In April 1986the Union of Soviet Socialist Republics (USSR) was shocked by the fierce Chernobyl nuclear plant explosionin the west of the country, which claimed the lives of dozens of people who worked there and released a toxic radiation mass that would cause the death of thousands during the following years.
Given this, the Government of the USSR reacted by building a structure to encapsulate the central But, with the passage of time, it deteriorated.
Therefore, in the 21st century, an immense construction was placed above the old one. However, recently, the HIM surprised the world by announcing that it is also damaged, which could imply a risk for the neighboring population.
The devastating Chernobyl accident and a precarious «sarcophagus»
On April 26, 1986while some technicians at the site were carrying out a safety rehearsal, there was a very strong explosion in reactor number 4 of the Chernobyl Nuclear Power Plant, located in the city of Pripyat, north of Ukraineat that time Soviet Union.
The catastrophe sent a cloud of radioactive fallout over hundreds of thousands of square kilometers of Ukraine, Russia and Belarus. It is estimated that the radioactive effects of the explosion were some 400 times more powerful than the bomb dropped on Hiroshima during World War II.
Due to the Chernobyl nuclear accident, 31 people died. Photo: archiveThe immediate consequences were devastating: 31 people died and 135,000 had to be evacuated from the area.
However, the long-term results would be even worse. The International Atomic Energy Agency (IAEA) and the World Health Organization (WHO) estimate that, due to health problems related to exposure to radiation, some 200.000 personas.
Weeks after the incident, the Government of the USSR began the construction of the «Safe Object», better known as the «Chernobyl sarcophagus«, which had the objective of covering reactor 4 of the nuclear power plant and contain radioactive contaminationin addition to protecting the premises from weather conditions.
Finally, in November 1986, the works were completed, and a huge concrete and steel building was inauguratedmounted on the reactor, more than 60 meters high, 150 meters long and 70 meters wide.
The first «sarcophagus» built above Chernobyl reactor 4. Photo: Wikipedia (CC BY-SA 2.0)However, this sarcophagus is not airtight and its structure is not firm enough, since it was made on the rubble of the destroyed reactor.
Likewise, over the years, radiation and storms deteriorated various parts of this type of shield. In 1988, Soviet scientists determined that the sarcophagus needed to be repaired, and consequently some work was carried out in that direction.
However, in 1992, the government of Ukraine, which was already independent, decided that It would be preferable to make a new sarcophagusand drew up an international tender for this purpose.
The construction of the «New Safe Confinement», the gigantic structure that protects Chernobyl
The call to build a new structure that would cover reactor number 4 of the power plant Chernobyl received more than 300 proposals.
After several years of study, finally, in 2007, the Ukrainian Government signed a contract with the French consortium New girl.
The final plan that would bring Novarka to reality consisted of a gigantic sliding archwhich would be built 180 meters from the reactor and then located above it using a sophisticated rail system.
This would far exceed the existing sarcophagus: It would be 108 meters high, 162 meters long and 257 meters wide. Besides, It would be resistant to many climatic phenomena, such as earthquakes.
It would be called «New Safe Confinement» (NSC, for its acronym in English), in reference to the fact that another radiation containment system already existed (the sarcophagus), but this would be much more effective.
The durability of the new work was estimated at 100 years and its cost at 1.5 billion euros. To be able to cover this high amount, Ukraine received the help of European Bank for Reconstruction and Development.
The explicit objectives of the NSC were contain radioactive materials in place to prevent future environmental contamination and mitigate the consequences of any potential collapse of the sarcophagus and/or reactor.
Likewise, it was expected that, once the New Safe Confinement was conceived, the old one could be dismantled, which would remain beneath it.
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This is how they placed the new protective structure of Chernobyl reactor 4
In November 2016, almost ten years after having won the tender and thirty years after the tragedy, The NSC was placed on the reactor and was inauguratedwith the characteristics that had been planned.
The worrying statement from the IAEA about the NSC: «It has lost its confinement capacity»
The NSC amazed the world and became the largest mobile structure of all existing ones. Thanks to its quality, it was also expected that it would perfectly contain the toxic radiation from the Chernobyl reactor and thus prevent more deaths related to it.
However, No scientist could foresee the phenomena that were unleashed starting in 2019.
The arrival of the pandemic of Covid, due to mobility restrictions and diversions of funding for the health system that forced, delayed the dismantling of the ancient sarcophagus, which still remains below the new one.
But, even worse, due to the war between Russia and Ukrainestarted in early 2022, The New Safe Confinement was broken.
On February 14, 2025, Ukrainian President Volodymyr Zelensky declared that an attack by russian drones had significantly damaged the structure. Likewise, the nuclear power plant released a statement indicating that the outer coating had been punctured and that the interior had also been damaged.
However, at the time, the Russian Government denied responsibility and the International Atomic Energy Agency (IAEA) did not assign responsibility to any side.
Months later, on October 1, Ukraine’s Energy Minister declared that power to the structure had been cut, also due to Russian attacks.
Finally, this December 5th, The IAEA, which depends on the UN, surprised by confirming that «The NSC has lost its main security functions, including confinement capacity».
As detailed on its website, at the end of November, a team completed a thorough evaluation of the site and was able to corroborate that the structure suffered serious damage in the February drone attack. The agency specified that this incident caused a serious fire in the exterior cladding of the NSC.
Rafael Grossi urged that a comprehensive repair of the NSC be carried out. Photo: Reuters/Elisabeth MandlGiven this, in the same statement, the Director General of the IAEA, Rafael Grossi, urged that a complete repair of the work. “Limited temporary repairs have been made to the roof, but timely and comprehensive restoration remains essential to prevent further degradation and ensure long-term nuclear safety,” he said.
In this sense, the organization reported that, in 2026 and with the support of the European Bank for Reconstruction and Development (EBRD), the Chernobyl site will undertake provisional repairs to support the reestablishment of the NSC’s containment function.
Guaranteeing the functioning of this protection system is vital to prevent, in the long term, a disaster from occurring. gradual or episodic release of radioactive dustespecially if the old sarcophagus has an internal collapse, which could harm the nearby population.
