Numerical Analysis For Coupled Thermo-hydro-mechanical Processes In Near Field Of Nuclear Waste Repository And The Sensitive Analysis Of Parameters Of Buffer Material

With the development of nuclear science, nuclear technique has been widelyused in many fields，such as national defense，industry and medicine, meanwhile,great amount of high-level radioactive waste(HLW) has been produced. Theattention has been devoted to the challenge of how to safely store nuclear waste atpresent. The deep geological disposal is regarded as the most reasonable andeffective way to safely disposal HLW in the world which is based on a multi-barriersystem that combines an isolating geological environment with an engineered barriersystem. Many countries are planning to construct the engineering barrier made bydensely compacted bentonite to dispose HLW at great depth owing to it has highswelling, low permeability and excellent radionuclide adsorptionproperties.Therefore, the research of the mechanism of the nuclear waste repositoryand the parameter sensitivity of the bentonite is very important.In the thesis, on the basis of reading the related literatures, FEBEX in-situ testunder the coupled thermo-hydro-mechanical action is analyzed using code-brightprogram. Based on the above results, the influence of the buffer material parameterson high level radioactive nuclear waste repository in near field is conducted, and themain details are shown as follows:(1) Taking the FEBEX in-situ for geological disposal of high level radioactivenuclear waste as the modeling object, a numerical analysis was carried out by usingcode-bright program.The variation of temperature, saturation degree, the suction, thestress and the displacement in bentonite and rock after the closure of nuclear wasterepository are obtained.(2) The FEBEX in-situ test for geological disposal of high-level radioactivenuclear waste is adopted as the calculation model. By changing the initialpermeability, the initial suction, the initial air entry value and the initial dry densityvalue, the variation of saturation degree, the suction, the stress and the displacementunder the coupled thermo-hydro-mechanical action is analyzed in near field of high level radioactive nuclear waste repository and analyzing the sensitivity of the theseparameters on these traits.Valuable reference is presented for planning, designing of the nuclear wasterepository and the selection of the buffer material.