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America's 10 worst man-made environmental disasters

Three Mile Island Pennsylvania

Photo: ZUMA Press

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Three Mile Island meltdown

The most significant accident in the history of American nuclear power took place on March 28, 1979, at the Three Mile Island Nuclear Generating Station in Dauphin County, Pa. The notorious accident was a partial core meltdown caused by a failure in the non-nuclear secondary system that was followed by a stuck valve that released radioactive gases.

Experts concluded that the amount of radiation released into the atmosphere was too small to result in health problems, and public record states that no one died as a result of the Three Mile Island accident. However, the Nuclear Regulatory Commission later told Congress it did not actually know how much radiation had been released.

More than 2,400 residents have filed class-action lawsuits demanding compensation for death and disease, but no open judicial hearing has been allowed. However, the owners of Three Mile Island paid millions in damages to area residents whose children were born with birth defects. The federal government did not track the health histories of the region’s residents, and some have accused the state of Pennsylvania of hiding the health impacts of the Three Mile Island accident.