TL;DR · 30-second read

The Short Version

Three American nuclear power plants that shut down between 2019 and 2022 are being brought back as computer centers running artificial intelligence push up electricity demand. One sits at Pennsylvania’s Three Mile Island, beside the reactor that partly melted down in 1979.

Microsoft and Google have signed 20- and 25-year deals to buy power from two of them. Together the three could supply about two million homes and businesses.

Reviving old plants is quicker than building new ones because the power lines already exist. But none is running yet: repairs, refueling and the federal safety regulator decide when they switch on.

Three retired US nuclear plants are being prepared to return to service, which would restore a combined 2.25 gigawatts (GW) of generating capacity. eeNews Europe reported on October 24, citing the Associated Press, that the US Department of Energy is providing up to $4.4 billion in loans across the projects, which together could supply roughly two million homes and businesses.

The projects are Holtec International’s 800 MW Palisades plant in Michigan, targeting a return around March 2027; Constellation Energy’s 835 MW Crane Clean Energy Center, formerly Three Mile Island Unit 1, in Pennsylvania, targeting 2027 and backed by a 20-year Microsoft power purchase agreement; and NextEra Energy’s 615 MW Duane Arnold Energy Center in Iowa, expected back in the first quarter of 2029 under a 25-year agreement with Google.

Executive Summary

Two of the largest technology buyers of electricity have now tied long-term contracts to reactors that were shut down for economic reasons only a few years ago. Microsoft has a 20-year agreement covering Crane, Google a 25-year agreement covering Duane Arnold, and federal lending of up to $4.4 billion sits underneath the three restarts. Constellation alone is spending about $1.6 billion on Crane, supported by a $1 billion government loan; NextEra has secured up to $1.9 billion in federal loans for Duane Arnold.

The significance for data center planning is where the remaining risk now lives. A new power plant typically spends years waiting for a grid connection. These three sites already have one, along with cooling systems and turbine equipment. What stands between them and electricity on the wires is inspection, repair, refueling and approval from the US Nuclear Regulatory Commission (NRC), the federal safety regulator. Palisades, the most advanced of the three, has already slipped on fuel-handling work, which is a useful preview of how these schedules will move.

The Grid Hookup Is Already Built. The Clock Is NRC and Fuel.

Grid-connection delays have become one of the main obstacles to data center expansion. Any new generator, whether a gas plant, a solar farm or a new reactor, normally has to enter an interconnection queue, the line of projects waiting for grid operators to study and approve their connection to the transmission network. A retired reactor does not start at the back of that line. Palisades, Crane and Duane Arnold already have grid connections, cooling systems and turbine equipment in place, which removes the step that often governs schedules for new power plants.

That shifts the critical path, the sequence of tasks that sets the earliest possible finish date, onto work inside the fence: inspections, repairs of ageing equipment, loading fresh nuclear fuel and securing NRC approval. Palisades shows what that looks like in practice. The 800 MW pressurised water reactor entered its refuelling phase in August 2026, fuel-handling work then ran into delays, and Holtec is now targeting a return to generation around March 2027. The most advanced restart in the country slipped on plant work, not on the grid.

For anyone counting these 2.25 GW in their plans, including Microsoft, Google and grid planners in Michigan, Pennsylvania and Iowa, the milestones that matter are NRC sign-offs, fuel-load dates and first power, not funding or contract announcements. A restart should be tracked like a regulatory and maintenance programme, because that is where its schedule risk now sits.

Faster Than New Nuclear, Still Measured in Years

Restarts are quicker than building reactors from scratch, and they are nearer-term than small modular reactors (SMRs), the smaller factory-style designs technology companies are also funding, most of which remain several years from commercial operation. But fast is relative. Duane Arnold closed in 2020 and is not expected back until the first quarter of 2029. Crane was retired in 2019 and is targeting 2027.

The 2.25 GW therefore arrives in stages over roughly two years rather than as a single block, and each unit, between 615 MW and 835 MW, is sized to the hundreds of megawatts of continuous supply that large technology companies now seek. Buyers planning AI capacity around these plants have to plan around three separate dates, each subject to its own technical work and regulatory approval.

Long Contracts and Federal Loans Rewrote the Economics

All three plants were retired when their operating economics became less favourable. What changed is the buyer. A power purchase agreement (PPA) is a long-term contract to buy a specific plant’s output, and 20- and 25-year commitments from Microsoft and Google give the owners revenue visibility that the wholesale market alone did not. Federal lending adds a second layer: $1 billion toward Crane and up to $1.9 billion for Duane Arnold, within the up-to-$4.4 billion total.

Contracts and loans reduce revenue and financing risk; they do not remove technical risk. Questions about ageing equipment, refurbishment costs and the use of public financing continue to accompany the projects, and those questions are fair ones that will only be settled once the units are generating. The claim that restarts are a quicker route to carbon-free power is well supported by the reuse of existing infrastructure. The claim that they will hit their dates is not yet proven by any of the three.

A Firm Megawatt Is a Different Product

NextEra’s third-quarter results, released October 21 and furnished to the SEC with an 8-K, show the scale of its other pipeline: the company added 3.7 GW of renewables and storage to its backlog in the quarter, bringing that backlog to about 36.7 GW. By nameplate, Duane Arnold’s 615 MW is less than 2% of that figure.

Nameplate understates the difference. A nuclear unit is designed to run around the clock, which matches the continuous load of a data center in a way that weather-dependent generation does not without storage. That is the product Google is buying for 25 years, and it explains why a single mid-sized reactor commands a contract longer than many renewable deals.

Background

The United States retired a number of nuclear reactors in the late 2010s and early 2020s as their operating economics deteriorated; Crane (Three Mile Island Unit 1) closed in 2019, Duane Arnold in 2020 and Palisades in 2022. Since then, electricity demand from data centers, driven heavily by AI computing, has grown to the point where large technology companies seek continuous supplies measured in hundreds of megawatts, and grid connections for new generation have become a significant bottleneck.

Constellation Energy is the largest operator of US nuclear plants; Holtec International is a nuclear equipment and decommissioning company that acquired Palisades after its closure; NextEra Energy is a Florida-based utility holding company that owns Florida Power & Light and NextEra Energy Resources, and is pursuing a combination with Dominion Energy that its shareholders approved in September 2026.

Sources

Source: Nuclear restarts: Holtec, Constellation, NextEra plan 2.25 GW (eeNews Europe), on three US reactor restarts, their offtake contracts and federal loan support.

Primary sources: NextEra Energy Form 10-Q for the quarter ended September 30, 2026 (filed October 21, 2026); NextEra Energy Form 8-K (filed October 21, 2026); NextEra Energy reports third-quarter 2026 financial results (Exhibit 99 to Form 8-K).