What really happened at Chernobyl? How the world’s worst nuclear accident happened (2023)

For free real time breaking news alerts sent straight to your inbox sign up to our breaking news emails

Sign up to our free breaking news emails

For most residents of Pripyat, Saturday 26 April 1986 seemed a relatively unremarkable day.

Some would have been aware of an incident at the nearby Vladimir Ilyich Lenin Nuclear Power Plant, around which the town had sprouted up in the decade prior, but, in the words of one off-duty engineer: “There was no panic. The city lived a normal life. People were sunbathing on the beach.”

But the warning signs were there.

Soviet Union officials were driving the streets, hiding their monitors as they gauged the levels of radiation washing over the pedestrians they passed. Traders had been warned not to sell fresh greens and cabbages at the local market, and street sweepers were washing the streets with foam.

But this had happened during a previous accident at the plant, of which there had been dozens in the past decade, and everything appeared to have been fine.


  • Ukraine war: Putin ‘humiliated’ by Kherson
  • Why did Russia invade Ukraine and what could happen next?

Illegal tour of Chernobyl visits forgotten sites

Show all 25
(Video) What Caused the Catastrophic Nuclear Accident in Chernobyl?

For Yuri Andreyev, who recounted this to BBC Ukraine 30 years later, it was only as he strolled to the far edge of the town with his daughter — a decision he said he would forever regret — and spotted Chernobyl’s fourth reactor “laying in ruins”, that he would realise something was seriously wrong.

Decades after the world’s worst nuclear accident, crucial elements still remain a mystery.

The likely death toll from the catastrophe is continually being revised to this day, the impacts of the fallout upon populations caught up in the nuclear slipstream — from Andreyev and his family to those living hundreds of miles away — still an active area of academic research.

Furthermore, the profound extent to which the accident, and the Soviet Union’s infamous handling of it, impacted the course of global history will never truly be known.

For the leader of the USSR at the time, Mikhail Gorbachev, the disaster wrought history anew. Rather than the collapse of the Berlin Wall, Chernobyl was “perhaps the real cause of the collapse of the Soviet Union”, he would later lament.

But, as with the disaster itself, the true starting point of such catastrophe is hard to pinpoint.

In the simplest sense, it began with a disastrous experiment during routine tests of reactor four. Technicians wished to see whether an emergency water-cooling system would work during a power outage and, shutting down the reactor’s emergency safety system, withdrew most of the control rods from its core while keeping the reactor running.

Moments after their re-insertion, at 1.23am, the resulting reaction caused a partial meltdown in the core, summoning a large fireball that blew the 1,200-tonne concrete and steel lid from the reactor, which would spew roughly 400 times more radioactive material into the atmosphere than the atomic bomb dropped on Hiroshima.

Two workers were immediately killed in the blast, which bent the plant’s thick concrete walls “like rubber”. Another plant worker, Sasha Yuvchenko, would later recall standing to watch as a pillar of blue ionising radiation ascended into the sky, “flooding up into infinity from the reactor”, reflecting: “I remember thinking how beautiful it was”.

Several hundred staff members and firefighters then tackled an inferno that blazed for 10 days. According to Andreyev, who was working that night, their dosimeters were taken away and they were told told to wash their shoes in manganese solution before entering, suggesting the radiation on the streets of Pripyat was feared to be worse than inside the incinerated plant.

The number of fatalities from this initial effort is still unknown, with the larger estimates suggesting 50 Soviet citizens lost their lives and scores more were hospitalised with gruesome and permanent injuries as a result of their efforts to protect their community. Until late 1986, the official death toll would recognise only the two who died in the immediate blast.

(Video) Chernobyl Disaster 1986: What really happened?

In those months, hundreds of thousands of emergency workers, troops, cleaners and miners were sent into the area during attempts to control the core meltdown and halt the spread of radioactive material, which would reach the US, China and northern Africa.

Dubbed “liquidators”, some 600,000 workers seeking to contain the spread were given special status that provided compensation in the form of fiscal benefits and additional health care.

While these liquidators were offered some compensation for their sacrifice, it appeared that Soviet authorities had known all along that there could be “accidents” at the nuclear plant.

