Three Mile Island Unit 1 Is Coming Back Online To Power Microsoft’s AI Needs

Putting TMI Into AI

If you are old enough to get most of the jokes and references made on the PCPer Podcast, you probably also have bad memories of Three Mile Island.  A partial meltdown in 1979 at TMI-2 spread a not insignificant amount of radiation across Pennsylvania, thankfully not enough to have serious health impacts on the neighbouring residents but enough to spark fears about the safety of nuclear power.  It’s core has long since been removed, but the full decommissioning hasn’t yet completed and is not likely to be finished until around 2050 or so.

Three Mile Island Unit 1 has never suffered similar issues, it was shut down September 20, 2019 as it had been operating at a loss for many years.  The full decommissioning would not have completed before 2079ish and would have come at a cost of ~1.2 billion, but thanks to Microsoft this is not to be.  They have promised Constellation Energy, the owner of TMI-1, that they will purchase 100% of the next two decades power output of the nuclear reactor and so Constellation will invest $1.6 billion into bringing the site back online.

This is both good and bad, with the bad being that the reactor was built in the late 60s.  As you might imagine the safety and efficiency of nuclear reactors has seen huge improvements over the last six decades and so TMI-1 won’t be able to benefit from the new designs.  That is not to say there are not ways to improve the operations of even older reactors, nor that the design is inherently unsafe; merely that a brand new reactor would be a better choice.

The good side is a huge amount of carbon neutral energy will be available to Microsoft to power their AI applications, which is a major win.  One of the sane reasons to oppose the rapid growth of machine learning and LLMs, aka AI, is the huge amount of energy the hardware it runs on consumes and the pollution that is created because of it.  Nuclear power is very clean and so a brilliant way to avoid the negative impacts the care and feeding of vast farms of NVIDIA hardware cause.   The use of a reactor which already exists and was running until recently is you can avoid the inevitable outcry of anti-nuclear protesters and their NIMBY backers.

Like it or not, AI will be around for at least a bit as the bubble continues to expand, so any way of reducing the environmental impact of the vulture capitalists encouraging it’s growth is a good thing.