The Chernobyl nuclear meltdown disaster occurred in 1986 in the Ukraine. The cause of the meltdown was a faulty reactor and mistakes made by plant operators. There were nearly 60 people killed due to the meltdown. The environmental impact is the actual disaster. Over 125,000 square miles of land in Belarus, Russia and Ukraine with radionucleotides. Multiple health issues have risen with the population which are thought to be the cause of the meltdown.
On March 11th 2011 a similar meltdown occurred at the Fukushima Daiichi Nuclear Power Station in Japan. The catalyst for this event was a tsunami which killed over 20,000 people. Not a single person died however at the hands of the meltdown. It will take at least 10 years to clean up the radiation located at the area evacuated around the plant. Over 90,000 people have had to leave their homes which were located around the site.