The protective arch over reactor four at the Chornobyl nuclear plant “lost its primary safety functions, including the confinement capability” following a Russian drone attack in February, the International Atomic Energy Agency (IAEA) reported on 5 December.
Russian attacks on Ukraine’s energy and nuclear infrastructure have repeatedly endangered civilian safety and essential services. Strikes on Chornobyl’s New Safe Confinement (NSC) and other power facilities risk radioactive release, creating ongoing threats to public safety and nuclear security.
February drone strike breached the structure
The NSC, which covers the destroyed reactor, was hit by a drone carrying an explosive warhead in February 2025.
The strike created a hole in the structure and sparked a fire, though the underlying load-bearing framework and monitoring systems remain intact. Ukrainian authorities classified the attack as a violation of the laws of war.
Grossi: Temporary fixes not enough, full restoration critical
IAEA Director General Rafael Grossi said temporary repairs have been made to the roof, but full restoration is needed. The agency recommended additional protective work, including humidity control, corrosion monitoring, and upgrades to the integrated monitoring system.
Earlier government estimates put the cost of full repairs at over €100 million, with partial funding already allocated.
The arch covers history's worst nuclear accident
The Chornobyl Nuclear Power Plant in northern Ukraine was the site of the 1986 disaster, the worst civilian nuclear accident in history. Reactor four exploded during a test, releasing large amounts of radioactive material.
The New Safe Confinement, completed in 2016, is a massive steel arch built to cover the old sarcophagus and prevent further radioactive release. Three other reactors at the site had previously been shut down, though some nearby facilities still produce electricity.
IAEA pledges to keep supporting Chornobyl restoration
Grossi said the IAEA will continue supporting Ukraine’s efforts to restore nuclear safety at Chornobyl. As part of ongoing assistance, the agency has delivered 188 shipments of safety equipment and medical supplies to Ukraine, valued at more than €21 million.
