Kairos Power has installed the reactor vessel for its third Engineering Test Unit (ETU 3.0) at Oak Ridge, Tennessee, marking a major milestone in developing advanced nuclear reactors.

Supported by the U.S. Department of Energy through a $303 million Technology Investment Agreement, the project tests faster, more cost-effective manufacturing and construction methods for Kairos Power’s future commercial fleet.

The 14-foot-tall vessel was fabricated by the University of Sheffield’s Advanced Manufacturing Research Centre (AMRC) and Cambridge Vacuum Engineering (CVE) using electron beam welding, which produces welds up to ten times faster than traditional arc welding.

ETU 3.0 will serve as a testbed for construction, quality assurance, and operator training, while also supporting the Hermes Low Power Demonstration Reactor. The facility includes a Modular Systems area to stage and test reactor equipment modules, advancing modular construction techniques that can reduce future plant costs and timelines.

Kairos Power’s ETU program continues to validate innovative engineering and manufacturing solutions that will accelerate safe, affordable, and scalable nuclear power deployment.