In order to safely dispose of the high-level radioactive waste (HLW), R&D guide of HLW disposal was published in February 2006 in China. The spent fuel from nuclear power plants will be reprocessed first, followed by vetrification and final disposal. A conceptual repository 3D configuration comprises a single vertical borehole in a continuous and homogeneous hard rock, containing a canister surrounded by an over-pack and a bentonite layer, and the backfilled upper portion of the gallery using FLAC3D. To take into account in situ stress, geothermal gradient and groundwater of Beishan area, thermal relief of HLW and swelling pressure of buffer/ backfill material made by GMZ01 bentonite, the TM, HM and THM evolution of the whole configuration is simulated over a period of 100 years. The results demonstrate that temperature is hardly affected by the couplings. In contrast, the influence of the couplings on the mechanical stresses is considerable. The repository has long-term stability in fully THM coupling action condition.
Safe disposal of high-level radioactive waste (HLW) and spent fuel (SF) is an important factor for the sustainable development of nuclear power. The basic concept for deep geologic disposal is encapsulation of the spent fuel or other waste in geologic formations such as salt, hard rock, or clay (Fairhurst 1999). The United States Department of Energy (DOE), Atomic Energy of Canada Limited (AECL), Swedish Nuclear Waste Storage (SKB), and National Agency for the Control of Radioactive Wastes (ANDRA) et al. are taking the multi-barrier deep geologic disposal approach, though they differ slightly in the barrier being selected (Wang 2006a).
China commenced its deep geological disposal of HLW programme in 1985 when a Coordination Expert Group for the HLW Geological Disposal was established under China National Nuclear Corporation. R&D guide of HLW disposal was published in February 2006 (CAEA 2006). The spent fuel from nuclear power plants will be reprocessed first, followed by vetrification and final disposal. The preliminary concept of geological disposal of HLW will be a shaft-tunnel model based on a multi-barrier system, located in saturated zones in granite. It takes the preselected Beishan area located in Gansu province as the research background and GMZ01 bentonite as the buffer material.
Heat generated from the waste in the repository will result in an increase in rock temperature and the rock mass tends to expand. Chan and Reid (1987) developed a three dimensional finite-element code, MOTIF (Model Of Transport In Fractured/porous media) to model the coupled processes of groundwater flow, heat transport, brine transport, and one-species radionuclide transport in geological media of Canadian Shield. Lee (Lee 1994) evaluated the thermo-mechanical stability of a rock mass around a nuclear fuel waste disposal vault which is to be located in a granitic pluton in the Canadian Shield based on computational methods and field observations. Hudson et al. reviewed coupled T-H-M issues relating to radioactive waste repository design and performance (Hudson 2001).