Evolution of Fracture Permeability in Granite Under Temperature, Confining Pressure and pH Conditions Prescribed

A suite of flow-through experiments in granite fracture is conducted under various temperature, confining pressure, and pH conditions, to examine the evolution of the fracture permeability. The well-controlled experiments are carried out at temperatures of 25 and 90°C, confining pressures of 5 and 10MPa, and pH's of 7 and 11. At 25°C, generally, the fracture permeability decreases with time and reaches a quasi-steady state within a few hundred hours. However, after the temperature is raised to 90°C, the permeability again resumed decreasing throughout the rest of the experimental periods. The higher temperature, confining pressure, and pH are prescribed, the faster evolutions of the fracture permeability are observed. These results may indicate that the near-field rock mass of HLW may become safer with time in terms of solute transport behavior.