THREE MILE ISLAND, Pennsylvania — Giant cooling towers at Constellation Energy’s CEG.OThree Mile Island nuclear plant in Pennsylvania have sat dormant for so long that grass has sprung up in the towers’ hollowed-out bases and wildlife roam inside. Armed guard stations at an entrance to the shut concrete facility, surrounded by barbed wire, sit empty. The plant, which would run so loud when operating that workers were required to wear hearing protection, is nearly silent. “It’s still eerie walking in here and it’s, just, quiet,” Constellation regulatory assurance manager Craig Smith said during a tour of the plant last week. Smith, who worked at Three Mile Island when Constellation shut the site’s remaining reactor in 2019, is now preparing for a restart. Constellation announced last month that it would revive the half-century-old Three Mile Island with the purpose of fueling Microsoft’s MSFT.O data centers. Microsoft is expected to pay at least $100 a megawatt-hour, nearly double the typical cost of renewable energy in the region, as part of the 20-year power contract. The agreement shows the dramatic lengths Big Tech is willing to go to procure electricity for its artificial intelligence expansion and the undertaking by the U.S. power industry to meet that demand. The effort to restore Unit 1 at Three Mile Island is expected to take four years, at least $1.6 billion, and thousands of workers to complete the unprecedented task of restarting a retired nuclear plant. Constellation has already ordered costly equipment for the site and identified fuel for the unit’s reactor core, with work expected to start early next year, according to Reuters’ interviews with company executives, contractors and a tour of the site. Successfully resurrecting Three Mile Island, which is widely known for a 1979 partial meltdown that cast a pall over the U.S. nuclear sector for decades, would put the plant at the front edge of an industry revival. Nuclear creates large amounts of carbon-free electricity. That is attractive to companies, like Microsoft, that have climate pledges and face increasing public scrutiny for their voracious power use. Microsoft would consider signing other power purchase agreements to restart shut plants, Alistair Speirs, senior director of Microsoft’s Azure Global Infrastructure, told Reuters. “I don’t think anything’s off the table,” Speirs said. Relaunching Three Mile Island would supply to the regional grid 835 megawatts of electricity – enough for all of Philadelphia’s homes – to help offset Microsoft’s power consumption. A restart of the plant, however, is not certain. Three Mile Island, which will be renamed the Crane Clean Energy Complex, still requires licensing modifications and permitting. Local activists have also vowed to fight the project over safety and environmental concerns. If the plan suffers the same lengthy delays and cost overruns that have plagued nearly every nuclear build in the country’s history, it could stymie other deals and set back Big Tech’s quest to rapidly expand, power experts say. Millions of feet of building Earlier this year, Constellation finished initial testing of the plant’s Unit 1 to determine whether it was financially reasonable to resurrect it. After learning that the central generator, which would cost hundreds of millions of dollars to replace, was in strong condition, the company moved ahead with its plan. “We have a perfectly ready-to-go main generator just waiting for the rest of the plant to get started,” said Smith, standing in front of a row of massive turbines. About a thousand carpenters, electricians, pipefitters and other tradesmen are expected to be deployed to the site, said Rob Bair, president of Pennsylvania Building Trades. Work will likely start in the first quarter of 2025 with restoring two 370-foot (113-m) high cooling towers, which were stripped bare after the plant shut. “There is a ton of equipment that has to go back in those towers,” said Bair, whose father helped build Unit 1, which opened in 1974. Workers will be hoisted up the top of the towers to install lighting and restock the buildings from within. The structures’ bases, which were once made of redwood, will be refurbished with modern materials. Next, restorations inside of the plant will begin: some major equipment will be replaced. Constellation recently ordered the site’s main transformer, which is expected to cost around $100 million including installation, to be delivered in 2027. Piping and electrical work, scrubbing condensers and cleaning out power generators, will be among the next tasks. A million-gallon tank will be filled with water. Much of the analog control room, with a panel installed in the early 1970s, will stay the same. A benefit of keeping the analog system is that it would be more secure against cyberattacks, officials said. Completing the job will require several million feet of scaffolding, built by scaffologists, or carpenters with special licenses, to be assembled repeatedly around the island. “And all of that has to be done before you can even put fuel on the site,” Bair said. The company has commissioned the fuel design for the reactor’s core, said Constellation Chief Generation Officer Bryan Hanson. The core holds the enriched uranium, the fuel source for the plant, stacked in pellets and sealed in tubes. Constellation, which is the biggest U.S. operator of nuclear plants, will tap into fuel from its existing enriched uranium reserves as one of the final steps before starting up. The effort is part of a recent turnaround of U.S. nuclear power, which suffered from competition from cheap fuel and fears of meltdowns, said John Ciampaglia, CEO of Sprott Asset Management, which manages a large physical uranium fund. In Michigan, Holtec is in the process of trying to restart another reactor site. Constellation’s stock price has soared by 135% so far this year amid fresh projections for record U.S. power consumption next year and a doubling of data center demand by 2030. Not everyone is enthused about the prospect of a nuclear comeback. The power plants produce waste that can remain radioactive for thousands of years. About a tennis court-size amount of spent nuclear fuel from Unit 1 is stored on Three Mile Island, which sits on a strip of land in the Susquehanna River. The decommissioning of Unit 2 is still underway about 45 years after the partial meltdown. Local activist Eric Epstein, who remembers the March 1979 incident, said he will fight Constellation’s request to resume operating and water use licenses. “It’s going to be a protracted battle,” Epstein said. The first chance for the challenges comes on Oct. 25, when the Nuclear Regulatory Commission has scheduled its initial public hearing on Constellation’s plan to restart Unit 1.