Radioactive waste management at the Paul Scherrer Institute, the largest Swiss national research centre

This paper presents the current radioactive waste management practices at the Paul Scherrer Institute (PSI). The PSI contributes to waste related problems in two aspects, namely to the scientific basis of waste management and disposal, and to the practical treatment and storage of radioactive waste. In addition to the tasks of treating on-site generated waste, PSI manages the wastes from medicine, industry, and research throughout Switzerland on behalf of the government. Therefore the Dismantling and Waste Management Section is a part of the Logistics Department at PSI. Proved and accepted methods have to be developed for the safe conditioning and storage of radioactive waste. Various waste treatment facilities exist at PSI. The conditioning facility is dedicated to sorting, compaction by a 120 t press, solidification with special cement, and embedding in concrete. Specialized facilities were constructed for waste from the decommissioning of research reactors. Activated aluminum and its alloys were melted in crucibles and embedded in concrete in a concrete container. After dismantling the structural material of the reactors, it was embedded in concrete in the same manner. For the conditioning of activated reactor graphite, a dedicated method was developed. Graphite was crushed to replace sand in the grout, for embedding radioactive waste in concrete containers. For accelerator waste, a walk-in hot cell equipped with an electrically driven manipulator is available where the highly activated large components (targets, beam dump) can be cut into pieces and embedded in concrete in containers. To guarantee the fulfillment of the demands of the regulators, the Dismantling and Waste Management Section applies an accredited quality management system for the safe collection, conditioning, and storage of radioactive waste.