Chornobyl's shield Russian strike will have 'consequences lasting decades'

A Russian Shahed drone costing as little as $50,000 (£38,000) is estimated to have inflicted tens of millions of dollars worth of damage to the site of the Chornobyl nuclear power plant, according to engineering experts.

- Dan Sabbagh

The full cost of repair is likely to be borne by western governments including the UK, because initial estimates are that a complete repair will cost more than the €25m (£21m) available in a special international contingency fund.

The strike did not cause an immediate radiological risk, but it significantly damaged the €1.5bn containment structure, which was built in 2017 to encase the destroyed reactor, and is likely to take months if not years to fix.

The 110-metre-high steel structure at Chornobyl was hit before 2am on 14 February, with sensors registering "something like a 6 to 7 magnitude earthquake", according to Serhiy Bokov, the chief engineer on duty. "But we clearly understood it wasn't that," he said.

The attack - quickly concluded to be caused by a drone flying low at a level where it could not be detected by radar - made a 15-sq-metre hole in the outer roof. It also caused a particularly damaging and complex fire to the inner cladding of the structure that smouldered and took more than a fortnight to put out.

Consisting of two double arches and longer than two jumbo jets, the New Safe Confinement structure was completed in 2017 to secure the hastily built, unstable Soviet-era sarcophagus that covers Chornobyl's ill-fated reactor No 4, the site of the world's worst nuclear disaster, which took place in April 1986.

The attack in February left the sarcophagus open to the elements again, meaning that radioactive dust could get out and rain water could get in, although Ukraine's environmental protection ministry has said "the radiation background is currently within normal level and is under constant control".

More significantly, the confinement structure is now more vulnerable in the longer term to rusting due to greater exposure to the elements and damage to the cladding. Two hundred small boreholes were also drilled into the structure in the effort to douse the cladding fire with water.