A friend pointed me towards this piece on the Damn Interesting site. It was so interesting that I just had to share it with my little audience. Do read the whole thing, but here are a few titbits to whet your appetite:
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Chelyabinsk-40 was absent from all official maps, and it would be over forty years before the Soviet government would even acknowledge its existence. Nevertheless, the small city became an insidious influence in the Soviet Union, ultimately creating a corona of nuclear contamination dwarfing the devastation of the Chernobyl disaster.
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In 1951, after about three years of operations at Chelyabinsk-40, Soviet scientists conducted a survey of the Techa River to determine whether radioactive contamination was becoming a problem. In the village of Metlino, just over four miles downriver from the plutonium plant, investigators and Geiger counters clicked nervously along the river bank. Rather than the typical “background” gamma radiation of about 0.21 Röntgens per year, the edge of the Techa River was emanating 5 Röntgens per hour.
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The facility itself was also beginning to encounter chronic complications, particularly in the new intermediate storage system. The row of waste vats sat in a concrete canal a few kilometers outside the main complex, submerged in a constant flow of water to carry away the heat generated by radioactive decay. Soon the technicians discovered that the hot isotopes in the waste water tended to cause a bit of evaporation inside the tanks, resulting in more buoyancy than had been anticipated. This upward pressure put stress on the inlet pipes, eventually compromising the seals and allowing raw radioactive waste to seep into the canal’s coolant water. To make matters worse, several of the tanks’ heat exchangers failed, crippling their cooling capacity.
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[T]he water inside the defective tanks gradually boiled away. A radioactive sludge of nitrates and acetates was left behind, a chemical compound roughly equivalent to TNT. Unable to shed much heat, the concentrated radioactive slurry continued to increase in temperature within the defective 80,000 gallon containers. On 29 September 1957, one tank reached an estimated 660 degrees Fahrenheit. At 4:20pm local time, the explosive salt deposits in the bottom of the vat detonated. The blast ignited the contents of the other dried-out tanks, producing a combined explosive force equivalent to about 85 tons of TNT. The thick concrete lid which covered the cooling trench was hurled eighty feet away, and seventy tons of highly radioactive fission products were ejected into the open atmosphere.
Incredible.