Chernobyl disaster

On 26 April 1986, reactor 4 of the Chernobyl Nuclear Power Plant, located near Pripyat in the Soviet Union, exploded. This was one of only two nuclear accidents ever rated at the maximum severity, and it remains the worst nuclear disaster in history. The explosion and fire released large amounts of radioactive contaminants into the air, affecting areas across the Soviet Union and much of Europe.

The disaster happened during a test to see how the reactor could cool down in very difficult conditions. Because of design problems, the test caused a huge power surge, leading to explosions and a meltdown. Fires burned for days, and the government had to evacuate around 117,000 people from nearby areas.

Many people were hurt by the radiation, and some died soon after the disaster. Over time, thousands more developed health problems linked to the radiation. The city of Pripyat was left empty, and a new city called Slavutych was built for people who had to leave their homes. Engineers worked hard to contain the damaged reactor, and a huge shelter was built to protect the area and help with cleaning up the site.

Accident sequence

The Chernobyl disaster began with a safety test on reactor number 4 at the Chernobyl Nuclear Power Plant. The test aimed to see if the turbine could power the reactor’s cooling systems during a power loss. However, mistakes during the test led to a dangerous drop in power.

As the test continued, the reactor became unstable. When the emergency shutdown was pressed, a sudden power surge caused an explosion. This explosion destroyed the reactor and released large amounts of radioactive material into the air. Firefighters worked to put out the fires, but many were exposed to high levels of radiation. The accident showed serious safety problems in how the reactor was operated and designed.

Crisis management

Evacuation

The city of Pripyat was not evacuated right away, and people were not warned about what had happened. Soon after the accident, many people fell ill with severe headaches, metallic tastes in their mouths, and uncontrollable coughing and vomiting. The government of Ukraine did not get quick information about the accident because the plant was run by authorities in Moscow.

A commission was set up to investigate the accident. They arrived at the power plant and found that the reactor was destroyed and radiation levels were very high. They ordered the evacuation of Pripyat. Residents were told to bring only what was necessary and that they would be evacuated for about three days. By the end of the day, 53,000 people were evacuated to the Kiev region. The evacuation area was later expanded to 30 km. The Chernobyl exclusion zone has remained ever since.

Official announcement

Evacuation began before the accident was publicly acknowledged by the Soviet Union. It was only after Sweden reported high radiation levels and pressed the Soviet government that they admitted an accident had taken place at Chernobyl. The Soviet Union first conceded only a minor accident, but as more people were evacuated, the full scale became known. The first official announcement was made on television, stating that there had been an accident at the Chernobyl Nuclear Power Plant and that efforts were underway to remedy the effects.

Core meltdown risk mitigation

To prevent the melted nuclear core from contaminating groundwater, efforts were made to freeze the earth beneath the reactor. When this idea was quickly scrapped, workers were sent to dig a tunnel below the reactor to create space for a cooling system. Later, the melted fuel was found to have stopped flowing, and the tunnel was filled with concrete instead.

Site cleanup

In the months after the explosion, efforts focused on removing radioactive debris from the roof of the reactor. Robots were initially used but often failed due to high radiation. Most of the cleanup was done by workers in protective gear, who could only spend short times on the rooftops due to high radiation levels.

The next step was to build a huge steel and concrete shelter around the wrecked reactor, known as the "Sarcophagus," to prevent the spread of contamination. Construction workers used special techniques to protect themselves from radiation while building the shelter.

Area cleanup

A large cleanup effort took place in the contaminated areas. Helicopters sprayed a special fluid to trap radioactive dust. Many vehicles used by cleanup workers remained in the area, though some parts were removed by scavengers. Workers involved in the cleanup, known as "liquidators," often worked in poor conditions without enough protection.

Site remediation

Work on two unfinished reactors at the Chernobyl plant stopped three years after the disaster. The damaged reactor was sealed with concrete to protect the remaining operating reactors, which continued running due to energy shortages.

In 1991, a fire damaged reactor no. 2 beyond repair. Reactor no. 1 was shut down in 1996, and reactor no. 3 was turned off in 2000, closing the entire site.

