(GRS 224) Thermal Effects on the Opalinus Clay

From October 2003 to December 2005, a joint heating experiment (HE-D) was performed at the Mont Terri Rock Laboratory by ANDRA and GRS to investigate thermal effects on clay formations hosting a repository for high level radioactive waste.
GRS participated in this experiment with in-situ measurements, laboratory experiments, and numerical modelling.
In the HE-D experiment the Opalinus clay was heated up to 100 °C by a heater of 6 m length installed in a horizontal borehole of 300 mm diameter and 14 m length. Two heating phases with power inputs of 650 and 1950 Watts were conducted and followed
by a cooling phase. Responses of the clay rock to the thermal loading were investigated by monitoring the temperature, pore-water pressure, gas migration, and deformation in the surrounding rock with 110 instruments installed in 24 boreholes.
Detailed information is given about the layout of the field test, the instrumentation, and the measurement results.