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The Emergence of Nuclear Power and the Meltdown at Three Mile Island: March 28,1979

Updated on December 22, 2023
Mark Caruthers profile image

Mark has a BA from the University of Arkansas (Fayetteville).

Three Mile Island

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Three Mile Island Unit 1 was still left  in operation decades after the incident. Note the steam escaping from its cooling towers.
Three Mile Island Unit 1 was still left  in operation decades after the incident. Note the steam escaping from its cooling towers.
Three Mile Island Unit 1 was still left in operation decades after the incident. Note the steam escaping from its cooling towers. | Source

Thirty Minutes from Disaster

The Atomic Energy Act of 1946 set a new path for the development of nuclear energy for the next three decades in the United States. The act took development of nuclear energy away from the military putting it into civilian control under the guidance of the Atomic Energy Commission (AEC).

The AEC succeeded the Manhattan Engineer District of the U.S. Army Corps of Engineers who secretly developed the atomic bombs dropped on Hiroshima and Nagasaki under the ultra-secret Manhattan Project.

Its goal was to bring the Second World War to an end. Research and production took place at more than 30 sites across the United States, the United Kingdom, and Canada at a cost of 14 billion dollars adjusting for today's dollar value.

The AEC would launch the development of nuclear energy for peaceful purposes. In the decades that followed the AEC authorized the building of over one hundred commercial nuclear power plants throughout the United States.

Corporate giants General Electric and Westinghouse battled over the lucrative contracts to build these nuclear power plants. The AEC stressed to the American people that nuclear power was a cleaner, safer, and a more effective alternative to generating electricity.

In March 1979 there were forty-seven nuclear power plants in the early stages of being built all around the United States. Nuclear power plants were considered the new beginning of an age of cheaper power production in the United States.

But that all screeched to a halt during the early morning hours of March 28,1979, on an island in the middle of the Susquehanna River near Harrisburg Pennsylvania. The accident at the Three Mile Island (TMI) nuclear power plant would become the most significant episode in commercial nuclear power plant history in the United States.

Not a single nuclear power plant has been built in the United States since that fateful day. On the seven-point International Nuclear Event Scale, the Three Mile Island accident was rated a five as an "accident with wider consequences".

It had been less than three weeks after the Hollywood epic "The China Syndrome" had been released, when the worst nuclear accident in the history of American commercial power generation occurred.

The accident at TMI was like a scene out of the movie. The film involved the character Elliot Lowell, a physics professor, who was opposed to nuclear power generation.

He claimed, "that if the fuel rods in the core of a nuclear reactor overheated, they could melt through the floor of a nuclear plant in a matter of minutes, creating an explosion powerful enough to release an invisible cloud of deadly radiation over the entire northeastern United States, killing millions of Americans and leaving the area uninhabitable for thousands of years".

It was a strange coincidence that Lowell would use the state of Pennsylvania as a comparison. Three Mile Island would become a major international crisis which resulted from mistakes, oversights, and misjudgments at every level. Today the image of the cooling towers at TMI have become a symbol to the dangers of nuclear power production.

The problem at TMI began at about four o'clock in the morning on March 28, 1979, when vital cooling water began to escape through an open valve in the newly built reactor at Unit 2. For the next two hours plant operators failed to read these symptoms correctly, failed to close the valve, and mistakenly shut off the emergency cooling system that would have operated automatically, consequently the reactor core over-heated, and the worse nuclear disaster in American history was well on its way by sun-up.

For nearly a year the nuclear power plant at TMI had been quietly generating electricity on an island in the middle of the Susquehanna River. It was located just ten miles from the state capital of Harrisburg, and only 100 miles downwind from the major metropolitan areas of Philadelphia, Baltimore, and Washington DC.

By the early morning of Wednesday March 28,1979, the exposed core in Unit 2 at TMI was beginning to cook, temperatures in the reactor reached over 4,300 degrees Fahrenheit, just 1,000 degrees short of meltdown.

The plant's operators desperately worked to reign in the out-of-control reactor core. Word of the accident first reached the public in a local radio report.

Lieutenant Governor William Scranton assured everyone that the owner of the plant, Metropolitan Edison, had the situation under control, and no radiation had been released outside the plant.

As Scranton left the podium, he would later learn radiation had been released, and he would no longer rely on Metropolitan Edison for information needed to make decisions.

