Constellation Energy signed a 20-year power purchase agreement with Microsoft in September 2024 to supply electricity from a restarted nuclear reactor at the former Three Mile Island site in Pennsylvania. The deal centers on Unit 1, which shut down on Sept. 26, 2019, and is now being renamed the Christopher M. Crane Clean Energy Center. With an 835-megawatt capacity and a $1.6 billion estimated restart cost backed by a $1 billion federal loan, the project represents the first serious attempt to bring a decommissioned U.S. commercial reactor back online specifically to feed power-hungry data centers.
Why a data-center power deal is reshaping nuclear restart timelines
The core tension behind this project is not whether Microsoft wants the power or whether Constellation can rebuild the plant. It is which layer of government approval will actually set the pace. The U.S. Department of Energy closed a $1 billion loan to Constellation Energy Generation, LLC in November 2025, but that financing is explicitly conditional on Nuclear Regulatory Commission (NRC) licensing approvals. At the same time, the Pennsylvania Department of Environmental Protection is tracking state-level permits for the refurbishment and restart activities at the Crane Clean Energy Center.
The hypothesis that state permit timelines at PA DEP will control the schedule more than the conditional federal loan or NRC exemption process has real weight. Federal milestones, including the NRC’s review of Constellation’s exemption request from decommissioning rules under 10 CFR 50.82, are proceeding through a formal docket. But state environmental and construction permits often carry their own review clocks, public comment windows, and appeal risks that can stall physical work on the ground even after federal regulators clear a path. Until PA DEP issues its permits, Constellation cannot begin certain site activities regardless of what Washington approves. Comparing the dates of state permit issuances against federal approval milestones over the coming months will reveal which track is actually the bottleneck.
For Microsoft, the timing question is not academic. Its data-center buildout assumes a steady stream of carbon-free baseload power that can anchor artificial intelligence workloads and cloud services for decades. If state-level permitting slows physical refurbishment, Microsoft could face a longer-than-expected gap between signing the PPA and receiving the contracted electricity. That risk is partly mitigated by Constellation’s broader nuclear fleet, but the Crane project is marketed as a flagship example of repurposing an existing nuclear site for digital infrastructure, so any visible delay would carry symbolic weight.
Federal filings and state records behind the Crane Clean Energy Center restart
The regulatory paper trail is already substantial. Constellation presented its restart plan and facility renaming proposal at a hybrid public meeting held on Oct. 25, 2024, the earliest formal regulator-facing session on record for this effort. That meeting, organized by the NRC, included a slide deck and notice filed through the agency’s ADAMS document system, though published transcripts or detailed attendee comment summaries have not appeared in publicly available dockets.
Separately, Constellation filed a formal request for exemption from certain license termination requirements under 10 CFR 50.82, a necessary legal step to reverse the decommissioning process that began after Unit 1’s 2019 shutdown. The NRC’s own dossier for the renamed plant confirms that a Restart Panel has been established to oversee the approval process and that multiple licensing actions are under review.
Those licensing actions are summarized in the NRC’s dedicated reactor information page for the Crane Clean Energy Center, which lists pending reviews but, as of the latest updates, provides limited narrative detail on their status. Each action is tied to an accession number in ADAMS, allowing interested parties to track filings but not necessarily to infer the likely timing of final decisions.
On the financial side, DOE’s project-level fact sheet lists the loan’s purpose as supporting 835 MW of baseload power for data centers, equivalent to electricity for roughly 800,000 homes. The Associated Press reported Constellation’s stated total restart cost at $1.6 billion, meaning the federal loan covers roughly two-thirds of the projected expense. The 20-year PPA with Microsoft, referenced by the Pennsylvania DEP’s project overview page, provides the revenue certainty that makes the economics work for Constellation, though the specific pricing terms of that agreement have not been disclosed in any primary filing or ADAMS record reviewed to date.
DOE’s environmental review for the loan decision relies on a 2009 NRC Final Supplemental Environmental Impact Statement, republished as the DOE Final EIS in August 2025. That approach, reusing a study completed more than 15 years before the loan closed, could draw scrutiny from environmental groups or intervenors who argue conditions at the site or in the surrounding community have changed. Issues such as climate-related flood risk, demographic shifts in nearby populations, and cumulative industrial activity in the region are all areas where critics may contend that a fresh analysis is warranted.
Open questions that will shape the Crane restart schedule
Several material gaps remain in the public record. The full terms of the Microsoft PPA, including the per-megawatt-hour price and any performance guarantees, are referenced by both PA DEP and DOE but have not been released in primary filings. Without those details, outside analysts cannot independently assess whether the deal gives Constellation enough margin to absorb cost overruns, a chronic risk in nuclear construction and refurbishment projects.
The current status of specific NRC licensing actions listed in the Crane Clean Energy Center docket is limited to accession numbers without final decisions posted. That means the public can see that reviews are underway but cannot yet determine how close any individual approval is to completion. The NRC has not published a projected timeline for ruling on the exemption request or other pending licensing actions, leaving stakeholders to infer progress from sporadic document uploads rather than from a consolidated schedule.
Cost transparency is also thin. Beyond the $1.6 billion figure reported by the Associated Press, no fresh breakdown from Constellation or DOE ties specific cost categories to the schedule risk. Key questions include how much of the budget is allocated to replacing or upgrading major components, what contingency is reserved for unexpected equipment degradation discovered during inspections, and how inflation or supply chain pressures since 2019 have been factored into estimates. Without that granularity, it is difficult to judge whether the loan and PPA revenues can comfortably cover both baseline costs and plausible overruns.
Another uncertainty is how quickly Constellation can rebuild and retain a specialized workforce for a plant that has been in decommissioning status for several years. Restarting a nuclear unit requires not only physical refurbishment but also extensive training, procedure updates, and demonstration of operational readiness to NRC inspectors. If hiring and training lag behind construction milestones, human-capital constraints could become an unexpected pacing factor.
Community engagement may also influence timing. The October 2024 NRC meeting marked an initial opportunity for public input, but as state permits move forward, PA DEP will run its own comment periods and potentially additional hearings. Local concerns could range from traffic and construction impacts to broader questions about long-term waste management and emergency preparedness. While such processes do not automatically delay projects, substantive objections or organized opposition can trigger extended reviews or legal challenges.
Finally, the broader policy context is in flux. Federal and state decarbonization goals, evolving grid reliability standards, and the rapid growth of data-center demand all create political pressure to deliver low-carbon baseload capacity quickly. That pressure may encourage regulators to prioritize the Crane docket, but it could just as easily invite closer scrutiny from opponents who view the project as a test case for nuclear restarts nationwide. How agencies balance speed with procedural rigor will set a precedent for any future attempts to revive retired reactors for digital-era power needs.
For now, the Crane Clean Energy Center stands at the intersection of three powerful trends: the search for firm, carbon-free electricity; the explosive growth of data-center loads; and the reimagining of legacy nuclear assets. Whether it becomes a model for similar projects or a cautionary tale about regulatory and financial complexity will depend on how the next few years of permitting, licensing, and construction unfold-and on which layer of government ultimately controls the clock.
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*This article was researched with the help of AI, with human editors creating the final content.
