Chalmers University of Technology discusses the importance of a closed nuclear fuel cycle in enhancing sustainability by recycling spent nuclear fuel, allowing for more efficient use of uranium and improved waste management. As the global energy system moves toward low-carbon solutions, nuclear power plants continue to play a role by delivering large-scale, reliable electricity with minimal operational carbon emissions. In Sweden, nuclear energy has long been a key component of the electricity system, accounting for about 30% of total electricity production in 2024. Globally, nuclear power contributed approximately 9% to electricity generation that same year.¹ A promising development for Sweden’s energy future is small modular reactors (SMRs), supported by the ANItA initiative, which links academia and industry to provide knowledge-based decision support. This article explores key questions on the closed nuclear fuel cycle, aligning with Anita’s vision.² What is spent nuclear fuel? During nuclear reactor operation, fuel produces energy while building up fission products and heavier elements like plutonium. The time fuel spends inside the reactor, called residence time, varies depending on reactor type, fuel …