After the earthquake and tsunami hit Japan in March 2011, the Fukushima nuclear power plant experienced a series of equipment failure and nuclear meltdowns. It was the worst nuclear disaster since the Chernobyl nuclear disaster in the Ukraine during 1986.
After the earthquake hit, back up generators turned on to continue cooling equipment. After the tsunami hit the island, all of the generators failed causing equipment to over heat and eventually fail. Days after the natural disasters, three of the six reactors experienced meltdowns and nearby areas where evacuated.
Workers from the plant where exposed to high levels of radiation. Many suffered from radiation burns and other serious injuries and some died.
http://en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disaster
http://www.globalresearch.ca/index.php?context=va&aid=24949
http://e360.yale.edu/feature/anatomy_of_a_nuclear_crisis_a_chronology_of_fukushima/2385/