Three Mile Island to be restarted to power Microsoft data centers

In a remarkable topical twofer, not only is Microsoft turning to nuclear power to run its data centers, it's commissioned the restarting of the infamous Three Mile Island station – the site of the worst commercial nuclear accident in US history.

This is one of those stories where it's hard to decide which angle to approach it from, so I flipped a coin and it came up Microsoft. One of the biggest trends in the tech field is how much big companies' data centers have been expanding as their internet services become more and more a part of our commercial and personal lives.

These power-hungry servers and databases were already becoming a drain on the electrical grid, but the explosion of AI has compounded the problem, with estimates of overall consumption of data centers in the United States reaching 35 GW by 2030, or almost twice of what it was in 2022.

That might not seem like much, considering that the US alone consumes 4,000 TW of electricity every year, but a lot of energy and environmental planning is based on estimated power consumption, with the expansion of data centers tossing the prediction figures right into the bin. Worse, the current policy in many parts of the developed world relies heavily on conversion to renewable sources like wind and solar, which are intermittent, while these data centers must run 24/7 without interruption.

To maintain reliable base power for these centers, the biggest tech companies are looking to nuclear power to provide them with electricity at near-zero carbon emissions. US companies like Amazon are locating new centers next to nuclear power stations and Sweden is considering installing modular reactors so tech consumers can get uninterrupted AI images of horses with too many legs or people shoving a pound of fries into their mouths all at once.

On the other hand, Microsoft has struck a 20-year deal with Constellation to draw power from what was once the Three Mile Island Nuclear Generating Station on the Susquehanna River in Londonderry Township, near Harrisburg, Pennsylvania and is now the Crane Clean Energy Center (CCEC).

On March 28, 1979, the reactor Three Mile Unit 2 suffered a core meltdown due to a strange combination of mechanical failure and human error that resulted in the reactor being severely damaged and radioactive water and iodine being released due to a failure of the pressurized water coolant system.

Though there were no casualties and long range studies were never able to confirm a causal rise in cancer cases in the area, Three Mile Island was the worst US commercial nuclear accident and arguably the third worst in the world after the later Chernobyl and Fukushima incidents. However, the impact of the disaster was swift. It brought the question of reactor safety to the fore and became the focus for environmentalists and anti-nuclear pressure groups. The result was the near-total paralysis of commercial nuclear power in the US and many European countries until very recently.

Contrary to popular belief, Three Mile Island wasn't completely shut down after the accident. The Unit 1 reactor continued operation until 2019 when it was decommissioned for economic reasons. Under the new Microsoft agreement, the restart will be the first ever for an American reactor after it has been shut down for good.

However, the restart of the 837-MW Unit 1 reactor won't be simply a matter of throwing a large and cinematic knife switch. According to Constellation, work will have to be done to refurbish the turbine, generator, main power transformer, and coolant and control systems. And then there's all the inevitable red tape with the US Nuclear Regulatory Commission as well as state and local officials.

"This agreement is a major milestone in Microsoft's efforts to help decarbonize the grid in support of our commitment to become carbon negative," said Bobby Hollis, VP of Energy, Microsoft. "Microsoft continues to collaborate with energy providers to develop carbon-free energy sources to help meet the grids' capacity and reliability needs."

Source: Constellation