The Three Mile Island nuclear power plant is closing for good — here's what happened on the day of the worst nuclear disaster in the US

Michael Abramson/The LIFE Images Collection via Getty Images/Getty ImagesDecades after the world’s worst nuclear disaster, the Three Mile Island nuclear power plant is closing.


Early on March 28, 1979, a combination of electrical and mechanical malfunctions, as well as human error, unleashed dangerous radioactive gases into the environment around the Three Mile Island nuclear power plant in Pennsylvania. It wound up being the worst nuclear disaster in US history.

Leif Skoogfors/Getty ImagesThe Three Mile Island Nuclear Generating Station on March 30, 1979.

Source: History


The plant sits on Three Mile Island in Susquehanna River.

Wally McNamee/Corbis via Getty ImagesAn aerial view of the Three Mile Island during the time of the nuclear accident in 1979.

Source: History


The island sits just outside of Harrisburg, Pennsylvania.

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Three Mile Island was owned by utility company Metropolitan Edison at the time of the accident. The facility had two units, one of which is still operational. The other has been shut and sealed since March 28, 1979.

ReutersA view of the Three Mile Island nuclear power plant on March 22, 1999.

Source: The Philadelphia Inquirer


Holly Garnish, who lived in the nearest house to the Three Mile Island plant at the time of the accident, told the Washington Post that it all started with a loud roar that “shook the windows, the whole house.”

Jonathan Ernst/ReutersA sign marks the Three Mile Island nuclear power plant on March 15, 2011.

Source: The Washington Post


The pipe that pumped water into the second reactor, known as TMI-2, to prevent it from overheating stopped working. That caused the reactor core to boil.

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Unaware of what had caused a problem, plant workers inadvertently made the situation worse by stopping further water flow to the reactor. So it kept overheating.

Bettmann/Contributor/Getty ImagesReactor 1 (not the reactor that experienced a meltdown) at Three Mile Island on the day of the accident.

Source: History


A valve popped open and allowed steam to escape from the reactor.

Source: History


About half of the reactor core melted from the overheated nuclear fuel, and about 20 tons of radioactive uranium poured out of the reactor core. It covered the steel floor and nearly burned through it.

Michael Abramson/The LIFE Images Collection via Getty Images/Getty ImagesAn aerial view of Three Mile Island on April 2, 1979.

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The melted fuel created a bubble of hydrogen inside the containment unit that could have caused an explosion.

Source: History


Reactor personnel did not notify local and state officials about the situation until three hours after the initial malfunction.

Report of The President’s Commission on the Accident at Three Mile Island: The Need for Change: The Legacy of TMI/Wikimedia Commons/Public DomainWorkers in the TMI-2 control room several days after the start of the accident at Three Mile Island.

Source: History


CBS News anchor Walter Cronkite reported on the Three Mile Island crisis, calling it the “first step in a nuclear nightmare.”

CBS Photo Archive/Getty ImagesWalter Cronkite reports on the Three Mile Island meltdown in 1979.

Source: The Washington Post


But the Three Mile Island nuclear crisis was a partial meltdown, not a full meltdown. So it could have been far worse.

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Other nuclear disasters, like Chernobyl in 1986 and Fukushima in 2011, are considered full meltdowns because the overheating caused the containment structures housing the reactors to split open. Those events released a much larger amount of radioactive material.

APAn aerial view of the Chernobyl nuclear power plant, the site of the world’s worst nuclear accident, in April 1986, days after the explosion.

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Fortunately, nobody died because of the Three Mile Island accident. Officials declared a state of emergency, but no official evacuation process had been established for this kind of scenario.

Michael Abramson/The LIFE Images Collection via Getty Images/Getty ImagesEvacuees in Civil Defence shelter at a local sports arena after the accident at the Three Mile Island reactor on April 2, 1979.

Source: History


Because of the lack of emergency planning, residents were unsure how to react and panicked.

Owen Franken/Corbis via Getty ImagesA sign announces the closing of the observation centre for the Three Mile Island nuclear plant in Pennsylvania, following an accident on March 28, 1979.

Source: History


Pregnant women and young children within a 5-mile radius of the plant were told to evacuate.

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Source: History


Some stayed in makeshift shelters at local sports arenas and other venues until the evacuation order was called off on April 9.

