Actinide, an advanced materials company based in Dallas, has become the first startup to produce high-assay low-enriched uranium (HALEU), according to the company. The enrichment was performed on the company’s first-generation calutron, an electromagnetic isotope separator that sorts atoms by mass inside a magnetic field.
HALEU is uranium containing more than 5 percent but less than 20 percent uranium-235. An independent ISO/IEC 17025-accredited laboratory assayed the produced material at 15.38% enrichment, according to the announcement. The material was produced in research quantities under the laboratory-scale exclusion in NRC regulations for experimental purposes.
The achievement addresses a significant domestic supply challenge. According to the Department of Energy, most advanced reactor designs require HALEU, yet there is currently zero available from domestic suppliers. While conventional centrifuge enrichment can produce enriched uranium hexafluoride gas, it must be converted into solid form before fuel fabrication—a process for which the United States has zero commercial capacity. The Department of Energy contracted six companies in 2024 to build deconversion capacity, but Actinide’s technology bypasses this bottleneck by producing solid HALEU directly.
Actinide’s calutron technology builds on electromagnetic isotope separation principles used in Manhattan Project calutrons at Oak Ridge’s Y-12, but incorporates modern magnets, vacuum systems, power electronics, and proprietary advances. According to Robert Mendelsohn, co-founder and CTO, the machines cost a few hundred thousand dollars, produce material within months, deploy anywhere, and can be reconfigured in days to separate various isotopes.
The company is building Fortitude, its second-generation separator. According to Actinide’s engineering estimates, a single Fortitude machine would provide roughly half the isotope-separation capacity of the U.S. government’s current electromagnetic fleet.
Actinide was founded in September 2025 after seven years of research and prototyping by Mendelsohn. CEO Eric Olszewski invested more than $1 million of his own capital before the company was incorporated. The company raised an oversubscribed seed round in March 2026 led by Onto Ventures, with participation from Neo Ventures, Mana Ventures, Discipulus Ventures, Shor Capital, and angel investors. The company has already produced and sold ytterbium-176 enriched to more than 95% purity to Oklo Isotopes.
Key facts
- Actinide is the first startup to produce high-assay low-enriched uranium (HALEU), enriching natural uranium to 15.38% uranium-235
- The U.S. has zero domestic suppliers of HALEU fuel, which most advanced reactor designs require
- The company’s technology produces solid HALEU directly, bypassing the need for a separate deconversion process that the U.S. currently cannot perform commercially
- Actinide’s second-generation separator, Fortitude, is estimated to provide roughly half the isotope-separation capacity of the entire U.S. government electromagnetic fleet
- In 2025, 77% of uranium enrichment services purchased by U.S. civilian reactor owners came from foreign sources, including 26% from Russia