Three Mile Island, Pennsylvania, 1979

Located in the Susquehanna River about ten miles south of Harrisburg, the capitol of Pennsylvania, Three Mile Island is surrounded mostly by farming and small residential communities, such as Middletown, Goldsboro, and Newberry. The island is not far from the antiquated Pennsylvania Dutch countryside of Lancaster County. Three Mile Island, or TMI, is also the location of the Metropolitan Edison Company’s nuclear power plant.

On Wednesday, March 28, 1979, Unit 2 at TMI was undergoing routine maintenance.  In the early morning hours, workers were cleaning the condensate polishers, filters filled with resin to ensure that only clean water enters the system. The workers had difficulty flushing a piece of resin from a pipe, and in the process of trying to clean it somehow caused the pumps in the polisher system to shut down. In turn, other pumps that fed water to the system (feedwater pumps) also shut down, thereby shutting down the turbines, and, ultimately, the reactor. The reactor had been operating at close to full capacity, and a tremendous amount of heat remained in the system. Although the reactor was shut down, coolant water was still required to keep the system stable, and the system was being deprived of it. That simple malfunction set in motion a chain of mechanical and operator failures that caused America’s worst nuclear nightmare.

For almost a week, a lack of information, misinformation, misjudgments and a great uncertainty about what was happening within the nuclear plant led to widespread fear and evacuations.  This was America’s worst nuclear disaster and the nuclear power industry has not yet recovered from the distrust engendered by events at TMI.

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