The Chernobyl Disaster. Everything you wanted to know: Radiation, deaths, tours to the Exclusion Zone, and more

The Chernobyl disaster is the biggest and most famous nuclear disaster, as infamous as the bombs of Hiroshima and Nagasaki, when the frightening power of the Atom was first demonstrated. 26^th April 1986, the night shift staff of the Chernobyl Nuclear Plant readied themselves to undergo a test on the reactor 4, when something went awfully wrong. The reactor exploded, releasing tonnes of steam and radioactive material. Initially ignoring the magnitude of the disaster, many of the staff and firefighters perished under the deadly levels of radiation released in and around the plant. When the higher echelons of the Soviet Union realised the true magnitude of the incident, the city of Pripyat, built to house the staff of the plant and their families, had to be evacuated. Those inhabiting a 30km Exclusion Zone followed, their former homes contaminated for hundreds, maybe thousands of years to come. The disaster bankrupted the already fragile Soviet state, precipitating its downfall in late 1991.

1# The Soviet Atom

The Chernobyl Nuclear Plant, officially known as Vladimir Ilyich Lenin Nuclear Power Plant, was the crown jewel of the Soviet civil nuclear program, intended to prove the benefits of the peaceful atom in contrast to the military uses that the Cold War, so far had given to nuclear energy. To support the growing plant, a new city was erected on the marshes of the river Pripyat, in northern Ukraine, thus taking the name of the river. A blossoming city of 50.000, with an average age of 26, Pripyat was a city with near zero crime, dynamic, green, and teeming with cafes, gyms, and schools.  

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Supervising both plant and Atomgrad (Atom city), was Viktor Bryukhanov, the plant director and one of the city founders. Under his direction, the nuclear plant expanded and met all deadlines demanded by the Communist Party of the USSR, the supreme authorithy in the country. But under the golden façade of efficiency and superior know-how of socialism over the bourgeoisie capitalism of the US, the stink of reality could no longer be concealed. Decades of planned economy, secretism, corruption, and the need for scientists and workers to square the reality to meet the demands of the Party, had dangerously strained the political, economic, and social pillars of the country. In 1985, Gorbachev , freshly appointed General Secretary of the Communist Party of the USSR (de facto head of state), promised Glasnost (openness) and Perestroika (restructuring), as the panacea to save the ailing Soviet economy, and curb the rampant corruption of the Apparat. 

2# The reactors in Chernobyl

To meet the exorbitant demands of their political supervisors and superiors, who in turn were pressed by their superiors in a vicious circle, workers and specialists worked under growing pressure, often choosing or forced to deliver low-quality products to meet the deadlines. The nuclear industry was no exception, and several important accidents, all zealously concealed by the KGB, had already occurred. Even the Chernobyl Nuclear Power Plant had had its share. The plant was fitted with four reactors RBMK, the star reactor in the USSR, but arrogance and propaganda had convinced the organs responsible for Nuclear energy and industry in the USSR, that the RBMK was inherently safe and better than its western counterparts. This was far from the truth.

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After several plants had been equipped with the RBMK, its designers had detected several flaws and glitches related to the control rods, meant to lower reactivity and shutdown the reactor. The engineers relayed the glitch, but somewhere in the entangled, corrupted, and politically-oriented chain of command, the message was ignored. The RBMK operators all across the USSR remained ignorant of the fact that they were tinkering with a bomb, potentially more dangerous that those of Nagasaki and Hiroshima. Coupled with this hazardous secretism, nuclear plants were overstaffed, overcomplacent, and infected with the hubris of their politicians. A giant, explosive, grenade waiting for someone to pull the pin.

3# How the reactor exploded

To meet the deadlines, plant director Bryukhanov had launched the latest reactor, reactor 4, without implementing many of the safety tests, including that aiming to check if the reactor could continue operating in the event of a sudden blackout. The test intended to use the inherent motion of the turbines to keep the reactor sufficiently powered once a blackout started, covering the gap that it took for the diesel engines to begin pumping energy to the reactor. The test was finally scheduled to 26^th April 1986, delayed to nightime because Kiev’s local authorithies didn’t want the subsequent power drop to jeopardise the daytime production of factories (under pressure to meet the Party deadlines). In truth, Bryukhanov wasn’t even informed by Nikolai Fomin, the Chief Engineer, that the test was being carried that day.

