The federal government is throwing its support behind one of the most dramatic nuclear comebacks in U.S. energy history. On Tuesday, the Department of Energy approved a $1 billion loan to Constellation Energy to restart the shuttered Three Mile Island Unit 1 reactor in Pennsylvania — a plant that ceased operations in 2019 and sits next to the site of the nation's most infamous nuclear accident.

Constellation, the country’s largest operator of nuclear plants, now plans to bring the unit — renamed the Crane Clean Energy Center — back online by 2027, helped in part by a long-term power purchase agreement with Microsoft to supply growing data-center demand in the region. The project’s total estimated cost is $1.6 billion.

The move marks one of the most consequential federal interventions in the nuclear sector in years and is poised to reshape the PJM Interconnection grid, which serves more than 65 million people across 13 states.

Federal Backing for a Nuclear Revival

Greg Beard, senior advisor to DOE’s Loan Programs Office, said Constellation likely could have financed the restart on its own — but the federal loan significantly lowers the cost of capital, helping reduce electricity costs for PJM customers.

“What’s important for the administration is to show support for affordable, reliable, secure energy in the U.S.,” Beard said. “This loan will make power cheaper for PJM ratepayers.”

The first disbursement is expected in early 2026.

The Crane Clean Energy Center is one of three shuttered nuclear reactors now moving toward a potential restart, part of a broader shift as nuclear gains new relevance amid soaring U.S. electricity demand driven by AI, electrification, and industrial reshoring. In Michigan, Holtec International is seeking a $1.5 billion DOE loan to bring the Palisades plant back online, while in Iowa, NextEra Energy has outlined plans to revive the Duane Arnold facility through a clean-energy supply agreement with Google that is currently under regulatory review. The push is also being shaped by federal direction: President Trump’s May 2025 executive orders instruct the Department of Energy to prioritize reactor restarts and accelerate new nuclear capacity—guidance that is increasingly reflected in the loan approvals emerging from the DOE’s Loan Programs Office.

Why Three Mile Island Matters Now

Three Mile Island Unit 1 supplied enough electricity to power 800,000+ homes before closing in 2019 amid market pressures from cheap natural gas. Its return comes at a moment when PJM faces some of the most severe load-growth projections in the country.

Electricity prices in multiple PJM states have climbed as AI data centers drive rapid, sustained demand that outpaces new generation and transmission.

Energy Secretary Chris Wright said last week that the administration plans to direct most of the DOE loan office’s available funds toward nuclear, citing the need for dispatchable, carbon-free baseload resources.

“We want to bring as much net addition of dispatchable, reliable electricity onto the grid as possible to stop the rise in electricity prices,” Wright said.

The restart of TMI Unit 1 symbolizes both a practical and symbolic shift: nuclear is no longer just a climate tool — it is increasingly treated as a reliability resource critical to keeping bills in check.

Microsoft’s Role — and the New Nuclear Customer Base

Constellation’s 2024 announcement of the restart came with a notable partner: Microsoft, which signed a long-term PPA to support the restart and secure carbon-free power for its AI and cloud infrastructure.

The deal signaled a new trend: hyperscalers turning to nuclear for round-the-clock power that satisfies both operational reliability and corporate climate goals. Microsoft has also pursued advanced nuclear solutions, including small modular reactor programs and next-gen nuclear partnerships.

The Crane restart showcases how tech-driven demand is reshaping the nuclear economics that once undercut older plants.

The Nuclear Regulatory Commission must still finalize approvals for restart operations — a process that will determine the exact 2027 timeline.

If successful, Crane will become a test case for whether restarting existing reactors can be faster, cheaper, and more scalable than building new ones. DOE officials say nuclear restarts offer cost advantages because they use existing sites, transmission interconnections, and previously licensed infrastructure.

For PJM customers, the stakes are high: continued load growth could otherwise mean more volatile wholesale markets and higher retail rates.