ABSTRACTThe HPF project (Hyperalkaline Plume in Fractured rock) at the Grimsel Test Site comprises an underground long-term field experiment in a shear zone, in-situ radionuclide transport experiments, two laboratory core infiltration experiments, sophisticated reactive transport modeling exercises, studies on radionuclide stability and solubility, innovative on-line measurement techniques and development of equipment for high-pH conditions (K-Na-Ca-OH, pH = 13.4 at 15 °C). Results to date indicate a decrease in the overall transmissivity of the tested shear zone over a duration of 2 years accompanied by channeling of flow as evidenced by repeat dipole tracer testing with Na-fluorescein, 82Br, 131I, 24Na, and 85Sr. The associated evolution in fluid chemistry indicates the in situ formation of Ca-Si-hydrates. Tracer transport modeling of dipole tests are based either on a heterogeneous porous medium approach or on discrete fracture models. Reactive transport modeling is achieving reasonable agreement with a laboratory core infiltration experiment. Integral to the project are supporting sorption / stability studies, colloid measurements, and development of analytical and measurement techniques.
Coupling Flow, Heat, and Reactive Transport Modeling to Reproduce In Situ Redox Potential Evolution: Application to an Infiltration Pond