Having been waiting since early morning, the grumpy and tired staff prepared for the test. Toptunov was the senior reactor engineer on the night shift, Alexander Akimov the shift foreman, and Anatoly Dyatlov the deputy-chief enginner, and thus the overall responsible.

Past midnight, the reactor was lowered to 200 megawatts. Akimov said the recommended minimum was of 700, but Dyatlov insisted he knew better. A mistake of Toptunov caused the reactor to plunge to 30 megawatts, less than 1% of its thermal capacity, but aided by fellow engineer Tregub, Toptunov lifted several control rods to increase reactivity, powering up to 200 megawatts. Instead of aborting the test in these unstable conditions, Dyatlov ordered the team to continue.

The programmed shutdown of external energy was triggered and the emergency diesel engines were switched on. During this one minute gap of no power, the team expected that the inertia of the waning turbines would feed the reactor. Although this was so, the input was insufficient, and the conditions in the reactor were less than ideal due to the problems experienced before. Steam (a worse absorbant than water) had pooled in the reactor in dangerous levels, but with the instruments giving no alarm, Dyatlov ordered to activate AZ-5, a scram mechanism to insert all the control rods back in the core. A shutdown mechanism. Toptunov pressed the AZ-5 button and the reactivity dropped according to plan.   

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Sudden and unexpectedly, the reactor’s thermal power spiked. Unbenknowst to the operators, the control rods had that fateful design glitch of the RBMK. To prevent reactivity to drop too much, the boron carbide (neutron absorber) rods had a graphite tip, which facilitated fission. Coupled with the critically slow insertion of the rods (another faulty design) it meant that during the first moments of AZ-5, the graphite dangerously increased the output instead of decreasing it, as it was meant. This glitch had already caused a partial meltdown in one of the Leningrad Nuclear Plant’s RBMK, but due to the Party’s orders to keep all accidents secret, nobody in the Chernobyl Plant knew of this. Inside the reactor 4, the graphite of the rods had displaced water in the lower part of the core, creating what is known as positive void effect: more steam was generated, which absorbs fewer neutrons than water, in turn increasing reactivity.

The following events are often contradictory, but it is believed that as some control rods jammed, the main pumps (in less than optimal power due to the test) failed to bring more water in, and that remaining inside the reactor turned into steam, further increasing the thermal power to a frightening 12 billion watts. A steam explosion occurred, heaving Elena, the two-thousand tonne, concrete-and-steel biological shield that capped the reactor, clear of its mountings. A second explosion shook the entire building like an earthquake, probably caused by a mixture of hydrogen and oxygen formed inside the reactor. Reactor 4 was shattered by a devastating blast that broke the walls and tossed Elena into the air, flipping it like a coin. Inside the baffled control room nobody knew it yet, but the unthinkable had happened. The reactor was completely destroyed, with tonnes of radioactive fuel and graphite ejected to the outside, together with a mixture of deadly gases carrying radioisotopes that streamed free into the open air.   

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4# Radioactive hell unleashed

Yuvchenko and Tregub were the first to comprehend, when they walked outside and witnessed the smoke and sparks flying from a crater, where Unit 4 used to stand. The roof was gone, one of the walls had been pulverised into a cascade of rubble, and from the crater, a pillar of bluish light climbed to the clear night sky. It was ionizing radiation, open to the atmosphere, unshielded. Several of the operators, included the control room, were dosed with dangerous doses of radiation, as they attempted to pump water and cool down the reactor they still believed in existence. In their experience a meltdown was simply unthinkable.

