Radiant Nuclear

Radiant Nuclear is a clean energy startup founded in 2020 and headquartered in El Segundo, California. It is developing Kaleidos, described as the world's first mass-produced, portable nuclear microreactor, intended to replace diesel generators with carbon-free power. The 1 MW reactor is helium gas-cooled, runs on HALEU TRISO fuel and can operate for up to five years without refuelling. An air jacket allows passive cooling by natural convection, and the unit is designed to be transported to wherever power is needed.

The engineering draws on established nuclear technology as well as newer manufacturing methods. TRISO fuel has been used in more than 30 grid-scale reactors since the 1960s, and Radiant emphasises a fail-safe design and meltdown-proof fuel to simplify regulatory approval. The company combines this with modern software engineering practices and a preference for well-qualified existing materials, aiming for rapid, pragmatic development and factory-built production. A factory in Oak Ridge, Tennessee is planned to build up to 50 reactors a year.

Radiant's stated timeline places a first fueled reactor test at Idaho National Laboratory in 2026, which would be the first new commercial reactor design to reach a fueled test in more than 50 years. Initial customer deployments are planned for 2028. The company's technical work spans nuclear engineering, microreactor design, TRISO and HALEU fuel technology, passive cooling and factory-built manufacturing, with target markets including backup and portable power generation, remote and defence applications.