Regulator extends Hermes 1 reactor construction deadline

Kairos Power was granted a construction permit by the Nuclear Regulatory Commission (NRC) in December 2023 for the Hermes 1 molten salt-cooled demonstration reactor at the Heritage Center Industrial Park in Oak Ridge, Tennessee. It was the first non-water cooled reactor to be approved for construction in the USA in more than 50 years. The permit prescribed the latest date for construction of the reactor to be completed as 31 December 2026.

Kairos Power broke ground for the scaled demonstration of its KP-FHR fluoride salt-cooled high-temperature reactor technology in July 2024, with excavation works completed in October of that year. Safety-related construction activities, which are subject to oversight from the NRC, formally began on 1 May last year, with the start of work on the piers that will form part of the building's foundation.

On 24 March this year, Kairos Power submitted a request to the NRC for the Hermes 1 construction permit to be amended, with the completion date extended to 30 April 2029. It said the extension request "is the result of development delays associated with the first-of-a-kind nature of the Hermes Test Reactor facility design and construction". The company asked the NRC to approve the amendment request by 30 October this year "to allow for the continued construction of the Hermes Test Reactor facility". 

Kairos Power said it has developed a revised estimate of the time and resources necessary to complete construction of the facility, which it now expects to complete in 2028.

In a 21 April notice in the Federal Register, the NRC issued  an environmental assessment and finding of no significant impact regarding Kairos Power's request to amend the licence.

Hermes 1 will be a 35 MW (thermal) non-power version of the company's fluoride salt-cooled high temperature reactor, the KP-HFR. Kairos Power submitted a construction permit application in July 2023 for Hermes 2, a proposed two-unit demonstration plant that would build on the learnings from Hermes 1 and would demonstrate the complete architecture of future commercial plants. The NRC approved the permit in November 2024. Kairos Power broke ground last week in Oak Ridge for Hermes 2, which will produce electricity. Hermes 2 is Kairos Power's first deployment under its 2024 agreement with Google to develop an advanced reactor fleet. It will supply up to 50 MW of electricity to the Tennessee Valley Authority grid, helping to decarbonise Google data centres in Tennessee and Alabama.

The Hermes demonstration reactors ared intended to help mitigate technology, licensing, supply chain, and construction risk to achieve cost certainty for KP-HFR technology, Kairos said. The company is targeting commercial deployments in the early 2030s.