EURAD-HITEC Influence of Temperature on Clay-Based Material Behaviour

Introduction

The HITEC WP has been selected for the first phase of EURAD as the activity “Characterise bentonite/clay-based material evolution under specific conditions to provide data on hydro-mechanical, thermal and chemical behaviour” was identified as a high priority subject in theme 3 (EBS properties, function and long-term performance) phases 1-3 of the roadmap. Furthermore, the theme 4 (Geoscience to understand rock properties, radionuclide transport and long-term geological evolution) topic of “Improved understanding of the influence of temperature on radionuclide migration and representation of effects in geochemical models” was also rated as a medium priority activity.

For the disposal of HHGW it is important to understand the consequences of the heat produced on the properties (and their long term performance) of the natural and engineered clay barriers. Most safety cases (for disposal concepts that involve clay) currently involve a temperature limit of 100°C. Being able to tolerate higher temperature, whilst still ensuring an appropriate safety standard, would have significant advantages (e.g. shorter above ground cooling times, more efficient packaging, fewer disposal containers, fewer transport operations, smaller facility footprints etc.).

This WP has the potential to effectively integrate with the parallel SFC RD&D WP (i.e. interrogate the validity of the currently applied thermal limits and also the accuracy of the assumed waste source term).

GTK performs bentonite wetting experiments and x-ray tomography in collaboration with University of Jyväskylä to study the effects of elevated temperatures on bentonite water uptake.

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