Kyshtym Disaster
A chemical explosion at a radioactive waste storage tank at the Mayak nuclear facility contaminated 23,000 km2 of Soviet territory.
The Explosion
A cooling system failure at a radioactive waste storage tank caused the waste to dry out over time. The dried mixture of ammonium nitrate and acetates then exploded with a force of 70-100 tonnes of TNT, launching the 160-tonne concrete lid 25 meters into the air and spraying radioactive material across the landscape.
Contamination
The explosion created the East Ural Radioactive Trace, a plume of contamination stretching northeast for hundreds of kilometers and covering 23,000 km2. About 22 villages were evacuated over two years. The area remains a controlled zone to this day, over 65 years later.
Soviet Secrecy
The USSR classified the accident for decades. The true scale only became known after dissident scientist Zhores Medvedev published accounts in the 1970s, which Soviet authorities publicly dismissed as anti-Soviet fabrication. Full official details were not released until after the Soviet collapse.
📅 Timeline
Non-nuclear explosion at waste tank
Radioactive plume rises 1-2 km into the atmosphere
90 km2 heavily contaminated
10,000+ people evacuated from contaminated zone
East Ural State Reserve established over contaminated zone