Mass Transfer & Porous Media (MTPM) - Andra

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P/<strong>MTPM</strong>/36200Bq/g18016014012010080604020profilesatdifferentdistances~4.5cm~7.5cm~10.5cm0-30 -25 -20 -15 -10 -5 0cmFigure 1: Experimental concentration profiles of HTO (left) and 2-D finite element grid used for modellingexperiments (right). Tracer is emplaced at the central green area.ACKNOWLEDGEMENTSThis work has been funded by ENRESA and EU within FUNMIG (FUNdamental Processes ofradionuclide MIGration) Project (Ref. FP6-516514). Partial funding for UDC contribution has beenobtained also from Spanish Ministry of Science and Technology (CICYT Projects HID98-282 and REN2003-8882), Xunta de Galicia (Incentive PGIDT05PXIC11801PM) and University of La Coruña througha research scholarship awarded to Q. Yang.References:Dai Z. and J. Samper. (2004), Inverse problem of multicomponent reactive chemical transport in porousmedia: Formulation and Applications Water Resources Research, Vol. 40, W07407, doi:10.1029/2004WR003248.García-Gutiérrez, M., Cormenzana, J.L., Missana, T., Mingarro, M., U. Alonso, , J. Samper, Q. Yang,(2007): Diffusion experiments in Callovo-Oxfordian clay from the Bure site, France: 1. Experimentalsetup and data analyses.Samper, J., Yang, C., Naves, A., Yllera, A., Hernández, A., Molinero, J., Soler, J.M., Hernán, P., Mayor,J.C. & Astudillo, J. (2006) A fully 3-D anisotropic numerical model of the DI-B in situ diffusionexperiment in the Opalinus Clay formation. Physics and Chemistry of the Earth 31, 531-540.Page 494INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENT
P/<strong>MTPM</strong>/37AN EXPERIMENTAL PROTOCOLFOR THE INVESTIGATION OF DIFFUSION OFIONS THROUGH ARGILLACEOUS BARRIERSM.A.M. Kedziorek, A.C.M. BourgEnvironmental HydroGeochemistry (LHGE), Université de Pau et des Pays de l’Adour, Pau,France (monika.kedziorek@univ-pau.fr)INTRODUCTIONRepositories for radioactive wastes will involve a series of barriers to retard the potential dissemination ofradionuclides towards the Hydro- and Bio-spheres. Clays are sought to achieve this objective for both nearfieldand far-field environments because of their low permeability and high adsorption capacity. In theANDRA approach the barriers investigated are compacted MX80 bentonite and Callovo-Oxfordian argilite,the first as added clay and the second as host rock formation.EXPERIMENTALIn order to investigate diffusive radionuclide transport in argillaceous barriers, we developed anexperimental set up which permits either through-diffusion or in-diffusion experiments. Typically, forthrough-diffusion experiments, the sample is set in a cell at the desired dry density, between two porousplates. Water is circulated through the porous plates (Figure1), the concentration of the element of interestis followed as a function of time in the upstream and downstream reservoirs.RESULTSTwo types of solids were investigated: MX80 bentonite and argilite (Callovo-Oxofordian). In a first step,the diffusion studies were performed on untreated raw bentonite, and subsequently to obtain representativeconditions more rapidly (concerning ionic strength and pH) the bentonite samples were pre-equilibrated forthe specific conditions before the experiments. The argilite samples were used, as delivered, under oxygenfreecontrolled atmosphere.Four elements (Cs, Ni, Pb, Se) were investigated for conditions either controlled by the argilite(compaction, pH) or imposed on the bentonite (pH, ionic strength, dry density) (Figure 2).Effective diffusion coefficients (De) were determined and discussed.Upstreamporous plateDownstreamporous plateClay plug (reactivetracers diffusethrough)Upstream solution(NaNO 3 + reactive tracers)Figure 1: Schematic description of the experimental set up.Downstreamsolution (NaNO 3 )INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENTPage 495
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Poster [MTPM]Mass Transfer & Porous
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P/MTPM/1The free energy cost of for
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P/MTPM/3DIFFUSION OF IONS IN UNSATU
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P/MTPM/4POROUS MEDIA CHARACTERIZATI
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P/MTPM/5Oxalate ionsQuartzQuartz +P
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P/MTPM/6borehole was capped with a
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P/MTPM/7Initial state with glass an
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P/MTPM/8The mesh of the elementary
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P/MTPM/9Moreover, using another sam
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P/MTPM/10Figure 1: Horizontal cross
Page 24 and 25: P/MTPM/11n t (mol)as received8 10 -
Page 26 and 27: P/MTPM/1210,9Degree of saturation (
Page 28 and 29: P/MTPM/13RESULTSFirst, we estimated
Page 30 and 31: P/MTPM/142.5Energy (M eV)1.6 1.7 1.
Page 32 and 33: P/MTPM/15C/Co10.90.80.70.60.50.40.3
Page 34 and 35: P/MTPM/16ModelIrmayvG-M1vG-M2vG-M3T
Page 36 and 37: P/MTPM/17Figure 1: Experimental HTO
Page 38 and 39: P/MTPM/18Diffusion experiments were
Page 40 and 41: P/MTPM/19Figure 1: Used mesh for co
Page 42 and 43: P/MTPM/201.81.61.41.2upstream compa
Page 44 and 45: P/MTPM/21490Pressure [bar]0 10 20 3
Page 46 and 47: 134P/MTPM/22through-diffusion exper
Page 48 and 49: P/MTPM/23HA (µg/g)3002001000(a):pH
Page 50 and 51: P/MTPM/24through each sample. The p
Page 52 and 53: P/MTPM/25FIRST RESULTSPreliminary c
Page 54 and 55: P/MTPM/26heterogeneous distribution
Page 56 and 57: P/MTPM/27Relative concentration (C-
Page 58 and 59: P/MTPM/280.75m0.25mTable 1: Cross s
Page 60 and 61: P/MTPM/29Figure 1: A. Scheme of the
Page 62 and 63: P/MTPM/30The presented theory is ex
Page 64 and 65: P/MTPM/31Furthermore, Van Loon et a
Page 66 and 67: P/MTPM/32RESULTSResults show that,
Page 68 and 69: P/MTPM/33Clay modellingPore size di
Page 70 and 71: P/MTPM/341.60E-11f H2-d total (kg.m
Page 72 and 73: P/MTPM/350.50η R ()0.400.300.200.1
Page 76 and 77: P/MTPM/37Argilite (ionic strength 0
Page 78 and 79: P/MTPM/38-Samples cored at 12m were
Page 80 and 81: P/MTPM/39APPLICATIONSCORE 2D has be
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Page 84 and 85: P/MTPM/41Figure 1: Thermal conducti
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Page 88 and 89: P/MTPM/43The available data are con
Page 90 and 91: P/MTPM/44Figure 1: Spatial extensio
Page 92 and 93: P/MTPM/45Relative concentration / (
Page 94 and 95: P/MTPM/46Figure 2: Swelling pressur
Page 96 and 97: P/MTPM/47then used in the transport
Page 98: P/MTPM/4820181614121086Gas pressure
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