Marathon Fusion

Founded: 2022

Website: https://www.marathonfusion.com/

Marathon Fusion – founded in late 2022 and based in San Francisco, CA – is a start-up focused on isotope-production and fusion fuel-cycle technology for fusion power plants. It does not seek to build a fusion reactor; instead it develops equipment and processes intended to help deuterium-tritium fusion plants operate at commercial scale, separating isotopes, recycling tritium from reactor exhaust and enriching lithium-6 for tritium breeding. The same isotope-production platform can also support radiopharmaceutical-isotope production and, longer term, transmutation-based material co-products.

The company positions its fuel-cycle technology as reactor-agnostic, addressing common requirements across different fusion architectures. Its central commercial thesis: selective, high-throughput fuel processing can reduce tritium inventories, improve plant economics and simplify the route to reliable, licensable fusion power.