Michael Abramson/The LIFE Images Collection via Getty Images/Getty ImagesEvacuees in a makeshift shelter on April 2, 1979.

Source: History


Everyone within a 10-mile radius of the plant was advised to stay indoors.

© Wally McNamee/CORBIS/Corbis via Getty ImagesChildren are taken from school on the day of the Three Mile Island accident.

Source: History


Evacuation orders aside, about 40% of people within a 15-mile radius of the plant evacuated themselves as worry spread.

Michael Abramson/The LIFE Images Collection via Getty Images/Getty ImagesEvacuation of the Lutheran Home for the elderly during the Three Mile Island accident.

Source: History


“It was like something out of a horror movie,” Christine Layman, who lived about 7 miles from the plant at the time of the incident, told The Philadelphia Inquirer. “No one knew what was going on.”

Bettmann/Contributor/Getty ImagesGwen Majette, 4, of Middletown, Pennsylvania, sleeps on her mother’s lap as Willie Majette reads the morning headlines about the evacuation from the 5-mile area around the Three Mile Island Nuclear Plant on March 31, 1979.

Source: The Philadelphia Inquirer


Local priests granted “general absolution,” a religious term referring to the forgiveness of all sins in times of crisis.

Bettmann/Contributor/Getty ImagesA youngster shows off a new T-shirt near the site of the Three Mile Island nuclear power plant on April 5, 1979.

Source: History


Evacuees clamored to withdraw funds from banks in the area on their way out of town.

Michael Abramson/The LIFE Images Collection via Getty Images/Getty ImagesA house on the market near Three Mile Island following the accident at the reactor.

Source: History


Some communities in the surrounding area became temporary ghost towns as residents scrambled to distance themselves from the plant.

Bettmann/Contributor/Getty ImagesA view of Middletown, Pennsylvania, with Three Mile Island in the background on April 2, 1979.

Source: The Philadelphia Inquirer


Two days after the accident, officials feared that the hydrogen bubble would burst, which could have led more radioactive material to leak into the surrounding environment.

Source: The Philadelphia Inquirer


To prepare for the worst, officials considered evacuating over 600,000 people within a 20-mile radius of the plant.

Source: History


But a few days after the accident, the bubble of hydrogen was determined to be stable.

Bettmann/Contributor/Getty ImagesJohn G. Kemeny, chairman of the president’s commission on the accident, at Three Mile Island on May 17, 1979.

Source: History


In total, about 2 million people within a 50-mile radius were exposed to small amounts of radiation because of the Three Mile Island nuclear accident. According to the US Nuclear Regulatory Commission (NRC), the radiation exposure equaled that of a chest X-ray.

© Wally McNamee/CORBIS/Corbis via Getty ImagesA man measures radioactivity with a Geiger counter after the Three Mile Island nuclear accident.

Source: The Philadelphia Inquirer


The process of cleaning up the reactor took 14 years and cost an estimated $US1 billion. The reactor was damaged beyond repair and was sealed shut with concrete following the accident. Its neighbouring reactor remained operational.

Source: History


In an eerie coincidence, a film called “The China Syndrome” about a fictional nuclear power plant disaster came out just 12 days before the Three Mile Island accident. The movie starred Jane Fonda and Michael Douglas.

Sunset Boulevard/Corbis via Getty ImagesJane Fonda and Michael Douglas on the set of ‘The China Syndrome.’

Source: The Philadelphia Inquirer


In the film, one character even says the fictional nuclear accident has the potential to “render an area the size of Pennsylvania uninhabitable” (though the disaster in the film takes place in California).

Bettmann/Contributor/Getty ImagesActress Jane Fonda and her husband, political activist Tom Hayden, are seen during a press conference outside the Three Mile Island nuclear plant on September 24, 1979.

Source: The Philadelphia Inquirer


The movie’s title, “The China Syndrome,” refers to the idea that melted radioactive material could travel from the US all the way through the Earth’s core to China.

Ed Eckstein/Getty ImagesA protester under the marquee of a theatre advertising the film ‘The China Syndrome,’ on March 29, 1979.

Source: The Philadelphia Inquirer


Nuclear-industry insiders scoffed at the premise at the time, saying it was almost impossible for reactors to overheat and experience such a nuclear meltdown.

