Thorium Atomics Inc. has officially commenced pre-application regulatory engagement with the U.S. Nuclear Regulatory Commission (NRC) for its Tesseract TGR advanced reactor. The company submitted a notice of intent letter on June 23, 2026, and the NRC responded on July 24, 2026, assigning Project No. 99902174 and a project manager to facilitate the process. This administrative step provides a formal channel for future communications and submissions, but does not imply NRC approval of the design.
The Tesseract TGR is a pebble-bed high-temperature gas-cooled reactor that uses helium coolant and TRISO fuel, a design that relies on passive safety features rather than active systems. It is a small modular reactor with a thermal output of 250 MWth, delivering about 100 MWe of electricity or process heat up to 750 degrees Celsius. The reactor is fueled by uranium enriched below 10% U-235, with a thorium blanket that converts thorium-232 into fissile uranium-233 during operation. This approach aims to reduce mined-uranium requirements by up to half compared to conventional light-water reactors, though this estimate is subject to further validation.
The company plans to engage under 10 CFR Part 53, the NRC’s risk-informed, performance-based licensing framework that became available on April 29, 2026. Dr. Jack Vecchiarelli, Chief Scientific and Regulatory Officer, noted that Part 53 is well-suited for high-temperature gas-cooled reactors. “Commencing that engagement while the design is still being developed serves to ensure that regulatory expectations are clearly understood and addressed, thereby informing the design development process and helping to de-risk the future licensing pathway,” he said.
Young Hwang, Founder and CEO, highlighted the broader progress: “This is a clear external marker of where our program stands. It comes alongside our application to Idaho National Laboratory’s Nuclear Energy Launch Pad program and our proposed pathway for independent, qualified-code reactor-physics verification at a U.S. national laboratory. We are deliberately building the regulatory, engineering, and technical-validation records in parallel.”
The NRC’s project number is an administrative reference and does not represent submission or acceptance of a license application. The notice of intent letter is publicly available in the NRC’s Agencywide Documents Access and Management System under Accession No. ML26189A392 (see here).
Thorium Atomics, with offices in Toronto and Knoxville, is also maintaining a parallel regulatory pathway with the Canadian Nuclear Safety Commission. The company’s focus on both regulatory fronts underscores its commitment to advancing the Tesseract TGR through a rigorous, transparent licensing process. The engagement with the NRC marks a critical milestone in the development of advanced nuclear technology, which is expected to play a key role in providing clean, firm energy and industrial heat while diversifying the nuclear fuel supply chain.
