Technology and Policy Aspects of Deep Borehole Nuclear Waste Disposal

The use of deep boreholes for the disposal of high-level radioactive waste is reassessed, emphasizing key enabling technical features and their strong linkage to national and international fuel cycle policy. Emplacement 2 to 4 km deep in widely available granitic continental bedrock, under a 1-km caprock layer of high-integrity bedrock, is shown in this analysis to have the potential to provide sufficiently low host rock permeability to prevent radionuclide escape by transport in water - the only plausible release mechanism. The modular nature of the concept enables multiregion siting in large user countries and is especially well-suited for small-user nations. Irretrievability can be built-in to better meet safeguards objectives, and the exceptionally high assurance of confinement makes the disposal of minor actinides (and troublesome fission products) an attractive alternative to their destruction by transmutation.