Ed Eckstein/Getty ImagesA protester under the marquee of a theatre advertising the film ‘The China Syndrome,’ on March 29, 1979.

Source: History


But during the Three Mile Island crisis, reactor staff really did fear that the nuclear fuel could melt through the containment structure and seep into the ground (though not through the entire globe).

Jonathan Ernst/ReutersThe Three Mile Island nuclear power plant is seen on March 15, 201.

Source: The Philadelphia Inquirer


As with other nuclear disasters, the health impacts of the Three Mile Island nuclear accident are still debated.

Bettmann/Contributor/Getty ImagesA technician for Metropolitan Edison measures the radiation inside Three Mile Island on May 17, 1979.

Source: USA Today and The Philadelphia Inquirer


The nuclear-energy industry, including the NRC, says the radiation in 1979 had no serious health consequences. The accident’s “small radioactive releases had no detectable health effects on plant workers or the public,” the NRC website says.

Rolls Press/Popperfoto via Getty Images/Getty ImagesRadiation levels are checked on a group of workers at the Three Mile Island Nuclear Power plant on March 28, 1979.

Source: US Nuclear Regulatory Commission


However, a 2017 study at Penn State Medical Centre found a possible link between the 1979 nuclear accident at Three Mile Island and cases of thyroid cancer in nearby parts of Pennsylvania.

Bettmann/Contributor/Getty ImagesTom Fox of the Department of Energy tests water samples along the Susquehanna River for radioactivity on April 3, 1979.

Source: USA Today and Penn State College of Medicine


The researchers behind that study relied on the same research method that was used after the Chernobyl nuclear disaster: They studied patients with thyroid cancer to see how many of them had a genetic mutation that makes them more prone to non-radiation-induced thyroid cancer.

Carlo Allegri/ReutersA man fishes in the Susquehanna River in front of the Three Mile Island plant on May 30, 2017.

Source: USA Today and Penn State College of Medicine


Their results suggested that while 83% of thyroid-cancer patients in a control group had this mutation, only 53% of thyroid-cancer patients who’d lived in at-risk locations at the time of the nuclear accident had the mutation.

Source: Penn State College of Medicine


The study wasn’t conclusive, however.

Jonathan Ernst/ReutersCars travel on a road near the Three Mile Island nuclear power plant on March 15, 2011.

Source: USA Today


Regardless of the health effects, the accident certainly had an impact on the anti-nuclear movement in the US, which coalesced in response to the nuclear arms race of the Cold War.

Keystone/Hulton Archive/Getty ImagesProtesters near Three Mile Island in 1979.

Source: History


Protests, both near the nuclear power plant and across the country, were held in response to the Three Mile Island incident.

Leif Skoogfors/Getty ImagesDemonstrators protest the use of nuclear power outside Three Mile Island on April 1, 1979.

Source: History


Public support for nuclear energy dropped following the Three Mile Island crisis, from 69% in 1977 to 46% in 1979.

Source: History


Following the accident, regulatory changes were made for nuclear-plant operations in the US to mandate improved safety controls and emergency response plans.

Dirck Halstead/The LIFE Images Collection via Getty Images/Getty ImagesA plant official, President and Mrs. Carter, Governor Thornburgh, and NRC’s Harold Denton at crippled Three Mile Island nuclear plant.

Source: History


Because of the new rules, the process of designing and building new nuclear power plants became longer and more costly. Since the Three Mile Island accident, no new nuclear plants have been built in the US.

Carlo Allegri/ReutersThree Mile Island is seen on May 30, 2017.

Source: History


Now, decades later, the Exelon-owned Three Mile Island plant is closing.

Carlo Allegri/ReutersThe entrance to the Three Mile Island Nuclear power plant is seen on May 30, 2017.

Source: Business Insider


The 1979 disaster aside, nuclear power plants in the US have also struggled due to competition from power plants that rely on natural gas.

Carlo Allegri/ReutersPeople work on a car across the river from the Three Mile Island plant on May 30, 2017.

Source: Business Insider


But the accident, of course, made the Three Mile Island plant’s struggle unique.

Jonathan Ernst/ReutersThe Three Mile Island nuclear power plant is seen at night on March 15, 2011.

Source: Business Insider

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