Kairos Power has completed its first installation of safety-related concrete, kicking off nuclear construction for its Hermes Low-Power Demonstration Reactor in Oak Ridge, Tenn., the company announced Thursday.
Under Nuclear Regulatory Commission (NRC) standards, safety-related concrete is designed to withstand certain levels of earthquakes and aftershocks.
Last July, the California-based nuclear company broke ground for the Hermes site and completed its excavation in October 2024. Kairos Power previously was approved for a construction permit for its Hermes reactor by the NRC in December 2023.
Hermes is a scaled demonstration of the Kairos Power’s fluoride salt-cooled high-temperature reactor technology. The test reactor will produce 35 megawatts thermal and will not produce electricity, according to its NRC application.
The reactor will use a combination of TRISO fuel and a molten mixture of lithium fluoride and beryllium fluoride, also known as FLiBe, as its coolant, Kairos said in its Thursday press release.
Safety-related construction activities, which is overseen by the NRC and requires a construction permit, began on May 1 with a focus on the structure’s foundation. The Hermes structure will have 51 piers, which are six-foot in diameter and will extend 40 feet underground to anchor the building to bedrock.
The first safety-related concrete pour followed months of preparation after two previous Oak Ridge site projects served as the “proving grounds” to test the drilled pier installation process, Kairos said.
The Barnard Construction Company-led construction team completed a full-scale test pier in November 2024. The test pier demonstrates the process from start to finish before drilling 70 piers for Kairos Power’s third non-nuclear Engineering Test Unit, which will be located in Oak Ridge near the Hermes’s site.
Kairos’s Hermes received risk reduction funding from the Department of Energy’s Advanced Reactor Demonstration Program. The company targets Hermes to be operational by 2027.
