Three Mile Island

An unlikely series of mechanical and human errors in Unit 2 of the nuclear generating plant at Three Mile Island, near Harrisburg, Pennsylvania, in 1979 resulted in an accident that profoundly affected the utility industry. A complicated combination of stuck valves, misread gauges, and poor decisions led to a partial meltdown of the reactor core and a release of significant amounts of radioactive gases. The near-total devastation of the nuclear power industry resulted, because the disaster at Three Mile Island tipped the scales in the ongoing controversy over nuclear power in favor of those opposed to it. Massive demonstrations followed the accident, culminating in a rally in New York City that attracted upward of 200,000 people. By the mid-1980s, the construction of nuclear power plants in the United States had virtually ceased.

The radioactive gases released by the accident prompted the governor of Pennsylvania to evacuate pregnant women from the area. An investigation by the Nuclear Regulatory Commission claimed that the amount of radioactivity released was not a health threat, but antinuclear activists and many local citizens disputed this. The reactor itself remained unusable-in fact, virtually unapproachable-more than a decade later.

The Reader's Companion to American History. Eric Foner and John A. Garraty, Editors. Copyright © 1991 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.