Documents published decades later by the Ukrainian Security Service (SBU), initially sent to the KGB in Moscow, suggested Chernobyl was subject to significant flaws throughout its construction, as early as its design stage, indicating materials used were sub-standard and that technicians often ignored safety regulations.

In January 1979, a KGB report on the plant said: “According to operational data, there were deviations from design and violations of technology procedures during building and assembling works. It may lead to accidents”.

The documents, released by the SBU in 2003, revealed that between 1977 and 1981 there were 29 accidents at the nuclear plant.

In 1982, another incident releasing what the documents described as “significant quantities of radiation” would lead officials to engage in a significant cover-up effort, but this relatively minor event merely foreshadowed the scale of the deception that would come four years later.

While engineers and firefighters toiled to extinguish the blaze in the days following 26 April, officials sought to bury the true scale of the disaster from the outside world, and to uncover suspected foul play — interrogating first responders such as Yuvchenko as they lay in hospital watching their bodies decay.

The more immediate response was guided by a litany of deadly miscalculations from officials, whose dosimeters were unable to process the vast amounts of radiation, allowing them to believe the reactor remained intact.

(Video) The Chernobyl Disaster: How It Happened

Some workers would defy orders, with Andreyev recalling how he and other colleagues, none of them wearing protective gear, shut off the other nuclear reactors in what he described as a lifesaving measure.

Approximately 36 hours later, as officials began to acknowledge the huge scale of the problem, the order was given for Pripyat to be evacuated for three days. Most residents would never return.

Efforts to downplay the scale of the disaster began within government itself — infamously exemplified by the Soviet foreign affairs minister’s attempt to allay a more senior official’s concern for residents’ health with the assertion that they were celebrating weddings, gardening, and “fishing in the Pripyat River”.

Three days later, the alarm was raised by Sweden, where the radiation was picked up at a nuclear plant.

The Soviet Union denied that an incident had occurred, but with Denmark, Finland and Norway also voicing concerns shortly afterwards, it eventually became impossible to hide the accident from the international community.

However, Moscow continued to downplay the true scale of the catastrophe, failing to tell even its own citizens to stay indoors and allowing the capital’s May Day parade to go ahead a week later. The ensuing secrecy surrounding the handling of the disaster in the years that followed, and the reluctance to warn citizens of the scale of the danger they continued to face, means the true toll is continually being revised.

The resulting suspicions that Moscow could not be trusted to tell the truth had directly devastating effects.

It is believed that up to 200,000 women across western Europe chose to end wanted pregnancies on the mistaken advice of doctors who were mistrusting of the Soviet Union’s official line on radiation levels and who feared a possible rise in birth defects. There was no such increase in babies born with congenital defects, the World Health Organisation would conclude in 2005.

One estimate by Kiev’s National Research Centre for Radiation Medicine suggests that in the former Soviet Union alone, five million people have suffered as a result of Chernobyl.

More than 5,000 people who were children at the time living in the affected areas in Ukraine, Russia and Belarus, have since developed thyroid cancers, which the UN attributes to radiation exposure.

While 330,000 people were moved out of the area, which now suffers far higher levels of poverty than other parts of the former Soviet Union, the upheaval proved “deeply traumatic” for many, according to the Chernobyl Forum.

(Video) Chernobyl Nuclear Explosion Disaster Explained (Hour by Hour)

A 2005 report by the UN group found: “Even when resettlers were compensated and offered free houses, many retained a deep sense of injustice. Many are still unemployed, without a place in society and have little control over their lives. Some older resettlers may never adjust.”

Amid decades of concern of a predicted rise in cancers, clear scientific evidence of which is hard to ascertain, the psychological toll upon those still living in the affected zones is clear, with residents tending to be more likely to suffer with their mental health or alcohol abuse.

Meanwhile, first responders are often forced to contend not only with the trauma of the event, but also a lingering stigma that has sometimes seen them shunned by peers fearful of a false radiation risk.

“I try not to talk about it. I don’t want people to know about it,” Yuvchenko told the New Scientist in 2004, at which point he still had to receive “constant” skin grafts.

“I have been given two medals, an order of honour for my actions that night and a medal 10 years afterwards, but everybody got one of those. I try to get on with my everyday life. My neighbours don’t know who I am. There is a stigma attached to it.”

