The disaster at the Chernobyl nuclear power plant, in Ukraine, on 26 April 1986, was the world’s worst nuclear accident.

The explosion in reactor four caused radioactive parts to be spread over the nearby area.

Hundreds of thousands of people were involved in the decontamination efforts, including soldiers and workers at the power station. They were known as the liquidators.

Some even had to run out onto the roof of the reactors to clear debris which had been scattered from the radioactive core.

Yurіy Skaletskyy was a radiological officer in the Soviet Navy. He monitored the radiation exposure faced by the liquidators and tells Tim O'Callaghan how workers improvised their own protective gear using sheets of lead foil.

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(Photo: The liquidators on the roof of the Chernobyl nuclear power plant. Credit: Sergei Supinsky/AFP via Getty Images)