Artificial intelligence has sent demand for electricity skyrocketing in the U.S. after years of virtually zero growth. That has sent Big Tech companies scrambling to secure generating capacity for their data centers.
For many, that has meant turning to nuclear fission. The power source has been experiencing a resurgence in the last few years following decades of plant closures. (Fission, used in all current nuclear plants, is distinct from fusion, the still-experimental approach to getting power from atoms that, while attracting investors, has yet to produce more electricity than it consumes.)
For tech companies, part of the appeal of fission is a stable, predictable source of power that flows 24/7, giving their data centers the potential to run computing loads whenever they require it.
But another part of the appeal lies in new reactor designs that promise to overcome the shortcomings of existing nuclear power plants. Where old power plants were built around massive reactors that could generate over 1 gigawatt of electricity, new small modular reactor (SMR) designs see multiple modules deployed alongside each other to meet a range of needs.
SMRs rely on mass manufacturing to bring costs down, but to date, no one has built one in the U.S. Still, that hasn’t kept Amazon, Google, Meta, and Microsoft away from the table. They’ve either signed agreements to buy power from nuclear startups or invested in them directly — or both.
Here are the nuclear fission startups backed by Big Tech.
Kairos Power received a vote of confidence from Google when the search giant promised to buy around 500 megawatts of electricity by 2035, with the first reactor targeted to come online by 2030.
The company’s small modular reactors rely on molten fluoride salt for cooling and to transport heat to a steam turbine. The salt’s high boiling point means that the coolant doesn’t need to be kept at high pressure, which should improve operating safety. The reactors contain fuel pebbles coated in carbon and ceramic shells, which should be strong enough to withstand a meltdown.
The Alameda-based startup has received a $629 million award from the U.S. government, including $303 million from the Department of Energy. In November 2024, Kairos received approval from the U.S. Nuclear Regulatory Commission to commence construction on two reactors in Tennessee. At 35 megawatts, the test units will be smaller than Kairos’ eventual commercial reactors, which are expected to generate 75 megawatts each.
Oklo is another SMR company targeting the data center world — no surprise given that it was backed by OpenAI CEO Sam Altman, who also took the nuclear startup public via a reverse merger with his special purpose acquisition vehicle, AltC, in July 2023. Altman served as chairman of Oklo until April, when he stepped down as OpenAI began negotiating with Oklo for an energy supply agreement. DCVC, Draper Associates, and Peter Thiel’s Mithril Capital Management are among the startup’s previous investors.