In 2007, a study of nearly 5,000 men involved in the cleanup effort between 1986 and 1991 found they suffered an increased risk of suicide, describing their findings as “concrete evidence that psychological consequences represent the largest public health problem caused by the accident to date”.

It may have also proved fatal for the Soviet Union itself, which collapsed fewer than six years later — with the intermediate period defined by public calls for greater transparency amid suspicions and anger over a perceived lack of public safety.

Gorbachev, the last leader of the USSR, would define Chernobyl as a “turning point”, which “opened the possibility of much greater freedom of expression, to the point that the system as we knew it could no longer continue”. It would strengthen his conviction in pursuing his perestroika (”reformation”) and glasnost policies, which celebrated the openness of ideas after years of a USSR famed for its “culture of secrecy”.

As these policies invited increasing criticism of the USSR, the apparent secrecy with which the Chernobyl disaster was handled gradually eviscerated people’s trust of their government, which eventually lost control to a public fraught with concern over radiation levels.

(Video) Inside the heart of the Chernobyl nuclear reactor | 60 Minutes Australia

While Chernobyl remains a cautionary tale to governments the world over — many of whom financed a £1.5bn sarcophagus to confine the reactor for another century, completed in 2019 — the area itself is effectively a ghost town.

Save for a few residents who refused to leave their homes, the 18-mile exclusion zone has gradually been repopulated by wildlife, including boars, wolves, beavers and bison.

Despite the dangers posed by the area — which is expected to be contaminated for another 24,000 years — researchers have suggested the animals are flourishing because the radiation poses less risk than the presence of humans.


How did the Chernobyl world's worst nuclear disaster occur? ›

The Chernobyl accident in 1986 was the result of a flawed reactor design that was operated with inadequately trained personnel. The resulting steam explosion and fires released at least 5% of the radioactive reactor core into the environment, with the deposition of radioactive materials in many parts of Europe.

What was really happening at Chernobyl? ›

1. What caused the Chernobyl accident? On April 26, 1986, the Number Four RBMK reactor at the nuclear power plant at Chernobyl, Ukraine, went out of control during a test at low-power, leading to an explosion and fire that demolished the reactor building and released large amounts of radiation into the atmosphere.

What was the worst nuclear accident? ›

Three Mile Island (March 28, 1979) The most serious nuclear accident in U.S. history took place at the Three Mile Island plant near Harrisburg, Pennsylvania, a brand-new facility lauded for its state-of-the-art design, efficiency and affordability during an era of energy crises.

What were the worst effects of Chernobyl? ›

Psychological or mental health problems. According to several international studies, people exposed to radiation from Chernobyl have high anxiety levels and are more likely to report unexplained physical symptoms and poor health.

How many people died because of Chernobyl? ›

The official death toll directly attributed to Chernobyl that is recognized by the international community is just 31 people with the UN saying it could be 50. However, hundreds of thousands of “liquidators” were sent in to put out the fire at the nuclear power plant and clean up the Chernobyl site afterwards.

Was Chernobyl worse than a nuclear bomb? ›

"Compared with other nuclear events: The Chernobyl explosion put 400 times more radioactive material into the Earth's atmosphere than the atomic bomb dropped on Hiroshima; atomic weapons tests conducted in the 1950s and 1960s all together are estimated to have put some 100 to 1,000 times more radioactive material into ...

Does Chernobyl still affect people today? ›

A radioactive catastrophe of this magnitude is too dangerous to be abandoned. To this day, more than 7,000 people live and work in and around the plant, and a much smaller number have returned to the surrounding villages, despite the risks.

How long can you survive in Chernobyl today? ›

For nearly everyone, you could live out your life completely unaffected. The radiation is low enough that it can only be shown statistically over a larger model of the population in which living in the exclusion zone may add a 1% or 2% increase in some forms of cancer.

Is Chernobyl reactor 4 still burning? ›

Chernobyl reactor 4 is no longer burning. The reactor was originally covered after the disaster, but it resulted in a leak of nuclear waste and needed to be replaced. The systems for a new cover for the reactor were being tested in 2020 and is sometimes referred to as a "sarcophagus."