Firefighters were called to out down the fires caused by graphite-ignited lumps, blazing on the roof of the inmediate reactor 3, and the turbines room. The bitumen roof (built against regulations) quickly burned under the incandescent, radiating pieces. Ignorant of the invisible danger surrounding them, the firefighters dosed the burning pieces, releasing deadly amounts of irradiated steam. Like the engineers, within a few minutes many found themselves vomiting, suffering nauseas and headache. Since they had no equipment to measure radiation, and those in the plant were capped to low levels, they all ignored that in some spots where they stood, the debris emmited gamma radiation estimated between 3,000 to 8,000 roentgen per hour. A dose of 500 rem (roentgen equivalent man) being enough to kill a human. In less than four minutes, many of the engineers and firefighters had absorbed 600 rem. 

When Bryukhanov later arrived, he was at odds to explain what had happened, refusing to believe his eyes. To do so would have meant facing the terrible implications of the disaster. He refused to warn the citizens of Pripyat and deferred, thus endangering them to the already alarming levels of radioactivity, and the radioactive particles that were carried and spread by the wind. By dawn, all the fires except that of the reactor itself were extinguished, and those poisoned with radiation brought to the hospital in Pripyat. There were ninety of them, including Leonid Toptunov; his shift foreman, Akimov; Dyatlov, and several firefighters. Later on, they would be flown to Moscow to be treated there.

5# Evacuation

On the opposite way, flown from Moscow a commission tasked by Nikolai Ryzhkov, Chairman of the Council of Ministers (Premier of the USSR), to take charge of the situation. Their main responsible was Ryzhkov’s deputy, Boris Shcherbina, and accompanying him featured Valery Legasov, deputy director of the Kurchatov Institute, the USSR’s leading institution in nuclear technology development. On the evening of the 26^th they reached Pripyat, and established their headquarters in the Biely Dom (White House), the Ispolkom’s (City Council) building by the Hotel Polissya, in Pripyat’s centre. Bryukanov himself had acknowledged by then that the reactor had been blown to bits, but even then, Shcherbina declined to evacuate the city. He hesitated, because an evacuation of an entire city couldn’t be concealed, and thus, was terrible propaganda.

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But on the morning of the 27^th, Shcherbina finally gave the order. More than a thousand buses, several river vessels, and three trains were comissoned for the task of moving 50.000 people out of the polluted city. None of them were told the truth, and were allowed to believe that once the city was clean, they would come back. The true extent of the disaster was kept to the government, and those involved in the following containment operations.

With the reactor still smouldering, the temperatures kept on the rise, as well as the radiation, with hotspots of up to 20.000 roentgens. Legasov and his team came up with the idea of bombarding the crater with a mix of clay, lead, sand, and dolomite, carried in sacks and dropped from the helicopters of General Antoshkin during several days. His men badly suffered from ionising radiation, as they flew over the smoking ruins to drop their cargo again and again. Why not water? Water only increased the steam and the ejected radiation, and so Legasov knew the effort of the plant’s staff to pump water in the smouldering reactor, had been counterproductive. But again, nobody had trained them for an emergency like that, because their arrogant superiors and politicians had believed the Soviet reactors were failsafe.  

6# The Exclusion Zone of Chernobyl

While the majority of Soviet citizens remained ignorant of the disaster unraveling in Pripyat, on 28^th April traces of highly irradiated particles were picked up in Sweden, and traced back to Ukraine. Since the USSR denied the accident and remained silent, foreign press begun speculating, and these rumours were often more damaging to the Soviet prestige than the truth itself. Gorbachev saw no choice but to publicly admit something had gone wrong. Details were not yet given, thus the cascade of speculation that flodded the western press kept unabated. With the number of Chernobyl victims hospitalised in Moscow peaking to 200, the Politburo (highest decision-making organ of the USSR) swung to action, mobilising the country’s full resources to combat the wild atom.

Back in the exclusion zone Shcherbina and his team relocated from the dangerously irradiated city centre to the town of Chernobyl, 20 km south. Specialists and operators now only approached the osobaya zona (special zone) on armored personnel carriers, while a fence was erected around a radius of 30km from the epicentre, evacuating close to 300.000 people and sealing the area. As the temperature inside the crater dropped, the commison breathed in relief, the 1.200 tonnes of sand and lead dropped by General Antoshkin’s helicopters having paid dividends. But when the worse seemed past, the temperature inexplicably spiked once more.

