14. Kyshtym Disaster (1957)
On September 29, 1957, a catastrophic explosion occurred at the Mayak nuclear facility near Kyshtym, Russia, releasing approximately 740 petabecquerels of radioactive material. This event, known as the Kyshtym disaster, resulted in the contamination of over 15,000 square kilometers, affecting around 270,000 people. The Soviet government initially concealed the incident, and it remained undisclosed until 1976. The disaster is classified as a Level 6 accident on the International Nuclear Event Scale, making it one of the most severe nuclear accidents in history. For more detailed information, refer to the Britannica article on the Kyshtym disaster. (britannica.com)