What is the safest place on earth during a nuclear war? ›

The Smart Survivalist named the Nordic country as the safest place in the event of a nuclear war. “Because Iceland is isolated from the rest of the world by the North Atlantic Ocean, it would be very difficult for a nuclear missile to reach Iceland without being detected first,” it said.

What was worse Chernobyl or Fukushima? ›

The accident at Fukushima occurred after a series of tsunami waves struck the facility and disabled systems needed to cool the nuclear fuel. The accident at Chernobyl stemmed from a flawed reactor design and human error. It released about 10 times the radiation that was released after the Fukushima accident.

What was worse 3 Mile Island or Chernobyl? ›

Under the INES, Three Mile Island is classified as Level 5, an accident with wider consequences, whereas both Fukushima and Chernobyl are Level 7, major accidents.

Did Chernobyl affect UK? ›

It is estimated that the explosion released about four hundred times more radioactive material into the atmosphere than both the bombing of Hiroshima and Nagasaki combined. Despite being over 1,600 miles apart, the United Kingdom felt the effects of Chernobyl's radioactive cloud.

How long will Chernobyl be toxic? ›

When Will Chernobyl Be Safe? With that being said, the most dangerous place to be in Chernobyl is anywhere near the reactor - that area will take at least 20,000 years to disperse as far as radiation breakdown.

Who lives in Chernobyl today? ›

The Chernobyl zone, one of the most radioactively contaminated places in the world, has remained closed since 1986, although a small number of people still live in the area — mostly elderly Ukrainians who refused to evacuate or who quietly resettled there later.

Why do the Russians want Chernobyl? ›

The route from Belarus to Kyiv through Chernobyl might be particularly appealing to Russian military planners because it would allow them to cross the Dnieper River in Belarus, avoiding a potentially hazardous crossing of the major river, which bisects Ukraine, behind enemy lines.

Who was blamed for the Chernobyl disaster? ›

But who was to blame? Viktor Bryukhanov was officially held responsible for what happened at Chernobyl. He had helped to build and run the plant, and played a pivotal role in how the disaster was managed in the aftermath of the reactor explosion. Here's more about Viktor Bryukhanov.

How does Chernobyl look today? ›

Today Pripyat is a ghost-town, its apartment buildings, shops, restaurants, hospital, schools, cultural center and sports facilities derelict and its streets overgrown with trees. The city lies in the inner exclusion zone around Chernobyl.

What is the most radioactive place on earth? ›

1. Fukushima Daini Nuclear Power Plant, Japan is one of the world's most radioactive places. When a 9.1 magnitude earthquake caused a tsunami in 2011, it overwhelmed the existing safety features of the Fukushima Daini Nuclear Power Plant and caused the worst nuclear power plant disaster since Chernobyl.

Why is Chernobyl still radioactive and Hiroshima is not? ›

The first was that the explosion at Chernobyl happened on the ground, whereas the explosion at Hiroshima happened high in the air above the city, which greatly reduced the radioactive levels. The second difference was the strength of the explosions.

Can Chernobyl still explode? ›

With no working reactors, there is no risk of a meltdown. But the ruins from the 1986 disaster still pose considerable dangers.

Did Chernobyl affect the earth? ›

The accident at the Chernobyl nuclear power plant in 1986 released radioactive substances – including iodine, caesium, strontium, and plutonium – into the atmosphere. In Central Europe, only caesium-137 is relevant for the radiation to which humans and the environment are still exposed.

What countries are still affected by Chernobyl? ›

Over 200 000 km2, of which 71% are in the three most affected countries (Belarus, Russia and Ukraine) were contaminated with caesium-137, which has a 30-year half-life. As shown in Figure 1, the deposition occurred in patches, as it was strongly influenced by rainfall. Data source: UN Chernobyl Forum, 2005.

Will Chernobyl ever be habitable again? ›

Experts have said it will be at least 3,000 years for the area to become safe, while others believe this is too optimistic. It is thought that the reactor site will not become habitable again for at least 20,000 years, according to a 2016 report.

Is Chernobyl still leaking radiation? ›

“Based on the information that we have, there is no imminent threat of large releases of radioactivity,” Nesbit said. The reason for that, he explained, is that the radioactive material is in a stable situation. The spent fuel has been removed from the reactors and is maintained either in cooling ponds or dry storage.

