Exactly 20 years ago, a stuck valve drained cooling water from the brand new Three Mile Island Reactor Number Two. The uranium core overheated, and contaminated water flooded the reactor's basement, CBS News Correspondent Jeffrey Kofman reports.
In the confusion and panic that followed, residents with young children were told to evacuate. Days later they were assured that, in fact, no radiation had escaped.
Lisa Nagle was 11 years old when the accident happened. Today she and her family still live in the shadow of Three Mile Island.
"I was scared," she remembered. "I was scared just like anybody would be, you know. You're sitting there and Three Mile Island's how many miles away from you? And your parents are telling you to get your stuff together and go."
What happened here 20 years ago didn't just change this corner of Pennsylvania, it forever changed America's attitude toward nuclear energy. Depending who you ask, Three Mile Island marks the end of nuclear power -- or a new beginning.
"The legacy of Three Mile Island is that the industry had enhanced operations, its safety, its reliability," said Angie Howard, who is senior vice president of the Nuclear Energy Institute.
"We've learned from that place that nuclear power is dead," says Eric Epstein, of TMI Alert, an anti-nuclear group. "There hasn't been a reactor order since '78. There won't be another reactor ordered. It's over."
With cheaper energy alternatives now available, America's 103 nuclear units now face extinction.
Says Harold Denton, former Nuclear Regulatory Commission chief safety officer, "I think in the U.S. they just grew up too fast, too big and too soon."
Three Mile Island's Reactor Number One is about to become the first nuclear plant sold in this country, for a fraction of its book value. In part this is due to the mothballed reactor next to it: A monument to the contaminated dream of what was to be a clean, safe nuclear-powered age.
Five activists were arrested during the demonstration, for trespassing. The five crossed over a set of railroad tracks onto the property of GPU Nuclear Corp. to close a predawn rally, and were arrested without incident.
The vigil marked the moment around 4 a.m. on March 28, 1979 when a pump stopped operating in a non-nuclear part of the plant's Unit Two. Mechanical problems and human error caused more than one-third of the reactor's uranium fuel to melt in the worst commercial nuclear accident in U.S. history.
The company and the Nuclear Regulatory Commission said only insignificant amounts of radiation escaped the plant during the days following the accident, but activists contend monitoring was inadequate and the true amount is unknown.
More than 100 people -- veterans of the nuclear debae and newcomers -- gathered in the rain outside the plant to light candles and speak out against continuing reliance on nuclear power.
"Half the crowd here was not alive when TMI happened," said Eugene Stilp, a veteran anti-nuclear activist with No Nukes Pennsylvania. "We're turning this over to a new generation."
The vigil culminated with the five activists crossing onto plant property in front of a phalanx of state troopers, other police and Three Mile Island security officers as the crowd chanted anti-nuclear slogans on public property a few feet away.
One by one, the protesters were led away by state troopers when they refused a plant official's request to leave the property.