The Kyshtym disaster was a radiation contamination incident that occurred on 29 September 1957 at Mayak, a nuclear fuel reprocessing plant in the Soviet Union. It measured as a Level 6 disaster on the International Nuclear Event Scale, making it the third most serious nuclear accident ever recorded behind the Chernobyl disaster, and Fukushima Daiichi nuclear disaster, both Level 7 on the INES. The event occurred in the town of Ozyorsk, a closed city built around the Mayak plant. Since Ozyorsk/Mayak (also known as Chelyabinsk-40 and Chelyabinsk-65) was not marked on maps, the disaster was named after Kyshtym, the nearest known town.
Shamelessly lifted from Wikipedia – Kyshtym disaster. (2013, May 1). In Wikipedia, The Free Encyclopedia. Retrieved 00:50, May 20, 2013, from http://en.wikipedia.org/w/index.php?title=Kyshtym_disaster&oldid=553051204