Fukushima nuclear accident, Japan

Fukushima nuclear accident

Fukushima nuclear accident

On March 11, 2011 in Fukushima occurred one of the worst nuclear accidents in history after the Chernobyl nuclear accident.

A 8.9 magnitude earthquake off the northwest coast of Japan and a subsequent tsunami severely affected Dahiichi Fukushima nuclear plant on the northeast coast of Japan.

At the time of the nuclear accident at the Fukushima reactors had 6. Reactors 1, 2 and 3 were operating while nuclear reactors 4, 5 and 6 were unemployed for maintenance.

After the earthquake Fukushima reactors that were still running is automatically stopped. To cool the reactors, in this type of nuclear power plants, electric power is needed, usually from the network, but because of the earthquake the grid did not work. They began to run diesel engines to generate this electricity but also broke down at 15:41 when the tsunami struck. At this point begin cooling problems with reactor core meltdown risk. Later the meltdown of reactors 1, 2 and 3 are confirmed.

The nuclear power plant suffered from the earthquake explosions following day. In the reactor 4 multiple indendios declared. In addition, some plants spent fuel stored in the spent fuel pools, which still lie emits large heat began to overheat because the water was evaporating pools of these reducing its water level.

Explosion at the Fukushima Daiichi nuclear power plant. Nuclear accident magnitude 7 on the INES scale.

The fear of radiation leaks prompted authorities to evacuate first Japana within twenty kilometers around the plant. Later this rado was gradually expanded to 40km. The plant workers suffered radiation exposicióna repeatedly and were temporarily evacuated at various times.

The accident was initially considered a level 4 in International Nuclear Event Scale (INES scale, by its acronym in English). Although these days the situation worsened and the nuclear accident eventually reached level 7, the same as the accident at the Chernobyl nuclear power plant.


Timeline of the Fukushima nuclear accident

Special events reported daya day at the Fukushima nuclear power plant after the earthquake.

Fukushina. Friday, 03/11/2011

An earthquake of 8.9 magnitude on the Richter scale near the north-eastern coast of Japana 14:46 (Japan time) occurs. This represents the strongest earthquake in the history of the strongest Japóny fifth of the planet since records began.

The earthquake triggered a huge tsunami. Desupés few hours the first waves reached 10 meters off the coast of Fukushima.

Automatically all nuclear reactors in the region may stand and as foreseen in the design of these nuclear power plants for these situations.

At the time, Japan had 54 nuclear reactors in operation producing approximately 29% of its electricity.

Expert working in the Fukushima nuclear power plant after the accident.

First, the state of emergency was declared in the 11 nuclear power plants in Japan in the prefectures of Miyagi, Fukushima and Ibaraki.

The following nuclear units were stopped:

Onagawa nuclear plant

Three units is automatically stopped.

Fukushima Daiichi Nuclear Power Plant.

Units 1, 2 and 3 is automatically stopped. The units 4, 5 and 6 were periodic maintenance shutdowns.

Cooling of this plant requires electricity and diesel machines are ready to generate electricity if the supply is cut. Though initially there was no electricity and diesel motors were damaged due to flooding after the tsunami. Therefore instructions evacuate residents within 3km of the center (about 2000 people) were given.

Subsequently, the power supply is then solved if the pressure in the reactor was now very high (more temperature higher pressure).

Fukushima Daini Nuclear Power Station

Its 4 units automatically stopped.

Tokai Nuclear Power Station

There is a single unit that stood automáticametne.

Fukushina. Saturday, 03/12/2011

The accident at the Fukushima nuclear plant became qualified to level 7 INES Scale by The International Agency for Atomic Energy.

Expanded radius around the nuclear plant to evacuate Populationa 20km.

Fukushina. Sunday, 13/03/2011

Nuclear accident at the Fukushima nuclear power plant, Japan

The reactor number three of the Fukushima Daiichi nuclear power plant suffered a hydrogen explosion.

To be started injecting seawater mixed with boric acid into the reactor to cool it and keep the integrity of the containment control.

In order to decrease the pressure in the nuclear reactor in Fukushima, a controlled release of gas from the containment held abroad (this action is called venting) as confirmed by the elé , Japanese ctrica TEPCO


Fukushina. Monday, 14/03/2011

At this point the Fukushima nuclear accident and began to cause policies in other countries.

