NUMERICAL SIMULATION OF A THC COUPLED PROBLEM AND ITS LONG-TERM EFFECT ON BENTONITE/GRANITE IN FEBEX TYPE REPOSITORIES
FEBEX-type repositories are composed of bentonite buffer material surrounding the nuclear waste canister and the natural geological barrier system (i.e. granite). Owing to heat generation of the high-level nuclear waste (HLW) canisters, geochemical reactions as well as flow processes can be largely influenced. Quantitative investigation of the long-term effects of such processes (for example dissolution/precipitation) on the hydrological properties (like porosity, permeability) of the bentonite and granite are essential to the long-term safety evaluation. Numerical investigation was undertaken using an object-oriented FEM simulator GeoSys/RockFlow coupling the geochemical simulator PHREEQC to simulate the 2D problem with two apparently different material groups. In the simulation, Modelling results show that with the increase of temperature, the liquid saturation of bentonite near canister decreases. After about one year, the liquid saturation increases gradually and reaches fully saturated state. The steady state downwards flow keeps the bentonite porewater renewing and cannot reach steady state in geochemical reaction. The geochemical reactions are active in the near fields of the canister. Dissolution/precipitation, for instance, occurs mainly in this zone. As a consequence, porosity and permeability of the material change.
M.Xie W.Wang T.Nowak H.Kunz H.Shao O.Kolditz
ZAG, University of Tuebingen, Tuebingen, Germany BGR, Hanover, Germany
国际会议
南京
英文
234-242
2006-05-22（万方平台首次上网日期，不代表论文的发表时间）