Workers completed a massive shelter over the Chernobyl nuclear plant's exploded reactor on Tuesday, one of the most ambitious engineering projects in the world that one expert said had closed "a nuclear wound."
The half cylinder-shaped shelter was locked in place over the plant's reactor No. 4 after being moved in on hydraulic jacks for two weeks. It marks a significant step toward containing the consequences of the world's worst nuclear accident, which occurred 30 years ago in what is now Ukraine.
Ukrainian President Petro Poroshenko described the new shelter as "the biggest moving construction that humanity has ever created."
Workers will now...