in an impressive feat of engineering, chernbyl's nuclear reactor has now been shielded. the shield will cover the aging shelter in northern ukraine that has been leaking radioactive material since the 1980s. according to the european bank for construction and development, the Chernobyl shield is the largest moveable, land-based structure ever built. The Chernobyl disaster in 1986 remains the works nuclear disaster in history. It was the result of a meltdown of one of Chernobyl's reactors which lead to an explosion 400 times more potent than an atomic bomb.