The sarcophagus under construction in 1986. Alamy Alamy

FOR ALMOST FOUR decades, the world has anxiously watched the creaking remains of reactor four at the Chernobyl Nuclear Power Plant in northern Ukraine.

This was the site of the world’s worst disaster relating to nuclear power, when a flawed reactor design and operator error during a safety test led to an explosion and the release of radioactive material across swaths of Europe (including, to a limited extent, Ireland).

The initial response to the disaster was calamitous, from an initial reluctance to accept the scale of the incident by local authorities, to a delay informing the wider world and the risk that thousands of ‘liquidators’ faced in having to clean up the debris.

A general view of the reactor prior to the NSC being put in place. Alamy Stock Photo Alamy Stock Photo

The radioactivity at the heart of the site was so intense that removing the destroyed reactor core and associated material — such as dust and a lava-like material formed during meltdowns — wasn’t an option. Instead, the entire reactor was encased in a concrete tomb.

Construction of the sarcophagus was completed by the end of 1986. Despite the immense volume of concrete used, it soon became clear that the structure would not be capable of containing the remains for the many hundreds of years required.

A close-up of additional measures put in place to shore up the structure. Alamy Alamy

It was unstable, with additional measures installed to shore up the walls and roof. A collapse of the sarcophagus would lead to a release of radioactive dust into the atmosphere with potentially far-reaching consequences.

The structure itself made it difficult to completely clean up the site, even with the help of modern techniques.

In the early 1990s, after the fall of the Soviet Union, the newly independent Ukrainian government sought to find a new method of keeping the site safe (during which time other reactors at the site remained active; the Chernobyl Nuclear Power Plant generated power for the grid up until the early 2000s).

The result was the New Safe Confinement (NSC), a structure valued at €1.5 billion. The figure surpasses €2 billion when the entire project is factored in.

A view of the mammoth NSC in place. Alamy Alamy

This is a mammoth steel arch aimed at securing the site for at least another century, as well as facilitating the clean-up of the reactor core and debris.

With the NSC in place, the dust released by a collapse of the sarcophagus would be safely contained.

And last night, an explosive drone struck the exterior — but what does this mean for the material inside?

CCTV footage posted by Ukrainian president Volodymyr Zelensky shows a bright blast on the side of the structure which appears to rock the entire complex.

Additional drone footage shows a fire on the roof, and other footage shows successful efforts to extinguish it.

Zelensky has pointed the finger of blame at Russia, while the Kremlin has denied that it was responsible for the attack.

The International Atomic Energy Agency (IAEA) also reported an “explosion” at the site.

The agency, which has had a team deployed at Chernobyl since the early stages of Russia’s invasion of Ukraine, published images apparently showing the drone on fire after crashing into the covering.

The IAEA said “radiation levels inside and outside remain normal and stable”. This is consistent with the expected conditions at the site as the sarcophagus is still in place.

Covid, then Russia’s invasion of Ukraine, added to existing delays to dismantling work.

The 1986 structure is highly unstable, even when additional measures to prolong its lifespan are taken into accoun. As long as it remains standing, the radioactive material at the core of concerns around Chernobyl is secured.

“During the night of 13-14 Feb, at around 01:50[am, local time], IAEA team at the Chornobyl site heard an explosion coming from the New Safe Confinement, which protects the remains of reactor 4 of the former Chornobyl NPP, causing a fire,” the IAEA said on X. “They were informed that a UAV had struck the NSC roof.”

“Fire safety personnel and vehicles responded within minutes. At this moment, there is no indication of a breach in the NSC’s inner containment. Radiation levels inside and outside remain normal and stable. No casualties reported. IAEA continues monitoring the situation.”

“[IAEA director general Rafael Mariano Grossi] said the incident at Chornobyl and recent increase in military activity around Zaporizhzhya NPP underline persistent nuclear safety risks. ‘There is no room for complacency, and the IAEA remains on high alert,’ he said.”

DG @rafaelmgrossi said the incident at Chornobyl and recent increase in military activity around Zaporizhzhya NPP underline persistent nuclear safety risks. “There is no room for complacency, and the IAEA remains on high alert,” he said.

— IAEA - International Atomic Energy Agency ⚛️ (@iaeaorg) February 14, 2025

Attention will now turn to the stability of the NSC. At the time of writing, the extent of the damage is not clear, or if it will have wider consequences in terms of the site’s security.

It is a robust structure, and rated to withstand extreme temperatures, strong earthquakes, and even an earthquake, although a drone strike represents a new test.

It will almost certainly contribute to an additional delay in the clean-up of the site, although it remains to be seen when this project could realistically get underway.

Additional reporting  © AFP 2025