The cooling towers still loom over the Susquehanna River like concrete ghosts. If you drive past Middletown, Pennsylvania, you can’t miss them. For decades, they stood as the ultimate symbol of "what could go wrong." Most people figured they’d just sit there forever, slowly crumbling into the landscape of the Rust Belt. But things change fast. Suddenly, everyone is talking about Three Mile Island today because the world’s thirst for electricity—specifically the kind of electricity needed to power Artificial Intelligence—has reached a fever pitch.
It’s kind of wild when you think about it.
In September 2024, Constellation Energy dropped a bombshell. They reached a deal with Microsoft to restart Unit 1. No, not the reactor that melted down in 1979 (Unit 2 is still being decommissioned and will never run again). We’re talking about its sibling. Unit 1 ran safely for decades before it was shut down in 2019 because it couldn’t compete with cheap natural gas. Now, thanks to the AI boom, it’s worth billions again.
The Massive Rebrand: Welcome to the Crane Clean Energy Center
They aren't even calling it Three Mile Island anymore. Well, officially, anyway. Constellation is rebranding the site as the Crane Clean Energy Center, named after Chris Crane, the former CEO of Exelon. It's a savvy PR move. They want to decouple the site from the 1979 accident and align it with the future of "green" tech.
Microsoft needs power. Lots of it.
The tech giant has committed to a 20-year power purchase agreement. This isn't just a small pilot project. We are looking at 835 megawatts of carbon-free energy. To put that in perspective, that’s enough to power roughly 800,000 homes. But these electrons won't be lighting up kitchens in Harrisburg; they’ll be feeding the massive, heat-spewing servers that make ChatGPT and Copilot function.
Honestly, the economics of Three Mile Island today are a complete reversal of where we were five years ago. Back then, nuclear was "too expensive." Now, because it provides steady, 24/7 "baseload" power without emitting carbon, it's the only thing that can satisfy the ESG goals of a company like Microsoft while keeping the lights on in their data centers.
What’s Actually Happening on the Island Right Now?
If you visited the site this afternoon, you wouldn’t see a humming power plant. You'd see a construction zone. Restarting a nuclear reactor that has been dormant for half a decade is not like flipping a light switch.
- The Turbine Overhaul: The main turbine—the massive piece of machinery that actually generates the electricity—needs a total refurbishment.
- The Cooling Systems: Engineers are inspecting miles of pipes and massive pumps to ensure they haven't corroded or seized up.
- Staffing Up: Constellation needs to hire about 600 high-skilled workers. You can't just hire a general contractor for this. You need federally licensed nuclear operators.
- NRC Hurdles: The Nuclear Regulatory Commission (NRC) is the ultimate gatekeeper. They have to approve the restart, which involves a grueling safety review.
It is a monumental task. No retired nuclear plant in the U.S. has ever been brought back to life like this. There is no blueprint.
The Unit 2 Shadow
We have to talk about the "other" reactor. Unit 2 is the one that suffered a partial meltdown on March 28, 1979. It’s a dead husk. A company called TMI-2 Solutions is currently in the middle of a decades-long decommissioning process. They are literally cutting up the reactor vessel and hauling away radioactive debris.
It’s a weird contrast. On one side of the island, you have workers trying to revive a giant. On the other, you have teams in hazmat suits slowly tearing another giant apart. It perfectly captures the split personality of the American nuclear industry.
Why This Matters for Your Electric Bill
You might think a private deal between Microsoft and a power company wouldn't affect the average person in Pennsylvania. That’s not quite how the grid works. PJM Interconnection, the organization that manages the power grid for 13 states, is facing a looming supply crunch.
They’ve warned that as coal plants retire and data centers proliferate, we might not have enough "always-on" power. By bringing Three Mile Island today back online, it adds a massive chunk of reliability back to the regional grid. It prevents the kind of volatility that leads to price spikes during winter storms or summer heatwaves.
However, it’s not all sunshine and rainbows. Critics, like those at the Three Mile Island Alert (TMIA) group, argue that the subsidies and tax breaks required to make this happen are a "bailout" for an old industry. They worry about the long-term storage of spent nuclear fuel, which is still sitting on the island in dry casks because the U.S. has no national repository.
The Technical Reality: Can They Really Pull This Off?
Safety is the elephant in the room. When Unit 1 shut down in 2019, it was actually one of the best-performing plants in the country. It had high "capacity factors," meaning it rarely went offline for repairs.
But metal fatigues. Seals dry out.
The restart requires a massive capital investment—estimated at around $1.6 billion. Constellation is betting that the federal production tax credits (PTCs) in the Inflation Reduction Act will bridge the gap. Without that government backing, Microsoft’s deep pockets wouldn't be enough.
Local Impact: The Economic Shot in the Arm
For the people of Londonderry Township and Middletown, the restart is basically a winning lottery ticket. When the plant closed, the local tax base took a massive hit. The school districts felt it. The local restaurants felt it.
- Jobs: 600 permanent jobs with average salaries well over $100k.
- Tax Revenue: Millions in local property taxes.
- Secondary Spending: Thousands of contractors coming in for the multi-year renovation.
It's a "save our town" narrative that you don't often see in the energy sector anymore.
Moving Past the 1979 Trauma
For people of a certain age, "Three Mile Island" is a trigger word. It reminds them of Jane Fonda in The China Syndrome and the terrifying uncertainty of those few days in March '79.
But the younger generation? The Gen Z engineers and tech workers? They see it differently. To them, nuclear is a tool to fight climate change. They look at the data—which shows that nuclear has one of the lowest mortality rates per terawatt-hour produced—and they wonder why we ever stopped building these things.
The story of Three Mile Island today is really the story of how our fears are being eclipsed by our needs. We need the data. We need the carbon reduction. We need the power.
Actionable Insights for Following the Restart
If you’re watching this story unfold, don't just wait for the headlines. There are specific milestones that will tell you if the project is on track or hitting a wall.
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- Watch the NRC Docket: The Nuclear Regulatory Commission's public filings will show the "Confirmatory Action Letter" process. If the NRC starts asking for major structural changes to the steam generators, the 2028 target date might slip.
- Monitor PJM Capacity Auctions: These auctions determine the price of power in the region. If prices remain high, it reinforces the business case for TMI.
- Follow the Labor Market: Look for hiring fairs in the Harrisburg area. If Constellation struggles to find qualified nuclear engineers, the restart could be delayed.
- Check Local Environmental Reports: The Pennsylvania Department of Environmental Protection (DEP) monitors the river water and air quality around the site. These reports are public and provide a ground-truth look at the plant's impact.
The planned restart in 2028 will be a watershed moment for the American energy landscape. If it succeeds, expect to see other shuttered plants—like the Duane Arnold plant in Iowa—get a second look from big tech companies. Three Mile Island is no longer just a monument to a mistake; it’s the test case for the next fifty years of American power.