Ukraine marked the 25th anniversary of the world's worst nuclear accident at its Chernobyl plant Tuesday (26 April), as global protests sparked by leaks from reactors at Japan's Fukushima plant continued. On 26 April 1986, the No. 4 reactor at the Chernobyl plant, then in the Soviet Union, exploded and caught fire after a safety test went badly wrong. The blast sent radiated clouds billowing across Europe. A total of 31 people died immediately but many more died of radiation-related sicknesses such as cancer, many of them in what is today's Belarus. Tens of thousands were evacuated, never to return, from Prypyat, the town closest to the site which then had a population of 50,000. Read the story here.