The Nuclear Regulatory Commission (NRC) has taken a historic step by voting to issue construction permits for Kairos Power’s 70-MWth Hermes 2, a “low power” advanced test facility comprising two 35-MWth molten salt reactors. “Following the Commission’s vote, Hermes 2 is now the first electricity-producing Gen IV plant to be approved for construction in the United States,” said Kairos Power.
Kairos plans to build Hermes 2 at the East Tennessee Technology Park Heritage Center (ETTP) in Oak Ridge, Tennessee. The site will also host the proposed single 35-MWth Hermes 1 test reactor, a non-nuclear engineering test unit, and potentially a Kairos Power fuel fabrication facility.
The NRC’s issuance of the Hermes 2 construction permit represents a key milestone in the two-step CFR Part 50 licensing process. Kairos Power will need to apply for and secure an operating license before the plant can commence operations. Once operational, Hermes 2’s two reactors are anticipated to have a licensed lifetime of 11 years.
The licensing milestone is another notch for the Alameda, California–headquartered engineering company, which has been developing and marketing nuclear power plant designs based on its fluoride salt-cooled, high-temperature reactor (KP-FHR) technology since its founding in 2016. The company is pursuing a notable “rapid iterative development approach,” which involves using iterative hardware demonstrations and in-house manufacturing “to achieve disruptive cost reduction and provide true cost certainty for commercialization.” Under the stepwise approach, Kairos is also looking to de-risk its technology and supply chain logistics and clear regulatory hurdles before scaling to full commercial deployment.
As POWER has reported, Kairos’s KP-FHR comprises a graphite-moderated, “randomly packed” pebble‐bed reactor with molten fluoride salt coolant (a chemically stable molten fluoride salt mixture of 2LiF:BeF2 [Flibe] enriched in Li‐7), operating at high temperature and near‐atmospheric pressure. The fuel in the KP-FHR is based on tri-structural ISOtropic (TRISO) particle fuel in pebble form with a carbonaceous‐matrix coated particle design.