Kairos Power on April 17 broke ground on the Hermes 2 Demonstration Plant in Oak Ridge, Tenn., the company’s first commercial-scale reactor and the first-ever power-producing Gen IV reactor to receive a construction permit from the Nuclear Regulatory Commission.
Hermes 2 is Kairos Power’s first deployment under its landmark deal with Google to develop an advanced reactor fleet.
The plant will supply up to 50 megawatts of electricity to the Tennessee Valley Authority grid, helping to decarbonize Google data centers in Tennessee and Alabama, Kairos said.
Through Kairos Power’s iterative development approach, Hermes 2 will build on lessons learned from the Hermes Low-Power Demonstration Reactor (Hermes 1), which commenced nuclear construction at the same site last year.
The Hermes series will be the first fluoride salt-cooled high-temperature reactors (KP-FHRs) ever built, "incorporating proven nuclear technologies that originated in Oak Ridge -- including TRISO coated particle fuel and Flibe molten fluoride salt coolant—which simplify the reactor’s design, lower capital costs, and yield robust inherent safety," the company said.
As the immediate precursor to Kairos Power’s full-scale commercial plants, Hermes 2 will further advance technology, licensing, supply chain, and construction certainty for the company’s future deployments, it said.
The groundbreaking event was not only a celebration of Hermes 2 but also a recognition of the cumulative progress Kairos Power has made to date at its Oak Ridge reactor demonstration campus. Key stakeholders, including elected officials, community members, and commercial partners, gathered to hear remarks from leaders and to tour the site.
Guests observed foundation work now in progress for Hermes 1 -– currently the only Gen IV reactor under active nuclear construction in the U.S. –- and saw firsthand the supporting infrastructure Kairos Power has built to enable testing and construction activities that will help drive down costs for the fleet, the company added.
Barnard Construction Company is serving as the general contractor for both Hermes reactor projects.
Kairos Power will fabricate Hermes 2 reactor equipment modules at its Manufacturing Development Campus in Albuquerque, N.M., and ship them to Oak Ridge for assembly, "pioneering a factory-built small modular reactor (SMR) concept with the potential to transform nuclear project delivery."
The Hermes 2 civil structure will leverage modular construction methods, incorporating precast concrete and a seismically isolated foundation.
According to Kairos, the construction methods piloted with the Hermes series are expected to shrink project timelines, lower nuclear construction costs, and enable a standardized, repeatable design.
Hermes 2 will be built on the footprint of the former Oak Ridge Gaseous Diffusion Plant at the K-33 site, which the U.S. Department of Energy reclaimed through a historic cleanup effort and returned to the community for economic development.
Kairos Power acquired the land in 2021, along with the adjacent K-31 site, for its reactor demonstration campus.
“Kairos Power represents a decisive step forward for America’s nuclear leadership,” said Matt Rasmussen, TVA Senior Vice President, and Chief Nuclear Officer. “With Hermes 2 moving into construction, we’re demonstrating how advanced nuclear will strengthen our nation’s energy dominance by delivering affordable, reliable power at scale. Kairos Power’s disciplined approach to next generation reactor design, paired with TVA’s first of its kind power purchase agreement, underscores how American innovation can set the pace for global nuclear advancement. This project shows what’s achievable when industry and technology leaders align to expand U.S. nuclear capability and secure a stronger, more resilient energy future for our country.”
