Even after the ongoing tragedy at the Fukushima reactor in Japan, the explosion and subsequent fire at the Chernobyl plant still ranks as the worst in history. The plant was in Pripyat, a now abandoned city in the modern Ukraine and the former Soviet Union. The death toll from the accident and radiation varies from a 4,000 individual estimate from the World Health Organization to about 200,000 from Greenpeace.
Construction of the "sarcophagus" at the Chernobyl Nuclear Power Plant in Ukraine, following the April 26, 1986 explosion. UPI/INS