Three Mile Island clings to survival 40 years after 1979 meltdown

Forty years after a partial meltdown, the Three Mile Island power station faces an uncertain future.

By Daniel Uria
Nuclear reactor Units 1 and 2 are seen at the Three Mile Island Nuclear Generating Station in Londonderry Township, Pa. Unit 2, at left, sustained a partial core meltdown on March 28, 1979. Photo courtesy Marque1313/Wikipedia Commons
Nuclear reactor Units 1 and 2 are seen at the Three Mile Island Nuclear Generating Station in Londonderry Township, Pa. Unit 2, at left, sustained a partial core meltdown on March 28, 1979. Photo courtesy Marque1313/Wikipedia Commons

March 28 (UPI) -- Four decades after the United States' first major nuclear core meltdown alarmed the energy industry, activists and the public, some Pennsylvania politicians are fighting to keep the Three Mile Island facility open.

Reactor Unit No. 2 at the plant overheated on March 28, 1979, prompting a general emergency that lasted for days. A stuck valve was later found to have caused the problem, which duped operators into withholding critical coolant from the core. Tens of thousands in Dauphin County and surrounding areas were evacuated.


Although radioactive releases had no detectable health effects on plant workers or the public, the reactor was never reactivated. Hazardous materials were removed and cleanup lasted into the 1990s.

The accident resulted in wholesale changes in the nuclear industry for safety, but also negatively affected public perception of nuclear energy. The plant is set to close before at the end of 2019, as nuclear power struggles to compete with other, cheaper forms of energy.


Almost as bad as Chernobyl

The meltdown at the Londonderry Township, Pa., plant, about 90 miles west of Philadelphia, began at 4 a.m. on March 28 when the secondary, non-nuclear section of the plant experienced a failure. The plant's turbine-generator and reactor automatically shut down after a mechanical failure prevented feedwater pumps from cooling steam generators that remove heat from the reactor's core. After the shutdown, operators received inadequate and misleading information that left them unaware they were dealing with a "loss-of-coolant accident."

Believing there was too much water in the core, the operators unknowingly made the accident worse by cutting the flow of coolant -- uncovering the top of the reactor's core. Steam reacted with the control rods and sent radioactive gases out of the open relief valve and into the skies surrounding Londonderry Township.

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Afterward, some engineers worried a hydrogen bubble may have formed in the containment vessel and could potentially explode, leading to a full meltdown and large-scale radioactive release.

Then-Gov. Dick Thornburgh never ordered mandatory evacuations, but advised pregnant women and preschool children within a five-mile radius of the plant to leave. Many others did so on their own. All told, about 140,000 people fled and thousands more holed up in their homes.


John Brabits, then assistant director of the civil defense in Dauphin County, said people were still afraid when they returned a week later.

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"I won't feel safe until the people at Three Mile Island say the reactor is in a cold shutdown state," he told UPI eight days after the meltdown. "I'm still concerned about the health and safety of the people."

Former President Jimmy Carter personally visited the plant just four days after the meltdown. His decision to do so is considered by many to have greatly contributed to calming a worried community, state and nation.

Experts later said the meltdown at Three Mile Island could have been as bad, or worse, than the 1986 disaster at the Chernobyl nuclear power station in the Soviet Union (now Ukraine), which killed dozens immediately and some say thousands more years later from fallout-related conditions.

ARCHIVE April 1979: Three Mile Island reactor beyond repair

Longstanding changes

In the years that followed, researchers tried to determine the effects of the escaped radiation at Three Mile Island while the nuclear industry made safety modifications. It was ultimately found, after thousands of environmental samples were tested, the release caused negligible effects on human and environmental health.


The 2 million people who lived near Unit 2 would've experienced an average radiation dose about 1 millirem above the usual background dose, regulators said -- or the equivalent of one-sixth the exposure from a chest X-ray. The effects on the industry were far more noticeable.

"The nuclear power industry became a lot more efficient and a lot more safe after Three Mile Island," Arthur Motta, chair and professor in the nuclear engineering program at Penn State University, told UPI recently. "There were a lot of changes that were put in place to communicate problems and to address safety issues that were not present before."

Federal regulation and oversight of nuclear power plants expanded and the Institute of Nuclear Power Operations was created as a direct result of the accident to provide industry oversight.

Plant design and equipment requirements fire protection, piping systems, auxiliary feedwater systems, containment building isolation, reliability of individual component and the ability of plants to shut down automatically were all upgraded. Steps were also taken to improve operator performance, stage more emergency drills and improve plant controls.

Motta said the capacity factor -- the ratio of energy output in a given period of time to the maximum possible output over that period -- increased from 68 percent in 1979 to 92 percent by the early 2000s.


"That's equivalent ... to building twenty some new nuclear power plants, because you're producing more power with the existing things that you have and you're doing it in a more safe manner," he said. "In a sense, it ended up being a positive influence."

ARCHIVE November 1980: NRC discounts Three Mile Island accident caused animal deformities

Future of Three Mile Island

The plant's other reactor, Unit No. 1, has never been taken offline since 1974, but the entire plant is set to close in September due to the high cost of maintenance and tough competition from cheaper natural gas and renewable power. Though it's been dormant since 1979, Unit 2 isn't set to formally close until 2036.

Some lawmakers, though, still see a future for the maligned nuclear station.

Pennsylvania Rep. Thomas Mehaffie has introduced a $500 million subsidy bailout that would add nuclear power to the list of energy providers that receive credit under the state's Alternative Energy Portfolio Standards Act -- a law he thinks will make Three Mile Island profitable again in the long term.

"House Bill 11 basically adds a third tier to AEPS and adds a third, carbon-free tier, so anything that's used to produce energy that has a carbon-free footprint would fall into this tier," he said. "It would pay a credit for the environmental attribute of having a carbon-free production of electricity.


"With the price of gas, it's hard for them to compete," he added. "They're not on a level playing field and that's kind of the real problem here.

"This bill would lock the plants into six years they would have to remain open. We think in that six-year time frame we'll have a more balanced approach moving forward."

Motta said that nuclear power plants should receive the same subsidies as other carbon-free forms of energy, adding that keeping the plants open helps reduce climate change.

"You should give credit where credit is due and allow those plants to reap the environmental benefits that they produce, because if you shut down a nuclear power plant you are essentially increasing emissions," he said. "These plants that you have down in Pennsylvania are precious assets and they should be maintained in order to keep our environmental goals."

Mandy Warner, senior manager for climate and air police for Environmental Defense Fund, said the advocacy group opposes the bailout, which she called a "band-aid" solution. She recommends setting a declining limit on climate pollution instead.

"It's more ideal that you set that carbon pollution limit and then you let the market decide what's the most cost-effective way," she said. "The way the [bailout] bill is structured, all the nuclear generators would be eligible for this and it wouldn't necessarily be based on economic distress."


Warner said a carbon limit would decline over time and based on research indicating that the power sector needs to attain carbon freedom before the middle of the 21st century. She said other states are looking to cut carbon emissions 30 percent by 2030. Under this model, Warner said, there would be room for the state's most economically viable nuclear plants to stay open while renewable energies grow.

"You could envision a world where you have Pennsylvania setting its own limit for the power sector, where nuclear power would still be a part of their resource mix," she said.

ARCHIVE November 1988: Health effects of Three Mile Island in question

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