Stories of Technology, Innovation, & Entrepreneurship in the Southeast

Kairos Power has started construction on the Hermes Low-Power Demonstration Reactor (Hermes 1), 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 more than 50 years.

The development, announced Tuesday, comes just days after the Nuclear Regulatory Commission (NRC) concluded there are no safety aspects that would preclude issuing the construction permit for the Hermes 2 facility. More important, the start of construction highlighted the continued evolution of the nuclear industry in the Oak Ridge region that was celebrated during the record breaking “Nuclear Opportunities Workshop” that wrapped up its two-day run on Wednesday afternoon.

Hermes represents a critical milestone on Kairos Power’s iterative path to commercializing advanced reactor technology.

Kairos Power has contracted with Barnard Construction Company, 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 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.

Targeted to be operational in 2027 at the East Tennessee Technology Park, 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.

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 NRC issued a construction permit for Hermes following an accelerated review made possible by Kairos Power’s extensive pre-application engagement dating back to 2018.

---