The US Nuclear Regulatory Commission (NRC) has published its final environmental assessment (EA) and finding of no significant impact for Kairos Power’s construction permit application for the dual unit Hermes 2 test reactor project.

The regulator has also exempted the project from the requirement for an environmental impact statement to support construction permits for test facilities: the Oak Ridge, Tennessee site where Hermes 2 is to be built was previously evaluated with an environmental impact statement for the Hermes 1 test reactor, which the regulator says is sufficient for it to grant the exemption.

The exemptions mean the NRC will be allowed to issue a final environmental assessement and Finding of No Significant Impact – or FONSI - instead of an environmental impact statement to meet its obligations under the National Environmental Policy Act of 1969 and its own regulations for the environmental review of the Hermes 2 application.

Kairos submitted its application for construction permits in July 2023 for the two fluoride salt-cooled, high-temperature reactors in July. The plant is be built on the same site as Hermes, a non-power version of Kairos Power’s fluoride salt-cooled high temperature reactor, the KP-HFR. Site work and excavation for Hermes, for which the company has already received a construction permit from the NRC, began in July.

As with Hermes, Kairos plans to build and operate Hermes 2 to demonstrate key elements of the technology for possible future commercial deployment, the NRC said in the final environmental assessment. Each Hermes 2 reactor would be similar in size and design to the Hermes reactor with some design differences, but the NRC concluded there would be no additional environmental impacts resulting from granting the exemptions.

NRC staff will now provide the Hermes 2 environmental assessment and its safety evaluation of the project to NRC commissioners who will vote on whether to authorise the construction licence. The company will need to submit a separate application for operating licences in the future.

The site is in the Heritage Center Industrial Park of the East Tennessee Technology Park, on land formerly owned by the US Department of Energy for the Oak Ridge Gaseous Diffusion Plant.