The Crane Clean Energy Center has advanced through a key regulatory milestone as Constellation Energy prepares to restart its 835 MW nuclear reactor in Pennsylvania. In September 2026, the US Nuclear Regulatory Commission completed its environmental assessment and issued a finding of no significant impact for the proposed restart.
The decision advances the review of federal actions needed to restore power operations at the former Three Mile Island Unit 1 facility. However, Constellation must still satisfy applicable licensing requirements and complete the work needed to return the reactor to service. The company continues to target a 2027 restart, supported by a $1 billion federal loan and a 20-year power purchase agreement with Microsoft.
Crane Clean Energy Center Project Advances Through Regulatory Review
The US Department of Energy closed the $1 billion loan to Constellation Energy Generation in November 2025. The financing supports the restart of the 835 MW reactor in Londonderry Township, Pennsylvania.
The reactor stopped commercial operations in September 2019 but did not complete full decommissioning. Therefore, the project focuses on restoring existing nuclear infrastructure rather than constructing an entirely new power station.
The Nuclear Regulatory Commission continues to oversee the process of returning the facility to operational status. Its responsibilities include reviewing licensing applications, inspecting restored components and verifying that safety requirements support renewed operation.
In September 2026, the regulator completed its environmental assessment and issued a finding of no significant impact. This milestone addresses environmental effects associated with the proposed federal actions. However, it does not itself constitute final authorisation to restart the reactor.
Crane Clean Energy Center Restart Targets 835 MW of Capacity
Constellation plans to restore 835 MW of nuclear generating capacity to the PJM Interconnection electricity market. The plant would provide dependable, low-carbon electricity to homes, businesses and energy-intensive data centers.
The company signed a 20-year power purchase agreement with Microsoft in September 2024. Under the agreement, Microsoft will purchase electricity from the restarted facility to support its data centres.
However, the restart faces technical and grid-connection challenges. In April 2026, Reuters reported that delays to transmission projects could threaten the planned schedule. Constellation sought regulatory relief to accelerate the plant’s connection to the grid.
Despite these challenges, Constellation continues to target a 2027 return to service. The company says the restart remains on schedule, while the NRC maintains oversight of the necessary licensing and inspection work.
The project also reflects a wider push to restore existing nuclear facilities as electricity demand rises. Similar investment in specialized nuclear infrastructure supports the US military’s propulsion program. The $2.4 billion Naval Nuclear Propulsion Project contract awarded to Fluor Marine Propulsion supports laboratory operations, engineering and technology for the Navy’s nuclear-powered fleet. These projects serve different purposes, but both demonstrate the strategic importance of maintaining complex nuclear infrastructure.
The Crane restart could support hundreds of permanent plant jobs and broader economic activity across Pennsylvania. Constellation also expects the project to contribute to regional tax revenues and strengthen electricity supply. Nevertheless, the 2027 target depends on regulatory approvals, successful restoration work and readiness of the grid connection.
Project Timeline
September 2024: Constellation signs 20-year PPA with Microsoft, announces restart plan.
January 2025: License amendment request submitted to NRC to rename plant and approve restart.
March 2025: Constellation proposes use of 2013 ASME Boiler and Pressure Vessel Code Section XI for inspections.
August 2025: DOE issues final EIS for the restart project.
November 2025: DOE closes US$ 1 billion loan for the Crane Clean Energy Center.
2027: Constellation targets to bring Three Mile Island Unit 1 back online.
Project Overview
Crane Clean Energy Center revival is a landmark project for the U.S. nuclear energy sector as much as it is for Constellation. If Constellation meets its set timeline and regulatory standards, CCEC will not only supply reliable nuclear energy to the grid and but also “help America win the AI race” as put by the developer.
Outlook on Crane Clean Energy Center Revival (formerly Three Mile Island Unit 1)
Also noteworthy is that the restart is not a fresh build. This brings in the possibility of significant technical risk associated with refurbishing old systems and ensuring safety standards. There is also the aspect of reputational risk as Three Mile Island was at the center of a 1979 nuclear accident which drew a lot public scrutiny. Additionally, if demand from Microsoft or other possible offtakers shifts, the long-term financial structure could be exposed. And even with a US$1billion loan, which is substantial, it may not cover all cost overruns, especially if unexpected retrofit issues emerge.
Nonetheless, the project creates a sizable employment impact and will significantly contribute to Pennsylvania’s local tax bases. If all goes as planned, the revival of Three Mile Island Unit 1 by Constellation as Crane Clean Energy Center by 2027 will be one of the pivotal shifter of Pennsylvania’s and the U.S.’s green energy and economic transitions.
Project Fact Sheet
Name: Christopher M. Crane Clean Energy Center, formerly Three Mile Island Unit 1.
Type: Existing nuclear power plant restart and infrastructure restoration.
Location: Londonderry Township, Pennsylvania, United States.
Project value: $1 billion federal loan supporting restart activities.
Generating capacity: 835 MW.
Original shutdown: September 2019.
Financing milestone: US Department of Energy closed the loan in November 2025.
Latest regulatory milestone: NRC environmental assessment and finding of no significant impact issued in September 2026.
Target restart: 2027, subject to required approvals and technical readiness.
Power purchaser: Microsoft, under a 20-year power purchase agreement.
Grid connection: PJM Interconnection.
Construction scope: Refurbishment, restoration and upgrades to existing plant systems; not a new-build nuclear power station.
Employment impact: Approximately 627 permanent US jobs supported, according to the Department of Energy.
Long-term objective: Constellation plans to seek an operating licence extension through 2054.
PPA: 20-year contract with Microsoft for data center power supply. Constellation is also the power marketer for Microsoft-backed Orion Nuclear Fusion Power Plant in Washington expecting completion in 2028.
Project Team
Owner and operator: Constellation Energy Generation LLC.
Federal financing authority: US Department of Energy, Office of Energy Dominance Financing.
Nuclear licensing and safety regulator: US Nuclear Regulatory Commission.
Electricity purchaser: Microsoft.
Regional grid operator: PJM Interconnection.
Plant restoration and restart: Constellation Energy’s engineering, operations and maintenance teams.
Regulatory inspections: US Nuclear Regulatory Commission staff.
Federal environmental review: US Nuclear Regulatory Commission, with the Department of Energy’s Office of Energy Dominance Financing as cooperating agency.
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