Deep Borehole Disposal Options

Many Member States (MS) have responsibility to manage an inventory of intermediate-level waste (ILW) or high-level waste (HLW) for which implementation of a mined geologic disposal facility does not a priori appear as cost effective. This may be because the national inventory of ILW and HLW overall is comparatively small or because a specific, smaller subset of the overall national inventory calls for a disposal solution distinct from a mined geologic disposal. Therefore, Member States with such smaller inventories could benefit from alternative disposal options – options that provide for the same protection levels, while potentially having lower associated programme costs and an earlier implementation. The concept of disposal in a (very) deep borehole considers disposal in a stable geologic formation at depths ranging from several hundred meters – comparable to those of a mined geologic disposal – to depths of several kilometers into the base rock. Such a disposal concept holds promise to address the specific disposal needs outlined above and the feasibility and safety have been previously studied based on generic concepts, albeit only as desktop studies supported by numerical simulations. The global knowledge base would substantially benefit from further developments, to support Member States' strategic decision on whether to pursue deep borehole disposal (DBD) as part of their national disposal programme. A sequence of focused feasibility studies on specific aspects of a DBD programme could also contribute to preparing a first global demonstrator for the deep borehole disposal concept. The planning for such a demonstrator could for example include a characterization borehole, technical demonstration of construction to provide disposal capacity, disposal operations, in-situ verification of disposal conditions, and the closure steps.