Thorium Atomics Inc., an advanced nuclear reactor developer with offices in Toronto and Knoxville, has commenced pre-application regulatory engagement with the U.S. Nuclear Regulatory Commission (NRC) for its Tesseract TGR 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 from the Office of Advanced Reactors to coordinate pre-application activities. This administrative step provides a defined point of contact and a trackable reference for future correspondence, meetings, and submissions.
The notice letter is publicly available in the NRC’s Agencywide Documents Access and Management System (ADAMS) under Accession No. ML26189A392, accessible at https://www.nrc.gov/docs/ML2618/ML26189A392.pdf. Importantly, the assignment of a project number is administrative and does not indicate NRC approval or endorsement of the design.
Thorium Atomics plans to engage with the NRC under 10 CFR Part 53, a risk-informed, performance-based, and technology-inclusive licensing framework that became available on April 29, 2026. The company is preparing a Regulatory Engagement Plan detailing the Tesseract technology, its licensing strategy, and the sequence of planned submissions. Dr. Jack Vecchiarelli, Chief Scientific and Regulatory Officer, noted that Part 53 is well suited for high-temperature gas-cooled reactors, and early engagement while the design is still being developed ensures regulatory expectations are clearly understood, informing the design process and de-risking the future licensing pathway.
The Tesseract TGR is a pebble-bed, high-temperature gas-cooled reactor that uses helium as coolant and TRISO fuel. It is a small modular reactor designed for 250 MWth thermal output, delivering approximately 100 MWe of firm electricity or industrial process heat up to 750°C. This high-temperature heat is currently supplied almost entirely by combustion, so the Tesseract could offer a low-carbon alternative for industrial applications.
The reactor uses uranium TRISO fuel enriched below 10% U-235 as the initial fissile driver and incorporates a thorium-bearing fertile blanket designed to convert thorium-232 into fissile uranium-233 during operation. This uranium-fueled, thorium-augmented architecture aims to diversify the nuclear fuel supply chain and improve lifetime uranium utilization. Current estimates suggest it could reduce mined-uranium requirements by approximately half per unit of energy compared to a Generation II light-water reactor, though this is subject to further engineering and independent validation.
Young Hwang, Founder and CEO, emphasized that this milestone aligns with the company’s application to Idaho National Laboratory’s Nuclear Energy Launch Pad program and its 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," he said.
The commencement of pre-application engagement is a significant step for Thorium Atomics as it advances the Tesseract TGR through the regulatory process. It signals the company’s commitment to transparency and early collaboration with regulators, which is crucial for novel reactor designs. The implications for the industry are substantial: successful licensing under Part 53 could set a precedent for other advanced reactor developers, potentially accelerating the deployment of next-generation nuclear technologies that offer firm, low-carbon power and high-temperature heat for industrial use.
As the company continues its pre-application work, it maintains a parallel regulatory pathway with the Canadian Nuclear Safety Commission. Further information is available at thoriumatomics.com.
