The Real Three Mile Island Disaster Was Shutting It Down

F or decades, “Three Mile Island” has been an argument against nuclear energy. That’s changing, thanks to a deal just struck between Microsoft and Constellation Energy to restart the operation of the Three Mile Island Unit 1 reactor. While the 1979 partial nuclear meltdown at the location still clouds public memory, the benefits of bringing the reactor back online — for local jobs, clean energy, and the economy — are sure to demonstrate that the biggest accident at Three Mile Island was our taking it offline.

Chernobyl, Fukushima, and Three Mile Island are some of the oft-cited examples against nuclear-energy projects, used by critics to invoke the thought of nuclear disaster and argue that the power source isn’t compatible with human life. But while Chernobyl is an extreme example of what a meltdown can look like without modern American safety controls and engineering standards, Fukushima and Three Mile Island prove that those standards and controls work, even in worst-case scenarios.

The safety of modern nuclear power, combined with the need for reliable, clean energy, is increasing its popularity. A majority of Americans now support nuclear power, and 88 percent of people who live right next to these plants have a high opinion of nuclear energy. Unlike older generations whose schoolyard memories include Cold War nuclear-bomb drills, younger Americans, many of them concerned about climate issues, have a different frame of reference. The numbers speak for themselves: According to a recent Wall Street Journal survey, four out of five first-time young voters support “new generation nuclear energy.”

Still, given general lingering hesitation around nuclear power, and the public memory of Three Mile Island specifically, private industry needed an economic incentive to lead the revival.

Though the public might be largely unaware, the site of America’s largest nuclear meltdown didn’t cease operations in 1979. It kept quietly operating until 2019, when Pennsylvania’s fracking boom made the cost of natural gas so cheap that it no longer made financial sense to keep producing nuclear power in the region.

However, changing market dynamics might spur a return to nuclear. Big Tech companies such as Microsoft have been meeting consumer demand for “emission-free” operations by offsetting their fossil-fuel use, which is necessary to keep data centers running reliably. Until recently, that is, when the AI boom began to change the economics of data-center operation. Historically, competition in the data-center space has centered on technical capabilities, namely cloud services’ availability, reliability, and flexibility. Now, because of the enormous amount of computing required by AI technologies, the name of the game is cheap and reliable power.

Enter nuclear. When it comes to reliability, nuclear energy’s capacity factor — measured as the percentage of time an energy source is producing maximum power — is the highest of any energy source we have. At 92 percent, it’s almost twice the capacity factor of natural gas and coal, and about triple that of solar or wind, thanks to its minimal maintenance and refueling downtime.

The agreement between Constellation and Microsoft is nothing short of historic — the first restart of its kind. Some speculate that it’s too early for celebration. Regulatory hurdles could threaten the plant’s permission to operate and perhaps even its financial viability. Still, the announcement sent Constellation Energy’s stocks soaring, as Microsoft agreed to purchase power from the plant for a contract period of two decades. Regulators and tech commentators are speculating that the partnership may be the first of many between Silicon Valley and nuclear-power companies.

America’s cold war against nuclear power may be slowly coming to an end. Public pushback is subsiding, and the business case is becoming impossible to ignore. For private industry and the planet alike, our peace treaty with nuclear energy would come not a moment too soon.