Fukushima Daiichi Nuclear Power Plant facts for kids

During the 2011 Fukushima nuclear emergency in Japan, three nuclear reactors were damaged by explosions.

The Fukushima Daiichi Nuclear Power Plant (also known as Fukushima I) is a nuclear power plant located in Ōkuma, Fukushima Prefecture, Japan. It was the first nuclear power plant built and operated solely by the Tokyo Electric Power Company (TEPCO).

In March 2011, serious nuclear emergencies happened at this power plant and other Japanese nuclear sites. These events made people question the safety and future of nuclear power. After the Fukushima nuclear disaster, the International Energy Agency cut its prediction for new nuclear power plants by half for the period up to 2035. The plant is now shut down.

Understanding the Nuclear Reactors

This picture shows a typical Mark I containment structure, like those used in units 1 to 5.

The nuclear reactors at Fukushima Daiichi were built by different companies. General Electric supplied units 1, 2, and 6. Toshiba supplied units 3 and 5, and Hitachi supplied unit 4. The company Ebasco designed the buildings for the General Electric units. All the construction work was done by Kajima.

Since September 2010, Unit 3 used a special type of fuel called mixed-oxide (MOX) fuel. Most of the units (1-5) had a "Mark 1" type of containment structure, which looks a bit like a light bulb. Unit 6 had a "Mark 2" type.

Unit 1 was a 439-megawatt (MW) boiling water reactor (BWR3). It was built in July 1967 and started making electricity on March 26, 1971. It was supposed to close down in March 2011. However, it was badly damaged during the 2011 Sendai earthquake and tsunami.

When Unit 1 was built, it had high safety levels for earthquakes. But by 2011, it was old and not as up-to-date as newer plants. No one expected such a strong earthquake to hit Japan.

The 2011 Fukushima Nuclear Disaster

In March 2011, a powerful earthquake and tsunami hit Japan. Soon after, the Japanese government told people to leave the area around the Fukushima I plant. They also declared a local emergency. Experts worried about a meltdown at Unit 1. The next day, a government official said a partial meltdown at Unit 3 was "highly possible."

Units 1, 2, and 3 had automatically shut down because of the earthquake. Units 4, 5, and 6 were already shut down for maintenance. The plant's back-up generators, which provide power for cooling, were damaged by the tsunami. They started at first but stopped working after about an hour.

Japan's government declared a nuclear emergency because the cooling systems failed. Cooling is always needed to remove heat from a nuclear plant, even after it's shut down, due to ongoing atomic reactions. Hundreds of Japanese troops brought generators and batteries to the site to help.

Damage to Reactors and Generators

After the back-up diesel generators broke down, emergency batteries ran out after about eight hours. More batteries and mobile generators were brought in, but connecting them to power the water pumps was difficult. The usual connection points for the diesel generators were in a basement area that had been flooded by the tsunami.

Here's a summary of the damage reported on March 21, 2011:

Later, Unit 4 at the nearby Fukushima II Nuclear Power Station also shut down due to its safety systems. Even though outside power became available, the damage at the Fukushima Daiichi plant was very severe.

Long-Term Safety Plans

Using Boron

The Tokyo Fire Department sent special fire trucks with tall water towers to Fukushima to help.

Officials considered using boric acid or other boron materials to help absorb neutrons in the spent fuel pools. Neutrons are tiny particles inside atoms. Boron helps stop nuclear reactions. France even sent 95 tons of boron to Japan in March 2011. Boric acid was put into the reactor cores, but it's not clear if it was also used when water was sprayed on the spent fuel pools.

A "Sarcophagus Tomb" and Liquid Metal

On March 18, 2011, a spokesman for Japan's nuclear agency was asked about burying the damaged reactors in a sand and concrete tomb, similar to what was done after the Chernobyl disaster. He said this idea was "in the back of our minds," but the main focus was on cooling the reactors first.

After the Chernobyl disaster, workers used sand and clay to cover the plant. However, these materials trapped heat inside. So, for Fukushima, experts thought about using a non-evaporating coolant, like a liquid metal, first. This would cool everything down. After that, a structure like the "sarcophagus tomb" built at Chernobyl could be considered.

Impacts of the Disaster

The nuclear emergencies at Fukushima Daiichi and other facilities made people around the world think differently about nuclear power. Many countries started to review the safety of their own nuclear reactors. The crisis also made people doubt how quickly new nuclear power plants would be built globally. The International Energy Agency cut its prediction for new nuclear power plants by half for the period up to 2035.

Media

Images for kids

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  Aerial view of the plant area in 1975, showing separation between Units 5 & 6, and the majority of the complex ・Unit 6: direction of Sōma ・Unit 4: direction of Iwaki

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  Plant still under construction circa 1971

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  Electricity generation for the Fukushima I

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  Three of the reactors at Fukushima Daiichi overheated, causing meltdowns that eventually led to explosions, which released large amounts of radioactive material into the air.

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  IAEA Experts at Fukushima Daiichi Nuclear Power Plant Unit 4, 2013

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  Prime Minister Yoshihide Suga inspected the Daiichi Nuclear Power Plant on September 26, 2020

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  Aerial view of the Fukushima I plant area in 1975, showing sea walls and completed reactors

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  Closeup of Units 4, 3, 2 and 1

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  Major buildings

See also

In Spanish: Central nuclear Fukushima I para niños