Microsoft signs historic nuclear power deal to fuel AI data centres
The owner of the infamous Three Mile Island nuclear plant in the US has announced a $1.6 billion plan to restart part of the operation to power a series of artificial intelligence (AI) data centres owned by Microsoft.
Constellation Energy expects the mothballed Unit 1 reactor in Pennsylvania will be reopened in 2028 after the company signed its largest-ever power purchase agreement with the global tech giant.
It is also believed to be the first time a single customer has agreed to buy a nuclear plant’s entire output.
Clean energy
The 20-year deal will allow for the restoration of Constellation’s pressurised water reactor to supply 835 megawatts of clean energy to power Microsoft’s AI business.
AI relies on data centres to fuel its technology, with each search entered into tools such as ChatGPT consuming about 10 times the energy of a standard browser search due to the number of calculations required.
Technology players such as OpenAI and Amazon Web Services are looking at nuclear power to meet forecast AI demand because of its relatively high and dependable output and the fact it is free of carbon emissions.
Facility refurbishment
Constellation purchased the Unit 1 reactor in 1999, producing enough electricity in the following years to power 800,000 homes for almost 24 months and offset more than 95 million tonnes of carbon (the equivalent of taking nearly 20 million cars off the road).
Despite operating at 96.3% capacity — considered above average at the time — the facility was closed in 2019 as new and existing nuclear plants struggled to compete with cheap natural gas and renewables.
The reactor is reported to be in “pretty good condition” prior to a planned refurbishment, with major equipment items such as the turbine, generator, main power transformer and cooling and control systems scheduled for replacement before it is connected to the local electricity grid.
The Microsoft power supply deal must be approved by the Nuclear Regulatory Commission, state officials and local authorities before Unit 1 can officially resume operations.
Meltdown incident
The Unit 1 reactor is adjacent to (but independent from) Three Mile Island’s Unit 2 reactor, where a combination of equipment failure and operator error caused part of the core to melt down in March 1979.
The accident released only a small amount of radioactive material into the atmosphere — thanks in most part to the reactor’s concrete containment structure — and did not cause any injuries or deaths.
The fuel was eventually cleaned up and removed along with the damaged reactor core debris and, in 1993, Unit 2 was placed in long-term, monitored storage to await decommissioning by owner Energy Solutions.
Widespread change
Three Mile Island became known as the site of the worst commercial nuclear power plant accident in US history.
It led to widespread changes in safety regulations for US nuclear plants and contributed to a sharp slowdown in approvals for new reactors in the late 1970s.
Constellation said the Unit 1 reactor would restart as a fully independent facility and its long-term operation would not be impacted by the Unit 2 accident.