Three Mile Island nuclear reactor restarts to power Microsoft AI operations | Nuclear power

The notorious Three Mile Island nuclear reactor in the US state of Pennsylvania is set to restart operations for the first time in five years after its owner, Constellation Energy, signed a contract to power Microsoft's growing artificial intelligence activities.

In March 1979, the plant experienced the worst nuclear meltdown and largest radiation leak in U.S. history when the loss of water coolant through a faulty valve caused reactor unit 2 to overheat. More than four decades later, the reactor is still in the decommissioning phase.

Constellation closed the adjacent but unconnected Unit 1 reactor in 2019 for economic reasons but will restart it after signing a 20-year power purchase agreement to supply Microsoft's energy-hungry data centers, the company announced Friday.

The restart – the first time a nuclear reactor in the U.S. has been shut down – will add an additional 835 megawatts of power to Pennsylvania's power grid, create 3,400 jobs and contribute at least $16 billion to the state's economy, Constellation said.

As part of the agreement, Three Mile Island will also be renamed the Crane Clean Energy Center to honor Chris Crane, the former chief executive of Constellation's parent company.

“Before its premature closure for economic reasons, this plant was one of the safest and most reliable nuclear power plants on the grid and we look forward to bringing it back online under a new name and with a renewed mission,” said Joe Dominguez, President and current CEO of Constellation.

Restoring the power plant will require significant investments, including replacing or overhauling the turbine, generator, main transformer, and cooling and control systems, Dominguez said.

In addition, the U.S. Nuclear Regulatory Commission will conduct a comprehensive safety and environmental review before granting approval to restart the reactor, which is scheduled to come online sometime in 2028. Constellation announced that it would seek licenses that would extend the plant's operation until at least 2054.

Technology giants like Microsoft, Google, Amazon, Meta and Apple are consuming more and more energy to fuel the artificial intelligence boom. According to Goldman Sachs, demand will increase by 160 percent by 2030. By then, data centers are expected to provide 8 percent of the electricity generated in the United States.

But as demand surges, so do concerns about environmental impact. An analysis by the Guardian published this week found that emissions from the data centers of four of the biggest tech companies – Google, Microsoft, Meta and Apple – are likely about 662% – or 7.62 times – higher than officially stated.