The dosimeters went off scale. A huge plume of smoke from the explosion shot a kilometer into the sky, and tons of nuclear fuel and graphite were scattered around the nuclear power plant. The shocked operators of the Chernobyl NPP could only watch in horror as the worst radiation disaster in history unfolded. Yet just a couple of hours earlier, no one could have imagined such a catastrophe.
A nuclear fairy tale
The Soviet Union was a pioneer in nuclear energy. In 1954, the world’s first nuclear power plant became operational in Obninsk. Enthusiasm soared as new plants were rapidly built across the country. By the late 1970s, as part of an extensive construction program, yet another NPP was built on the banks of Pripyat River near the city of Chernobyl. A city named after the river quickly sprang up around the plant. Pripyat was a clean, well-kept city surrounded by nature. It had a population of 50,000 people – primarily the nuclear power plant’s personnel and their families. The NPP itself, with its combination of cutting-edge technology and industrial achievement, embodied the utopia of the late Soviet era. Nuclear power plants were at the height of popularity at the time; nuclear energy was seen as the simplest, most reliable, and safest way to access unprecedented amounts of energy.
The area’s geographical features played a major role when disaster struck. The area was sparsely populated, and there were no major cities nearby – most of the people affected lived in Pripyat itself. However, the long Pripyat River, with many streams and creeks flowing into it, and the area’s wet soil allowed groundwater to carry radioactive particles far from the explosion’s epicenter.
Even in those years, there was an understanding that unforeseen incidents could occur at nuclear power plants. In 1979, a serious accident happened at the Three Mile Island Nuclear Generating Station in Pennsylvania. The reactor core suffered damage, forcing the temporary evacuation of around 200,000 people. Fortunately, there were no fatalities. The incident at Three Mile Island remained largely an economic issue.
The Chernobyl Nuclear Power Plant consisted of four RBMK-type reactors. To understand what happened there, we need to say a few words about them. The reactor core was a seven-meter-high cylinder filled with nuclear fuel and graphite. A constant nuclear reaction occurred there, heating the fuel rods. Water was continuously pumped into the core through special circulation pumps, where it boiled and turned into steam. The steam drove the turbines, converting thermal energy into electricity. The introduction of cold water also prevented the fuel rods from overheating. After passing through the generator, the steam went to a condenser, cooled down, turned back into water, and was then recirculated in the core.
211 control rods made of neutron-absorbing material were used to regulate the reactor’s power output. These rods were inserted and removed through special channels in the reactor core; the deeper they were inserted, the lower the reactor’s power output. If all the rods were fully inserted, the reactor would shut down; if all were removed, it would accelerate uncontrollably. At least 30 rods always had to be in place for safety reasons. This system was quite reliable when all safety regulations were observed.
The night of fire
On April 25, 1986, an experiment was scheduled at Reactor no. 4 of the Chernobyl Nuclear Power Plant. Operators planned to shut down equipment – including the pumps supplying water to the reactor core – to see how long the turbine could continue generating power through inertia alone. The goal was to calculate the time available for operators to switch to backup power sources.
The problem was that conducting these tests required disabling a significant portion of the plant’s automation, including the emergency cooling pump system.
At midnight on April 26, the operators working on shift were: Shift supervisor Alexander Akimov, reactor control engineer Leonid Toptunov, and Anatoly Dyatlov, the deputy chief engineer responsible for the experiment. The operators planned to start the experiment at 1:00 AM. However, just before 1:30 AM, the first unexpected issue arose. Due to the shutdown of the automatic control system, they were unable to smoothly reduce the reactor’s power. Instead, it plummeted far beyond what was intended. This drop led to ‘reactor poisoning’ from decay products – xenon and iodine – which didn’t allow power to be restored to normal levels. Then, the operators made a questionable decision: They removed the safety control rods that limited the reactor’s power output. As power stabilized, Dyatlov ordered the experiment to proceed, despite Akimov and Toptunov’s growing doubts. Meanwhile, none of them realized that the situation was already spiraling out of control and that the emergency cooling system had to be immediately activated.
The water and steam levels in the reactor became unbalanced, but the personnel managed to address the issue. However, the pressure spikes in the water system – critical for energy generation and reactor cooling – were not just warning bells but major alarm signals. The pumps gradually slowed down. The reactor temperature rose, but there was not a single control rod left in the reactor core, and the operators completely lost control of the situation.
At that moment, the Chernobyl Nuclear Power Plant was already on the brink of catastrophe.
To this day, no one knows exactly what happened at around 1:23 AM. What is undeniable is that the reactor core overheated uncontrollably. Realizing things had gone out of control, the operators attempted to insert all control rods back, essentially trying to shut the reactor down. The rods were lowered but stopped short after only two meters (out of the seven needed) as the overheating caused the deformation of the technological channels. Akimov rushed to the control panel and disabled the servo-drive mechanisms, hoping that the rods would fall into the core under their own weight. There was nothing else he could do – all systems that could have assisted with emergency cooling had been manually disabled by the operators themselves.
