Kairos Power has broken ground on its Hermes 2 demonstration plant in Oak Ridge, Tenn. over the weekend.
The Hermes 2 plant is Kairos’s first commercial-scale reactor and was issued a construction permit from the Nuclear Regulatory Commission in 2024. Barnard Construction, which is currently working on the Hermes low-power demonstration reactor, will serve as the construction contractor to build Hermes 2, according to Kairos’s April 17 press release.
The Hermes 2 reactor is a fluoride salt-cooled high-temperature reactor designed to generate up to 50 megawatts. Hermes 2 will produce electricity, while the Hermes low-power demonstration reactor will not.
Kairos’s Hermes 2 demonstration plant will be built on the Department of Energy’s Oak Ridge Gaseous Diffusion Plant at the K-33 site. The company acquired the land and the adjacent K-31 site in 2021.
This will be the company’s first reactor under the deal it made with Google in 2024, according to the release. In addition to that deal, Hermes 2 will supply 50 megawatts to the Tennessee Valley Authority’s (TVA) grid and power Google data centers in Alabama and Tennessee. TVA entered into that deal with Google and Kairos in August 2025.
“For nuclear projects to be successful, we need more than just the right technology. We need to understand every aspect of project delivery. Hermes 2 is where that all comes together,” Kairos Power CEO and co-founder Mike Laufer said.
“We’re training a real workforce to do nuclear construction, learning from the Hermes 1 experience, and translating that knowledge to the Hermes 2 project next door,” Laufer added.