The Nuclear accident from Chernobyl (April 26, 1986) - History Key

The Nuclear accident from Chernobyl (April 26, 1986)

The explosion of reactor four at the Nuclear Power Plant in Chernobyl is one of the biggest man-made disasters. According to specialists, the effects from the Chernobyl accident can be compared with an explosion of 500 nuclear bombs with the size of those in Hiroshima and Nagasaki. Unfortunately, more than 60,000 people died as a result of radiation and more than two million suffered after this tragedy.

The test that led to disaster

The Chernobyl Nuclear Power Plant was located in a forested area about 130 km north of Kiev and it consisted of four nuclear reactors capable to produce 4 GW of electrical power. At the time of the accident, another two reactors were under construction. Just like other nuclear power plants, Chernobyl project had a reactor core that contained Uranium radioactive fuel.

Chernobyl Nuclear Power Plant
Chernobyl Nuclear Power Plant © Image Source: MIGnews.com.ua

A day before the disaster, the Chernobyl crew from reactor four began preparing for a test to determine how long the turbines can continue to power if an event of a loss of electricity will occur. The test was made before in 1985, but the turbines didn’t provide the necessary power. The test had to be done in certain conditions. It was necessary to reduce the capacity of the reactor at least to 30%, but the Soviets authorities didn’t approve it. Therefore, the reactor staid at 50% for about 9 hours and all the safety systems were shut down. On April 26 the test began with the capacity of the reactors at 50%. At that point, the first mistake was made by an operator: instead of keeping the level at 50% he forgot to reset an important device which caused a drop of the capacity to 1%. This level was too low to run any tests.

Another major mistake was the simultaneously removal of the control rods in order to increase the level of energy production to 7%. When the rods were inserted back at the same time, it determined a dramatic increase of the energy level that destroyed the reactor. One and a half hour after the midnight, the explosion occurred and discharged about 8 tons of radioactive substances from the reactor outside the atmosphere.

The evacuation took place too late

Radioactive steam plumes continued to be generated days after the initial explosion
Radioactive steam plumes continued to be generated days after the initial explosion © Image Source: Wikipedia

In the next 10 hours water was pumped into the core of the reactor to extinguish the fire and to stop the release of more radioactive material into the atmosphere. The next few days, another attempts to extinguish the flames consisted in the disposal of 2,400 tons of led and 1,800 tons of sand by 30 military helicopters. Unfortunately, this operation aggravated the situation because the temperature in the reactor increased. Subsequently, the core was cooled down with nitrogen and the radioactive emissions were kept under control on May 6.

Right after the explosion, people from the area had no idea what actually happened and the workers were discharged only a day later on April 27. Also the distribution of iodine (prevents the absorption of radioactive iodine) began just on May 23, which was too late, since the radioactive substances were released within the first ten days. More than 600 people were involved in this accident and all of them were severely irritated. 31 workers died shortly after the accident. According to specialists, about 800,000 people were involved in the cleaning operations until 1989.

2525 is the year when the radiation level will be at normal rates

The abandoned city of Pripyat with the Chernobyl facility visible in the distance
The abandoned city of Pripyat with the Chernobyl facility visible in the distance © Jason Minshull /Image Source: Wikipedia

The most part of the radioactive substances were thrown into the atmosphere and it contaminated the neighbouring areas. The gases were carried along Ukraine, Belarus, Russia, Poland, Czechoslovakia, Austria, Germany, Romania, Greece, Bulgaria and Turkey. However, the highest risk of irradiation was in northern Ukraine, southern and eastern Belarus and the western area on the border between Russia and Belarus. At the time of explosion more than 7 million people lived in these regions of which 3 million were children. To stop the radioactive emissions, the active area of the reactor was covered with concrete that stops the radiations. The city of Chernobyl has been totally evacuated and probably will never be inhabited until the radiation level will reach normal rates, around year 2525.

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