For decades, we have treated used nuclear fuel as high-level waste to be buried and forgotten. Now, scientists and energy experts are asking a fundamental question: What if we recycle that waste as an untapped power source-
Rising global demand for nuclear energy, coupled with enabling technologies such as AI, has created an opportune time to reinvent fuel recycling and "close the nuclear fuel cycle," said Amanda Lines, an expert in nuclear fuel processes and monitoring technologies at Pacific Northwest National Laboratory (PNNL).
The nuclear fuel cycle spans every stage in the life of nuclear material, from uranium mining and electricity generation to used fuel management. By "closing" this cycle through advanced recycling, potentially reusable materials can be separated from used fuel and fabricated into new reactor fuel, minimizing waste and environmental impact.
The Power Left Behind
Used nuclear fuel - sometimes called "spent" fuel - contains a complex mixture of radioactive elements, leftover fissile material, and chemical byproducts. Researchers at PNNL are working to unlock its remaining energy potential through nuclear fuel recycling, a suite of chemical and physical processes that recover materials for reuse as reactor fuel or other industrial applications.
The goal is to develop more effective methods to recover usable materials, both to reduce long-term waste and to help fuel the next generation of nuclear reactors.
Yet the challenge of managing used fuel is only part of the story. Just beneath the surface lies a surprising truth: the fuel we once called "spent" still holds enormous potential.
Today's commercial nuclear power plants remove fuel not because all the energy is gone, but because the buildup of byproducts reduces reactor efficiency. Much of today's used fuel still retains more than 90 percent of its original energy-producing potential. However, recovering a substantial share would require advanced recycling technologies and reactors designed to use recycled materials.
"We are reimagining the entire nuclear fuel cycle," Lines said. "That means studying how fuels behave under irradiation, how used materials change over time, how best to recover valuable components and how to contain what remains."
Sponsored by the Department of Energy (DOE)'s Office of Nuclear Energy, PNNL studies over the past several decades have explored how innovations in chemistry, materials science and safeguards are redefining what fuel recycling can look like.
Genesis Mission Takes On Fuel Recycling
Nuclear fuel recycling received a recent boost when DOE announced Phase I funding awards for the Genesis Mission. The initiative brings together national laboratories, industry and universities to use artificial intelligence to advance scientific discovery, energy innovation and national security.
One of the funded projects, "AI-Driven Co-Optimization of Closed Fuel Cycles: Balancing Economics, Security, and Waste," is a collaboration among the lead institution Colorado School of Mines with PNNL and materials-informatics company Citrine Informatics. The project will develop AI-assisted tools for evaluating fuel-cycle designs and operating strategies across three interconnected considerations: cost, security, and waste generation.
During the first phase, researchers will build a prototype and assess whether it can accelerate analyses, evaluate more scenarios, and provide better information for decision-makers.
The Genesis project builds on PNNL-led research that brings together specialists from several fields to address the economic, security, and waste-management challenges of nuclear fuel recycling. Recent examples include:
Balancing Cost, Security and Performance
Even with scientific advances, the future of fuel recycling depends on more than technology alone. Economic realities and security considerations continue to shape whether - and how - these processes are adopted.
France, for example, operates one of the world's largest commercial reprocessing programs, while other countries, including Japan, have pursued various recycling strategies. Although several countries reprocess spent fuel, the United States largely adopted a "once-through fuel cycle" in the 1970s because of policy and nuclear nonproliferation concerns.
Fuel recycling is not a single technology, Lines notes. Several pathways exist, each suited to different reactor types and material streams. The suitability of each method depends on the fuel's composition and physical form, the materials to be recovered, the reactor in which they might be reused and the desired waste forms.
Economic and security goals often overlap, and they represent two major challenges:
PNNL teams analyze how materials behave at the microscopic and atomic levels, test new extraction chemistries and design waste forms, such as durable glass that securely contains radioactive elements for millennia.
For more than 60 years, PNNL scientists and engineers have worked with and studied nuclear materials. Today, research at PNNL spans every stage of a fuel's life cycle: development, reactor performance, recycling, waste management, materials science, safety, and modeling.
For example, the Radiochemical Processing Laboratory allows researchers to work safely with radioactive materials. Sophisticated computer modeling helps assess fuel-cycle options, forecast waste behavior, and inform regulatory planning. And increasingly, scientists are using AI and machine learning to interpret complex data and accelerate discovery.
Supporting Next-Generation Reactors
Support for next-generation reactors will progress in stages. Because many of their fuels have different compositions and higher enrichments, advanced reactor designs could increase interest in recycling by enabling the use of fuel streams that conventional reactors cannot use.
Some recycled nuclear materials may have potential applications in isotope production for medical, industrial or scientific uses, although energy production remains the primary focus of most fuel recycling efforts. Looking further ahead, certain isotopes could support deep-space missions that require compact, long-lasting power sources.
The long-term vision includes integrated systems in which advanced reactors and recycling facilities operate together - maximizing resources, minimizing waste, and delivering reliable energy.
"This is one pathway to strengthening the long-term fuel supply and operational resilience of advanced reactor systems," Lines said.
A Different Future for Used Nuclear Fuel
As these technologies mature, they're reshaping not only science and engineering conversations but also public discourse. The growing emphasis on energy security and resource stewardship is opening the door to a broader reconsideration of how used nuclear fuel can be used.
Public views of nuclear energy are shifting. In recent years, support for nuclear power plants has grown. According to a 2025 Pew Research Center survey, 59% of U.S. adults now say they favor more nuclear power plants to generate electricity.
PNNL's work reflects that shift. By demonstrating that used fuel contains materials that may be recovered, reused or repurposed through advanced recycling technologies, rather than being treated solely as waste, research is laying the scientific and technological foundation for a safer, more efficient and more sustainable nuclear future.
"The promise of nuclear fuel recycling is not only about producing more energy," said Lines. "It is about strengthening America's energy security, supporting scientific advances, and redefining what spent nuclear fuel can become."