Alternative Disposal Options for High-Level Radioactive Waste

Abstract. Are alternatives to the disposal of high-level radioactive waste in a geology repository conceivable? We present the results of the first phase of a research project on the state of the art in science and technology for alternative disposal options. The project is financed by the Federal Office for the Safety of Nuclear Waste Management. Most recently, in 2015, the German Commission on the Storage of High-Level Radioactive Waste (Endlagerkommission) evaluated possible disposal technologies and classified them as either promising, conceivable, or to be pursued further. Only final disposal in a geological repository was considered promising. Conceivable, but not immediately available or not advantageous, were storage in deep boreholes (DBs), long-term interim storage (LTIS), and partitioning and transmutation (PT however, this also postpones the disposal issue indefinitely into the future with undetermined methods. DB storage would involve sinking the storage containers into boreholes with depths of up to 5000 m. This could reduce the expense and be particularly advantageous for smaller inventories, although the potential for the use of engineered barriers would be limited and retrievability precluded according to the current state of the art in science and technology. P&T is primarily intended to separate long-lived transuranic elements from high-level radioactive waste and then convert them to short-lived fission products by neutron irradiation in reactors. The main goal is to reduce the necessary containment times in the repository by changing the inventory, but the effort to treat the waste would be significant and a repository for high-level nuclear waste is still needed. More exotic ideas for alternative disposal include deep geological injection of liquid waste, waste forms that melt themselves into rock, storage inside the ocean floor or subduction zones, shipment to space, burial in ice sheets, or dilution in the atmosphere and oceans. None of these exotic options is currently being actively pursued.