1986 Disaster at the Chernobyl Nuclear Power Plant

Chernobyl nuclear power plant is located near the Dnipro river on the Pripyat river. In 1986 it was a major energy centre of 4 million kilowatt output.  
The first power-generating unit was commissioned in 1977, followed by the second, the third and the fourth in December 1978, 1981 and 1983 respectively.

Prior to 1986 there was one serious breakdown at Chernobyl plant – a rupture of process tube on the first power-generating unit in 1986. It led to lengthy repairing work and plant staff being significantly exposed to radiation within norm. There was also one incident when some dozens of the plant territory were polluted with decontaminating agent. In general there were less incidents on Chernobyl plant then on other nuclear power plants in the USSR. Prior to the disaster power generation on Chernobyl plant was about 28 billion kilowatt per year.
On 26 April 1986 at 1:28 a.m. shifting into a mode of electrotechnical tests staff of the fourth power-generating unit committed a mistake in turning from local automated control to automated control of main range capacity. Due to this reactor’s heating capacity dropped to 30 MW and as a result it automatically started a process of self-poisoning of temporary fission products.

By itself this process carried no nuclear threat. Moreover as it is in progress, a reactor’s ability to support chain reaction is reduced up to its complete stop regardless of operators’ will. In the whole world in such cases reactor is stopped and then one should wait for a couple of days till it recovers its operability. This procedure was considered routine and did not seem a problem to experienced staff of the fourth power-generating unit.

However on nuclear power plants’ reactors this procedure is quite troublesome and takes a lot of time. In our case it frustrated a completion of electrotechnical tests – with all sequential troubles. And then, “in an attempt to get done with test as soon as possible” as the staff explained later, they started to extract gradually control rods from the reactor’s active zone. This extraction should have compensated a drop of reactor’s capacity due to self-poisoning processes. This procedure is also ordinary on nuclear power plants’ reactors and constitutes a nuclear threat only when too many control rods are extracted for the current reactor’s condition. When there were 15 control rods remained the staff had to stop the reactor. It was their direct duty of service but they did not do it…

By the way the first such violation happened on 25 April 1986 at 4:10 a.m., i.e. a day before the disaster, and lasted till 2 p.m. It is interesting to note that since then operational staff shifts changed, shift supervisors of the 4th power-generating unit changed, shift supervisors of the nuclear power plant changed and no one sounded alarm as if everything was ok although the reactor was on the verge of explosion. A thought inevitably comes to mind that violations of such kind must have been common not only on the 5th shift of the 4th power-generating reactor.

The second time was on 26 April 1986 soon after midnight. But for some reason the staff would not stop the reactor and continued to extract control rods. As a result at 01:22:30 a.m. there were 6-8 control rods in the active zone. However even this did not stop the staff and they started electrotechnical tests. One can safely assume the staff continued to extract control rods till the explosion. No one in the world works in such a way because there are no technical means to operate safely a reactor in the process of self-poisoning.

As a result the reactor shifted into mode of sustaining of chain reaction on fast neutrons. Due to this within hundredths of a second heat generation in the reactor rose by 1500…2000 times, nuclear fuel heated to 2500-3000 °C and then a process started which is called a reactor’s thermal explosion. Its aftermaths made Chernobyl nuclear power plan “famous” around the world.

The investigation showed that if the system of the emergency shutdown of reactor had not been turned off as soon as there was a signal that steam ceased to come to the last turbine, the disaster would not have happened. The reactor would have been stopped automatically. But the staff planned to repeat experiment several times on different parameters of operating of generator’s magnetic field. The reactor shutdown would not have allowed this.

In 1991 the second state committee formed by the Inspectorate for Nuclear and Radiation Safety and consisted primarily of operatives gave its explanation of the reasons of Chernobyl disaster. Its gist was that the reactor of the 4th power-generating unit has some “constructional deficiencies” which “helped” the shift on duty to bring the reactor to the explosion. It is not widely know that soon after Chernobyl disaster there was a committee of inquiry which was formed by “competent authority” and tried to find out reasons of the disaster. It did not draw big public attention to itself and it carried out its own investigation using its unique information means. On fresh tracks during the first five days 48 people were interrogated and a lot of documents related to the disaster were copied. However the conclusions which went under “highly classified” were let known to a very limited circle of people. Only recently the Security Service of Ukraine decided to declassify a part of Chernobyl materials in its archives. But although these materials are not officially classified anymore they are still practically unavailable to public.

As it turned out the preliminary conclusions had already been made by the 4th May 1986 and the final ones — by the 11th May 1986. To be short just let me give only two citations of these unique documents: “… the general cause of the disaster was low culture of the power plant staff. It relates not their qualification, but to work culture, internal discipline and responsibility” (Document №7 of May 7, 1986). “The explosion came as a result of a number of gross violations of safety regime while working on the reactor of the 4th power-generating unit of the nuclear power plant” (Document №31 of May 11, 1986). It was the final conclusion of the “competent authority”. Later on they would never come back to this issue.

The aftermaths of this disaster can hardly be overestimated. Today in the foreground there are oncological diseases, especially thyroid gland cancer. It happened as a result of a powerful iodine “stroke” in the first days after the disaster. Today the greatest risk comes of strontium. It influences immune system of people and increases susceptibility to different diseases. Besides there are more and more cases of cardiovascular and gastrointestinal diseases among the population of Ukraine.

Some mysticism…
Soon after Chernobyl disaster in 1986 English newspaper “Daily Telegraph” told that Chernobyl means “wormwood” in Ukrainian. Book of Revelation 8:10-11 says about a falling star which will cause a lot of tragical deaths because of poisonous evaporations. “And the name of the star is called Wormwood”. A reader of “Daily Telegraph” also noted that Chernobyl means “black true story”. However there are even more associations. Chernobog is a Slavic god of underground, black sun under the earth. If the reactor had burnt the land, the radioactive poison would have soaked into ground waters and destroyed the Dnipro river. In 1986 Ukrainians would still curse their foes with the words: “May you be punished by Chernobog”.
Dmytro Chernenko
20.11.2009