See Chernobyl on iwonder in the 30 Years On documentary. 2016 marks thirty years since history’s worst nuclear accident in Chernobyl, Ukraine. Killing thousands and threatening the lives of millions, the site is still one of the most dangerous places on the planet. The barriers covering the old reactor have been slowly leaking for years, so now it’s time for a massive new construction project. A gigantic sarcophagus is being built to cover the damaged nuclear power plant.