A nuclear factory in Tennessee, 50 reactors a year, each one fitting inside a standard shipping container. Radiant, a California-based startup headquartered in El Segundo, has chosen Oak Ridge — the very site of the Manhattan Project — to build what it aims to make the world’s first dedicated serial production facility for portable nuclear generators. The plant has been named R-50, a nod to both its production target and the historic weight of its location.
The product is Kaleidos: a 1-megawatt electric microreactor cooled by helium, with a graphite core and TRISO fuel — low-enriched uranium particles encased in ceramic layers engineered to withstand extreme temperatures. Generator, cooling system, reactor, and radiation shielding are all contained within a single unit. It loads onto a truck, a train, a ship, or a cargo aircraft. No water in the cooling circuit, no fixed infrastructure required, and a single fuel load lasting five years. The stated goal is to replace diesel generators wherever the electrical grid is absent or unreliable.
Tennessee’s Department of Economic and Community Development announced a $280 million investment and the creation of 175 jobs in Roane County. Radiant is the sixth company to establish a presence in Tennessee through the state’s Nuclear Energy Fund, a $70 million fund built up over multiple successive legislative sessions. Construction of the R-50 facility is scheduled to begin in early 2026, with the first commercial delivery of a mass-produced Kaleidos unit targeted for 2028. The intended market is broad: military bases, remote data centers, isolated communities, and disaster response scenarios. Radiant has already disclosed to the Nuclear Regulatory Commission letters of intent exceeding $10 billion.
The broader environment could hardly be more favorable. Testing at the National Reactor Innovation Center at Idaho National Laboratory is ongoing: Radiant aims to bring the reactor to full thermal power and demonstrate 150 hours of autonomous operation — a step beyond the zero-power tests already completed by other competitors. On the regulatory front, an executive order signed by President Trump in May 2025 pushed the Department of Energy to fast-track licensing procedures for advanced reactors. The administration had set a goal of achieving criticality with at least three new reactors by July 4, 2026 — a milestone that was met. Radiant was not among the three that reached zero-power criticality by that date, but its testing schedule remains on track.
The underlying logic is straightforward. One megawatt is modest: it powers roughly 800 to 1,000 homes, or a mid-sized server room. But if fifty units can be produced per year and deployed in multi-unit configurations, the aggregate output becomes significant — without waiting years for grid connections or the permitting process for large-scale plants. It is the same logic that made modular production attractive in the aerospace industry: economies of repetition, not of scale. Kaleidos does not compete with a 300-megawatt plant. It competes with a diesel generator and years of waiting for a high-voltage line. If the R-50 factory hits its projected output, the model could redraw the rules of energy distribution in regions where today the only alternatives are fossil fuels or nothing at all.
