Thermal-Mechanical-Hydrological-Chemical Responses in the Single Heater Test at the ESF Thermal-mechanical-hy drological-chemical responses in the Single Heater Test at the ESF

Abstract The Single Heater Test (SHT) is conducted in the Exploratory Studies Facility (ESF) to study the thermal-mechanical responses of the rock mass. A set of boreholes were drilled in the test region for conducting a scoping test of the coupled thermal-mechanical-hydrological-chemical (TMHC) processes. The holes for the TMHC tests include elecrncal resistivity tomography (ERT), neutron logging/temperatum, hydrological, and optical multiple point borehole extensometers. A 4-kW heater was installed in the heater hole, and was energized on August 26, 1996. Some observed movements of the water around the heater are associated with a possible dry-out region near the heater. The water that has been moved is more dilute than the in situ ground water, except for the concentration of Ca. This indicates that fractures are the major water pathways, and the displaced water may have reached an equilhiurn with carbonate minerals on the fracture surfaces. No mechanical-hydrological coupling has been observed. The tests are ongoing, and more data will be collected and analyzed