Can you stay overnight in Chernobyl? ›

How long can you stay in the Chernobyl Exclusion Zone? There are two exclusion zones in Chernobyl; a 10km inner and 30km outer Exclusion Zone. It is safe to stay in the outer Exclusion Zone overnight. There is a small hotel in Chernobyl town where our trips spend the night.

Were Chernobyl victims buried in cement? ›

Most of the direct victims are buried at the Mitino cemetery in Moscow. Each body is sealed in a concrete coffin, because of its high radiation. Although the power plant is named after the small town of Chernobyl, a new town was built much closer to the power plant; the town of Pripyat.

Would the UK survive a nuclear war? ›

If it came down to a nuclear war between Russia and the United States, Britain would be caught in the crossfire. As would most of the global population. According to a new study, more than five billion people would die through famine in the aftermath of a nuclear conflict.

Can Russian nukes reach UK? ›

Could they reach the UK? Intercontinental ballistic missiles (ICBMs) in Russia's possession have the capability to reach and destroy major global cities such as London or Washington. ICBMs can reach a top speed around 10 minutes after launch which could see one fired from Russia reach the UK in just 20 minutes.

Can UK stop a nuclear missile? ›

There is no real credible capability to shoot down an incoming intercontinental ballistic missile. No nation really has a credible capability in this respect. Whilst anti-ballistic missile technology exists, current technological advances do not stretch to a capable system to protect against even a limited ICBM attack.

How far did radiation spread from Chernobyl? ›

However, radiation affected the environment over a much wider scale than this 30 km radius encloses. According to reports from Soviet scientists, 28,000 square kilometers (km2, or 10,800 square miles, mi2) were contaminated by caesium-137 to levels greater than 185 kBq per square meter.

Do animals live near Chernobyl? ›

Contrary to what one might assume, Chernobyl — the site of the deadliest nuclear accident in history — is a virtual refuge for wildlife. From deer, wolves, and dogs to more exotic species like lynx and uniquely named Przewalski's horse, the animals of Chernobyl and the surrounding Red Forest are numerous.

Do people still live on 3 mile Island? ›

Yes, people do still live near Three Mile Island, located in Londonderry Township, Dauphin County, Pennsylvania.

Why did Chernobyl explode? ›

The accident occurred during a safety test meant to measure the ability of the steam turbine to power the emergency feedwater pumps of an RBMK-type nuclear reactor in the event of a simultaneous loss of external power and major coolant leak.

Did Chernobyl radiation reach Scotland? ›

It was only in 2011 that restrictions on Scottish sheep movements due to contaminated soil were lifted and radioactive isotopes from Chernobyl still show up in fish and marine sediments around Scotland.

How much radiation did Chernobyl get UK? ›

NRPB have estimated that the average total UK dose from Chemobyl fallout was 0.05 mSv, although the dose to people living in areas of high deposition was higher (e.g., the average dose per person in Cumbria was 6 times the UK average).

Which country was most affected by Chernobyl? ›

Belarus, Ukraine and Russia suffered the worst effects of the nuclear disaster. In 2005, the WHO estimated around five million people still lived in areas most contaminated by Chernobyl radionuclides. About 100,000 of these people lived in areas once deemed under “strict control”.

Will Chernobyl ever stop being radioactive? ›

Radioactive pieces of the reactor are still embedded in the surrounding soil where they continue to infect their environment. Scientists have estimated that the surrounding areas will remain contaminated from anywhere from 20 to hundreds more years.

What does Chernobyl mean in English? ›

Chernobyl in American English

(tʃɛrˈnoʊbəl ) city in NC Ukraine: site of a nuclear power plant where a serious accident occurred in 1986.

Was the Chernobyl disaster caused by human error? ›

Key Facts. The 1986 accident at the Chernobyl nuclear power plant in Ukraine, then part of the former Soviet Union, is the only accident in the history of commercial nuclear power to cause fatalities from radiation. It was the product of a severely flawed Soviet-era reactor design, combined with human error.

