A Russian drone has hit the protective shelter over Chernobyl’s damaged nuclear reactor, Ukrainian President Volodymyr Zelensky has said.
The overnight strike at the site of the world’s worst nuclear accident caused a fire that has since been extinguished, he added.
The UN’s nuclear watchdog (the IAEA) said radiation levels inside and outside Chernobyl were normal and stable – but later the plant’s chief engineer, Oleksandr Titarchuk, said the possibility of radioactive substances leaking “now exists”.
Russia has denied any claims it attacked Chernobyl, stating its military does not strike Ukrainian nuclear infrastructure and “any claims that this was the case do not correspond to reality”.
The International Atomic Energy Agency (IAEA), which monitors nuclear safety around the world, said fire safety personnel and vehicles responded within minutes to an overnight explosion. No casualties were reported, the agency added.
The agency remains on “high alert” after the incident, with its director general Rafael Grossi saying there is “no room for complacency”.
Mr Titarchuk told Ukraine’s state news agency that “the situation is under control”.
A catastrophic explosion at Chernobyl in 1986 sent a plume of radioactive material into the air, triggering a public health emergency across Europe.
While the immediate disaster was mitigated and an area where people were told not to live established, the incident saw a rise in cancer rates in the surrounding population.
The radiation shield is designed to prevent further radioactive material leaking out over the next century. It measures 275m (900ft) wide and 108m (354ft) tall and cost $1.6bn (£1.3bn) to construct.
Zelensky posted footage on X appearing to show damage to the giant shield, made of concrete and steel, which covers the remains of the reactor that lost its roof in the explosion.
“Another 15 metres [50ft] to the side and there would have been a radiation accident,” Hryhoriy Ishchenko, chief of the agency that manages the exclusion zone around Chernobyl, told reporters, according to local media.
Since 1990, Prof Jim Smith from the UK’s University of Portsmouth has studied the aftermath of the Chernobyl nuclear disaster and, while he admits the strike was a “horrendous attack on a very important structure”, he is “not concerned” about the radiation risk.
Prof Smith told the BBC a thick concrete “sarcophagus” below the damaged outer shield covers radioactive particles and dust from the explosion.
Simon Evans from the European Bank for Reconstruction and Development (EBRD) was head of the Chernobyl Shelter Fund, which oversaw the construction of the protective dome in the 2010s.
He described the apparent strike as “an incredibly reckless attack on a vulnerable nuclear facility”.
The shield “was never built to withstand external drone attack”, he told the BBC, but a “complex piece of decommissioning kit” built to contain the radioactive materials inside and to help safely deconstruct the broken reactor.
The strike appeared to hit the maintenance system of a crane designed to remotely take the reactor apart, he said.
There appears to be “pretty serious” damage to the outer and inner cladding, he added, but said a fuller assessment of the damage will be needed before the bank can determine its costs.
Mr Evans said the mission to build the shelter was the “world’s largest ever collaboration on nuclear safety”, with more than 40 counties working together on it.
“Ever since the start of the war, it’s been tragic to see that international co-operation undermined by reckless acts,” he added.
Zelensky claimed the attack showed Russian President Vladimir Putin was “definitely not preparing for negotiations”, after US President Donald Trump said Putin had agreed to begin talks to end the war earlier this week.
The incident at Chernobyl comes after increased military activity around the Zaporizhzhia Nuclear Power Plant in southern Ukraine, the IAEA said.
In December, Ukraine and Russia accused each other of launching a drone attack on a convoy of vehicles transporting IAEA experts heading to the Zaporizhzhia plant, which is Europe’s largest nuclear station.
The agency last year urged restraint when an attack on Zaporizhzhia raised the risk of a “major nuclear incident”. Russia and Ukraine traded blame over the attack in August.
“I’m more concerned about Zaporizhzhia than Chernobyl,” Prof Smith said.
“The reactors [at Zaporizhzhia] are currently shut down but there is more live fuel there. Chernobyl is still very radioactive, but it’s not in a ‘hot state’ because of its age.”
The number of people who died in the Chernobyl disaster remains disputed.
According to the official, internationally recognised death toll, just 31 people died as an immediate result of Chernobyl while the UN estimates that 50 deaths can be directly attributed to the disaster.
In 2005, it predicted a further 4,000 might eventually die as a result of the radiation exposure.
