Work begins on first US Gen IV reactor

Tuesday, 30 July 2024

Hermes is a non-power version of Kairos Power's fluoride salt-cooled high temperature reactor, the KP-HFR and is the first and only Gen IV reactor to date to be approved for construction by the US Nuclear Regulatory Commission (NRC). Targeted to be operational by 2027, the reactor will be the company's first nuclear build, and is a critical step on the company's iterative path to commercialising advanced reactor technology. Its primary objective will be to demonstrate the ability to produce affordable nuclear heat, but it will not produce electricity: that will come in the next iteration, the proposed Hermes 2 plant.

Kairos Power has contracted with heavy-civil construction company Barnard Construction Company, Inc for the work at the Hermes site in Oak Ridge, Tennessee. At the same time, the companies are also collaborating to build the third Engineering Test Unit (ETU 3.0), a non-nuclear demonstration facility co-located with Hermes 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, the company said.

Kairos Power CEO and co-founder Mike Laufer described Hermes as a pivotal step towards deploying advanced reactor technology. "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," he said.

Both Hermes and ETU 3.0 will be built using modular construction techniques, with reactor modules fabricated in Kairos Power's facility in Albuquerque, New Mexico, which will be shipped to Oak Ridge for assembly. This will demonstrate the potential of a factory-built small modular reactor design to transform conventional nuclear construction, the company said.

Architect's rendering of the Hermes plant (Image: Kairos Power)

Hermes is a joint effort by Kairos Power and partners including Oak Ridge National Laboratory, Idaho National Laboratory, EPRI, and Materion Corporation. Kairos Power is partnering with Los Alamos National Laboratory to produce TRISO pebble fuel for the Hermes plant, and has a cooperative development agreement with the Tennessee Valley Authority to provide engineering, operations, and licensing support.

The NRC issued a construction permit for Hermes last December. Kairos Power has also applied for a construction permit for the electricity-generating Hermes 2 test reactor, which will also be built at Oak Ridge and will feature two 35 MWt units similar to the Hermes plant. Earlier this month, the regulator announced the completion of its final safety evaluation for the Hermes 2 construction application, finishing its review of the design nearly four months ahead of schedule and using about 60% fewer resources than expected, thanks to lessons learned from its earlier review of the Hermes plant.