The concept of highly radioactive waste (HLW) disposal in very deep boreholes in a new perspective

Two basically different concepts for disposal of highly radioactive waste are the often cited KBS-3 method and a concept termed VDH (Very Deep Boreholes). So far, the deep hole concept has been ranked as number two because the canisters are not assumed to be retrievable and because some of the techniques for installation of the waste are not yet at hand. Reconsideration of the design and function of VDH shows that, in addition to the advantage of no transport of released radionuclides by groundwater flow up to the ground level because of the almost stagnant salt groundwater at depth, the rock at depth is considerably less permeable than for mined repositories at shallow depth. A further advantage is that VDH will be less affected by future glaciations. Less good is that precise adaption of canister and seal positions to the rock structure cannot be made until boring of the deep holes is complete. Furthermore, the deep holes need to be supported by casings and all work deeper than 500 m must be made with mud in them. Retrieval of damaged casings and stuck canisters may be more difficult than in mined repositories.Validerad; 2013; 20121210 (mohhat)