On the inclusion of high temperature effects in the behaviour of buffer material

Bentonite is considered as the sealing/buffer material in the European Nuclear waste disposal concept due to its high swelling capacity. Therefore, the accurate prediction of the behaviour of the buffer material is crucial for the performance assessment. Consequently the modelling of the thermo-hydraulic behaviour of the buffer material is significant. This paper presents a study of thermo-hydraulic behaviour of a highly compacted bentonite subjected to an elevated thermal load and a hydraulic gradient. This is achieved via the application of a numerical model, COMPASS, which implements a coupled thermo/hydro/mechanical approach to model the behaviour of bentonite subjected to a higher temperature. The experimental work considered for the numerical simulation is a thermo-hydraulic experiment conducted on MX-80 bentonite at a temperature of 85°C in the laboratory of Cardiff University. The model is employed to solve a series of transient problems ranging from 1 day to 30 days and numerical results compared against thermal and hydraulic results from experiment. RÉSUMÉ La bentonite