The coupled calculation in near field of a Hlw deep geological disposal repository

Long-term safety disposal of high-level radioactive waste (HLW) is a very urgent item in peace utilization of the atom energy is the world. The method of deep geological disposal is regarded as a suitable one to disposal HLW. It is very important to do the research of thermo-hydro-mechanical (THM) coupled process associated with HLW disposal repository. The 3-D coupled equations, which are used to descript THM coupled process and suit to saturated-unsaturated porous media, are given out in this paper. The initial condition and two kinds of stress boundary condition, two kinds of hydraulic boundary condition and three kinds of temperature boundary condition are introduced. The finite element method with mid-interval backward difference scheme and the predictor-corrector solute is used to solve these nonlinear full-coupled equations. The finite element code, which is based on above THM coupled equations and its numerical method, is developed by the authors. This code is suit to the plane strain or axis-symmetry problem. Then, the code is used to simulate the THM coupled process in the near field of a certain ideal HLW disposal repository. The data on temperature distribution vs. time, water head vs. time and stress vs. time after the closure of disposal repository are presented. The results show that, in such assumed condition, the impact of temperature is much longer (over 10 000 years) in near field of a certain HLW disposal repository and the impact of water head is much shorter (about 1 year). Since the stress is induced by temperature and water head in this condition, the impact time of stress is just as that of temperature. (author)