A nuclear reactor at Three Mile Island could be brought back online in 2027 – about a year ahead of schedule – to power Microsoft data centers.
Constellation Energy, the Exelon spinoff that owns the remaining viable reactor at the nuclear power plant outside Harrisburg, is bumping up grid connections and hiring workers to accelerate the opening of the renamed Crane Clean Energy Center.
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"We're on track to make history ahead of schedule, helping America achieve energy independence, supercharge economic growth, and win the global AI race," Constellation CEO and President Joe Dominguez said Wednesday at a press conference joined by Pennsylvania Gov. Josh Shapiro and members of the building trades.
Constellation struck a deal last year to sell Microsoft the energy for the tech company's AI operations for the next 20 years. Competition among tech companies and the strain on electrical grids due to the energy demands of AI computing systems has driven Microsoft along with Amazon and Google to turn to nuclear power.
The restart of Three Mile Island – infamous for its partial meltdown on March 28, 1979 – could be the first time a shuttered nuclear plant has ever been brought back into service. The facility shut down its Unit 1 reactor – which was not involved in the 1979 crisis and was its last viable reactor – in 2019 citing to economic reasons.
Another plan is underway in Michigan to restart the Palisades plant that was shut down in 2022.
"This restart will safely take advantage of existing infrastructure while creating thousands of energy jobs and strengthening Pennsylvania's legacy as a national energy leader," Shapiro said about Three Mile Island at the press conference.
Constellation believes the timeline can be shortened, because PJM Interconnection – the company that operates the regional electricity grid – helped secure expedited approvals for Three Mile Island's grid connections. Nuclear power projects often face delays and other setbacks to due their high costs. Constellation estimates the restart will cost about $1.6 billion, which the company seeks to back with a federal loan guarantee.
Microsoft officials said they view the facility as a key step toward becoming a carbon negative company.
The partial meltdown at Three Mile Island's Unit 2 reactor forced thousands of people in nearby Pennsylvania communities to evacuate over fears of exposure to radioactive fallout, and cast an enduring pall over the nuclear energy industry in the United States. Some experts have cautioned that the restart project may require major investments in refurbishments and maintenance beyond the period when it resumes service, in addition to concerns about water usage and challenges related to sharing a site with a decommissioned reactor.
Constellation officials said the facility is now 64% staffed, with about 400 full-time employees onboard and dozens more starting in the coming weeks. The company also has completed technical inspections at the plant and made major equipment purchases, including new power transformers that are expected to be delivered next year. Regulatory filings are under review with the federal Nuclear Regulatory Commission.
Before Three Mile Island was shut down, the facility provided energy to about 800,000 homes. It closed because it was unable to compete with cheaper energy sources.
"The U.S. nuclear industry is uniquely positioned to meet the rising demand for clean, reliable, and affordable energy," Maria Korsnick, president and CEO of the Nuclear Energy Institute, said in a statement. "The Crane Clean Energy Center is a powerful example of how our industry is rising to the challenge."