When operational, steam pushes through four turbines, turning a shaft in the generator at the front of the room to create electricity. The turbine hall at Three Mile Island Unit 1 is seen here on Oct. 16, 2024.
Rachel McDevitt / StateImpact Pennsylvania
Rachel McDevitt / StateImpact Pennsylvania
When operational, steam pushes through four turbines, turning a shaft in the generator at the front of the room to create electricity. The turbine hall at Three Mile Island Unit 1 is seen here on Oct. 16, 2024.
Water, oil and workers is all it will take to get the shuttered Three Mile Island nuclear plant back up and running, according to the plant’s owners.
That, plus months of training, inspections and navigating regulatory approval.
The plant’s proposed restart, enabled by a deal with Microsoft to buy TMI’s electricity, is being closely watched by nuclear boosters and skeptics alike. No nuclear plant in the country has ever turned back on after shutting down.
Patrick White, research director of the nonpartisan Nuclear Innovation Alliance, which promotes advanced nuclear energy, said TMI’s reopening is exciting.
“This is something that, five years ago, people wouldn’t have taken seriously,” White said.
Others are more cautious. Edwin Lyman, the director of nuclear power safety at the Union of Concerned Scientists, said he will be watching for more detailed reports from federal regulators as the plant attempts to power back up.
“The fact is when they shut the plant down, there was no reason to put it in a state to restart again,” Lyman said.
Constellation, owner of the TMI Unit 1 reactor, opened up the closed plant to media last week to show their confidence that the site can repower without issue. The company owns 14 active nuclear plants and two retired plants.
“It’s just work that we do day in, day out at all of our other facilities and that we’re quite good at,” said Bryan Hanlon, Constellation’s chief generation officer.
Rachel McDevitt / StateImpact Pennsylvania
Three Mile Island Unit 1 equipment is seen here on Oct. 16, 2024.
Plant officials compared some aspects of the restart to routine maintenance outages. Equipment was switched off and drained of water or oil and left to sit idle for the last five years, instead of a few weeks.
The air in the plant was cool during the tour and the only sound was the hum of ventilation systems and air compressors.
Craig Smith, who worked as an operator at TMI-1 and is now the regulatory assurance manager for the plant, said it’s strange to be in the quiet facility. When the plant was running, he said it was hot and workers needed to wear hearing protection.
TMI-1 opened in 1974 and produced electricity until 2019, when its owners said it could not compete economically.
TMI Unit 2, now owned by TMI-2 Solutions, suffered a partial meltdown in 1979–the worst nuclear accident at a commercial plant in U.S. history. It never came back online and is now undergoing cleanup.
Under a power purchase agreement with Microsoft, the tech giant promised to pay for all the electricity generated at TMI-1 to offset the power used at its data centers in the region. Constellation plans to reopen TMI-1 by 2028 and to rebrand the plant to the Crane Clean Energy Center.
What it will take to reopen
Constellation is applying for a $1.6 billion federal loan guarantee to help finance its restart plan, according to the Washington Post.
Hanlon said they will need to invest in new transformers – which move electric current – and refurbish or replace equipment. He said past investments will make it easier to restart the plant; TMI’s steam generators were replaced in 2009.
A big cost for restart will be labor.
TMI-1 employed 600 people before it closed and Constellation expects to employ the same number at the restarted plant. New employees will need to go through extensive training and testing before the federal Nuclear Regulatory Commission will allow the plant to restart. Hanson said the training period for operators takes 18 months.
Rachel McDevitt / StateImpact Pennsylvania
Inside the turbine room at Three Mile Island Unit 1 on Oct. 16, 2024.
Smith said important equipment is still in good working order.
Copper bars had corroded inside the main generator, which creates the electricity that’s sent to the grid. Smith said technicians used an acid solution to clean the bars and restore them to their original condition. The generator is now flooded with nitrogen gas to prevent corrosion.
One of the plant’s cooling towers will need to be restored. Staff did not say how much that specific piece would cost. The original structure inside the tower that allowed water to flow down and cool off had become brittle and a safety hazard, and was torn down when the plant closed. The structure inside the second tower was refurbished several years before closure.
A novel process
White said he will be keeping an eye on Constellation’s public investments in the plant and how it engages with the NRC. He said required reports to the agency will show how the plant’s systems were taken care of and how they can be brought back online.
The licensing process will be novel, White said, since TMI-1 and a plant in Michigan are the only two to ever ask to restart after retirement.
Constellation is scheduled to outline its planned timeline for reopening TMI-1 at a public meeting with the NRC on Friday, Oct. 25.
NRC spokesman Neil Sheehan said the actual time to move through the regulatory process will depend on the complexity of the actions and the quality of information provided by Constellation.
Sheehan said safety is the primary focus for NRC staff.
Smith, with Constellation, said he did not believe repowering TMI-1 while TMI-2 is being cleaned up would cause any issues.
Sheehan said the two plants are owned by separate companies, but share things such as a fuel handling building and security features. He said coordination with TMI-2 Solutions will key to understanding impacts to both a potential restart and decommissioning activities.
Lyman said he has concerns generally about the safety of the country’s nuclear fleet. He said Constellation, as one of the largest operators of nuclear power in the U.S., has a lot of sway in the industry. And industry, he said, always tries to minimize its operating costs.
“Constellation pushes the envelope of how little they can spend to satisfy the NRC,” Lyman said.
Lyman had hoped to see stronger safeguards following the Fukushima nuclear accident in Japan in 2011, but said an NRC task force’s recommendations were ignored or watered down.
Nuclear plants are gaining some public support because they do not emit the planet-warming pollution that coal or gas plants do. But Lyman said nuclear can only play a role if it meets high safety standards.
Hanson said he understands the concerns about TMI-1, especially being next door to TMI-2’s partially melted reactor. But, he said the 1979 incident “created the greatest opportunity for the rest of the nuclear industry to learn.”
“So many fundamental changes have occurred in our industry,” Hanlon said.
Rachel McDevitt / StateImpact Pennsylvania
One cooling tower will need to be refurbished as part of the restart of Three Mile Island Unit 1, which is being renamed the Crane Clean Energy Center. Photo taken Oct. 16, 2024.
