In 1932, in Cavendish University, J. D. Cockcroft and E. T. S. Walton bombarded lithium with protons from a particle accelerator. The protons caused the lithium atom to split. Many scientists realised that if they continued to split uranium and plutonium atoms, with the protons from one atom splitting another and the process repeating in a process called fission, they could make a new source of energy. Much of this energy was harnessed in Nuclear Power Plants. By 1986, there were 389 power plants, 37 of which resided inside the Soviet Union.
Reactor 4 of the Chernobyl Nuclear Power Plant was constructed in 1983, with Viktor Bryukhanov, manager of construction of the plant, telling higher ups in the Communist Party of the Soviet Union that a test had been conducted in order to ensure the safety of the reactor. However, this was false. Bryukhanov would later defend this saying that completing work ahead of schedule entitled party members to significant bonuses. Despite the lack of the safety check, the plant went into operation.
Eventually, Nikolai Fomin, Chief Engineer, authorised the test to go ahead on April 25th, 1986 and the test would be performed by the workers of the afternoon shift. However, party officials from Kyiv requested that the test be delayed to late that night, as they did not want citizens to lose power in the middle of the day. Despite the workers of the afternoon shift being debriefed on what to do, the night shift workers were tasked with going ahead with the test instead.
Anatoly Dyatlov, deputy Chief Engineer, was monitoring the test, with the nightshift foreman, Alexander Akimov, and the Senior Reactor Control Engineer, Leonid Toptumov, who was only 25. Toptumov had only been operating the reactor for 2 months before the test, whilst neither Akimov or Toptumov had ever done the test before and weren’t properly briefed, with the test manual being heavily annotated and thus hard to follow. This meant that the two men were relying entirely on Dyatlov, as he was the most experienced in nuclear energy. In order to conduct the test, the reactors power levels had to be reduced to around 700 MW. However, an error was made by Toptumov.
Control rods help moderate the fission reactions, which heat up the water, which spins the turbines that generate the electricity. Toptumov’s mistake was that he had put these control rods in far too deep and the reactor practically went offline. Dyatlov was infuriated at the error but still insisted that the test go through anyway, despite the lack of power that was required to do so. He ordered that the control rods be raised, in an attempt to bring the power back up. The workers did what they were told and raised all but 8 control rods, whilst the minimum amount for safety is around about 30.
Many debate what happened next. Dyatlov claimed that everything was going as planned and part of the test was to press the emergency shut down button. However, many others testified that the power levels began to rise incredibly fast to dangerous levels. Whatever the case may be, what we know for certain is that Akimov pressed the AZ-5 emergency shut down button, which re-inserted every single control rod into the core.
Logically, this was supposed to immediately shut down all power. However, due to cutting cost, the rods were tipped with graphite, which got stuck at the heart of the core due to steam pressure. Graphite, when reacting with the radioactive elements, causes an increase in energy, before the control rods shut it down. The levels of energy rose higher and higher and, with the added steam pressure, the 1000 ton lid of the reactor was blown clean off. Then, once the core was exposed a second, undetermined, reaction occurred, causing and even larger explosion that blew the roof off the factory.
At 1:23 in the morning, the explosion echoed around the nearby city of Pripyat. Decimeters in the plant, that were only capable of detecting 3.6 roentgen per hour, broke due to the overload. The reactor was actually emitting over 15,000 roentgen per hour. Firefighters quickly arrived on the scene, many of whom succumbed to radiation sickness. Once they arrived at Pripyat Hospital, their highly radioactive clothes had to be taken off and we thrown into the basement, where they still rest to this day.
Over 45,000 residents from Pripyat had to be evacuated. Eventually, a large sarcophagus was built over the reactor to contain the radiation, which was replaced by the Chernobyl New Safe Containment in 2016.
Dyatlov was sentenced to 10 years in prison for criminal negligence and failure to comply with the safety regulations of the test. He was released after serving only 4 years due to health concerns and died in 1995, aged 64 of bone marrow cancer, likely caused by his exposure to the plant’s radiation. Tomin, despite attempting to commit suicide multiple times, was also sentenced to 10 years in prison. He was also released from prison early and, as far as we’re aware, he is still alive today, living with his family in Udomlya. Bryukhanov sentenced to 10 years also, for gross violation of safety regulations, creating conditions that led to an explosion, mismanagement by understating the radiation levels after the accident, administrative negligence and sending people into known contaminated areas. He was released for good behaviour in 1991 and died in 2021 from an undisclosed disease, although we know he had Parkinson’s later in life.
To this day, the Russian Government still claims that only 31 people died from the disaster, whilst UN estimates claimed that 50 deaths were caused as a direct result of the explosion, with a further 4,000 succumbing to radiation sickness or other illnesses related to exposure such as cancer. Many scientists cite the Chernobyl Disaster as the worst disaster in the history of nuclear energy.