New offshore fiber system raises $7M to absorb uranium from seawater for nuclear fuel

Fluxnium has raised $7 million to develop a technology that could recover uranium directly from seawater. The startup says its approach could create a new domestic source for the U.S. nuclear industry. Congruent Ventures led the seed round, with participation from Constellation Technology Ventures and Active Impact Investments. Fluxnium will use the funding for technology development, pilot testing, and scale-up. The company is developing a specialized fiber that captures dissolved uranium as seawater flows across its surface. Fluxnium developed the material with a U.S. national laboratory. The approach targets a difficult engineering problem. Oceans contain enormous quantities of uranium, but the element exists at extremely low concentrations. Fiber targets ocean uranium Seawater contains an estimated 4.5 billion metric tons of uranium. That resource dwarfs currently identified deposits on land. Extracting it economically remains difficult because uranium atoms are spread across vast volumes of water. Fluxnium’s system focuses on capturing those atoms without pumping seawater through a large processing facility. Its fiber provides a large surface area for uranium adsorption. The material can sit inside longline systems deployed in open water. Fluxnium modeled the infrastructure on marine farming systems. Seaweed and mussel operations already use similar longline structures in offshore environments. Operators would retrieve the fiber after it collects uranium. Processing would then recover the uranium before crews redeploy the material. That cycle could allow production capacity to grow through additional fiber deployment. It could also avoid the lengthy development process associated with opening new uranium mines. U.S. nuclear fuel supply The technology arrives as the United States looks to strengthen its nuclear fuel supply chain. Fluxnium says the country currently imports more than 90% of its uranium. Jeff Green, Fluxnium’s CEO and founder, said rising electricity demand could increase pressure on nuclear fuel supplies. “Fluxnium is developing a new domestic and sustainable supply of uranium,” Green said. He pointed to offshore infrastructure as a potential path toward competitive production. The company also argues that seawater extraction could avoid some impacts associated with conventional uranium mining. Those include mine tailings and groundwater concerns. Economic performance will remain a major test for the technology. Fluxnium says its projected costs could compete with conventional uranium mining. Constellation sees the technology as another potential option for future nuclear fuel supplies. Jason Murphy, its vice president of nuclear fuels, said new domestic uranium sources could support growing nuclear demand. Scaling offshore system Fluxnium now needs to demonstrate that its laboratory-developed material can perform reliably at larger scales. Offshore deployment introduces engineering challenges beyond simply capturing uranium. The fiber must operate in seawater while surviving marine conditions. Engineers must also develop practical methods for retrieval, processing, and redeployment. Fluxnium’s seed funding will support that next stage. The company says its system could expand output by adding more collection infrastructure. That model could give uranium production a different path to expansion. Instead of developing another mine, operators could add more offshore collection capacity. The concept remains under development, however. Commercial viability will depend on extraction rates, material durability, processing costs, and performance at pilot scale. Get the latest in engineering, tech, space & science - delivered daily to your inbox.Aamir is a seasoned tech journalist with experience at Exhibit Magazine, Republic World, and PR Newswire. With a deep love for all things tech and science, he has spent years decoding the latest innovations and exploring how they shape industries, lifestyles, and the future of humanity.