Here are the nuclear fission startups backed by Big Tech
The surge in artificial intelligence (AI) is dramatically increasing electricity demand in the U.S., prompting major technology companies to secure reliable power sources for their energy-intensive data centers. A notable trend is the renewed interest in nuclear fission, offering a stable and predictable energy supply. Unlike nuclear fusion, which remains experimental, fission is currently used in all operational nuclear plants.
Big Tech’s interest in fission stems from its consistent 24/7 power supply, crucial for uninterrupted data center operations. Furthermore, innovative reactor designs promise to address the shortcomings of older nuclear plants. Small modular reactors (SMRs) are gaining traction for their potential to be mass-produced and deployed in varying capacities.
Despite the fact that no SMRs have been built in the U.S. to date, companies like Amazon, Google, Meta, and Microsoft are actively investing in or securing power purchase agreements with nuclear startups. Here’s a look at the nuclear fission startups receiving Big Tech backing:
Kairos Power
Kairos Power has garnered significant attention, including a commitment from Google to purchase approximately 500 megawatts of electricity by 2035, with the first reactor slated for operation by 2030. (Source: TechCrunch)
Kairos Power’s SMR design employs molten fluoride salt for cooling and heat transfer to a steam turbine. This design enhances safety by operating at lower pressures. The reactors utilize fuel pebbles encased in carbon and ceramic shells, engineered to withstand meltdowns.
The U.S. government has awarded the Alameda-based startup $629 million, including $303 million from the Department of Energy. Kairos received approval from the U.S. Nuclear Regulatory Commission in November 2024 to begin constructing two test reactors in Tennessee. (Source: TechCrunch) These test units, producing 35 megawatts each, will be smaller than the planned 75-megawatt commercial reactors.
Oklo
Oklo, backed by OpenAI CEO Sam Altman, focuses on serving the data center industry. Altman took the nuclear startup public through a reverse merger with his special purpose acquisition vehicle, AltC. (Source: TechCrunch) Other investors include DCVC, Draper Associates, and Peter Thiel’s Mithril Capital Management.
Oklo’s reactor design, cooled by liquid metal, is based on a U.S. Department of Energy concept aimed at minimizing nuclear waste. While its initial license application was denied in January 2022, Oklo intends to resubmit in 2025. The company has secured a deal to supply data center operator Switch with 12 gigawatts by 2044. (Source: TechCrunch)
Saltfoss
Saltfoss (formerly Seaborg) also specializes in molten salt-cooled SMRs. Its unique approach involves deploying these reactors on ships, creating what it calls a Power Barge. The startup has raised approximately $60 million, with investments from Bill Gates, Peter Thiel, and Unity co-founder David Helgason. Saltfoss partners with Samsung Heavy Industries to build the ships and reactors.
TerraPower
Bill Gates founded TerraPower is developing the Natrium reactor, cooled by liquid sodium and incorporating molten salt energy storage.
Construction of the first power plant began in Wyoming in June 2024. The Natrium design is projected to generate 345 megawatts of electricity, enhanced by its molten salt heat storage system, which allows for continuous reactor operation even when demand is low.
TerraPower’s investors include Gates’ Cascade Investment fund, Khosla Ventures, CRV, and ArcelorMittal.
X-Energy
X-Energy secured $700 million in a Series C-1 round led by Amazon’s Climate Pledge Fund. (Source: TechCrunch) The SMR startup has development agreements to deploy 300 megawatts of new nuclear capacity in the Pacific Northwest and Virginia.
X-Energy’s high-temperature, gas-cooled reactors utilize helium gas to absorb heat from fuel pebbles, driving a steam turbine. Each Xe-100 reactor is designed to generate 80 megawatts of electricity.
