The crisis here on March 28, 1979, led to “changes throughout the world’s nuclear power industry,” as a state historical plaque on Route 441 notes. It also altered the mindset of this small town in central Pennsylvania, creating a permanent state of vigilance that has been heightened this past week by Japan’s nuclear catastrophe.
“What’s happening in Japan has brought back a lot of memories,” said Robert G. Reid, who is still Middletown’s mayor, just as he was in 1979 when he dispatched his family to Connecticut but stayed behind to guide the town’s response. “But we’re much better prepared now than we were in 1979.”
Over the decades, Three Mile Island has become a touchstone for attitudes toward nuclear power: a symbol of fear for anti-nuclear activists and of the success of emergency safeguards for nuclear supporters.
Comparisons between what happened at Three Mile Island and what is unfolding at the earthquake-damaged Fukushima Daiichi nuclear plant are inevitable. On Friday, Japan’s nuclear agency raised the severity of the crisis on the International Nuclear Events Scale from Level 4 to Level 5, the same number the United States used to classify the far less serious accident at Three Mile Island.
A different disaster
The crisis at Three Mile Island started with the venting of steam at 4 a.m., became a partial meltdown, and didn’t fully end until the last of the filtered water from the flooded containment building finally evaporated in 1993.
But there was never any loss of electrical power, no earthquake or tsunami, only a mechanical problem compounded by human error. The only explosion took place inside the containment vessel, and it withstood the blast. Water pumped in to cool the reactor stayed inside the containment structure.
While pregnant women and small children were ordered to evacuate, the decision to leave was voluntary for everyone else.
“We proved at Three Mile Island that all that [radioactive] stuff stays inside the containment structure,” said Howard Shaffer, an engineer at the American Nuclear Society. “That’s why I call it the garbage can over the tea kettle. Its whole mission in life is for this event. We ran a test for that, inadvertently, at Three Mile Island.”
But veterans of the Nuclear Regulatory Commission remember Three Mile Island as a time of disarray.
Victor Gilinsky, an NRC commissioner then, learned of the incident when he arrived at work March 28, 1979, a Wednesday. Staffers told him that a small pinhole in the zirconium alloy jacket around the uranium pellets used as fuel had caused overheating in the reactor, but that there was no danger.