By Michail Hengstenberg, Gesche Sager and Philine Gebhardt
The Soviet nuclear testing site in present-day Kazakhstan is just one of many places in the world that remain dangerously radioactive to this day.
Everyone knows about Chernobyl, Three Mile Island and, now, Fukushima. But what about Semipalatinsk, Palomares and Kyshtym? The world is full of nuclear disaster zones -- showing just how dangerous the technology really is.
04/12/2011 - Wednesday, Mar. 28, 1979. In the Three Mile Island nuclear power station in Harrisburg, Pennsylvania, the nightmare scenario of nuclear physicists was about to unfold. At four in the morning, employees in the control room noticed the failure of a pump in the reactor's water cooling loop. When a bypass valve failed to trip, water stopped flowing to steam generators, resulting in an emergency reactor shutdown. But the reactor continued to generate so-called decay heat. A relief valve opened automatically but then failed to close, allowing coolant to flow out at a rate of one ton per minute. The control panel erroneously indicated that the cooling system was functioning normally, meaning technicians initially failed to recognize the problem.
By 6 a.m., the top of the reactor core was no longer covered in cooling water -- and the fuel rods began to melt. At the last moment, a technician noticed the problem and closed the relief valve. A full-scale meltdown was only barely averted.
Still, the series of events had a devastating effect: Not only was radioactivity released into the atmosphere, but contaminated coolant escaped into the nearby river. Cancer rates in the local population later rose dramatically. In addition, large parts of the reactor and the power plant site were contaminated. The clean-up operation in Harrisburg took 14 years and cost more than $1 billion. And the reactor ruins are radioactive to this day. {continued}
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