According to one theory, this decision was the final nail in the coffin. The graphite tips of the rods didn’t slow down the reaction; they accelerated it. This effect should have been instantly countered by the main body of the rods, but the simultaneous lowering of 211 graphite tips caused a rapid increase in pressure. This is just one explanation, but regardless, the rods became jammed in the overheated and deformed channels. A chain reaction occurred. The sudden surge in pressure (rising by 15 atm per second) caused the pump valves to slam shut, cutting off all water supply to the reactor. Then, the reactor’s water system ruptured from within. A variety of tumultuous chemical reactions unfolded in the reactor core, causing an explosive mixture to brew in just 18 seconds.
And then it detonated.
The 130-ton separator drums flew off their mounts, the 500-ton reactor roof blew off, and nuclear fuel shot into the atmosphere, with graphite scattering across the station and igniting. At that moment, Akimov exclaimed:
“What the hell? We did everything right!”
Around 50 tons of nuclear fuel were released into the air, and another 70 tons settled in the area around the station. The amount of radioactive material that escaped was equivalent to ten Hiroshima bombings, while 800 tons of graphite continued to burn inside the reactor. One member of the shift died on the spot, and another passed away a few hours later. The reactor staff could only guess at the radiation levels around them since the dosimeters read ‘off scale’. The country faced an unprecedented nuclear disaster, and thousands of people were about to confront unimaginable challenges.
There will come soft rains
At 1:30 AM, Major Leonid Telyatnikov, the head of the Chernobyl fire brigade, was awakened by a sudden phone call. Minutes later, fire trucks raced toward the nuclear plant.
Cold blue lights flickered in the darkness – those were the burning ruins of Reactor No. 4. Firefighters clad in their usual attire climbed onto what remained of the station’s roof. They worked at heights of dozens of meters amid thick smoke. Telyatnikov himself twice climbed to the roof of the turbine hall and the reactor section, 70 meters above the burning abyss.
The firefighters managed to contain the blaze and prevent it from spreading. Fortunately, Yury Bagdasarov, the shift supervisor of the neighboring reactor, acted swiftly and decisively, shutting down his reactor and instructing his crew to don respirators and take potassium iodide – thereby saving many lives. While firefighters were extinguishing the fire in Reactor No. 3, those working in Reactor No. 4 started collapsing from acute radiation sickness. The bodies of these first responders were almost completely destroyed. Radiation sickness kills slowly and painfully; many of Telyatnikov’s subordinates died three weeks later. Among the first to die were fire service lieutenants Vladimir Pravik and Viktor Kibenok, both just 23 years old. The doctor said:
“They needed new bodies; nothing of the old ones remained.”
Major Telyatnikov himself died 18 years later from cancer caused by radiation exposure. The personnel at the station also suffered fatal doses of radiation: Shift supervisor Akimov and his assistant, Toptunov, died within weeks, while Dyatlov passed away several years later.
On April 27, the evacuation of Pripyat and the 30-kilometer area around it began. To transport the people, the authorities mobilized 1,225 buses and 360 trucks. The government ordered residents to leave their belongings behind; their possessions were contaminated with radiation, and there wasn’t enough transport to evacuate 100,000 people with their belongings. One of the tough moral decisions in those first days was the order to leave animals behind. Their fur had absorbed radiation, making it dangerous to take them along. Stray dogs left behind in the area began attacking cats and then attempted to attack people. A special team was sent to hunt down and shoot the poor animals. Soldiers were also deployed to catch looters.
Some residents resisted evacuation. One man tried to flee in a car packed with contaminated items. The military forced him out of the vehicle and ran over the car and its contents with an armored personnel carrier. Initially, evacuees were taken to a village 50 kilometers from the plant, where they dispersed across Ukraine, many on foot. Military helicopters buzzed overhead. That was the end of Pripyat – the city of dreams, and the beginning of its history as a ghost town.
Equipment for the clean-up operation was gathered from all over the country. The cleanup crews needed engineering machinery, earth-moving equipment, and helicopters. The latter played a crucial role in mitigating the aftermath of the catastrophe. From the sky, the NPP was bombarded with a mixture of boron carbide to absorb neutrons, dolomite to capture thermal energy, sand, and clay to slow the spread of radioactive particles. Helicopters buzzed over the columns of departing refugees.
At first, the helicopters dropped their loads directly onto the NPP, hovering above it. However, pilots received lethal radiation doses, and it was decided to drop the cargo rapidly, without stopping.
On the ground, clean-up work continued. Initially, volunteers showed up at the disaster response headquarters, but most of the work was done by soldiers. Armed with only rudimentary protective gear, they undertook an immense amount of labor. They needed to entomb the destroyed reactor under a concrete sarcophagus, establish a drainage system for the river, and decontaminate Pripyat and its surroundings. Furthermore, it was necessary to isolate the NPP underground to prevent radioactive leaks into the soil, which could then contaminate Pripyat and Dnieper rivers.
