On Tuesday, officials from all over the world gathered about a football field away from the Chernobyl disaster site in Ukraine. They were there to celebrate the final placement of a massive, high-tech shelter over reactor 4, which exploded in April 1986.
The shelter, called the New Safe Confinement (NSC), is a feat of engineering. Because it was too dangerous to assemble the NSC over the original shelter that was built in the weeks after the explosion, the NSC was instead built at a distance and moved—slowly, over days—on a pair of tracks parallel to the original shelter. But even that was no simple task. The NSC is 354ft (108m) tall and 843ft (257m) wide, making it the largest mobile metal structure in the world.
from Decades after Chernobyl disaster, engineers slide high-tech shelter over reactor