nuclear milestone
Hermes reactor rendering
Rendering of Hermes reactor
Kairos Power

Kairos Power received approval from the Nuclear Regulatory Commission (NRC) to start the construction of its Hermes reactor. 

The reactor will be built in Oak Ridge, TN and used to inform the development of the company’s fluoride salt-cooled high-temperature reactor.  

Kairos is planning to have Hermes operational as early as 2026. 

Vote of Confidence 

NRC Commissioners voted to approve Kairos Power’s construction permit application (CPA) that was first submitted back in September 2021. 

The vote comes nearly two months after the NRC held its final review of the application on October 19, where the company and NRC staff addressed any outstanding questions on the safety and environmental reports completed earlier this year.  

The entire process took just over two years to complete and includes dozens of technical and topical reports which were developed, in part, with support from the U.S. Department of Energy.  

Kairos will file a separate application for a Hermes operating license from the NRC in the future. 

“Kairos Power is thrilled to have achieved this major regulatory milestone as we make final preparations to start construction at the Hermes site next year," said Mike Laufer, Kairos Power co-founder and CEO. "We are excited for this next phase in the deployment of the Hermes reactor, and we remain committed to being a good community partner to our neighbors in Oak Ridge as we bring value to the region and build on its nuclear legacy."

This is a huge milestone for the nuclear energy sector,” said Kathryn Huff, the Assistant Secretary for Nuclear Energy. “NRC’s approval of the first ever CPA granted to a Generation IV reactor charts a path forward for future design applications as we work toward deploying new reactor technologies. This accomplishment is a testament to the collaborative work among Kairos, the NRC, DOE and all stakeholders involved in the project.”  

Here Comes Hermes 

Hermes is one of several new reactor technologies DOE is supporting through its Advanced Reactor Demonstration Program. The low-power reactor uses a TRISO fuel pebble bed design with a molten fluoride salt coolant to achieve a thermal power level of 35 megawatts.  

The KP-FHR is based, in part, on DOE-sponsored Integrated Research Projects led by several universities, national labs, and international partners to advance fluoride salt-cooled high-temperature reactors. 

The commercial version of the reactor is expected to be deployed in the 2030s.  

What’s Next? 

Kairos Power is conducting salt operations at its first engineering test unit (ETU) in New Mexico. The ETU is a non-nuclear, full-scale mockup of Hermes that will demonstrate key systems and components of the reactor, test the supply chain, and allow workers to gain operational experience.   

Kairos will build and operate a total of three ETU iterations before constructing Hermes.