P/<strong>MTPM</strong>/33Clay modellingPore size distributionDe=f(clay, pore water) %i600 mEffective diffusioncoefficientCartographie minérale(Microsonde LIBS, MEB)DeArgiliteDe (HTO)Figure 1: Up-scaling method.References:[1] F. Goutelard, N. Diaz “How to define the major parameters controlling diffusion behaviour of anionicspecies in clayey rock ? The use of an Experimental design” submitted to Journal of ContaminantHydrology.[2] Menut, D., Descostes, M., Meier, P., Radwan, J., Mauchien, P., Poinssot, C. Europium Migration inArgilaceous Rocks: On the Use of Micro Laser-Induced Breakdown Spectroscopy (Micro LIBS) as aMicroanalysis Tool, in Scientific Basis for Nuclear Waste Management XXIX (Mater. Res. Soc. Symp.Proc. 932), 141. (2006)Page 488INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENT
P/<strong>MTPM</strong>/34NUMERICAL MODELLING OF COUPLEDMECHANICS AND GAS TRANSFERP. Gerard 1 , R. Charlier 1 , J.-D. Barnichon 2 , J.-F. Shao 3 , G. Duveau 3 , D. Hoxha 4 ,C. Chavant 5 , F. Collin 11. Université de Liège, département ArGEnCo, Chemin des Chevreuils 1, 4000 Liège, Belgium( pgerard@ulg.ac.be , Robert.Charlier@ulg.ac.be , F.Collin@ulg.ac.be )2. ANDRA, ( jean-dominique.barnichon@andra.fr)3. Université de Lille ( jian-fu.shao@polytech-lille.fr , gillesduveau@yahoo.fr)4. INPL ( dashnor.hoxha@ensg.inpl-nancy.fr )5. EDF ( clement.chavant@edf.fr )INTRODUCTIONDuring long-term storage of high-level nuclear waste, steel containers will be corroded and some organicmaterial will be irradiated. The two processes lead to hydrogen production. This paper deal with thenumerical modelling of the gas migration and of it’s coupling with the mechanical strains and stresses.The basic equations are recalled. They concern the water transfer, the gas transfer, and the mechanicalequilibrium. The storage of water and gas are related to fluid state equation and to porosity changes,including the Biot effective stress, dissolved gas in liquid, water vapour. Perfectly rigid rock, elastic rockand elastoplastic rock cases are compared.A benchmark exercise has been proposed. Two steps are considered. They refer to a waste disposal in clay,but the disposal geometry is highly simplified. First a simple 1D radial problem is considered: a gallery of0.35m radius is drilled. Then the state of stress and the water transfers evolve freely during 2 years.Eventually a gas production is considered during 100 000 years. Three different finite element codes(LAGAMINE, MPPSAT and ASTER) have been used and give very similar results, what is a validationof these codes. Secondly a 2D axisymetric case in modelled (figure 1). Different material properties arehere concerned.The results show that transport of gas in dissolved phase is the most important phenomenon. The waterboundary condition plays also an important role. This remains an open question (Gerard et al, 2007). Thegas degree of saturation is very low and may induce some numerical difficulties. A classical way toL*HRemblairR1Vide : épaisseureR2ZBouchonde bétonBouchond’argileColisLa Lb Lc Ld/2Figure 1: 2D case – geometry.INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENTPage 489