It's one of the most infamous events in history, but many of us have the facts wrong. What really happened at Chernobyl in April 1986?
Sampling Eras is a column by Rubee Dano that explores the intersection of science and history. Rubee is a history and philosophy student, with a particular interest in the history of science and academia.
Andrew Leatherbarrow’s book Chernobyl 01:23:40 begins: “Radiation is perhaps the most misunderstood phenomenon known to humanity,” and rightly so. The 1986 Chernobyl nuclear disaster is an event most of us have heard of, but one few of us know the truth of. Before reading Leatherbarrow’s book and doing my own research, I thought 'Chernobyl' meant the immediate shutdown and evacuation of the surrounding area, brave divers going into radiation soaked water to disable a volatile reactor, and that radiation meant immediate death for those exposed. But this isn’t the case.
Misrepresentations of Chernobyl in the media are widespread, and it is at times difficult to separate the facts from misconception.
What occurred during the Chernobyl incident?
The V. I. Lenin Atomic Power Plant was constructed in 1970, about 15km from the Ukrainian city of Chernobyl. A town, Pripyat, was simultaneously erected a few kilometres from the plant to house its workers, their families, and other necessary staff.
Unfortunately, in a fashion somewhat typical of communist construction projects (according to Leatherbarrow), some amount of concrete was missing from the Chernobyl plant, and the construction was not entirely perfect. This resulted in incomplete containment buildings, which were meant to act as the final defence against a nuclear accident, should all other methods of prevention fail. It is this short cut, and other similar ones in the design of the safety systems of Chernobyl, that resulted in the catastrophic failure of the Unit 4 reactor.
Leatherbarrow said, citing Grigori Medvedev’s Chernobyl Notebook: “Conventional wisdom at the time was that the RBMK could never cause a large-scale accident, because industry safety regulations would always be adhered to. Extra safety measures, they decided, were unnecessary.” It is perhaps for this reason that, for a long time, the blame for Chernobyl was laid on its operators — when in reality a combination of shortcuts in both building the plant and training its staff was responsible for what happened on April 26, 1986. The fact that there were 29 emergency shutdowns of reactors within the plant in its first four years of operation says that something was amiss. Only eight of these were caused by staff miscalculations, according to Leatherbarrow.
Shortcuts also occurred in the cooling devices necessary to keeping reactors at the ideal temperature. “The plant was originally going to be fitted with gas-cooled reactors, but this was eventually changed because of a shortage of the necessary equipment,” said Leatherbarrow.
The Chernobyl accident occurred when night operators of the plant tested a safety feature: allowing Unit 4 — a RMBK class graphite-moderated reactor — to power itself for about a minute, in case the power failed for some reason. According to the plant’s design, cooling water is supposed to flow into a reactor continuously, because without this it would overheat, because even if it is shut down and not operational, it still generates heat due to the decay of its nuclear fuel.
Theoretically, given the backup procedures in place at Chernobyl, water should still have flowed into the reactor to cool it. This, however, didn’t happen, and the appropriately trained staff were not present for the test. Leatherbarrow described the test as originally being scheduled for 5pm the previous day, with day staff who were fully briefed and trained for the test — however, it was delayed, evening staff took over, and soon they too went home to be replaced with night staff with very little knowledge of what to do. The test took place at about 1am on April 26, 1986.
To complicate matters even further, the reactor was not at an ideal stage for such a test to take place, being at a point in its cycle where a lot of old fuel had built up, making it hot and heavy with radioactive products. Power was reduced to a low enough level to make the reactor’s safety systems believe there was a power failure, and other safety systems were switched off in order to test safety features should all power fail, which was essentially the last line of defence against a full nuclear meltdown. At any rate, the instructions for the night staff to complete the procedure were convoluted, with hand annotations and some instructions struck out.
Power levels soon dropped too far and the reactor began to be poisoned by the release of xenon-135, an isotope that inhibits the fission reaction of the reactor. Leatherbarrow commented that if this massive drop in power hadn’t happened, the test likely would have proceeded without issue, and nothing out of the ordinary would have happened. The manager conducting the test, however, Anatoly Dyatlov, wanted the test to occur because it was postponed earlier, and he pushed it forward, meaning that the reactor became unstable. Dyatlov threatened staff who refused to conduct the test at this stage due to safety concerns, and eventually they complied. Leatherbarrow said the test was conducted at a point in time where its results would have been useless, and Dyatlov’s stubbornness prevented the reactor from being shut down at the last moments where it could safely have been. Leatherbarrow argued this reasoning is particularly illogical on Dyatlov’s part, and it is possible he was suffering a lot of pressure from his higher-ups, resulting in the irrational push to continue the test even when it was actively unsafe to do so.