President Carter Visits Three Mile Island

President Cater walking through the control room at Three Mile Island soon after the meltdown of the core of its reactor.
President Cater walking through the control room at Three Mile Island soon after the meltdown of the core of its reactor. | Source

Aerial View of Three Mile Island

Unit 2 is on the left hand side of the site.
Unit 2 is on the left hand side of the site. | Source

The Accident's Revealed a Meltdown

What happened at TMI in the next five days would become history as scientist scrambled to prevent the nightmare of a meltdown. Government officials rushed to calm the public's fears, and thousands of residents fled the area surrounding the plant to emergency shelters.

Perhaps, the worse moment of the crisis is when The Associated Press ran an urgent news bulletin stating that a hydrogen bubble inside the stricken reactor was about to explode. Americans that lived close around the plant lived their lives on a razors edge as the crisis unfolded.

The U.S. Department of Energy laid out the worst-case scenario for state officials explaining that if an explosion broke open the containment vessel lethal doses of radiation would escape.

One state official predicted the release of "extremely high" radiation dose rates in the thousands of rems per hour. For anyone living close to the plant it would have been lethal. Five hundred rems per hour of radiation is considered a lethal dose.

President Carter visited TMI to help control the crisis and calm the public's fears around the stricken plant the Sunday following the disaster.

Carter, a former nuclear submarine officer, probably was more familiar with the workings of nuclear reactors than any other president to occupy the office before or since. He displayed a great deal of courage as he walked around the plant inspecting the damage.

At a news conference in Middletown after the tour, Carter urged the public to remain calm if the call came to evacuate. Carter's visit would mark the end to the crisis.

That afternoon, scientist finally determined that the reactor core had stabilized. Residents slowly began returning to their homes. Although they were told that an insignificant amount of radiation had been released during the accident, many local residents would be plagued with doubts for years afterward.

Three years after the accident, a robotic camera was lowered into TMI Unit 2's core providing the first real look at what had happened that early morning back in 1979.

Roger Mattson, a senior NRC engineer, described what was revealed announcing to the public "We had a meltdown at Three Mile Island".

"Fifty percent of the core was destroyed or molten and something on the order of twenty tons of Uranium found its way to the bottom head of the pressure vessel. That's a core meltdown. No question about it."

Large quantities of radioactivity leaked from the reactor, but most of it was contained. The cleanup would cost over a billion dollars and would last until 1993 when the last of the hazardous material was transported out of the plant.

Clean up at Three Mile Island

The clean-up of Three Mile Island would take fourteen years and cost in the billions dollars. The plant came within 30 minutes of a full core meltdown.
The clean-up of Three Mile Island would take fourteen years and cost in the billions dollars. The plant came within 30 minutes of a full core meltdown. | Source

The Clean-up and Cover-Up: What Really happened at Three Mile Island

The "Big Lie" was that the public was told that radiation releases at Three Mile Island were "insignificant." But the stack monitors at Three Mile Island which were needed to monitor the radiation were saturated and unusable.

The NRC (Nuclear Regulatory Commission) later told Congress it didn't know and still does not know, how much radiation was released at Three Mile Island, or where it went. The public was told that there was no melting inside the reactor core at Unit 2.

Robotic cameras later showed a very substantial portion of the fuel core did melt down, twenty tons of uranium to be exact.

The public was told there was no need to evacuate anyone from the area. But Pennsylvania Governor Richard Thornburgh ordered the evacuation of pregnant women and small children from the area around Three Mile Island.

Unfortunately, many were sent to nearby Hershey, which was showered with fallout. In fact, the entire region should have been immediately evacuated.

The public was assured the government would follow up with meticulous studies of health histories of the region's residents.

The state of Pennsylvania hid the health impacts, but they could not hide an apparent tripling of the infant death rate in nearby Harrisburg and much more.

Using unsubstantiated estimates of how much radiation was released, the government issued average doses allegedly received by people in the region, which it assured the public were safe.

But the estimates were utterly meaningless, among other things ignoring the likelihood that high doses of concentrated fallout could come down heavily on specific areas.

Official estimates said a uniform dose to all persons in the region was equivalent to a single chest x-ray. But pregnant women are no longer x-rayed because it has long been known a single dose can do catastrophic damage to an embryo or fetus in utero.

The most reliable studies were conducted by local residents like Jane Lee and Mary Osborne, who went door-to-door in neighborhoods where the fallout was thought to be the worse.

