Coupled flow of heat and moisture through compacted geomaterials

A deep geological repository, DGR is an underground disposal facility for the safe disposal of high-level radioactive wastes. In DGR, the radioactive waste is vitrified and placed in metallic canister, which is encrusted with a thick layer of engineered geomaterial called buffer material. As the radioactive waste generates moderate amount of heat due to its decay, a thorough performance evaluation of the buffer material demands the knowledge of their thermal properties and rate of moisture loss. With this in view, it is proposed to investigate the coupled flow of heat and moisture. Experimental study involves imposing heat flux to the buffer material using a constant heat source representing radioactive waste contained canister. Thereby, the soil near the vicinity of the heat source is subjected to a higher temperature when compared to the rest, causing heat and moisture migration from the surface of the heat source towards the periphery. From the spatial and temporal variation of temperature and relative humidity (RH) obtained experimentally by means of deploying sensors over varying depth and radial distance, the vapor flow within the system is demonstrated in terms of its isothermal vapor diffusion coefficient.