Radiant

Radiant is an El Segundo, California-based nuclear energy startup founded in 2020 that is building the world's first mass-produced portable nuclear microreactors. Its flagship product, Kaleidos, is a compact 1 MW electric (1.9 MW thermal) failsafe microreactor designed to replace diesel generators in remote, off-grid, and defense applications. The unit is factory-assembled, fueled, and tested before shipment, then delivered via truck or aircraft and operational within a day of arrival - requiring no site excavation or on-site water. Kaleidos uses TRISO fuel (ceramic-coated uranium particles proven in over 30 reactors since the 1960s) and helium gas cooling, making it inherently meltdown-proof. It can operate for 5+ years on a single fuel load, with a total product lifetime of 20 years across four refueling cycles.

Radiant's technology is purpose-built for contexts where reliable, clean power is otherwise unavailable or prohibitively expensive. Key target markets include remote villages, military installations, hospitals, and data centers. The reactor boasts over 110x the energy density of diesel systems, can operate from 30-100% output to support microgrids alongside solar or wind, and can be monitored autonomously through Radiant's centralized fleet management platform. The company is on track to conduct a first-ever fueled test of the Kaleidos reactor at Idaho National Laboratory's DOME facility in 2026 - which would be the first new commercial reactor design to achieve a fueled test in over 50 years.

Radiant is strategically significant to the US energy supply chain on multiple fronts. The company has secured its first military contract through the Defense Innovation Unit and the Department of the Air Force to deliver a microreactor to a US military base in 2028, and the Air Force has selected Radiant to power Buckley Space Force Base. Radiant is also building the first commercial nuclear microreactor factory in America on a historic Tennessee Manhattan Project site, targeting production of 50 reactors per year. With DOE support, partnerships with Standard Nuclear for domestic TRISO fuel manufacturing, and NRC licensing underway, Radiant represents a vertically integrated push to make portable nuclear power a scalable American-made energy solution.