// Long-term Safety Studies

TEE

Investigation on thermal expansion effects in clay formations

At the Mont Terri URL, a heater test named HE-D has been performed to analyse the THM rock mass behaviour. A couple of observation boreholes have been drilled and equipped with sensing devices for temperature, pore water pressure and deformation measurement. The obtained measurement results during the entire test together with laboratory investigations on drill core samples provided a huge data set, which enables for numerical back analysis. During thermal and hydraulic modelling a good fit of calculation and measurements has been achieved, and a plausible parameter set for the rock behaviour has been found. At the Bure URL a vertical mine-by test, the so-called REP experiment, has been performed, aimed at characterizing the hydro-mechanical response of the Callovo-Oxfordian Clay formation due to the ongoing shaft sinking. Analogous to the test at Mont Terri, a huge amount of data has been obtained from observation boreholes. This enables for verification of significant effects and processes and validation of parameters within numerical simulations. A comprehensive understanding of the HM-behavior has been achieved during predictive and interpretive modelling.