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Dates That Matter

March 28, 1979

A nuclear accident at Three Mile Island, Pennsylvania frightens Americans.

 Why does it matter?

The Three Mile Island Nuclear Power plant near Harrisburg, PA was the site of the most serious nuclear accident in US history. In the early morning hours, a valve in the Unit-2 reactor became stuck open, causing a core meltdown. Although the reactor was contaminated, the accident was contained, and there were no deaths and no injuries as a direct result of the incident. Of course, it is impossible to say whether the small amount of radiation that was released into the atmosphere caused any long term health effects to the people around TMI, although most studies have said the impact was minimal, and perhaps nonexistent. The accident stopped further development of nuclear power facilities in the United States, however, amid concerns about safety.

In a strange coincidence, the accident happened just days after the release of the movie "The China Syndrome" about a meltdown at a nuclear power plant. In the movie, one of the characters notes that a meltdown could contaminate an area "the size of the state of Pennsylvania."">

For more information...

The American Experience: Meltdown at Three Mile Island
PBS site associated with an American Experience episode on the Three Mile Island accident. There is a Shockwave animation showing how the meltdown happened, a chronology of events, maps and teacher resources.

Three Mile Island 1979 Emergency
This site was originally developed by a group of faculty and students at nearby Dickinson College and includes an overview of both the accident and the subsequent efforts to return TMI to production, as well as extensive resources for those who wish to research local reaction to the accident including transcripts of a number of eyewitness accounts and primary sources in audio and text formats.

NMAH: Three Mile Island
A Smithsonian/National Museum of American History site, this includes photos, artifacts, and in-depth, technical narrative about the accident.