EDITOR'S NOTE: On March 28, 1979, the Three Mile Island nuclear power plant south of Harrisburg, Pennsylvania, suffered a partial meltdown that instilled fear in hundreds of thousands of nearby residents and changed the way Americans viewed the technology. With the announcement Tuesday that Exelon Corp. plans to close the plant unless the state gives it some financial help, The Associated Press is republishing an April 8, 1979, story examining the day of the accident and the seven days that followed.
Continue Reading Below
THREE MILE ISLAND, Pa. (AP) — In the darkness before dawn, in the chill mists that rise from the Susquehanna River, the atomic powerhouse on Three Mile Island defied its human keepers and threatened catastrophe.
In the small neighboring towns like Yocumtown and York Haven, Goldsboro and Pleasant Grove, there was confusion, then fear.
"We all live in Pennsylvania," chanted protesters in Germany.
Indeed, the whole world had a stake in Three Mile Island.
There is a nuclear plant in Hiroshima, witness to atomic energy at its worst; and near Leningrad, Frankfurt, Buenos Aires. There are 223 nuclear reactors at power plants around the globe; two of them at Three Mile Island.
One of the Three Mile Island reactors was shut down for routine refueling on March 28. The other, Unit 2, was humming along quietly until, at 3:53 a.m., terrible events began with a whoosh.
The failsafe system failed. Three valves on auxiliary pumps that should have been open weren't. And the chain of human error and mechanical breakdown grew, multiplied, and turned a routine glitch into the worst nuclear accident in the 22 years since the nation began using nuclear power.
This time, nobody was just a spectator.
"Everybody knew there was danger," recalls one federal nuclear official. "An awful bash had been given the plant."
But a confusion of voices, contradicting, reassuring, frightening, made it difficult at first to learn just how bad things were.
There was no radiation, they said, though there was. Nobody was overdosed, though four workers were. There was no human error, there was. There was no radiation leak, there was. The leak was totally controlled, it was not.
"It was not that close to a catastrophe," an official said. Was it?
A "meltdown" — synonym for nuclear catastrophe — was indeed a possibility. For seven days, and seven nights, those within 20 miles of Three Mile Island lived with the specter of unknown power out of control. How close was the call?
Even among those who live in its shadow, few understand nuclear power, and how it is harnessed to make the heat that makes the steam that turns the turbines that make electricity; the greatest force known to man used to heat his teakettle.
During the midnight shift on Three Mile Island, on Wednesday, March 28, 1979, the harness slipped. It loosed the unknown, unseen threat of radiation.
We live with radiation all of our lives but never see, or smell, or feel, or hear it, and so tend not to understand. We know that too much is bad. After all, don't Xray technicians duck for cover after placing machine against tooth?
A full generation into the nuclear age, it's still like science fiction, this business of chain reactions, a formula dimly recalled from high school physics:
A chain reaction is set off by neutrons, striking, almost like bullets, the nucleus of other uranium235 atoms, splitting them. Again and again, neutron bullets, reproducing. This is "critical mass" — unleashing the power of the atom.
This occurs in a reactor penned inside a waterfilled steel tank that sits at the center of a huge building with fourfootthick concrete and steel walls.
The reactor's core contains a shock of uranium rods, bound closely together, intensifying the frenzy of the neutron bullets. If it loses its covering of water it could heat to incredible temperatures, devouring its own container and — if theory is correct — melt through the bottom into the earth, spewing and spreading deadly radiation.
A runaway reactor, the stuff of fiction, the movie "China Syndrome" come alive.
Harold Denton saw the film in late March; he told his wife he was impressed by its technical accuracy and by Jane Fonda. A week later, the script was real. Denton himself was in the drama, cast by President Carter who saw in Three Mile Island a possible unraveling of trust in a power source that he considers indispensable.
Two of the 72 nuclear power reactors in the United States are at Three Mile Island. Ninetysix others are under construction. Thirty more are on order. In 21 other countries, there are 151 plants in operation, 45 on order and 235 in the planning stage.
The seven days at Three Mile Island began with a gush of steam, a sound not unlike a jet engine at full howl. It awoke those within earshot, but it was not a cause for alarm. It had been heard before, any time there was a sudden shutdown of the generator, a not infrequent occurrence.
Day One. Wednesday, March 28
Between 3 a.m. and 4 a.m., maintenance work was done on Unit 2's feed pump system. Whether that had anything to do with what followed is not known.
At 3:53 a.m. the condensate and feed pump failed, shutting down the steam turbine in a building behind the reactor container. In the reactor, 69 control rods slid smoothly into the hellfire furnace, creating an atomic sponge to soak up the neutron bullets.
The nukes, as people who work in such plants are called, refer to the sudden shutdown of fission as a scram.
Turbine shutdowns are not all that uncommon. But the aftermath of this one demonstrated for the world that a nuclear accident was possible.
