Radiant sends 1-MWe microreactor on 1,000-mile test trip

A trailer has become Radiant’s first proving ground. Since August 12, the California company has been moving its 1-MWe Kaleidos microreactor more than 1,000 miles from El Segundo to Idaho National Laboratory, where the unit will enter the DOME test bed.

DOME uses the repurposed containment structure of a former experimental breeder reactor. Once installed, Kaleidos will be loaded with tri-structural isotropic (TRISO) fuel, fabricated by Standard Nuclear to Radiant’s specifications earlier in 2026, under the oversight of the U.S. Department of Energy and Idaho National Laboratory.

The test campaign is designed to build from a controlled start to sustained operation. It will begin with zero-power criticality, then examine heat and power generation, advance to full-power operation and finish with 150 hours of continuous operation without operator assistance. Radiant says each phase will produce data for its license application to the U.S. Nuclear Regulatory Commission.

The significance is also industrial. Radiant says the Idaho unit has the same design, scale and commercial fuel load planned for reactors from its proposed R-50 production facility in Oak Ridge, Tennessee—not a simplified stand-in. The company is targeting completion of the testing campaign in the third quarter of 2026 and regulatory approval for the factory in the final quarter of 2026.

So what changes in practical terms? Radiant is testing whether a transportable reactor can move by trailer and then undergo a complete operating campaign in a dedicated facility before commercial delivery. The company has signed an agreement to supply its first commercial microreactor to Buckley Space Force Base, with delivery scheduled for 2028. Those milestones remain targets: the reactor still has to complete testing, and Radiant’s licensing and production plans remain under review.