Nuclear transmutation: an alternative to waste disposal?

Recent advances in nuclear technology have rekindled interest in transmutation as part of a circular nuclear fuel economy. Rather than treating spent fuel as waste, this approach views it as a resource: long-lived radionuclides — particularly plutonium and minor actinides such as neptunium, americium, and curium — can in principle be recycled and transformed into shorter-lived or stable isotopes through neutron-induced reactions in fast reactors (such as, e.g., molten salt reactors) or accelerator-driven systems (ADS). Within such a closed fuel cycle, partitioning and recycling enable repeated use of fissile material, extracting significantly more energy from the original uranium while reducing the long-term radiotox-icity of the remaining waste. In this sense, transmutation is not a stand-alone solution but an integral component of a system designed to minimize material losses and environmental impact, aligning nuclear energy more closely with broader principles of resource efficiency and sustainability. As a result, requirements for final geological disposal could be substantially eased, with smaller repository footprints and shorter timescales for safe isolation. For Switzerland (and most nations employing nuclear power as part of their energy mix), this would imply a shift from the current once-through strategy toward a circular framework, potentially integrat-ing advanced reactor systems into a future low-carbon energy mix. In the context of a nuclear re-naissance, transmutation thus represents a pathway toward closing the fuel cycle while reducing the legacy burden of radioactive waste.