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7# Liquidators

Legasov and the other specialists feared that if the molten fuel, a body of radioactive lava inside the reactor, reached 2,800 degrees centigrade, it could burn through the reinforced concrete floor, and plunge to the safety pools below. The contact with water threatened to cause yet another chain reaction, a second more powerful steam explosion that would blow up the other three reactors, and scatter their radioactive fuel to the air. This would potentially render most of Europe uninhabitable for centuries to come. It was also feared that the lava kept melting the soil, plunging further into the bowels of the earth, and since Pripyat was build on a marsh, that meant eventually finding a great mass of water. The clock was ticking.     

The commission was at odds about how to proceed. A new team headed by Ryzhkov’s deputy chairman, Silayev, and Evgeny Velikhov, Gorbachev’s personal assessor in matters of nuclear energy, arrived in Chernobyl on 2^nd May, to replace the exhausted Shcherbina and his men. Legasov chose to stay, often discussing with his archnemesis Velikhov (both aspired to the post of director of the Kurchatov Institute) on how to proceed. As the temperatures inside climbed to 2,000 degrees, the comission formulated a plan to drain the pools underneath the reactor, a mission entrusted to the growing military presence in the zone, young conscripts recruited in secrecy, and told to prepare for ‘war’. But for the next step someone who knew the plant well was needed. Three plant engineers, Baranov, Ananenko, and Bespalov, were sent to bypass the labyrinthic maze under the reactor, where they found and activated the valves to empty the safety pools. By 8^th May the threat of a second steam explosion had been averted.

Next step was to freeze the ground underneath the foundations with liquid nitrogen, thus cooling the radioactive lava that they feared was chewing through, and install a heat exchanger to accelerate the cooling. For this purpose, miners were brought from all across the USSR to excavate a tunnel. Like the soldiers, they were ignorant of the inherent dangers, often ignoring the protective equipment under the blazing summer heat, smoking outside and working past the compulsory dose of 25 rem per person, either under orders or out of a feeling of duty and sacrifice for the motherland.

Above the surface, the liquidators had begun to clean the area. Their methods included dropping glue and bitumen to stick the radioactive dust and prevent it blowing elsewhere, and then scrapping it safely; burying the most contaminated trees, soil, and entire houses in waste disposals; killing the pets, for their irradiated fur was a serious health hazard, and organising the evacuated citizens to return to collect some belongings. The prospects of radioactivity didn’t deter some to loot, thus flooding the black market with irradiated furniture and personal belongings from the Exclusion Zone.

If you wish to see a picture of the Red Forest of Chernobyl, known as such because radiation turned it crimson, click here. If you look closely you’ll see the Nuclear Plant looming on the background. Pripyat stands on your back

8# Radiation can kill

The highly speculative news that seeped from the west, in contrast with their silent government, had caused the Soviet people to become very mistrustful of any official statement claiming to have the situation under control. In Kiev, only 130km from the Exclusion Zone, all children were evacuated, and its citizens rightly feared an imminent general evacuation. In Moscow, more than 207 people affected with various degrees of ionising radiation had been admitted in the Clinical Department of Hospital Number Six of Moscow, specialised in treatment of ionising radiation.

Headed by Dr. Guskova, the clinic checked in the men of Pripyat, who arrived vomiting, but overall in good spirits and improving after the initial symptoms ceased after a few days. But Guskova, who had treated serious radiation injuries before, knew what was ahead. In a matter of days, the most severe symptoms appearead. Alopecia, burnings that left the skin raw, necrosis, severe vomiting, diarrhea, and hemorrhaging, together with countless minor infections that could and did prove fatal, since the immune system of the patients failed, as a result of the absorbed radiation.

Guskova and her doctors fought it the only way they could, using blood transfusions and bone marrow transplants, but in the most serious cases, it was in vain. In total, 31 men and women died, including Toptunov and Akimov, who could have helped to clarify the circumstances surrounding the explosion. For many years the Soviet government would only admit these 31 dead as the overall casualties derivated from the accident. Yet another empty claim.   

