From the Executive Director features news and reflections on the work of PHMC by its chief administrator.


Even after twenty years, mere mention of these three letters triggers an immediate response from anyone who lived through the harrowing week beginning Wednesday, March 28, 1979, when the entire world held its collective breath and contemplated the possibility of a nuclear catastrophe.

The accident at Three Mile Island near Harrisburg is one of the defining events in twentieth-century American history. The debate over its causes and effects continues to rage. What is known is that technical malfunctions and human error led to a series of mechanical failures that partially exposed the nuclear reactor core within TMI’s Unit Two. Radiation was released and a hydrogen bubble in the reactor caused temperatures to rise dangerously, threatening to cause a core meltdown.

For nearly a week, scientists struggled to reduce the size of the hydrogen bubble while government officials, among them President Jimmy Carter and Governor Dick Thornburgh, confronted a potential emergency of unprecedented proportions. The governor ordered the closing of schools and the evacuation of seven thousand people. Another one hundred thousand people – more than fifteen percent of the Harrisburg area – chose to leave, returning only after federal and state officials announced that the hydrogen bubble had dissolved.

The plant did not resume operations for nearly seven years and the cleanup and decontamination of Unit Two took more than a decade. Although no direct injuries occurred from radiation, the long-term effects of radiation exposure were never determined. Over the years, health officials documented the psychological stress on people in the region who lived through the event.

The political and economic fallout from the accident were equally significant. Fundamental changes occurred in the operation and regulation of nuclear power plants throughout the world. Plans to build new facilities dropped sharply. Confidence in the leaders of the nuclear industry and in federal regulatory agencies suffered. The fear and suspicion associated with those fateful days linger as powerful memories.

In March, the Pennsylvania Historical and Museum Commission and the Department of Environmental Protection dedicated a state historical marker for the incident at Three Mile Island. Some may question why we commemorate a negative event that serves only to remind us of human and technical fallibility. My response is to point out that history is a resource that helps us lead our daily lives, to make decisions, and to set priorities. Only by confronting and knowing the full story of the past, replete with heroes and villains, successes and failures, can we operate effectively in a world filled with complexities and contradictions. By this measure, the accident at TMI – and its aftermath – offers one of history’s most sobering, enlightening, and enduring lessons.

Brent D. Glass
Executive Director