Marathon Fusion Demonstrates Lithium and Hydrogen Isotope Enrichment Using Proprietary Plasma Centrifuge Technology

SAN FRANCISCO, Aug. 27, 2026 /PRNewswire/ -- Marathon Fusion, a leader in isotope production for the radiopharma and fusion industries, announced today the successful enrichment of hydrogen and lithium isotopes in its proprietary plasma centrifuge.

Fusion energy has the potential to provide terawatts of clean, affordable and firm power. To reach that ambition, the industry needs scalable isotope enrichment technologies compatible with the demands of commercial fusion. Hydrogen isotope enrichment is essential for sustained plant operation, and lithium isotope enrichment enables the production of tritium to fuel fusion reactors.

Advanced Fusion Fuel Processing

The US Department of Energy's Fusion Science and Technology Roadmap (https://www.energy.gov/fusion/fusion-energy) published in June identified tritium processing as a core challenge, noting that "Progress in this area is critical for enabling sustained DT operation… and demonstrating the viability of fusion as a large-scale energy source."

The objective of Marathon's plasma centrifuge is to enable a process called differential pumping, which could decrease tritium flow rates and the size of the associated tritium processing systems by a factor of ten or more. Their initial separation results are already of a magnitude that would substantially decrease tritium flow rates in the fusion fuel cycle. 

"Marathon's results on isotope separation are impressive and important for the fusion industry. By enabling selective tritium pumping, their technology can improve fusion power plant performance while dramatically reducing the required tritium inventory," said Dennis Whyte, an MIT Professor of Nuclear Science & Engineering whose research quantified the impact of selective pumping in the fusion fuel cycle. "Their approach could also enable improved lithium isotope separation, which is a key process in improving tritium production efficiency in fusion power plants. Lithium isotope separation is both a near term opportunity for Marathon, as well as one that grows to massive scale as fusion energy deploys."

Marathon Fusion's development of the plasma centrifuge is supported by the US Department of Energy through the highly competitive ARPA-E VISION OPEN program. Marathon Fusion is one of just three private fusion companies supported by this program.

Lithium Isotope Separation

A report on the fusion supply chain (https://www.scsp.ai/resource/fusion-supply-chain-report/) published by the Special Competitive Studies Project, a non-partisan U.S. think tank founded in October 2021 by former Google CEO Eric Schmidt, identified lithium enrichment as the single highest risk supply chain gap, adding that "there is no domestic commercial supply".

Marathon Fusion's work demonstrates meaningful commercial progress against both of these requirements, and constitutes a key step towards demonstrating the commercial viability of fusion energy. Both demonstrations make use of the same underlying physics, using a common architecture to address two distinct challenges. At the core of both programs is Marathon's expertise in plasma mass separation.

"Nuclear engineers have searched for an ideal coolant to move massive amounts of heat at low pressure and high temperature. The answer, from a pure heat capacity perspective, is the molten salt called FLiBe. This molten mixture of lithium and beryllium fluorides packs atoms together almost as densely as in solid graphite. In liquids, each atom stores nearly equal heat, so FLiBe has the highest volumetric heat capacity of any nuclear coolant, along with tremendous neutron stopping power," said Per F. Peterson, Distinguished Professor of Nuclear Engineering at UC Berkeley and advisor to Marathon Fusion. "The catch is that the lithium in FLiBe must be isotopically enriched in lithium-6 for fusion, or lithium-7 for fission. Today the world makes less than a tonne of enriched lithium each year, with a mercury-based process now used only in Russia and China. The terawatt-scale deployment that our world needs will require hundreds of thousands of tonnes of enriched lithium to be in service, produced with clean lithium enrichment technology."

Marathon's experimental results have tracked closely with their computational models, validating the underlying theory, and enabling predictive modeling to inform the design of upcoming systems. With enrichment demonstrated, Marathon will progress towards the demonstration of its first commercial pilot facility, capable of producing isotopes to enable gigawatt-scale fusion deployments.

"In fusion, isotope separation is an essential step in the fuel cycle," said Charles Swanson, VP of Fusion Systems at Thea Energy. "Marathon's results point to an intriguing way to make this system smaller and more practical.

Marathon Fusion announced last year a breakthrough in the scalable production of gold from mercury isotopes using fusion reactors. Today's announcement further cements Marathon Fusion's leadership in isotope production for fusion applications.

About Marathon Fusion
Marathon Fusion is an isotope production company, enabling an abundant supply of radioisotopes for the radiopharma industry, and developing isotope technology to deliver clean fusion energy more quickly with better economics. Marathon is supported by leading institutions including the Department of Energy's ARPA-E, Breakthrough Energy Fellows, 1517 Fund and Übermorgen Ventures. For more information, visit www.marathonfusion.com.

CONTACT: Kyle Schiller; [email protected]

SOURCE Marathon Fusion, Inc.