US Radiant 1MWe Kaleidos Microreactor Arrives in Idaho

en.Wedoany.com Reported - US startup Radiant has loaded its 1 MWe-class Kaleidos microreactor onto a dedicated trailer deck and transported it 1,000 miles by road from its El Segundo facility to the Idaho National Laboratory (INL). The microreactor will be installed in the refurbished "Microreactor Experiments Demonstration" (DOME) facility at INL for testing, with the reactor loaded with tristructural isotropic (TRISO) fuel manufactured by Standard Nuclear.

The testing, overseen by the Department of Energy (DOE) and INL, proceeds in five phases: the installation phase safely positions the physical containment and loads TRISO fuel; the criticality phase starts the unit to achieve initial zero-power nuclear criticality; the thermal validation phase raises operating power to maintain a stable 1 MW thermal output; the full-power operation phase starts the system at maximum commercial temperatures and full generating conditions; and the unattended operation phase culminates in a continuous 150-hour endurance test with no operator intervention. The entire test program is targeted for completion in the third quarter of 2026.

Real operational data from the testing will support Radiant's commercial expansion strategy, and insights from the tests will directly support its license application to the Nuclear Regulatory Commission (NRC). Meanwhile, the NRC is reviewing Radiant's Part 70 application for its R-50 microreactor production facility in Oak Ridge, Tennessee, with an approval target of the fourth quarter of 2026.

Radiant holds active contracts with the US Air Force and the Defense Innovation Unit, with plans to deploy its first commercially manufactured unit at Buckley Space Force Base by 2028. The unit is designed to fit entirely within a standard shipping container, relies on fan cooling for zero on-site water use, and serves as a rapidly deployable diesel alternative for remote communities, disaster zones, data centers, and defense installations.

INL's DOME facility has been upgraded for microreactor testing. The DOE awarded Radiant exclusive access to the facility for one year following a competitive selection process. Kaleidos will be the first reactor to achieve criticality and full-power operation at the facility in decades. In 2026, no other reactor developer is conducting full-scale, full-power, extended-duration testing, and Radiant is testing the exact same unit that will be delivered to commercial and military customers.

Radiant's 80-acre campus in Oak Ridge will house the R-50 fuel manufacturing and production facility, with the NRC license application under accelerated review and construction underway; the facility is expected to be operational in January 2027.

Radiant notes that achieving criticality alone produces no meaningful power, hence the term zero-power criticality—it only demonstrates fundamental neutron physics. Radiant's test campaign at DOME is centered on a harder, more substantive goal: proving Kaleidos' viability as a commercial product. Conducting subscale, zero-power criticality experiments might be faster on paper, but it would not advance progress in demonstrating the full commercial capabilities needed to move from concept to mass manufacturing. Radiant has deliberately chosen the harder path.