U.S. Approves First Non-Water-Cooled Nuclear Reactor in Over 50 Years

California startup Kairos Power receives permit for its molten salt-cooled Hermes reactor, paving the way for a new era in nuclear power.

The U.S. Nuclear Regulatory Commission has issued a construction permit to California startup Kairos Power for its Hermes demonstration reactor in Tennessee, marking the first approval of a non-water-cooled nuclear reactor in over 50 years.
The Hermes reactor will use molten fluoride salt as a coolant, a technology that remains liquid at high temperatures and low pressure, potentially offering a safety advantage over water-cooled systems.
The Hermes reactor will not generate electricity but is expected to pave the way for the Hermes 2 project, which would use two of the same reactors to produce a combined total of about 28 megawatts of electricity.
Kairos Power plans to begin construction next year on its $100 million project and expects the system to be complete by the end of 2026.
The company's long-term goal is a commercial project that would use two larger reactors and would have more than 100 megawatts of capacity.