NRC signs off on environmental review for Hermes 2 test reactors

This is the latest win for the dual-unit Hermes 2 test reactor project in Oak Ridge, Tenn. In July, a safety evaluation done by the NRC found no concerns that would preclude issuing a construction permit to Kairos.

Because the site was previously evaluated by the NRC for the original Hermes test reactor (sometimes referred to as Hermes 1), the agency's staff approved an exemption from that step for Hermes 2.

The exemption allows the NRC to issue a final environmental assessment and FONSI (finding of no significant impact), instead of an environmental impact statement to meet its obligations under the National Environmental Policy Act of 1969 and NRC regulations.

A closer look: The proposed Hermes 2 project would include twin 35-MW pebble-bed reactors with ping-pong ball–sized solid fuel pebbles containing HALEU in TRISO particles, with molten fluoride salt coolant. They would have an intermediate molten salt heat transfer loop and share a turbine to demonstrate electricity generation. Each unit would be of similar size and design as Hermes 1.

Kairos Power submitted its application for Hermes 2 construction permits in July 2023. The company still needs to apply for the reactors’ operating licenses in the future.

What’s next: The NRC will provide the Hermes 2 environmental assessment and its safety evaluation of the project to the commissioners for the final phase of the licensing process. They will determine if the staff’s review supports the findings necessary to issue the construction license and vote on whether to authorize its issuance.