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9# The Sarkofag. Entombing the reactor

In Chernobyl, it was discovered to the great relief of the liquidators, that the temperatures inside the reactor were in steep decline. The heat exchanger was no longer necessary, and the attention of Legasov and the others veered towards how to dispose of the tonnes of radioactive fuel that still remained inside the ruins. Radionuclides couldn’t be broken down nor destroyed, and given the need for air to cool down the fuel, it was decided to build a containment device, a sarkofag (sarcophagus), to forever entomb the remains of reactor 4.

With radiation still peaking to 10,000 roentgens around the epicentre, no man or woman could approach it. Moreover, highly irradiated graphite and debris remained where the explosion had ejected them, on the roof of unit 3, which together with the other two functional reactors, was scheduled to reconnect to the grid before the year ended. The Soviet government was determined to prove to the West that they had the situation under control. Remote-controlled robots were sent to the roof to push the graphite back to the crater. But soon the robots broke under the gamma field emmanating from the ruins.

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There was no other choice but to send humans to do the dirty work. Protected by lead overalls, fresh conscripts were brought under the lead of General Tarakanov, who like his men, often recklessly exposed himself to dangerous levels of radiation. Known as the Biorobots, Tarakanov’s team limited each stay on the roof to one lifetime trip of two minutes and thrity seconds, the time it took them to absorb around 25 rem, using this time to scoop debris and throw it back to the crater. Like all other liquidators, after reaching 25 rem they were supposed to be sent back home, never to step into the Zone again, but many returned to the rooftops several times.

On October 1st, Tarakanov reported to Shcherbina, again in charge of the comission, that the rooftop had been cleaned. That same day Reactor 1 went back online. The other two would follow soon, as promised. By mid November, the Sarcophagus was complete, a gigantic structure built by more than 20.000 people, which had costed 1.5$ million a day, and was expected to last a hundred years. 

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10# Deaths, cancer, and wildife

The consequences of the Chernobyl Disaster are manifold and varied. Some were brief and others will span for thousand, or even millions of years. The Exclusion Zone remains to the day, uninhabitable, but for a temporary thousand liquidators and another hundred peasants, the latter allowed to return to their ancestral homes, still contaminated beyond tolerable levels. Besides humans, the Zone thrives with wildlife. Wolves, bears, and elk have returned, together with wild dogs descendants of those pets that were left behind. They are studied to see the effects of radiation in animals and plants, and while it seems some species are little affected, others presented deformations and genetic abnormalities, like some fish growing to unnatural lengths.

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When it comes to the effects on humans, radiation is far more puzzling, for its very hard to pinpoint or predict the long-term effects. During the last years of the Soviet Union, doctors were pressed to diagnose those affected with radiation with other diseases, so the state wouldn’t have to foot the bill for the expensive treatments and compensations for a staggering total of 600.000 liquidators. As a result, the true number of casualties derived from the disaster is difficult to ascertain. Studies conducted by the Internation Atomic Energy Agency (IAEA) and others predicted 5.000 deaths of cancer, and the same amount of thrydoid cancer cases diagnosed in children and adolescents from the most contaminated areas. Another 25,000 deaths of cancer in the rest of Europe were also expected. However, the UN saw these numbers statistically insignificant within the five million people living in affected areas, and given the fact that cancer is a common cause of death worldwide.

11# The fall of the Soviet Union

Contamination spread around Europe, as the winds blew first north, and then west and south. Until 2012, sheep’s meat from areas in North Wales and Scotland, was banned due high concentration of  radioactive isotopes on their bodies. Other countries had similar restrictions. Still, the worst befell those evacuated. Few of they 300.000, included the citizens of Pripyat, would see their homes again. They were relocated in different parts of the USSR, mostly Slavutych, Moscow, and Kiev, where their new neighbours would receive them with hostility. They blamed them for the catastrophe and told their children not to play with the so-called radioactive kids. A fear grounded in truthy it seems, for their brand new flats presented higher-than-normal levels of radiation. Together with the liquidators, they would live in permanent fear of the invisible ravages that the radiation had caused to their bodies.