A temporary concrete cover built after the disaster wasn’t meant to last. In 2013, part of a nearby roof collapsed, raising concerns about the cover’s safety. An international effort began in 1997 to build a stronger, permanent cover. This new structure, completed in 2016, was moved over the old cover to protect the damaged reactor. However, a drone strike in 2025 caused damage to this protective shelter.

Used fuel from the reactors was stored in special pools. A new storage facility was built to safely keep the fuel for many years. This facility can hold over 21,000 fuel units and includes ways to process and store the fuel safely.

The area around Chernobyl became an exclusion zone, largely returning to nature. Some people returned to live there, and the zone opened to tourists in 2011. However, tourism stopped after fighting began in the area.

No. 4 reactor confinement

Waste management

Fuel-containing materials

Exclusion zone

Recovery projects

Tourism

Main article: Chernobyl New Safe Confinement

Main articles: Chernobyl Exclusion Zone

See also: Polesie State Radioecological Reserve

Long-term effects

Release and spread of radioactive materials

The Chernobyl disaster released a large amount of radioactive material into the environment. It is estimated that this release was about 400 times more than the combined atomic bombings of Hiroshima and Nagasaki. The most affected areas were in Belarus, Ukraine, and Russia, but lower levels of contamination were found across Europe.

Rain helped spread the contamination, especially in mountainous regions like the Alps, Welsh mountains, and Scottish Highlands. Efforts were made to remove radioactive particles from clouds heading toward populated areas, but much of the contamination remained.

Environmental impact

The disaster had significant effects on water bodies, plants, animals, and fungi. A large area of pine forest turned brown and died, known as the "Red Forest." Some animals in the worst-hit areas died or stopped reproducing. Studies showed increased mutation rates in plants and animals due to the release of radioactive materials.

Human impact

The immediate effects of the disaster included deaths among plant workers and firefighters, with some dying from severe radiation sickness. In the years following the accident, more people died from various causes, though not all were directly linked to radiation exposure.

The most notable long-term health effect was an increase in thyroid cancer among children, largely due to exposure to radioactive iodine. The psychological impact was also significant, with widespread fear of radiation leading to stress and harmful behaviors.

Socio-economic impact

The economic cost of the disaster was enormous. The Soviet Union spent a large amount of money on containment and decontamination efforts. The disaster had political impacts as well, contributing to greater freedom of expression in the Soviet Union and influencing international relations at the end of the Cold War.

Significance

Nuclear debate

Main articles: Nuclear power debate, nuclear power phase-out, and anti-nuclear movement

Because people did not trust the leaders of the Soviet Union, who tried to hide what happened, many discussions about the event happened around the world soon after it occurred. This made people worry even more about nuclear power plants everywhere.

The accident caused many people to worry about the safety of nuclear power. It led to the cancellation of many new nuclear power projects. The cost of making plants safer and dealing with worried people became very high, which slowed down the building of new nuclear power plants after 1986.

The accident also showed that the Soviet Union did not always follow safety rules, which made people less trusting of their government. This helped lead to changes that eventually contributed to the end of the Soviet Union.

In Italy, the accident led to a vote in 1987 where people decided to stop using nuclear power. Germany created a special ministry to handle environmental issues and decided to stop using nuclear power, though this decision was changed for a short time before being made again after another accident in 2011.

After the Chernobyl accident, countries agreed to tell each other quickly if a nuclear accident happens that could affect others. This helps make sure everyone stays safe.

In popular culture

Main article: Cultural impact of the Chernobyl disaster

The Chernobyl disaster has inspired many artists and storytellers. Famous examples include the HBO series Chernobyl and the book Voices from Chernobyl by Svetlana Alexievich. Ukrainian artist Roman Gumanyuk created paintings called "Pripyat Lights, or Chernobyl shadows" about the event.

Video games such as S.T.A.L.K.E.R.: Shadows of Chernobyl and its follow-up games are set in the area around the disaster. Another game, Chernobylite, also uses real locations from the area. Movies and documentaries, like Chernobyl Heart and The Babushkas of Chernobyl, explore the effects of the disaster on people and the long-term impact of radiation. The miniseries Chernobyl (2019) tells the story of the disaster and the efforts to clean it up.