Scientists contain radiation in Chernobyl, Ukraine, with a newly built shield. Engineers working at the site of the famous nuclear reactor failure 30 years ago are close to finishing a new protective shelter to house the reactor and protect the surrounding area from more radiation. The radiation shield is to be the largest movable structure ever built, weighing 30,000 tons and standing the size of the Notre Dame cathedral in Paris. It is to replace the previous radiation shelter, which was hastily built by Soviet engineers right after the meltdown and only supposed to last 20 years.