When it was already too late, an emergency shutdown was attempted by one of the plant’s workers who originally refused to comply, but control of the reactor had already been lost. The emergency shutdown resulted in a further loss of control, and due to an issue with reactor design, the graphite rods used to control the reactor fell into the core, meaning that the emergency shut down button essentially did the opposite of what it was meant to do. To make things worse, the resulting explosion destroyed water pumps that would otherwise have supplied more coolant to the core, facilitating further disaster. However, had staff not stayed and followed the correct procedures after Unit 4 exploded, fire would have broken out, resulting in the destruction of the remaining three reactors, and the subsequent disaster would have been unthinkable.
Conflicting reports of what happened to cause the Chernobyl accident stem from the Soviet government’s initial claims that the tests were part of a new reactor feature, rather than a fairly standard one, and an initial report reaching Moscow of a hydrogen explosion in a safety system, rather than the reactor core explosion that had happened. Leatherbarrow could not account for where this false report came from, but said that the damage would have made it immediately obvious the core was damaged.
What happened immediately after the explosion?
Staff remained in the plant trying to control the situation, initially believing the reactor was undamaged and the explosion was due to hydrogen in a water cooling system. The only available radiation monitor capped at 1000 micro Rotogens, a high, but not deadly, level; it is likely levels were several orders of magnitude higher. When a more accurate monitor was uncovered, Dyatov dismissed it, claiming it must have been broken. He started to succumb to radiation poisoning within hours, spending six months in hospital and eventually surviving.
Firemen came to fight the blaze caused by the explosion, which had worsened due to the plant’s poor construction. Leatherbarrow described the roof of the plant as being constructed of bitumen in parts, a highly flammable substance. The roofing material was supposed to be resistant to fire, but a lack of the right materials lead to the plant’s construction being pushed ahead and bitumen used in its place. None of the firemen who went to battle the fire on the roof survived.
Evacuation was not ordered until late the following morning, though during this time roadblocks were set up to stop people leaving or entering the area. The only reason for this, Leatherbarrow said, was likely that the government did not want news of the disaster spreading. When the evacuation message did get out, it spoke of a temporary evacuation only, and was quite misleading. The evacuation itself, however, was fairly efficient. The initial exclusion zone, 10km, was rethought and increased to 30km a few days later, meaning some people were relocated twice. Pregnant women were taken to a distance of 60km, and many of those who were relocated headed farther away anyway.
The operator of the plant and the manager who originally approved the test that triggered the Chernobyl accident were both sentenced to 10 years in a labour camp and were kicked out of the Communist Party.
Misinformation about the explosion began to circulate as knowledge of the accident became public. Despite the death toll being 2 when this happened, newspapers were quoting 2,000 dead, 80 as a result of the explosion itself. Curiously, this count of 2 deaths doesn’t include firefighters, as far as I can tell — likely because they didn’t die of radiation but from the toxins released by the bitumen, and because the melted bitumen stuck to their boots, limiting their mobility on the roof where they would die.
Sand was dropped on the still-alight reactor, cooling the fire, but many pilots later died from radiation exposure. The weight of the sand, however, led to fears that the foundations of the plant could not withstand the additional weight. If they did not hold, it was possible the plant would collapse and cause a steam explosion from the underground reservoir used for emergency cooling, causing the other three reactors to blow, and contaminating all of northern Ukraine and the south of Belarus, according to Leatherbarrow. While the sand had been mixed with boron to absorb neutrons from the fission reaction, none of this made it to the unstable core. Instead, the sand essentially sealed off entrance to the core, making the fire even hotter, and the pool of water beneath it needed to be drained.
The Chernobyl divers
Perhaps the largest mistruth about Chernobyl is the fate of the Chernobyl divers: most accounts (for example: 1, 2, in the top 4 results on Google) say the divers knew they were facing certain death, but donned wetsuits and dove into the radioactive water in the plant’s basement to release the valves to empty the dam underneath the reactor, saving the plant from further destruction.
The water flooding the basement had earlier been drained by firefighters. Some remained, but at its deepest it was only about knee-high. Three men, Ananenko, Baranov, and Bezpalov, entered the basement in order to find the valves that would allow for the draining of the reservoir. They would become known as the famous Chernobyl divers, however perhaps more surprisingly, they would survive.
All three ‘divers’ wore two dosimeters, the valves were found relatively quickly, and they retreated unharmed, for the most part. There are images of two of the divers in hospital, but they do not look particularly ill according to Leatherbarrow. Leatherbarrow said that two are likely still alive, though the third died in 2005 following heart problems.
The medical fallout
A total of 127 reactor workers, firemen and emergency personnel on site sustained radiation doses sufficient to cause radiation sickness (over 1,000 mSv); some received doses high enough to be lethal (over 5,000 mSv). Over the subsequent six months, 54 died from their radiation exposure. And it’s been estimated that 22 of the 110,645 clean-up workers may have contracted fatal leukemias over the next 25 years.
– Timothy J. Jorgensen, Georgetown University for The Conversation.
