The Three Mile Island nuclear plant in Pennsylvania is expected to restart a year ahead of schedule, with Unit 1 now targeted to come online in 2027 instead of the original 2028 timeline, according to Constellation Energy Corporation. The accelerated restart represents a milestone in the nuclear industry's revival, driven by surging demand from technology companies seeking carbon-free power for data centers.
Constellation announced the accelerated timeline as work to revive the shuttered reactor progresses faster than anticipated12. The company has already hired more than 200 full-time workers and completed key milestones including restoration of the main office building and enhancements to the training center23.
Dave Marcheskie, community relations manager for the facility, told reporters that the project is moving "ahead of schedule"2. The company expects the Nuclear Regulatory Commission to complete its safety and environmental review by 20274.
The restart requires thousands of inspections and equipment upgrades, including replacement of the main transformer and installation of three new main power transformers scheduled to arrive in 20263.
The restart hinges on a 20-year power purchase agreement with Microsoft announced in September 202412. The tech giant will buy electricity from the plant to power its data centers, reflecting growing energy demands from artificial intelligence and cloud computing operations.
"We've seen an increase in demand in energy with a lot of these tech companies," Marcheskie said2. The plant will generate 835 megawatts of electricity—enough to power all of Philadelphia's homes3.
Constellation plans to invest $1.6 billion in the project using its own financing rather than seeking government support24. An economic impact study estimates the restart will create 3,400 jobs and add $16 billion to Pennsylvania's GDP5.
Unit 1 shut down in 2019 for economic reasons and is separate from Unit 2, which suffered a partial meltdown on March 28, 197912. The 1979 accident released radioactive gases but resulted in no deaths or injuries, according to the Nuclear Regulatory Commission3.
Environmental groups including Three Mile Island Alert have raised concerns about the restart4. However, Marcheskie emphasized Unit 1's safety record, noting it "was one of the best-performing plants in the country" when it closed1.
The restart would make Three Mile Island the second U.S. nuclear plant to resume operations after economic shutdown, following Michigan's Palisades plant5.