People working around the plant continued to receive high doses of radiation and accidents occurred during cleanup operations. However, within seven months, considerable progress was achieved. Toxic substances ceased to spread beyond a relatively broad, yet sparsely populated area. Over 206 days, a concrete sarcophagus, officially called Shelter Object, was constructed over Reactor No. 4. The other reactors were decontaminated as well. Concrete walls were built around the reactor, followed by a 12-meter cascade wall. In addition to concrete walls, a ventilation system and a comprehensive monitoring system were installed. During construction, another tragedy occurred when a helicopter, snagged by a crane cable, crashed, killing the crew. Finally, the work was done and the destroyed reactor was enclosed in a sarcophagus.
While almost all people left the Chernobyl exclusion zone, it has never been truly deserted. With the absence of humans, wildlife flourished. In the first year after the evacuation, mouse populations around Pripyat surged as the rodents feasted on abandoned grain fields. The cooling pond of the reactor became home to massive catfish. A small research center was even established in the Zone for scientific studies. Various animals were brought there, including some species that had never lived in the area before. The forests became populated with boars, elk, and deer.
In a way, the Chernobyl zone transformed into a sanctuary, filled with lynxes, bears, and even Przewalski’s horses, which had been brought there as part of an experiment. For a time, the few people who remained in the zone and the animals were troubled by an overpopulation of wolves. However, rangers quickly reduced their numbers, leaving behind a grim reminder – a wolf’s head with its jaws wide open placed on the radiator of a ranger’s vehicle. Interestingly, the horses played a role in culling the wolves, as rangers often witnessed herds charging at the predators. A pack of wild dogs also settled in the area; initially, they guarded the perimeter of the nearby research facility, but eventually adapted to life in the wild by hunting and even fishing in the technological channels of the abandoned plant.
Officially, only workers from the exclusion zone remained in the area. However, some people known as ‘samosely’ (self-settlers) settled in the nearby forests. These are mostly elderly residents who returned to their homes. Out of 70,000-100,000 evacuees, around 1,200 returned to their former homes. They managed to avoid the most contaminated areas and did not succumb to radiation. Attempts by the police to evict them proved futile, as they stubbornly returned to the area.
Most of these individuals engage in farming to sustain themselves. They learned to navigate the area, identifying places less affected by contamination. Being quite poor and living around 50 kilometers from the nearest inhabited town, they scavenge building materials from the abandoned cities of Chernobyl and Pripyat. Some settled in the abandoned cities, but most built huts in the surrounding forests. Most of the samosely are elderly people.
The area is patrolled by police, including mounted units. They regularly conduct raids to catch illegal tourists, but they aren’t just looking for ‘stalkers’ in the zone. Poachers, scrap metal hunters, and escaped criminals are far more dangerous. Murders are a frequent occurrence. Moreover, both poachers and self-settlers hunt using firearms and set traps and snares. There are also areas of significant radioactive contamination. Not all parts of the zone are equally dangerous, but traveling through it without knowledge of the area can take a major toll on one’s health.
After the Chernobyl disaster, the government launched an investigation into the causes. Decisions made by the staff, the reactor’s design, and the events of that fateful night on April 26 became subjects of several official inquiries and numerous unofficial discussions. Initially, nearly 100% of the blame for the accident was attributed to human error.
The director of the Chernobyl NPP, Viktor Bryukhanov, Anatoly Dyatlov, and chief engineer Viktor Fomin, along with several others, faced trial for their roles in the disaster. Although none served their full sentences, the psychological impact of the events haunted them all. Dyatlov spent the rest of his life trying to justify his actions and comprehend what went wrong that fateful night, while Fomin ended up in a psychiatric hospital.
However, later investigations significantly shifted the narrative surrounding the incident. Many of the operators’ decisions, initially viewed as criminal, were found to have been made in strict accordance with protocols. Lessons were learned from the catastrophe, prompting humanity to revise its approaches to radiation safety, nuclear power plant operations, responses to technological disasters, and treatment for radiation sickness – all at a tragic cost. The immediate aftermath of the Chernobyl disaster resulted in fewer than 30 direct fatalities, but the effects of radiation exposure lingered for decades. Statistically, cleanup workers and evacuees were 20% more likely to develop cancer, suggesting that anywhere from several thousand to tens of thousands of people might have died of radiation-related illnesses. The challenge lies in the fact that this is an impersonal statistic; it was often impossible to determine whether a cleanup worker died from natural causes or as a consequence of radiation exposure. Yet, there is no doubt that the Chernobyl disaster claimed and shattered countless lives.
The Chernobyl exclusion zone became a destination for extreme tourists. The ruins of Pripyat, preserved in their original state since the 1980s, the old Soviet radar systems, and abandoned radioactive vehicles attracted travelers. However, nature and time played their role in destroying these last remnants of Soviet civilization. Tragically, the number of ruins and abandoned towns in Ukraine has grown due to the ongoing conflict with Russia. In 2022, the exclusion zone briefly became a battleground between Russian and Ukrainian forces. Fortunately, both sides managed to avoid prolonged and intense fighting near the site of the old reactor… but leaving behind these old ruins, the army marched toward new ones.