Kairos Power
Kairos Power is developing two demonstration projects in Oak Ridge, Tennessee, as it works towards enabling up to 500 MW of new advanced-nuclear capacity for Google by 2035.
What they do
Kairos Power is developing a fluoride salt-cooled high-temperature reactor (KP-FHR). Unlike conventional nuclear reactors that use water as a coolant, its design uses molten fluoride salt, which can operate at high temperatures and low pressure. The reactor is designed to use TRISO fuel particles embedded in graphite pebbles.
The proposed commercial configuration consists of two 75 MWe reactor units, providing a combined 150 MWe. Kairos is developing the technology through non-nuclear test systems and nuclear demonstration projects, rather than proceeding directly to a commercial plant.
The company is also developing its own capabilities in fuel fabrication and molten salt production, two areas that will be necessary for its planned reactor fleet.
Where they are
Kairos has two nuclear demonstration projects in Oak Ridge, Tennessee.
Hermes, a low-power test reactor that will not generate electricity. It received its construction permit from the US Nuclear Regulatory Commission (NRC) in December 2023. Kairos broke ground at the site in July 2024 and began nuclear safety-related construction in May 2025. In May 2026, the NRC approved an extension of the construction completion deadline from December 2026 to April 2029.
Hermes 2 received construction permits in November 2024, with groundbreaking following in April 2026. The original permitted concept comprised two 35-MWth test reactors, but Kairos subsequently revised the project to a single 50-MWe reactor in connection with its Google–TVA agreement.
In September 2026, Kairos signed a binding term sheet with Samsung C&T covering up to $100 million in investment and engineering services, subject to regulatory approvals.
What’s next
Hermes 2 is scheduled to begin supplying electricity to the Tennessee Valley Authority grid in 2030, under an agreement intended to support Google’s data centres in Tennessee and Alabama.
The broader agreement with Google envisages up to 500 MW of nuclear capacity by 2035. Meeting that target will require Kairos to complete its demonstration programme, obtain operating licences and establish the manufacturing and construction capacity needed for multiple commercial reactors.
As of October 2026, neither Hermes nor Hermes 2 has yet demonstrated electricity generation using the company’s reactor technology.
Why it matters
Kairos Power is seeking to become the first company to bring an FHR into commercial operation. Its high operating temperatures could enable more efficient electricity generation, depending on the power-conversion system, and support high-temperature industrial heat applications. The use of solid fuel also avoids some of the fuel-processing challenges associated with liquid-fuel molten salt reactors.
Technical note
The KP-FHR combines established TRISO fuel technology with a fluoride salt coolant, but the complete reactor system has not yet operated. Hermes and Hermes 2 are intended to provide evidence of how the fuel, coolant and structural materials perform together. Long-term materials behaviour and fuel performance remain important areas for qualification.
Company data
| Founded | 2016 |
|---|---|
| Headquarters | Alameda, California, United States |
| Leadership | Mike Laufer, CEO and co-founder; Edward Blandford, CTO and co-founder |
| Sector | Nuclear energy / Advanced nuclear energy |
| Technology / Product | Fluoride salt-cooled high-temperature reactor (KP-FHR) |
| Key Project(s) | Hermes and Hermes 2, Oak Ridge, Tennessee |
| Development / Commercial Stage | Hermes and Hermes 2 demonstration projects under construction; no operating commercial reactors |
| Ownership / Investors | Privately held; Samsung C&T has agreed to pursue a strategic investment |
| Funding | Up to $303 million in DOE support for Hermes; Samsung C&T has separately agreed to provide up to $100 million through a combination of direct investment and in-kind engineering services |
| Markets / Customers | United States; Google and Tennessee Valley Authority arrangements |
| Website | kairospower.com |
What to watch
- Completion and commissioning of Hermes.
- Hermes 2 operating licence and first electricity generation.
- Licensing and construction plans for the first commercial KP-FHR units.
