Kairos Power has started construction on the Hermes Low-Power Demonstration Reactor, the first and only Gen IV reactor to be approved for construction by the U.S. Nuclear Regulatory Commission and the first non-light-water reactor to be permitted in the U.S. in over 50 years. Hermes represents a critical milestone on Kairos Power’s iterative path to commercializing advanced reactor technology.
Kairos Power has contracted with Barnard Construction Company, Inc. (Barnard), a heavy-civil construction company, to perform site work and excavation at the Hermes site in Oak Ridge, which began earlier this month. In tandem with Hermes, Barnard and Kairos Power have also started collaborating to build the third Engineering Test Unit (ETU 3.0)—a non-nuclear demonstration co-located in Oak Ridge that will generate supply chain, construction, and operational experience to inform the Hermes project. This iterative approach will allow lessons learned from ETU 3.0 civil construction to transfer seamlessly to the Hermes facility.
Both Hermes and ETU 3.0 will be built using modular construction techniques piloted at Kairos Power’s testing and manufacturing campus in Albuquerque, N.M. Reactor modules will be fabricated in Albuquerque and shipped to Oak Ridge for assembly, demonstrating the potential of a factory-built small modular reactor design to transform conventional nuclear construction.
Targeted to be operational in 2027, Hermes will be Kairos Power’s first nuclear build. The fluoride salt-cooled high-temperature reactor will leverage proven technologies that originated in Oak Ridge—a novel combination of TRISO coated particle fuel and Flibe molten fluoride salt coolant, which yields robust inherent safety while simplifying the reactor’s design.
Building on lessons learned from the Engineering Test Unit program, Hermes’ primary objective will be to demonstrate Kairos Power’s ability to produce affordable nuclear heat. Hermes will not produce electricity.
Kairos Power has committed to invest at least $100 million and create 55+ high-paying, full-time jobs in East Tennessee to support Hermes’ construction and operation. Rising from the footprint of the historic Oak Ridge Gaseous Diffusion Plant, the project will continue the region’s distinguished nuclear legacy and promote its resurgence as a hub for advanced nuclear innovation.
The U.S. Department of Energy will invest up to $303 million in the project through a performance-based milestone contract funded by the Advanced Reactor Demonstration Program to support Hermes’ design, construction, and commissioning.
Hermes is a joint effort by Kairos Power and its partners, including Oak Ridge National Laboratory, Idaho National Laboratory, EPRI, and Materion Corporation. In addition, Kairos Power is partnering with Los Alamos National Laboratory to produce TRISO pebble fuel for Hermes in the lab’s Low-Enriched Fuel Fabrication Facility. Kairos Power has also established a cooperative development agreement with the Tennessee Valley Authority to provide engineering, operations, and licensing support for Hermes.
In December 2023, the U.S. Nuclear Regulatory Commission issued a construction permit for Hermes following an accelerated review made possible by Kairos Power’s extensive pre-application engagement dating back to 2018.
Hermes is named after the mythological messenger of the gods, who was renowned for his speed, reflecting the urgency of Kairos Power’s clean energy mission. Lessons learned from Hermes will help de-risk technology, licensing, manufacturing, and construction for the company’s future commercial deployments.
