The U.S. Nuclear Regulatory Commission (NRC) issued a construction permit to Kairos Power for the Hermes reactor in December 2023. Kairos’ reactor uses molten salt for cooling and is the first non-light-water reactor to be permitted in the U.S. in over 50 years.

Kairos Power said Barnard Construction Company began to perform site work earlier this month at the Hermes site. 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.

Both Hermes and ETU 3.0 will be built using modular construction techniques piloted at Kairos Power’s testing and manufacturing campus in Albuquerque, New Mexico. 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.

The project aims to be operational in 2027. Hermes’ primary objective will be to demonstrate Kairos Power’s ability to produce affordable nuclear heat. Hermes will not produce electricity.

However, Kairos Power aims to develop a larger version for commercial electricity that could be used in the early 2030s. It says the construction permit is a big step forward as it works to deploy clean, safe, reliable and affordable energy.

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 (TVA) to provide engineering, operations, and licensing support for Hermes.