Fukushima-1: accident and its consequences

The accident at Fukushima-1 was caused by an earthquake and the tsunami that followed. The station itself had a reserve of strength and would withstand one of the spontaneous actions.

The disaster was caused by the fact that two natural disasters hit the nuclear power plant at once . Because of the earthquake, the power supply to the station was cut off, immediately after that the emergency generators turned on, but they too did not work for a long time because of the tsunami.

Causes of an accident

The Fukushima-1 nuclear power plant was built in the 70s of the last century and at the time of the accident it was simply morally obsolete. The project of the nuclear power plant did not anticipate the availability of accident management tools that would be outside the project.

And if the earthquake has withstood, the tsunami, as mentioned above, left the nuclear power plant without electricity.

Before the accident, three power units were operating, and they were left without cooling, as a result - the level of the coolant was reduced, but the pressure that was initiated by the steam became, on the contrary, increased.

The development of the disaster began with the first power unit. That the reactor is not damaged due to high pressure, the steam is decided to be dumped into a hermetic block. But it also quickly increased pressure.

Now, to save it, the steam began to be thrown directly into the atmosphere. Hermetic shell was preserved, but hydrogen, which was formed due to the fire of the fuel, seeped into the construction of the reactor compartment.

All this led to an explosion at the first power unit. It occurred the day after the March 12 earthquake . The explosion partially destroyed concrete structures, but the reactor shell was not damaged.

Developments

After the explosion at the power unit, the radiation level increased greatly, but fell after several hours. On the territory of the NPP "Fukushima-1" samples were taken, and studies showed the presence of cesium. This meant that the integrity of the reactor was broken.

To cool the reactor, seawater was pumped in. The next day it turned out that in the third block the emergency cooling system was damaged. And there was a suspicion that the fuel elements were partially bare, and again there could be an explosion of hydrogen.

We began to dump steam from the hermetically sealed shell and pump seawater. But it did not help, and the explosion occurred on March 14. However, the reactor vessel was not damaged.

Continue the work on the restoration of electricity on the first and second blocks. Also, they continued to pump water on the first and third blocks.

On the same day, the emergency cooling system also failed at the second power unit. Began to pump seawater for cooling. But suddenly the valve to break the steam broke, and it was impossible to pump the water.

But on this the troubles of "Fukushima-1" did not end. The explosion at the second power unit did happen on the morning of March 15. Immediately, the nuclear fuel storage at the fourth power unit exploded. The fire was extinguished only two hours later.

On March 17, morning, sea water was dropped from the helicopters into the basins of Blocks 3 and 4. After it was possible to restore the diesel station on the sixth block, it became possible to pump water using pumps.

Elimination of the accident

In order for the established systems to function, it was necessary to restore power supply. And for its restoration it was necessary to pump out water from flooded turbine compartments.

Everything was complicated by the fact that the level of radiation in the water was very high. The question arose: where to pump this water. To this end, they decided to build a sewage treatment plant.

The company, which owns the Fukushima-1, said that it will have to drop 10,000 tons of low-radiation water at sea in order to release the tanks for highly radioactive water from the first three nuclear power units.

According to the plan, complete elimination of the consequences will take about forty years. The reactors of the nuclear power plant were stopped and the extraction of spent nuclear fuel from the basins began. Later it is planned to completely dismantle the reactors of the Fukushima-1 nuclear power plant.

Consequences of the accident

As a result of all events, a radiation leak occurred. The government had to evacuate the population from the 20-kilometer zone around the nuclear power plant. It was strongly recommended that those who lived 30 kilometers from the Fukushima-1 nuclear power plant be evacuated.

Japan, Fukushima-1 and its surroundings are contaminated with radioactive elements. They were also found in drinking water, milk and some other products. The norm was lower than permissible, but they were temporarily banned for reinsurance.

Radiation was detected in sea water and soil. In some regions of the planet, the radiation background has increased .

In addition to environmental pollution, there are financial losses. The company TERSO is obliged to pay compensation to the victims of the accident.

Fukushima-1 today

Liquidation works are continuing at the plant today. In May 2015, a leakage of radioactive water occurred. Also, the purification of water, which was extracted from the blocks, continues.

This is one of the main problems. Highly radioactive water is very abundant, and in the process of cooling the reactors it becomes even greater. It is pumped into special underground storages, gradually cleansing.