In the aftermath of the Second World War, exploration of nuclear power as a renewable source of energy was mainstream, with the United States’s development of ‘Fat Man’ and ‘Little Boy’ – the warheads used in Hiroshima and Nagasaki respectively – and the Soviet Union’s Tsar Bomba. Both nations held a common goal in constructing industrial power plants to harness energy emitted from the splitting of large, unstable nuclei and power cities with minimal costs. The United States had Three Mile Island in Pennsylvania while the USSR had Chernobyl in Ukraine. While both reactors succumbed to disaster, Chernobyl damaged the Soviets to a much larger extent; according to Nikolai Gorbachev, it acted as the untimely accident leading to the collapse of the Soviet Union. The drastic effects of Chernobyl’s radiation poisoning, coupled with the negligence of the Soviet government, is felt to this day.
Between 1970 and 1972, construction of a new power plant Chernobyl was proposed at Pripyat, a Ukrainian rural ‘atom town’ located near the Belarus border. This town would house all Chernobyl employees and their respective families. While Chernobyl was regarded as an ambitious project in propagating Soviet pride in the nuclear industry, glaring problems in the plant was overlooked by complex bureaucratic processes. When Deputy Chief Engineer Grigori Medvedev suggested applying pressurised water reactors (PWR) over a boiling water reactor (RBMK) due to the latter emitting forty times more radiation, he was snubbed by the Ministry of Energy. An RBMK reactor would be the cheapest alternative in producing electricity across the Union.
Six years later, the production of four functioning RBMK reactors was complete. It is here that the prominent design flaws observed in Reactor 2 were obscured by the KGB. Other information on the safety procedures were deliberately withheld from on-site engineers. The asymmetry in information extended in 1982 with the RBMK 1 core meltdown. Although the repair was conducted within months, knowledge of the accident was not made public until 1985. Following the accident, the Minister of Energy Anatoly Mayorets issued a law stating all public media broadcasts on Chernobyl and its accidents were forbidden. This recurring problem in Soviet communication would continue to claim many more lives in the second reactor disaster. Moreover, poorly trained engineers contributed to the gross incompetency of the Soviet nuclear force, as quoted by Lyubov Kovalevska, senior manager of the Chernobyl plant “substandard workmanship and concrete…along with bureaucratic incompetence, are creating a time-bomb.” These factors were heavily weighed in on April 25, 1986, the day of Chernobyl reactor safety test.
The fundamental physics behind the Chernobyl reactor is nuclear fission, or the splitting of a large unstable nucleus into smaller nuclei. When a free neutron struck the uranium isotope – U-235 – energy in the form of gamma rays (accounting for the deadly radiation) would be emitted as the isotope split into the noble gas Xenon. The Xenon is then burned away in the reactor as nuclear waste.
As more uranium atoms split and collide with one another, overall reactivity increases. To control this, boron control rods absorb the neutrons to collectively slow the rate of nuclear fissions. In addition to boron rods, cool water acts to absorb the energy of reactions in the form of heat, effectively changing the state of matter from liquid to steam. To measure how reactivity is affected by the amount of steam produced, nuclear engineers use a void coefficient. A higher rate of reactions leads to a higher rate of boiling, which in turn leads to higher reactivity. To disrupt the cycle of high reactivity, a negative temperature coefficient raises the overall temperature of the nuclear fuel to lower reactivity.
Aleksandr Akimov was only 25 years old when he took on the on-site shift duty in undergoing the reactor safety test, supervised by Deputy Chief Engineer Anatoly Dyatlov. Upon receiving the instructions for the safety test, Akimov and his crew realised certain steps were crossed out in the paper. Dyatlov ordered his men to follow all the steps crossed out.
Akimov’s hesitantly followed his orders, causing the power to fall by 98% from 1500 MW to 30 MW. He protested that the safety procedure was unsafe at low power. However, Dyatlov was indifferent, threatening Akimov to raise the power to normal or he would be fired. Due to the delay in action from the control team, the xenon byproduct failed to burn out in the reactor and continued to accumulate in the core. As Akimov raised the power, it continued to rise and stabilise at 200 MW, where it would not rise any further.
Dyatlov proceeded with the test despite a power shortage of 500MW. The low water level and dysfunctional turbines triggered an automatic shutdown by the system. This shutdown was overridden to avoid the test from being aborted. To raise the power output, reactivity was increased by withdrawing the boron control rods. Of the 211 total rods, only six remained in the reactor. The pumps, designated to supply water to the reactor, are closed. All measures to slow the uranium’s rate of reactions at this moment are suspended. The high reactivity caused the remaining water in the reactor to boil and generate steam, further perpetuating the cycle of increasing reactions. At this moment, there is a dramatic surge in power. Panicked, Akimov pressed the AZ-5 emergency button to shut the reactor down in the hopes that the boron control rods would mitigate high reactivity and bring the system to normal.
However, as seen throughout the construction of Chernobyl, the control rods were tipped with graphite as a cheap, cost-efficient alternative. The graphite did not lower reactivity, but augmented it to an extreme extent. With an unstable core and graphite control rods, AZ5 acted as a primer to a ghastly bomb.
A sudden blast, caused by the constrained pressure from the steam, tore the plant’s 3000 ton steel roof to the air. This caused oxygen to seep inside the reactor and ignite the graphite tips. The fuel tubes, upon coming into contact with the water, began to produce flammable hydrogen gas. The fire on the control rods sparked the hydrogen, leading to another fiery explosion. All engineers, firefighters, emergency responders, and nearby onlookers caught deadly doses of gamma radiation – the pent up energy emitted during the nuclear fissions. This led to horrific symptoms such as cancer and internal bleeding within days of exposure.
On a railway bridge overlooking the plant, thousands of civilians – most of them families of the employees – watched Chernobyl burn in the dark. The children were fascinated by the radioactive particles carried by the wind. The parents shared a brief moment of joy. Today, the bridge has eared an infamous title ‘The Bridge of Death’, for all 4000 men, women, and children that stood on the bridge that night died fatally.
Chernobyl was one of such disasters whose damage extends over generations; it is a poison that kills slowly. Apart from the initial count of engineers that died on the night of the explosion, thousands more would succumb to disease and bleeding in the later months. Families were forcibly relocated and were forbidden to return to Pripyat. The shortage of skilled labor led to the deaths of many more young, inexperienced men as they ventured into the deadly radiation of the core. But the true casualty of Chernobyl was the integrity of the Soviet Union. The Soviets would accept their mistake in 1990, four years after suppressing all evidence accusing Dyatlov and the Soviets of gross incompetency, finally shattering the facade of Soviet pride in 1991.
35 years later, Chernobyl today is no less dangerous. Remnants of the tragedy, including clothes, tools, and debris still report close to 600 rads, enough to kill an adult in a short amount of time. The subsequent spike in birth defects, cancer amongst children, and a legacy of lies represents the permanent scar Chernobyl left behind to the world. The official death toll of Chernobyl, forever obscured to the world, lies behind a mask of just 31.