In the coolant system, a valve closed, causing water pressure to build. A second valve, designed to relieve overpressure, opened properly but failed to close when the pressure dropped below safe levels.
Precious coolant — dropped, exposing the uranium rods at least two feet below the top. They overheated so badly that they expanded, broke through their protective shields and sent the radioactive products of fission swirling through the 40foot high vessel.
An operator tried to close the relief valve by remote control. It wouldn't close. Any human trying to go in to close the valve manually would have been on a suicide mission. Coolant spurted out of the valve, covering the floor with 80,000 gallons of highly radioactive water.
Three auxiliary pumps kicked in, but their valves had been turned off two weeks earlier during routine maintenance so the water output was blocked
"It would have been an entirely different outcome if they had been operational," Denton would say later.
Not far away, in a control room half the size of a tennis court, a computer measured the temperature of the core, the nuclear fuel, and found nothing abnormal. The operators apparently had no inkling that the top of the core was uncovered.
Another cooling system, the emergency system, automatically sent tons of water into the reactor. But an operator, getting false readings from the computer, turned the system off after four minutes and 30 seconds.
Now there was nothing to hold down the temperature.
The emergency system was the last line of defense.
All this took only five minutes. That was long enough, however, for growing radiation and pressure to send meters off their scale.
It was 7 a.m., three hours later, when Metropolitan Edison, the plant operators, declared a site emergency. At 7:30 they called it a general emergency and notified federal, state and local officials.
"It doesn't look like a very serious accident at this point," Met Ed vice president Jack Herbein told reporters, vanguard of a news army to come. "There is absolutely no danger of a meltdown," said Met Ed spokesman Dave Kluscik. "We are not in a China Syndrome type situation."
Lt. Gov. William Scranton III held a briefing to assure people "everything is under control."
At exactly the same time, Met Ed relieved pressure in the auxiliary building by venting radioactive steam into the air.
Five hours later, an angry Scranton declared "the situation is more complex than the company first led us to believe. Metropolitan Edison is giving you and us conflicting information."
Day Two. Thursday, March 29.
More explanations from the company. The gist: "Don't worry."
"We didn't injure anybody, we didn't overexpose anybody and we certainly didn't kill a single soul," Herbein said.
But lowlevel radiation was measured 16 miles away. And the stubborn reactor, mysteriously, wouldn't cool down.
Protests were mounting around the world. And Dr. Ernest Sternglass, a radiology professor at the University of Pittsburgh journeyed 200 miles to address a rally in Harrisburg, the state capital.
"What we're dealing with is fallout, plain old, bombtype fallout," he said. "People should stand up and scream. It is not a disaster where people are going to fall down like flies. It's a creeping thing."
Still the situation seemed safe. Said NRC inspector Charles Gallina, "The danger is over for people off site."
Day Three. Friday, March 30.
Hell breaks loose. Officials detect an "uncontrolled and unexpected" burp of radiation that lasts from 6:40 a.m. to 9. Gov. Dick Thornburgh, in office only 2 1/2 months, must decide whether to evacuate up to 950,000 people, from a radius of perhaps 20 miles.
It would be an exodus of stupendous scope and complexity, and the governor decided such a drastic step was not yet necessary. But he urged preschool children and pregnant women living within five miles of the plant to leave. They are particularly vulnerable to radiation.
Twentythree schools in the area near the plant were closed.
Evacuation centers were opened. At Hershey, where the seductive odor of chocolate permeates the air, 188 people slept on cots set up in a covered ice rink.
Shortly before noon, a siren wailed in Harrisburg. It was an unauthorized alarm set off by a fire official and was intended to warn people within 10 miles of the plant to stay indoors. Its effect was to fuel the fright.
The governor's decision notwithstanding, the exodus began. There was no panic, no urgency, but people started leaving. Streets jammed with cars, many piled with what people grab when they're fleeing. Long distance phone calls, in and out, became difficult.
President Carter told officials "to err on the side of caution."
For the first time, the NRC said a meltdown — the superdisaster — was a "remote possibility."
Denton, now on the scene for the president and obviously in charge of the massive Nuclear Regulatory Commission operation, said, "This is easily the most serious accident in the licensed reactor program."
Day Four. Saturday, March 31.
A gas bubble in the reactor, mostly hydrogen, was described by NRC officials as a major problem. The best nuclear minds in the country and the world didn't know what to make of the dangerous buildup.
Nowhere in the three 2inchthick binders of emergency procedures for Three Mile Island is there a suggestion for getting rid of a bubble trapped in the reactor roof. "It's a new twist," said Denton.
At its height, the bubble grew to 1,800 cubic feet, according to the NRC estimates, acknowledged to be approximate. The danger was that it could grow and choke off the core from its coolant, triggering a chain of events that might lead to a meltdown.
Another complication: Oxygen was being produced by chemical wastes. The mixture of hydrogen and oxygen in the right proportions could become explosive and rip the lid off the reactor or containment building. That would release lethally radioactive vapor.
