among the top officials attending the in actual it, ukrainian president petro poroshenko.he had high praise for what he called an historic construction, comparing the new encasement to the eiffel tower and the statue of liberty. "today the consortium guarantees 100 years of nuclear safety. a lot of people had doubts. a lot of them didn't believe in this. congratulations. yes, we did it." it took almost a decade to build the cover, and 36,000 tons of steel. technicians at firms from all over europe helps complete the 2 billion-euro project. the steel encasement forms in cover over the ill-fated reactor number four, the site of europe's first nuclear disaster 30 years ago. on the 26th of april, 1986, there was an explosion at chernobyl's reactor number four. a radioactive cloud spread over large parts of the then-soviet union, reaching as far as western europe. a provisional and casing was hastily built to contain the radiation. but it soon became unstable and threatened to cave in. many areas of the countryside are still considered radioactive. >> moving together, 2 halves,