Kyshtym tragedy, buried nuclear waste from a plutonium processing factory near Kyshtym, Chelyabinsk oblast, Russia (then in the USSR), exploded on September 29, 1957, in the Chelyabinsk region of Russia. In spite of the fact that 9,000 square miles (23,000 square kilometers) of land had been contaminated, more than 10,000 people had been evacuated, and probably hundreds of people had died as a result of radioactivity, until 1989 the Soviet government refused to acknowledge that the event had taken place. IAEA rated the Kyshtym disaster as a Level 6 nuclear and radiological event on the International Nuclear and Radiological Event Scale after more information became available. This level is reserved for the nuclear disasters at Chernobyl and Fukushima after they occurred.
To aid Soviet efforts to build nuclear weapons, Kyshtym was established in the 1940s with the construction of its nuclear reactors and plutonium processing factory. Mail for the plant and its employees had to be addressed to Post Office Box 40 in Chelyabinsk, a significant city 55 miles (90 kilometers) away from Kyshtym, hence the code name Chelyabinsk-40 became popular. Chelyabinsk-65 and Ozersk were later renamed for the nuclear facility. It was situated on the eastern slopes of the central Ural Mountains, where surrounding lakes supplied water for cooling the reactor and also acted as nuclear waste dumps. The Soviet Union's nuclear program was so rushed and its technology was so young that workers and their neighbors were constantly at risk.
The Kyshtym accident was caused by the inability to fix a failing cooling system in a subterranean tank where liquid nuclear waste was stored. Radiation decay heated the tank's contents slowly for over a year before it burst on September 29, 1957, with a force estimated to be 70 tons of TNT or more. Nonnuclear explosion blasted off tank's one-meter thick concrete cover, releasing a plume of radioactive fallout, including huge quantities of long-lasting cesium 137 and strontium-90. Kyshtym emitted around two-fifths as much radiation as Chernobyl did. Officials took their time issuing evacuation orders even though the cloud traveled hundreds of miles to the northeast through an area home to tens of thousands of people. As a result, local hospitals were overflowing with patients suffering from radiation illness in the following months.
The first Western media accounts of a nuclear disaster in Russia date all the way back to the early '50s. It wasn't until 1976 that the exiled Soviet biologist Zhores A. Medvedev published a study in the British journal New Scientist on the Kyshtym disaster. A scientist exiled from Russia, Lev Tumerman, backed up Medvedev's claim that he drove from Sverdlovsk (now Yekaterinburg) to Chelyabinsk across a barren wasteland with no residences or fields, despite road signs warning cars not to stop and instead to go at top speed. In spite of this, several Western experts rejected the possibility that a storage disaster could have resulted in such severe radioactivity, and others suggested that a distant nuclear weapons test may have been responsible.
As a follow-up, Medvedev conducted a review of Soviet scientific literature on the ecological impacts of radiation experiments. The authors and censors suppressed or fudged numerous facts, but Medvedev was able to find many occasions in which there was just too much radiation spanning too large an area for experiments to have taken place. His investigation also revealed that the "experiments" had taken conducted in the Ural region and that the contamination must have taken place in 1957 or 1958. Anti-nuclear activists in the United States organized by Ralph Nader issued a Freedom of Information Act request for the findings of the U.S. Central Intelligence Agency, which was known to have flown over the Urals in a U-2 spy plane. The agency appeared to back up Medvedev's claim, but it didn't disclose any further information. Even when others raised the issue, the US administration remained mute and remained uncommunicative about the disaster, fearing that it would raise doubts in American minds about the safety of their country's nuclear program. It wasn't until 1989 that the Soviet Union finally admitted there had been a catastrophe, despite all of the evidence to the contrary.
In part because of Soviet secrecy and in part because of Chelyabinsk-40's long-term systematic release of hazardous quantities of radioactive waste into the environment, it was impossible to analyze the long-term impacts of the Kyshtym tragedy. Cancer, malformations, and other severe health issues have afflicted residents of the area.