Angela Merkel, German Chancellor, confirmed the suspension for three months of the extension of German nuclear power plants that allowed them to run for longer than originally set.

Merkel held that the supply of electricity in Germany will not be affected as the country was eminently energy exporter.

Fukushina. 15-3-2011 Tuesday

During the night there was a new explosion at Fukushima nuclear plant, according to the Agency for Nuclear Safety. The affected nuclear reactor number 4 FUIE at the time of the earthquake was already standing. Tokyo Electric Power reported the explosion caused a fire in the nuclear reactor.

The remaining 50 workers at Fukushima Daiichi nuclear plant trying to cool the reactor by the high level of radioactivity was evacuated.

Fukushina. 16-3-2011 Wednesday

On Wednesday evacuated workers returned from the Fukushima nuclear plant to continue in the attempt to bring down the temperature of the reactor.

Because of the difficulty of using sea water to cool the reactor was throwing intentntó do with an army helicopter that was not possible because of the high radiation area. Later they try to do with high pressure hoses used to disperse protesters.

The situation in the six reactors at the nuclear plant, at this time was very severe: significant damage was observed in reactors 3 and 4. The No. 4 reactor recorded a new fire. In reactors 1 and 2 nuclear fuel rods were also completely or partially damaged. The reactor 5, which was already off, the water level continued to fall.

Fukushina. Thursday 17.03.2011

helicopters dumping water on the Fukushima nuclear power plant to cool it

On Thursday army helicopters could fly and the Fukushima plant to take seawater.

The power company Tepco, which owns the nuclear plant, decided to send tankers with distilled water to fill the pools.

The pools are the first destination of spent fuel. When the spent fuel is removed from the reactor still generate too much heat and radiation so that it can move to any plant nuclear waste management, must first pass through these pools for cooling


Due to the heat of the Fukushima plant water filling the pools was evaporating. Therefore it was necessary to fill-the.

The last resort was to install an electric cable 1km to run electrical generators that allow the cooling of the reactors.

Spokesmen for TEPCO and NISA belied that the spent fuel from Unit 4 had been completely emptied although still making efforts to improve their situation.

Fukushina. Friday 18-3-2011

Japan decided to raise right now at level 5 the emergence of the Fukushima nuclear power plant of the 7 levels has the INES scale of nuclear accidents. This meant that a nuclear accident would have far-reaching consequences, not of local significance as before.

They managed to stabilize the situation in Fukushima. So the state of the reactors not worsened and the state of the containing spent fuel pools could be filled.

Yet still working to re-establish the electricity in nuclear reactors to use their own cooling systems.

Fukushina. 20-3-2011 Sunday

According to the International Atomic Energy Agency (IAEA) radioactive iodine was found in food products in Fukushima Prefecture. Although the duration of the radioactivity of iodine is short (about 8 days) may be detrimental to health.

What seemed obvious became official: The Japanese government announced it will dismantle the nuclear plant in Fukushima I.

Fukushina. Thursday 24.03.2011

Two workers of the Fukushima nuclear power plant were hospitalized to have received high radiation doses as they continued their tasks to carry electricity to the reactor 3 used refrigeration systems.

Fukushina. Monday 28-3-2011

Finally Tepco asked the French technical assistance to combat nuclear crisis in Fukushima.

Plutonium was found in five points Fukushima nuclear plant.

The Japanese government said it believed could have cast the plutonium fuel rods in the second reactor of Fukushima on contact with water to cool the reactor blew. This would explain the high level of radiation found in water.

Fukushina. 4/12/2011 Tuesday

Authorities in Japan raised the severity of the Fukushima nuclear accident from Level 5 to Level 7. The highest of the International Nuclear Event Scale. (Scale INES). The same with the Chernobyl nuclear accident, the worst in history so far qualified.

The reason for the nuclear accident rated at level 7 was the release of radioactivity to the outside.

Although Chernobyl and Fukushima have the highest level of severity, at this time, the released radioactive material was estimated to be approximately 10% of the released in the Chernobyl accident.

The nuclear accident in Japan has risen to the level 7 gravity


In Unit 1 nuclear power pressure primary containment building, compared to the values ​​of the last days increased. From April 6 Was injecting nitrogen gas is the primary containment building of Unit 1 to prevent hydrogen explosions occurring. It will inject nitrogen proceeded tambiéna primary containment buildings of Units 2 and 3.

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Last review: October 5, 2013