Why does the disaster at Chernobyl rank as the worst nuclear disaster in European history? ›

Though scientists are still studying the impact of all three disasters, Corkhill sees Chernobyl as "by far the absolute worst." What makes the accident such an unparalleled tragedy, she said, is the combination of an explosion that released radiation into the air and a fire that spread these radioactive particles for ...

What caused the reactor to explode in Chernobyl? ›

It's not a nuclear explosion, but a steam explosion, caused by the huge buildup of pressure within the core. That blows the biological shield off the top of the core, ruptures the fuel channels and causes graphite to be blown into the air.

Why did they think Chernobyl couldn't explode? ›

The core couldn't explode in the way a nuclear bomb explodes, destroying everything for miles around it. However, due to some really big design flaws it could rapidly overheat, causing the water to boil, which caused the reactor to rupture like a pressure cooker.

Who was to blame for the Chernobyl accident? ›

But who was to blame? Viktor Bryukhanov was officially held responsible for what happened at Chernobyl. He had helped to build and run the plant, and played a pivotal role in how the disaster was managed in the aftermath of the reactor explosion. Here's more about Viktor Bryukhanov.

How long did the firefighters live after Chernobyl? ›

Two workers died at the site of the explosion, another died in hospital soon after due to their injuries and 28 operators and firemen are believed to have died within three months of the accident. The UN estimates that only 50 deaths can be attributed to the disaster, but the true toll will probably never be known.

What was worse Chernobyl or Japan? ›

The accident at Fukushima occurred after a series of tsunami waves struck the facility and disabled systems needed to cool the nuclear fuel. The accident at Chernobyl stemmed from a flawed reactor design and human error. It released about 10 times the radiation that was released after the Fukushima accident.

Where is the most radioactive place on earth? ›

1. Fukushima Daini Nuclear Power Plant, Japan is one of the world's most radioactive places. When a 9.1 magnitude earthquake caused a tsunami in 2011, it overwhelmed the existing safety features of the Fukushima Daini Nuclear Power Plant and caused the worst nuclear power plant disaster since Chernobyl.

How long until Chernobyl is habitable? ›

Experts have said it will be at least 3,000 years for the area to become safe, while others believe this is too optimistic. It is thought that the reactor site will not become habitable again for at least 20,000 years, according to a 2016 report.

Is Chernobyl still producing power? ›

Although the reactors have all ceased generation, Chernobyl maintains a large workforce as the ongoing decommissioning process requires constant management. From 24 February to 31 March 2022, Russian troops occupied the plant as part of their invasion of Ukraine.

How did the three divers survive Chernobyl? ›

Valeri Bespalov, Alexei Ananenko, and Boris Baranov were lucky to survive, managing to absorb less than a lethal dose of radiation.

Is Chernobyl still being cooled? ›

The flow hardened and cooled over time into what is now a sand-like solid. It is no longer 'melting', but parts of it are still apparently hot enough for the uranium atoms to fission more than expected, spewing out neutrons that break more uranium atoms apart.


1. Chernobyl: Worst Accident Ever
(Illinois EnergyProf)
2. The Chernobyl Disaster: How It Happened
(Radio Free Europe/Radio Liberty)
3. National Geographic Documentary 2014 What Really Happened at Chernobyl Full Documentary HD 1
4. What Exactly Happened at Chernobyl?
5. Chernobyl Nuclear Disaster | Why it happened? | Dhruv Rathee
(Dhruv Rathee)
6. The Worst Nuclear Disaster in History: Chernobyl! What really happened?
(Gizmo Planet)
Top Articles
Latest Posts
Article information

Author: Pres. Lawanda Wiegand

Last Updated: 02/14/2023

Views: 6583

Rating: 4 / 5 (51 voted)

Reviews: 82% of readers found this page helpful

Author information

Name: Pres. Lawanda Wiegand

Birthday: 1993-01-10

Address: Suite 391 6963 Ullrich Shore, Bellefort, WI 01350-7893

Phone: +6806610432415

Job: Dynamic Manufacturing Assistant

Hobby: amateur radio, Taekwondo, Wood carving, Parkour, Skateboarding, Running, Rafting

Introduction: My name is Pres. Lawanda Wiegand, I am a inquisitive, helpful, glamorous, cheerful, open, clever, innocent person who loves writing and wants to share my knowledge and understanding with you.