U.S. nuclear operators could gain a long-term domestic fuel source if Fluxnium’s approach scales, reducing reliance on a small set of foreign uranium suppliers and easing an emerging price squeeze. Prices for yellowcake rose 75% in the last five years, the U.S. Energy Information Administration reports, while policy aims to triple U.S. nuclear capacity by 2050.
The ocean holds the prize: more than 4 billion metric tons of uranium, a stock Fluxnium’s founder Jeff Green described as “It’s like a thousand times more than all identified hard rock mines combined.” The company says its method can extract that dissolved uranium using fibers built from chemistry licensed from U.S. Department of Energy national labs.
Fluxnium’s core product is a specially configured polymer fiber that attracts uranium dissolved in seawater. The startup kept work under wraps while it refined production and the fiber geometry, focusing on increasing surface area to pull more material from each deployment. In an earlier national lab demonstration the approach extracted uranium at more than $200 per pound, a cost the company says it has driven down through design and manufacturing changes.
Deployment is simple in concept, and resembles seaweed farming. Long braided lines are hung from buoys offshore, left in the water for 30 to 60 days, then brought ashore. The uranium is eluted from the material, purified into yellowcake, and the fiber lines are reused for multiple cycles. “Then we sell that just as any other mine into the supply chain,” Green said.
Fluxnium recently emerged from stealth with a $7 million seed round led by Congruent Ventures and participation from Active Impact Investments and Constellation Energy, which runs the largest nuclear fleet in the U.S. Green is a repeat founder, having helped start Stamps.com in 1996, desalination company NanoH2O in 2005, and carbon removal firm 1PointFive in 2020.
The immediate test for Fluxnium is economics. Much of the cost sits in fiber manufacture and ocean deployment, and the company’s path to competitiveness depends on cutting those expenses while preserving reuse. If Fluxnium can lower production costs enough, seawater extraction would offer a geographically diffuse supply of uranium that could loosen strategic constraints on future nuclear expansion. For now the company is focused on scaling production and proving the unit economics in repeated field cycles.
