US-based Kairos Power has started construction on the Hermes Low-Power Demonstration Reactor. Kairos contracted Barnard Construction Company to perform site work and excavation at the Hermes site in Oak Ridge. Barnard and Kairos Power have also started collaborating on construction of 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. Kairos says this iterative approach will allow lessons learned from ETU 3.0 civil construction to transfer seamlessly to the Hermes facility.
Hermes is the first Generation IV reactor to be approved for construction by the US Nuclear Regulatory Commission (NRC). The fluoride salt-cooled high-temperature reactor is targeted for operation in 2027, Hermes will leverage proven technologies that originated in Oak Ridge – a combination of TRISO coated particle fuel and high-purity fluoride salt coolant – known as FLiBe – a eutectic mixture of lithium fluoride and beryllium fluoride.
Both Hermes and ETU 3.0 will be built using modular construction techniques piloted at Kairos Power’s testing and manufacturing campus in Albuquerque. 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.
Building on lessons learned from the ETU programme, Hermes’ primary objective will be to demonstrate Kairos Power’s ability to produce affordable nuclear heat. Hermes will not produce electricity.
The Department of Energy will invest up to $303m 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, 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.
“The lessons we take away from the construction and operation of this reactor will be invaluable to enable continued innovation in our testing programme and accelerate Kairos Power’s progress toward delivering true cost certainty to our customers.” said Mike Laufer, Kairos Power CEO and co-founder.