Their surveys point the other way showing very substantial plagues of cancer, leukemia, birth defects, respiratory problems, hair loss, rashes, lesions and much more.

Historical evidence among the local human population within 10 miles of Three Mile Island has been devastating. Large numbers of central Pennsylvanians suffered sunburns, skin sores, and lesions that erupted while they were out of doors as the fallout rained down on them.

Many residents quickly developed large, visible tumors, breathing problems, and a metallic taste in their mouths similar to some of the men who dropped the bomb on Hiroshima, and who were exposed to nuclear tests in the south Pacific and Nevada (the atomic soldiers).

Investigations by epidemiologist Dr. Stephen Wing of the University of North Carolina, and others significantly challenge the official government story on both radiation releases and health impacts.

Arnie Gundersen, a former nuclear industry official and a leading expert on nuclear engineering, says: "When I correctly interpreted the containment pressure spike and the doses measured in the environment after the Three Mile Island accident, proved that Three Mile Island's releases were about one hundred times greater than the industry and the Nuclear Regulatory Commission (NRC) claim, in part because the containment vessel leaked."

In fact, all containment vessels are known to leak, because of all the pipes and electrical conduit that pass through the walls.

The cost of sealing all those penetrations is considered too high, so the federal regulators allow a certain amount of leakage.

Other experts estimate that the radiation releases at Three Mile Island could have been a thousand times greater than NRC estimates, what madness to allow an industry to build such a structure knowing the possibility that radiation could escape from the very structure designed to contain it.

Living with Nuclear Power

Can we believe the Federal Government's findings at Three Mile Island?

The nuclear crisis at Three Mile Island marked the high-water mark for nuclear power plant construction in the United States. No new permits to build nuclear power plants have been given after the accident at Three Mile Island.

We can only hope we follow Germany's lead and begin to shut down all of the nuclear power plants in the United States and find an alternative means to create our electricity before something happens, we can't clean up.

Ironically, like Chernobyl, Three Mile Island Unit 2 was a state-of-the-art reactor. Its official opening came on December 28, 1978, and it melted down exactly three months later.

Had it operated longer, the accumulated radiation spewing from its core almost certainly would have been far greater. The "Big Lie" remains officially intact.

That Three Mile Island was "success story " because " no one was killed." But in mere moments that brand new reactor morphed from a $900 million asset to a multi-billion-dollar liability.

Every reactor now operating in the U.S. is much older, it has been three decades since Unit 2 at Three Mile Island melted down, and their potential fallout could dwarf what came down in 1979.

To further underscore the horrors experienced by the people of central Pennsylvania during the crisis, the legendary then-CBS News anchor Walter Cronkite commented soon after the event at Three Mile Island, warning that "the world has never known a day quite like today.

It faced the considerable uncertainties and dangers of the of the worst nuclear power plant accident of the atomic age. And the horror tonight is that it could get much worse. If Three Mile Island happened today, we would have a data-center full of new capabilities to assess any damage or threat.

The accident helped in the creation of a new group of experts within the Department of Energy, whose sole job is to model how dangerous fine particulates from a nuclear fallout or chemical explosion can be as they will drift across our landscape.

The National Atmospheric Release Laboratory is housed at the Lawrence Livermore National Laboratory and is our defense against nuclear and chemical accidents or attacks.

It was created in the aftermath of the Three Mile Island crisis. At the time of the crisis no one was able to determine exactly how much of the tasteless, odorless, invisible radiation was released and where it was drifting.

The sensors designed to measure radioactive release were overwhelmed, the instrumentation that was installed at the plant was not designed to handle the scope and scale of the release at Three Mile Island.

As intermittent emissions of radioactive gas tumbled into the sky, the outcome became clouded and on one will ever truly know what happened out on the Susquehanna River that early morning in March 1979. The Three Mile Island accident will never be fully understood forever lost in the realm of the unknown.


Gray, Mike. The Warning: Accident At Three Mile Island A Nuclear Omen for the Age of Terror. W.W. Norton & Company Ltd. New York. London, Castle. House, 75/76 Wells Street London WIT 3QT. 1982

Walker, Samuel J. Three Mile Island: A nuclear Crisis in Historical Perspective. University of California Press, Berkeley, Los Angeles & London., 155 Grand Ave Ste 400, Oakland, CA 94612. 2004


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