactors in the Fukushima II Nuclear Power Plant are Boiling Water Reactor|BWR-5 type with electric power of 1,100 MW each (net output: 1,067 MW each).

The reactors for units 1 and 3 were supplied by Toshiba, and for units 2 and 4 by Hitachi. Units 1–3 were built by Kajima while the unit 4 was built by Shimizu Corporation|Shimizu and Takenaka Corporation|Takenaka. The design basis accident for an earthquake was between 0.42 g-force|g (4.15 m/s2) and 0.52 g (5.12 m/s2) and for a tsunami was 5.2 m.

Electrical connections
The Fukushima Daini plant is connected to the rest of the power grid by the Tomioka Line (富岡線) to the Shin-Fukushima (New Fukushima) substation.

1989 incident
In January 1989, an impeller blade on one of the reactor coolant pumps in Unit 3 broke at a weld, causing a large amount of metal debris to flow throughout the primary loop. As a result, the reactor was shut down for a considerably long time.

2011 earthquake and tsunami
The March 11, 2011 Tōhoku earthquake and tsunami|2011 Tōhoku earthquake resulted in maximum horizontal ground accelerations of 0.21 g (2.10 m/s2) to 0.28 (2.77 m/s2) at the plant site, which is well below the design basis. All four units were Scram|automatically shut down immediately after the earthquake, according to Nuclear Engineering International, and the diesel engines were started to power the reactor cooling. TEPCO estimated that the tsunami that followed the earthquake and inundated the plant was 14 meters high which is more than twice the designed height. This flooded the pump rooms used for the essential service water system transferring heat to the sea, the ultimate heat sink of the reactors. While the cooling system for unit 3 was undamaged, the other reactors were affected. The cooling systems remained operational, but heated up due to the lack of a heat sink. The high pressure coolant injection (HPCI) system (powered by reactor steam) was used as additional cooling. On March 12, the Nuclear reactor technology|cooling system for three reactors (numbers 1, 2 and 4) at the torus had topped 100 °C between 05:30 and 06:10 Japan Standard Time|JST, rendering all cooling systems (depending on temperature difference between the torus and the reactor) ineffective.

Image:Fukushima_accidents_overview_map.svg|thumb|328px|Fukushima I and II Nuclear Accidents Overview Map showing evacuation and other zone progression and selected radiation levels.

The coolant systems in the pump room were repaired and activated in Units 1, 2 and 4 in the days following the emergency shutdown after cooling could recommence Coolant temperatures below 100 °C (cold shutdown) were reached in reactor 2 about 34 hours after the emergency shut down (SCRAM). Reactors 1 and 3 followed at 1:24 and 3:52 on March 14 and Reactor 4 at 7:00 on March 15. The loss of cooling water at reactors 1, 2 and 4 was classified a level 3 on the International Nuclear Event Scale (serious incident) by Japanese authorities as of March 18.

Officials made preparations for release of pressure from the plant on March 12. As of March 20, however, no pressure release had been reported.

An evacuation order was issued to people living within of the plant, subsequently expanded to.

Air traffic was restricted in a radius around the plant, according to a NOTAM. These zone were superseded by the 20 km evacuation and 30 km no-fly zones around Fukushima I on March 12 and 15, respectively.

TEPCO announced that a worker who had been seriously injured by the earthquake, and trapped in the crane operating console of the exhaust stack was transported to the ground at 5:13 p.m. and confirmed dead at 5:17 p.m.

Smoke was escaping from one of the buildings on 30 March 2011. It was emitted from equipment which supplies electrical power to a motor pump that collects outdoor water and stopped after workers disconnected the motor.

By March 15th, all four reactors of Fukushima II reached cold shutdown which remained non-threatening through April.