Few names in American energy carry more weight than Three Mile Island, the Pennsylvania site of the country’s worst commercial nuclear accident. Now one of its reactors, silent for years, is being brought back to life for a distinctly modern customer: the data centers that power a technology giant’s artificial-intelligence ambitions. The move turns a symbol of nuclear caution into a test case for whether decades-old plants can be summoned back to meet a demand no one anticipated when they first went dark.
Bringing Unit 1 back online
The reactor in question is Three Mile Island Unit 1, a plant that operated safely for decades and was retired for economic reasons rather than any fault, entirely separate from the Unit 2 reactor involved in the 1979 accident. Its owner, Constellation Energy, is now restarting it and has renamed the facility the Crane Clean Energy Center.
Reviving a mothballed reactor is a substantial undertaking. According to World Nuclear News, the revival is running ahead of its original schedule, with the plant targeted to return to the grid in 2027. Equipment must be inspected and refurbished, staff rehired and retrained, and regulators satisfied that the plant can operate safely, a process that spans years and requires significant investment before a single watt flows.
The 20-year deal with Microsoft
What makes the restart economically viable is a long-term buyer. Microsoft has signed a 20-year power purchase agreement to take the plant’s output, locking in a steady supply of electricity to feed its expanding fleet of data centers. As the American Nuclear Society detailed, that guaranteed demand is what gives Constellation the confidence to fund the return of a reactor that had been switched off.
Once running, the plant is expected to add roughly 835 megawatts of carbon-free electricity to the regional grid. A two-decade contract of that length is unusual, and it reflects how seriously large technology companies now treat securing reliable, low-emission power for the long haul.
Why AI is reaching for nuclear power
The arrangement is a vivid example of a wider trend, as the electricity appetite of AI computing pushes technology firms toward nuclear energy. Data centers run continuously and demand power that does not flicker with the weather, a profile that suits the steady output of a reactor far better than intermittent sources on their own. For companies pledging to cut emissions, nuclear also offers large amounts of carbon-free generation without the variability of wind or solar.
Reviving an existing plant carries a particular appeal over building anew. The site, the licenses, the transmission connections, and much of the equipment already exist, which can make a restart faster and cheaper than constructing a reactor from the ground up. Locking in a single large source also shields a technology company from the price swings and congestion that can afflict the open market, giving it a predictable cost for one of its biggest expenses over decades rather than years.
Support that smoothed the path
The project has drawn backing beyond its corporate partners. Federal financing support and an accelerated grid-interconnection review have helped clear obstacles that might otherwise have slowed the timeline, allowing the operator to move the restart earlier than first planned. Those forms of assistance underscore how policymakers and grid managers have come to view added firm capacity as valuable at a moment of rising demand.
A wider revival of American nuclear power
The restart is one of several signs that a long-dormant industry is stirring back to life. After decades in which plants closed and few new ones were built, rising electricity demand and climate goals have renewed interest in nuclear energy, from proposals for large conventional reactors to a wave of smaller modular designs still working toward approval. Reviving an already-built plant is the fastest route to new capacity, requiring far less time than starting from bare ground.
Constellation and its peers are betting that reliable, carbon-free power will command a premium as data centers, electrified transport, and manufacturing all draw more from the grid. Whether that bet pays off depends on costs staying manageable and on the plants performing as promised once they return, but the direction of travel marks a sharp reversal from the retirements that defined the recent past.
The legacy the name carries
Restarting a reactor at Three Mile Island inevitably stirs the memory of 1979, even though the unit being revived was untouched by that accident and compiled a strong operating record of its own. The renaming to the Crane Clean Energy Center is partly an effort to signal a new chapter. Whether the public embraces that framing or not, the plant’s return marks a striking reversal for an industry that spent years in retreat and now finds itself courted by the fastest-growing corner of the technology economy. Either way, the revived reactor stands as one of the clearest signs yet that the appetite of artificial intelligence is reshaping decisions in industries far removed from Silicon Valley, reaching all the way to the cooling towers of a river island in Pennsylvania.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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