Crane Clean Energy Center (TMI Unit 1 Restart)

Under construction in Londonderry Township, Dauphin County

Current stage

Restart targeted for 2027, with NRC inspections and licensing through 2026 and a FERC waiver granted to work around PJM transmission delays.

Decision body

Londonderry Township

Top issues

Residents and officials have focused on the size of the electrical load and what it does to regional capacity costs, what remains in the ground from the site's industrial past, water use, continuous mechanical noise, and emissions from backup generation.

Restart of TMI Unit 1; Microsoft 20-yr PPA covers full output (~7M MWh/yr). $1B DOE loan (Nov 2025). NRC license extended to 2054. PJM transmission upgrades may not finish until 2030/31. $16B PA GDP impact (Brattle); 65% staffed Dec 2025. Constellation announced a 20-year power purchase agreement with Microsoft on September 20, 2024 to restart Three Mile Island Unit 1 as the Crane Clean Energy Center, named for former Exelon chief executive Chris Crane. Unit 1 is a separate reactor from Unit 2, which partially melted down in 1979 and is still being decommissioned by EnergySolutions. The restart returns about 835 MW to the grid, and Constellation cites roughly 600 jobs and has sought license renewal to at least 2054. Constellation moved the target from 2028 to 2027. NRC staff determined a full environmental impact statement was not required and a less intensive environmental assessment sufficed, with the draft published in June 2026 and comment closing July 8. PJM transmission upgrades needed for the restart could run to 2030 or 2031, so Constellation asked FERC to transfer capacity interconnection rights from the retired Eddystone plant, and FERC granted a waiver in June 2026. About 90 plant operators are in NRC licensing and fuel delivery was set for late 2026. Gov. Shapiro has backed the restart since 2023. The power goes to the grid rather than to a dedicated on-site campus, with Microsoft matching its PJM data center consumption.

• 2024-09-20Constellation-Microsoft TMI/Crane 20-yr PPA announced Constellation Energy
• 2025-11-18DOE $1B loan to Constellation for Crane Clean Energy Center
• 2026-01-13NRC Crane license amendment (Constellation rename) NRC
• 2026-03-31Constellation files CIR-transfer waiver at FERC NRC

• 2026-01-13
  NRC license amendment NRC · (NRC)

  Crane license amendment for site rename (TMI Unit 1 → Crane Clean Energy Center).

  Constellation · Issued
• 2026-03-31
  FERC waiver FERC · (2026 filing)

  Capacity Interconnection Rights transfer waiver request.

  Constellation · Pending

• 2026-08 Pennsylvania Capital-StarConcern persists as former Three Mile Island nuclear plant progresses toward 2027 restartEnvironmental assessment instead of full EIS; emergency planning questions
• 2026-02-17 Pennsylvania Capital-StarMicrosoft describes Three Mile Island plant as a once-in-a-lifetime opportunity$1.6B deal framing; local political support
• 2025-08-01 Pennsylvania Capital-StarFederal regulators hear from the community about planned Three Mile Island restartNRC community hearing; building trades support, 600 jobs cited
• 2024-09-20 Constellation EnergyConstellation to Launch Crane Clean Energy Center, Restoring Jobs and Carbon-Free Power to The Grid20-year Microsoft PPA announced; restart of TMI Unit 1
• 2024-09 Data Center DynamicsThree Mile Island nuclear power plant to return as Microsoft signs 20-year, 835MW AI data center PPA835 MW dedicated to data center load; license renewal sought to 2054