A lot of times, people feel like nuclear energy is way off into the future and doesn’t really impact anything today. But even when companies announce they’re working on new designs, there’s rarely a lot of fanfare. Instead of big changes, you see small stuff happening — mostly reactor permits getting approved or planning milestones being met. That isn’t exactly true in Oak Ridge, Tennessee. One very slow‑moving project just reached a major milestone.
From paper to steel on the ground
Oak Ridge‑based Kairos Power has started building its Hermes 2 Demonstration Plant, marking the beginning of actual work on Kairos’s first full‑scale commercial reactor project. The site is located about 30 miles west of downtown Knoxville on land that once housed a U.S. Department of Energy facility.
Following the issuance of a construction permit by the U.S. Nuclear Regulatory Commission, the location moved beyond preparatory activity and into active construction. What had been a site readying itself for a future build transitioned into one where work is now visibly underway.
Hermes 2 is one half of a larger demonstration campus. The other half, Hermes 1, is currently under construction and is designed to produce nuclear heat rather than electricity. By operating Hermes 1 first, Kairos can validate materials, systems, and construction methods before applying those lessons to Hermes 2. This phased approach ensures Hermes 2 is not built in isolation, but as part of a broader continuum of development.
Why Hermes 2 matters in the broader picture
As the first Generation IV (Gen-IV) nuclear fission power plant that will begin generating electricity and obtain an NRC construction permit, Hermes 2 signifies that the US Nuclear Regulatory Commission is now actively engaged with licensing non-light-water reactor technologies. Upon Hermes’ initial operation, additional Gen-IV-type nuclear fission power plants should have a better-defined pathway to go from the conceptual or pre-production stage to commercial-scale production.
It’s expected that Hermes 2 will provide up to 50 MW of electricity to TVA (the Tennessee Valley Authority). Under a prior announcement, some or all of that electricity will support Google data centers located in Tennessee and Alabama. Unlike many new nuclear projects, which focus on meeting peak power demands, Hermes 2 will directly tie into current power needs — meaning it will support whatever is already on the grid right now.
Also, unlike many other nuclear projects, Hermes 2 is not focused on sheer size. It’s focused on demonstrating how well Kairos can build a reactor quickly and reliably, how predictable the permitting process was for them, and how easily they can integrate into the existing grid infrastructure. Historically, those three things have been some of the biggest challenges for new nuclear builds — not just new reactor tech.
What Hermes 2 is testing beyond reactor design
Kairos Power is testing a new construction model for nuclear projects through the use of Hermes 2. The structure will utilize modular construction methods that include pre‑cast concrete sections and a seismically isolated foundation. All major equipment modules will be made at Kairos’ manufacturing development campus in Albuquerque, NM, and then shipped to TN for final assembly.
General contractor Barnard Construction Co. has worked on both Kairos projects, Hermes 1 and Hermes 2, providing continuity between phases. To reduce timelines and limit cost uncertainty—two persistent challenges in nuclear development—Kairos has focused on building repeatable components and processes. The company expects the lessons from Hermes 2 to support the commercialization of its next generation of nuclear reactors.
While Hermes 2 does not purport to address every issue confronting nuclear energy, it does signify a marked movement toward action. Through their focus on developing construction discipline, engaging with regulators, and developing repeatable methodologies, Kairos believes they will demonstrate whether advanced reactors can advance incrementally — and if so, what that could mean for future commercial deployment.
