Washington-based start-up Curio has completed laboratory-scale demonstrations of its Nucycle fuel recycling technology in collaboration with four US Department of Energy (DOE) laboratories. Idaho National Laboratory (INL), Oak Ridge National Laboratory (ORNL), Pacific Northwest National Laboratory (PNNL), and Sandia National Laboratories took part in the project supported by DOE’s ARPA-E CURIE programme and GAIN voucher initiative.
DOE’s Gateway for Accelerated Innovation in Nuclear (GAIN) awarded four fiscal year 2025 vouchers in January, one of which was to Curio for work at PNNL. GAIN voucher recipients do not receive direct financial awards. Vouchers provide funding to DOE laboratories to help businesses overcome critical technological and commercialisation challenges.
According to the ARPA-E website, “NuCycle is a modular, integrated, compact, and proliferation-hardened process designed to avoid production of pure plutonium (Pu) streams and dramatically reduce waste volumes compared with existing processes. NuCycle significantly reduces facility footprints, leverages well-understood chemical processes, and accommodates a variety of fuel types, including molten salts and nitride fuels. The advanced head-end processing and fluorination steps will produce UF6 that is suitable for re-enrichment while keeping plutonium with the remaining actinides and fission products for further processing.”
NuCycle is the first nuclear fuel recycling technology, designed from the ground up with safeguards and proliferation-hardening integrated into its process, to be tested and validated at the lab scale. Curio said multiple patents cover its fully integrated, safeguarded-by-design process for safely recycling the US’s 90,000 tonnes of used nuclear fuel and the design of a reactor that completes the closed fuel cycle, transforming this liability into new, proliferation-hardened fuel and valuable isotopes.
“Nuclear energy cannot power America’s future without solving the back end of the cycle,” said Yehudah and Rabbi Yechezkel Moskowitz, founders of Curio and managing partners at the Synergos Fund. “That’s what NuCycle delivers: not just a technology, but a safeguarded industrial platform that transforms spent fuel into a secure, domestic supply of next-generation reactor fuel. We see this as the foundation of a truly closed fuel cycle that will strengthen US energy independence for generations.”
Vik Singh, Chief Innovation Officer and Principal Investigator of the lab scale programmes, said: “Our philosophy was simple: harness breakthroughs demonstrated in petrochemicals and metallurgy – modularity, process intensification, automation – and apply them to the nuclear back end. NuCycle is the result: an integrated, modular, proliferation-hardened recycling process built from the ground up with safeguards, automation, and economic viability as core principles.”
In partnership with ORNL, Curio demonstrated its innovative voloxidation techniques, offering unprecedented efficiency and scalability in decladding spent nuclear fuel. Voloxidation is a high-temperature, gas-solid reaction process. Its purpose is to achieve two goals: volatilisation of fission products and fuel pulverisation. Volatisation removes problematic radioactive isotopes that are volatile (gaseous) at high temperatures such as tritium, carbon-14, iodine-129, krypton-85 and xenon-131. Fuel pulverisation converts solid uranium dioxide fuel pellets into a fine, ceramic powder. This causes the fuel to swell and crack, breaking it away from its metal cladding.
The ORNL lab-scale tests released more than 99.75% of the fuel from its zircalloy cladding, providing validation for a process intended to replace the more burdensome, costly, and less environmentally friendly methods currently used worldwide. Under DOE’s GAIN voucher programme, ORNL completed criticality safety assessments of Curio’s next-generation equipment designs with no safety constraints identified.
The pulverized product from the decladding process was then shipped to PNNL, where Curio’s fluorination circuit was validated. The process achieved decontamination levels of sub-parts-per-million levels for key contaminants that yielded enrichment-ready uranium hexafluoride (UF6) at some of the purest levels ever recorded from a single-stage process. Working with partners at PNNL, Curio successfully scaled this essential chemistry from milligram-level experiments to 100 grams proving both its viability and scalability. Eliminating the need for additional conversion and distillation steps, this achievement established a new critical pathway for domestically sourced UF6 for the US market, and promises major cost savings.
At INL, Curio acquired world-first data that enables its advanced electrolysis process. This work, which spanned all actinides present in used fuel, was conducted in a molten-salt bath. By systematically varying temperature and concentration, the teams were able to study the fundamental redox chemistry that will enable co-extraction of plutonium with uranium and minor actinides in a proliferation-hardened manner, providing crucial insights and validation for the future of comprehensive fuel recycling and its re-use. “In the last couple of years of collaboration, INL was able to measure key performance metrics of the NuCycle process, yielding data that will guide pilot-scale equipment design,” said Jess Gehin, Associate Lab Director of the Nuclear Science and Technology Directorate at INL.
The data from these foundational lab-scale experiments are now informing Curio’s work with Sandia to develop a comprehensive safeguards and security model. This collaboration will conduct iterative material control and accounting (MC&A) analysis, using the experimental results to create the first-ever nuclear fuel recycling process that is safeguarded by design.
“We are moving at a pace the industry has never seen to deliver a fundamentally new, safeguarded-by-design platform that will redefine the economics and security of the entire nuclear fuel cycle,” said Ed McGinnis, CEO of Curio. “These unprecedented results demonstrate the strength of public–private collaboration in advancing sustainable nuclear solutions. ARPA-E and GAIN support allowed us to bring a truly closed fuel cycle within reach.”
Curio’s ARPA-E CURIE award, received in 2023, enabled side-by-side lab demonstrations of the complete NuCycle flowsheet at INL, ORNL, and PNNL, which have now met key milestones, delivering unprecedented insights into the process chemistry and kinetics. “ARPA-E’s support for Curio’s lab-scale demonstrations exemplifies our commitment to innovation in energy solutions and nuclear fuel recycling,” said Dr Jenifer Shafer, ARPA-E CURIE Program Director. “We’re proud to advance technologies that enhance waste minimisation and resource recovery that also enable nuclear energy deployment.”
Curio is leveraging these results to finalise engineering specifications for its pilot-scale NuCycle modules, targeting demonstration by the end of 2027. Curio intends to complete its lab-scale demonstration with actual spent nuclear fuel at INL, and is actively exploring a first pilot with the DOE. The company continues to engage with regulators to secure licensing, and secure offtake agreements with multiple industry partners ahead of commercial operations.
