On April 26, 1986, the explosion of a nuclear reactor in Chernobyl, Ukraine, caused the most serious disaster in the history of civil nuclear power. It left indelible traces and yet, since 2022, the war launched by Russia has made the country's nuclear installations targets and goals of war, rekindling the fear of a new accident.

Published on: 04/25/2026 - 2:08 p.m.

On April 26, 1986, in the middle of the night, the core of nuclear reactor No. 4 at the Vladimir Ilyich Lenin power plant in Chernobyl exploded, following a hazardous experiment carried out by plant personnel. The two thousand tons of concrete slab covering the reactor shattered. A huge fire breaks out and pours a plume of radioactive smoke into the atmosphere for several days.

Taken by surprise by this scene of apocalypse, the Soviet authorities of the time struggled to react. They wait 36 ​​hours before ordering the evacuation of populations living near the power plant, first and foremost the 50,000 inhabitants of the model town of Pripyat, which houses the power plant workers and their families.

The worst nuclear disaster in history

They also send to almost certain death "liquidators" who DIY protection against radiation to "suffocate" the molten core of the reactor and clean the area of ​​the most radioactive debris. They call themselves "biorobots" because they replace robots brought on site which prove incapable of functioning due to the dizzying levels of radioactivity.

On May 14, three weeks after the explosion, the liquidators managed to smother the molten nuclear core and stop radioactive releases into the atmosphere. A 30 km exclusion zone around the power plant is set up. This led to the evacuation of nearly 250,000 people. 40 years later, it is still in force. The official report recognizes around forty deaths when the WHO counted in 2005 at least 4,000 deaths linked to exposure to radiation.

Inspired by the collection of testimonies by Belarusian writer Svetlana Alexievitch ("The Supplication"), the series "Chernobyl", released in 2019 on HBO, faithfully describes these nightmarish weeks and depicts the incompetence of those responsible at the time, their lies, and the bankruptcy of the Soviet system ending up protecting its population.

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"The reaction of the authorities was criminal. Instead of evacuating the area, straight away, they summoned so-called specialists from Moscow to examine the situation. It took several days for them to start evacuating the area, which caused considerable damage and radioactivity pollution which covered practically the whole of Europe" says Martin Pohl, professor of nuclear physics at the University of Geneva, for whom the Chernobyl accident can be qualified as a "crime against humanity".

A few days after the explosion, the Soviet authorities were forced to recognize an “incident” because abnormal levels of radioactivity were detected in several Western European countries.

Driven by the wind, the radioactive cloud will water the populations for several weeks. In Germany, Poland and Sweden, the consumption of fresh milk and green vegetables is prohibited for several weeks. In France, the government suggests that the cloud "stopped at the border".

30 years after the disaster, the Nuclear Safety Authority (ASNR) published a map of the radioactive deposits linked to the Chernobyl disaster which have become permanently established on French territory.

The liquidators, last heroes of the USSR

In December 1986, titanic work involving around 600,000 workers made it possible to finalize the construction of a concrete sarcophagus around the reactor. The Soviet authorities then declared the invisible enemy defeated and celebrated the heroes of this fight.

“The Soviet propaganda discourse highlights the heroism of the liquidators in their fight against the radioactive monster, which was perceived as an external enemy,” explains Tatiana Kasperski, associate researcher at Södertörn University in Stockholm.

“This heroic speech was very recognizable for the Soviet populations, because it took up the cult of the victory of the Soviet Union against fascism during the Second World War. But the problem is that in fact, this speech served the authorities to hide their own responsibilities” continues the co-author of the book “Chernobyl, the atomized memory” (Editions JC Lattès).

The breakup of the USSR in 1991 left Ukraine, Belarus and the Russian Federation to deal with the legacy of the most serious nuclear disaster in history. In the economic and political chaos of the 1990s, we still celebrate the anniversaries of the catastrophe and the heroism of the liquidators. But, little by little, differences appear.

“In Russia and Belarus, the Soviet celebration of liquidators continues, but at the same time, their social rights and benefits obtained at the end of the Soviet era are being reduced. In Ukraine, there are much fewer challenges, the State remains indebted to the liquidators,” explains Tatiana Kasperski.

Nuclear installations, battlefields of the war in Ukraine

In 2022, the Russian offensive aimed at conquering Ukraine stuns the world and puts Chernobyl back on the front page of international news. The plant site was occupied by Russian troops from Belarus from February 24 to March 31. The staff manages to inform that they deactivate the radioactivity monitoring sensors, carry out armored movements on contaminated soil and finally disconnect the plant from the electrical network for several days.

Also read With the war in Ukraine, should we rethink nuclear security?

Concern is then at its height, the Chernobyl site still being active, particularly in the treatment and monitoring of radioactive waste. In February 2025, a Russian drone pierces the "Chernobyl Ark", a metal structure 108 meters high and 162 wide financed by the EU, which has covered reactor number 4 since 2016.

Also read: Chernobyl: how a drone strike revived the risk of a nuclear incident

For the IAEA, the ark is no longer able to block radiation and according to Greenpeace the containment function of the new enclosure could not be “fully restored”.

In southern Ukraine, since the outbreak of the Russian-Ukrainian war, another nuclear facility has become a battlefield. For more than 4 years, the Russian army has occupied the Zaporizhia nuclear power plant, the largest in Europe. To gain control, she did not hesitate to fire artillery shells inside the site, provoking responses from the Ukrainian army.

The IAEA, which still has access to the site, notes that the Russian state company Rosatom is present on the site and is working to take over the Zaporizhia power plant to connect it to the Russian electricity network.

Civil nuclear power, the issue of new wars

From Chernobyl to Zaporizhzha, control of Ukrainian nuclear installations has undoubtedly become one of the Russian war aims. An unimaginable situation for “the international community and nuclear security organizations which had given very little thought to the risks posed by civilian nuclear installations in a context of war”, affirms Tatiana Kasperski.

“This is the first time in history that a war has taken place on the territory of a country which has a vast nuclear infrastructure, ranging from the extraction of uranium to the operation of nuclear power plants through the storage of radioactive waste,” continues the researcher. And she denounces "the European and French nuclear sectors in particular which continue to do business with Rosatom (...) in some way facilitating Russia's nuclear terrorism in Ukraine".

For Martin Pohl, the Chernobyl disaster and the war led by Russia in Ukraine show that "100% safe civilian use of nuclear power does not exist. Accepting the nuclear risk is a societal choice. In France, we are ready to accept it, not in Germany for example. (...) In my opinion, a war on European soil is an unimaginable catastrophe. With or without a nuclear power plant."

For her part, Tatiana Kaspersky wants "that we integrate military risks, and not just terrorist risks, on civilian nuclear installations into our debates around the risks and benefits of the nuclear sector".

A reflection that sounds like an emergency. During the five weeks of conflict between Iran and Israel and the United States, the Iranian Bushehr nuclear power plant was targeted at least four times. These strikes caused no damage or casualties but caused the departure of Russian technicians who participated in its operation.

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