The diverse range of long-lived radioactive wastes without significant heat output specified for deep geological disposal (here termed TRU) pose challenges that are potentially more serious than those from vitrified high-level waste and spent fuel. Despite this, the latter tend to be the focus of R&D in national programmes. Such challenges are particularly severe for the case for countries that are not considering evaporite host rocks or have a volunteering approach to siting and for those with inventories of TRU resulting from reprocessing of spent fuel. While there is little doubt that safe disposal of TRU is feasible, it is tricky to develop a convincing safety case for a site during early stages of characterisation as, compared to HLW/SF, less credit can be taken for robust, long-term performance of current designs of the engineered barrier systems. In order to improve this situation and increase flexibility with respect to host rock properties, two different options are available — improving the conditioning of particular waste streams or improving the overall repository safety concept. Although the former has been a focus for work in some countries (particularly Japan), much less effort has been invested in the latter and hence this will be illustrated by some examples. These options are compared in terms of their pros and cons with respect to practicality of implementation, environmental impact and cost. Additionally, the ease with which the resulting safety case can be supported by demonstrations of key arguments will be discussed, which may indicate the likely degree of acceptance by stakeholders.

This content is only available via PDF.
You do not currently have access to this content.