The Chornobyl Nuclear Power Plant, where Ukraine accused Russia of striking a radiation containment structure on Friday, is a defunct facility in Ukraine which was the site of the world's worst civil nuclear catastrophe in April 1986.

The outer shell that was struck is a protective cover built in 2016 over a heavy concrete containment structure. Soon after the 1986 disaster, the inner layer (in which there was no indication of a breach on Friday morning), was placed on the plant’s fourth reactor. The containment shells seek to prevent radiation leaks.

Ukrainian President Volodymyr Zelenskyy said a Russian drone struck the protective covering of the nuclear reactor that exploded at Chernobyl in 1986.