Chernobyl is the worst nuclear accident to have occurred to date, including the Fukushima disaster in 2011, and has caused an increase in the number of cases of thyroid cancer in the local geographic region — and is likely to cause more cases in the future. The culprit? Iodine-131, a fission product released from the reactor during the meltdown, Luckily for the people of Japan, iodine-131 was released at Fukushima at much lower levels than at Chernobyl, leading to thyroid doses that were far less dangerous.
However, the number of immediate deaths due to Chernobyl is often over-estimated — although this is likely because many counts include the number of deaths from radiation exposure in the long-term, as opposed to simply those who died immediately of radiation sickness.
Only two men died during the actual explosion of Unit 4: Valeriy Khodemchuk and Vladimir Shashenok. Khodemchuk was in the reactor room when the core exploded and was killed instantly; his body was never found. Shashenok received an extremely high dose of radiation while he was monitoring pressure gauges, resulting in substantial burns all over his body. He died in hospital only 4.5 hours later. Two trainees died two weeks later of severe radiation poisoning after Dyatlov sent them to attempt to remove the cores manually, a decision he immediately regretted and tried to correct, but it was too late: he did not reach them in time. Many of the staff who stayed after Unit 4 exploded died in the subsequent weeks, having been exposed to multiple lethal doses of radiation in their attempts to prevent further damage.
Many firefighters were rushed to hospital in Pripyat to be treated for radiation sickness — however, the hospital was not well prepared for this, and many doctors and nurses, exposed to the fission products contaminating their patients, suffered from radiation poisoning as well.
Those who suffered the effects of radiation in the initial response — firefighters, workers — were taken from Pripyat to Moscow. Many of them died over a number of weeks as the effects of radiation exposure took hold. Initially, headaches, vomiting and nausea were common, but later the radiation caused their skin to disintegrate from the burns — it would crack and blister, and eventually turn necrotic — as well as prompting internal bleeding and organ failure. Other than in cases of high level acute exposure, radiation typically takes a while to kill. Often, patients feel they are getting better as the initial symptoms subside, before their bodies begin to slowly shut down. 18,000 people were hospitalised and treated for radiation related sickness after Chernobyl.
Miners who attempted to install refrigeration machinery around the still-hot reactor also suffered the effects of radiation. While some survived, Leatherbarrow estimated that at least a quarter of the miners recruited (though no accurate number exists) were killed — all of them were between 20 and 30 when they were sent to dig, and none of that quarter reached 40. The refrigeration machinery was never installed; the core began to cool, and heat-resistant concrete filled that space instead.
While scientists debate the impact Chernobyl has had on animal life, the general consensus is that insects and birds have suffered declines in populations and the ill effects of chronic radiation exposure (such as deformity, sterility and cancers), while some larger animals have actually flourished. Boar and deer numbers, for example, are on the increase, with similar numbers reported outside of the exclusion zone in uncontaminated reserves.
In general, though, we are still taking stock of the damage caused by Chernobyl. Due to the nature of radiation, it is difficult for scientists to know the long-term effects, as they are still occurring.
The dangers of nuclear energy
In the opening chapter of Chernobyl 01:23:40, Leatherbarrow described the number of global energy-related radiation accidents as fairly low. Compared to other forms of power generation, such as coal mining and petroleum drilling, nuclear energy is responsible for far fewer deaths, and less accidents in general, even considering Chernobyl and Fukushima.
Most of the few nuclear accidents have been caused by the fact that nuclear power is still relatively new, which is worth considering. Nuclear energy is something we are still learning about as a society. It has been responsible for fewer deaths than other energy-generation methods we have been using for far longer, it can hardly be deemed unsafe if we consider that more people still die in mines, which we know a lot more about than nuclear power. By contemporary Western standards, Chernobyl would not have been operational, and so it is arguable that Chernobyl was not a failing of nuclear energy in general — the problem was entirely in its construction and management.
Anti-nuclear proponents cite greenhouse emissions inherent in reactor construction and the current unavailability of newer model reactors that restrict or prevent weapons proliferation, waste products and accidents like Chernobyl and Fukushima, as reasons why nuclear power is not worth the risk. This risk is what is often called into question — is it acceptable? The nuclear decision these days comes down to whether the risks involved are acceptable, and essentially involves weighing the pros and cons of safety, possible accidents, and other effects such as climate change and economics.
I would argue that incidents like Chernobyl and Fukushima polarise opinions on nuclear energy, while there is not a lot of general understanding of nuclear power out there. We can see by the myths surrounding Chernobyl, even now — thirty years on — that nuclear power and the effects of radiation are not well understood. That the cause of the Chernobyl accident is frequently misrepresented surely speaks to the idea that Chernobyl is not a reason to be used in an argument about the flaws of nuclear power. At worst, it could be described as an example of human error and shortcuts taken in construction, rather than an argument against nuclear power.
Edited by Jack Scanlan.