For the first time in this country, an insurance company opened a field office to compensate victims of an atomic power plant accident.
Curfews were imposed. "It looks like a ghost town now," said Ken Myers, mayor of Goldsboro, less than half a mile from the plant. Already, 500 of his 600 townspeople had gone into selfimposed exile.
In Middletown, three miles from Three Mile Island, Mayor Robert Reid ordered police to shoot looters. For once even the predators were scared. No looting was reported.
One of the 83 small children bedded down in the Hershey arena — sixyearold Abby Baumbach — told a reporter: "Something's wrong with the air. My mommy told me it could kill me."
Thornburgh visited the evacuation center to comfort the nuclear refugees. "Keep your chin up. You'll be going home soon," he said. But that wasn't true either.
In Washington, Senate Majority Leader Robert Byrd was puzzled.
"We have been assured time and time again by the industry and federal regulatory agencies that this was something that was impossible, that it could not happen," he said.
Nuclear reactor experts from private industry and from government poured into Harrisburg. Babcock and Wilcox, the firm that built both units at Three Mile Island, sent a contingent of 46. Burns and Roe, the designer, sent 12. The NRC dispatched more than 100.
President Carter, in Milwaukee for a Democratic Party fundraiser, announced he would come to Pennsylvania to assess the situation for himself.
Day Five. Sunday, Aprils Fool Day.
Evacuation was not ordered. But tens of thousands of residents — estimates ranged from 50,000 all the way to 250,000 — left anyway.
In one York County township, officials distributed flyers. "Be prepared to leave with one blanket and medical supplies," the handbill said. "We hope with God's help this action will not be necessary."
Atomic experts were riveted to their control panels, trying to eliminate a bubble they didn't understand. They made slow headway but didn't know why.
President and Mrs. Carter flew from Washington by helicopter. They were driven onto Three Mile Island in a school bus, first donning yellow boots to protect their feet from possibly radioactive dust. Carter, trained in nuclear engineering, was briefed in the plant's control room amid the dazzling array of dials, gauges and lights. The President nodded in grim understanding.
After a few minutes, Carter was driven to the Middletown Borough Hall, three miles away. Hundreds lined the route. "First president I ever seen in this town," said a man of about 80.
Standing in the freethrow circle of a blacktiled basketball floor in the town hall, Carter told residents to follow their governor's instructions "calmly and exactly." Any evacuation would be purely precautionary, he said, not exactly raising hopes that things were getting better.
A Middletown woman said her mind was eased by the presidential visit. "If it had been dangerous he would have sent Vice President Mondale," she said. In churches, earlier in the day, the prayers were said grimly.
"Those who are making the decisions have awesome responsibilities. I think God has been very kind to let us go as far as we have in this world. But I think he's now saying, 'Be careful,'" preached the Rev. Richard Deardorff in the Goldsboro Church of God.
"We are in a position now that we can respond to any foreseeable change. We must be prepared to roll with the punch when — and if — the situation changes for the worse," said Gov. Thornburgh.
He received nightly briefings from Denton, with charts and graphs turning his office into something like a war room. This night he heard encouraging news. The bubble was shrinking.
Day Six. Monday, April 2.
Progress, sweet progress. George Troffer, a spokesman for Met Ed, broke a dayold order from the White House that its voice was the only one to be heard. He told a reporter, in so many words, the danger had passed, at least so far as the bubble was concerned.
Not much later, at a news conference in Middletown, Denton confirmed engineers had achieved a "dramatic decrease" in the bubble's size. They still didn't know why. "I am certain it is cause for optimism," said Denton.
Core temperatures fell and radiation was being confined.
A hydrogen recombiner, encased in lead bricks to guard against leakage, was fired up to siphon off more of the troublesome hydrogen. And the regular system was slowly, very slowly, diffusing hydrogen with coolant, then releasing it like champagne bubbles in another building.
Day Seven. Tuesday, April 3.
The bubble had vanished. But the reactor still had to be brought to a cold shutdown. Tensions eased. People started trickling back home. But there was still danger that radiation could leak during the shutdown process. So Thornburgh advised the children and pregnant women to stay away. Met Ed said its pregnant employees could stay away if they liked, but without pay. The utility is reported to have two pregnant women on its local payroll.
Speculation grew that the reactor may never be fired up again, that it might be filled with concrete and junked; a monument to the failsafe system that failed. "It might be more expensive to clean up the plant than it was to build it," said Sen. Gary Hart, DColo.
Jay Waldman, top aide to Gov. Thornburgh, characterized the crisis as one of national and international proportions. "We're talking about an unprecedented, unparalleled nuclear accident," he said. And Thornburgh ended the seven days of tension by saying: "Anyone who wants to resume or expand nuclear programs will have a heavy burden of proof with this Pennsylvanian."