To paint the bleak panorama with bright colours, the Soviet authorithies took to set a cult of Chernobyl heroes. Firefighters, soldiers, specialists and liquidators, were praised and awarded, many with the title of Hero of the Soviet Union, the highest award of the country. And while one hand pinned the medals, the other wielded the stick. Bryukhanov, Fomin, and Dyatlov (who had survived despite absorbing a lethal amount of radiation) were trialed for a breach of safety regulations. Their negligence was declared as the single cause of the tragedy.

In private however, the Politburo admitted that the flawed RBMK carried most of the blame, and those in operation were fitted with new safety measures. Playing to the gallery, the state couldn’t admit that the Soviet technology and scientists whom they had showered with praise in the past, were responsible for the biggest embarassment of Soviet engineering, and an ecological disaster such as the world has never seen before. But nothing couldn’t hide the magnitude of the episode. The Soviet people were fed up with both the politicians and their lackeys, the scientists who had fawned over them instead of doing their job properly. The state’s failed attempts at concealing the accident opened the eyes of the people, to the corruption and incompetence of their leaders. If the peaceful Atom, which the Communist Party had praised so much, was a lie, then the illusion that Communism knew better, was broken.

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The already fragile Soviet economy was a shambles after Chernobyl, reeling at the cleaning bill of 128$ billion, the equivalent to the Soviet defense budget for 1989. And this didn’t include further maintenance of the Exlcusion Area or subsidies for the liquidators. Weakened by corruption, incompetence, and incapable to adapt itself to the new times, the political system floundered. On 25th May 1991, the Soviet Union’s flag was lowered in the Kremlin for the last time. It was the end of the political system that had created the circumstances allowing a disaster like Chernobyl. Only after its fall, would the truth start to trickle out, about what had happened inside the Exclusion Zone, from that fatidic night of 26th April 1986.

The weak economies of the new Ukrainian and Belarussian states meant that liquidation could not be given priority over the manifold needs of the nascent states. Maintenance of the disposal grounds was poor, and despite the strong objections of a vast majority of people against Nuclear Energy, the remaining reactors of the Nuclear Power Plant Vladimir Ilych Lenin in Pripyat, remained operative until 2000. As a result of Chernobyl, the world experienced a wave of anti-nuclear opposition, ebbing in time, and ressurected as a result of the Fukushima nuclear disaster in 2011. Even as today, the debate continues over whether nuclear energy can be fully discarded in favour of cleaner, safer, sources.

12# The Arch and the Chernobyl Tours

Several expeditions inside the ruins of the reactor 4 eventually found the melted remains of the core, now cooled, and fears of another explosion were finally put to rest. More alarming was the poor state of the Sarkofag, presenting several gaps and cracks from where dust or contaminated water could seep out. A new containment device, costing 1.5 billion euros and funded by forty-three countries, was designed. A giant steel arch, 108 metres high, packed with dehumidifying equipment and designed to dismantle the remains of the deteriorating unit 4 inside.

Known as the New Safe Confinement (NSC) or informally as the Arch, it was built at some distance from the old sarcophagus, and was later slid over the latter using rails. Its construction was completely finished by 2019, and it is expected to last a hundred years, an eyeblink compared to the thousands of years that the Exclusion Zone is estimated to remain uninhabitable. But not unvisited, for since 2011 the Ukrainian government allows tourists to visit the Zone, including the city centre of Pripyat and a close view of the entombed Unit 4 from the grounds of the Nuclear Power Plant.

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Since radiation is focalised in hotspots, mostly vegetation, and given how little time you stay around, there’s no real danger in these visits, as long as one doesn’t go stuffing irradiated soil in the mouth. Myself I took a trip there in 2014, before the NSC was finished. There are several Chernobyl tour operators, all dependant on official permission from the Ukrainian Government to allow you access, for no more than a few hours and only accompanied by a guide, who takes you the heart of a ghost city that once was home of 50.000 people, now reclaimed by nature.    

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