Input sought on Kairos test reactor construction permit

February 23, 2022, 9:30AMNuclear News

The Nuclear Regulatory Commission is requesting public input on environmental issues that the agency should ponder as it reviews Kairos Power’s application for a construction permit to build the Hermes low-power demonstration reactor at the East Tennessee Technology Park in Oak Ridge, Tenn.

In a notice published in the February 18 Federal Register, the NRC says it will conduct a scoping process to gather information necessary to prepare an environmental impact statement (EIS) for the proposed project.

Alameda, Calif.–based Kairos submitted the first part of its application for Hermes in September of last year, completing the process the following month with its submittal of an environmental report. On November 30, the NRC announced that it had accepted the application for review.

The invitation: Members of the public can submit comments on the scope of the Hermes EIS through April 19 via the federal rulemaking website at, with a search for docket ID NRC-2021-0193; by email to; or by mail to Office of Administration, Mail Stop TWFN 7 A60M, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001.

Background: Hermes is a fluoride salt–cooled high-temperature reactor that uses solid tristructural isotropic (TRISO) fuel in pebble form. The proposed unit is intended to demonstrate complete nuclear systems, advance Kairos’s manufacturing capabilities for critical components, test the supply chain, and facilitate licensing certainty for the technology. The company expects Hermes to be operational in 2026 and to lead to the development of a commercial-scale, 140-MWe version, dubbed the KP-X.

In December 2020, Kairos received a Department of Energy Advanced Reactor Demonstration Program award for risk-reduction funding to support the development, construction, and commissioning of Hermes in collaboration with Oak Ridge National Laboratory, Idaho National Laboratory, Materion Corporation, and the Electric Power Research Institute. The total award value (over seven years) is $629 million, with the DOE contributing $303 million.

Kairos has also established a cooperative development agreement with the Tennessee Valley Authority to provide defined engineering, operations, and licensing services for Hermes.

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