Mass Transfer & Porous Media (MTPM) - Andra

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P/<strong>MTPM</strong>/37Argilite (ionic strength 0.001 M)90008000700060005000400030002000100000 50 100 150 200 250time (days)Cs (ppb)Ni*10 (ppb)Pb (ppb)Se/10 (ppb)Figure 2: Through diffusion with argilite.ACKNOWLEDGEMENTSThis work was funded by ANDRA.Page 496INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENT
P/<strong>MTPM</strong>/38GAZ PERMEABILITY OF AN ARGILITE :MEASUREMENTSAND PARAMETERS IDENTIFICATIONL. Malinsky , H. Gharbi and P. ValliLaboratoire de Mécanique des Solides, Ecole Polytechnique, F-91128 Palaiseau(malinsky@lms.polytechnique.fr)INTRODUCTIONThe effects of gas production due to metal corrosion in a radioactive waste disposal is an important issue.Depending on both rock behavior and corrosion rate, the gas can escape by diffusion in water or waterdisplacement if the capillary pressure reaches the gas entry pressure. If the gas pressure reaches thegeostatic stress, rock fracturation could occur. In this paper we present results of gas permeability testsperformed under various hydric and mechanical loading on argilite samples cored at different distances ofthe access well of the future ANDRA URL at Bure.EXPERIMENTAL PROGRAMMTwo kind of permeability test are performed in order to investigate the gaz permeability and gaz entrypressure of argilite samples at different water contents and confining pressures. A first device consists inunconfined gaz permeability tests on hollow cylinders. The experimental set-up is a tight box in whichrelative humidity is imposed by saline solutions. Two hollow rock cylinders are tested simultaneously. Gascan be injected in the inner cavities when permeability tests are performed. Gas pressure can be imposedby the mean of an electrovalve, and flow rates as low as a few mg/h are measured. One sample can beuniaxially mechanically loaded and the other is continuously wheighted. Strains are also measured indifferent directions on the samples surface. Permeability tests are performed at hydric equilibrium. In a firtstep, pressure is suddenly built up in the cavity and held constant. The transient flowrate analysis providea linearized apparent permeability and a gas porosity. Gas pressure is then built up step by step up to0.6MPa in order to investigate permeability evolution according to gaz pressure. In a last step, the samplecavity is insulated. The subsequent pressure decay is analysed to identify the intrinsic permeabiliy and theKlikenberg coeffcient. Both the Simplexe algorithm (Nelder et al. ,1965) and the Levenberg-Marquardalgorithm are used to carry out the parameters identification in transient tests. In low permeability porousmedia, Klikenberg effect and Knudsen diffusion cannot be neglected. Moreover the gas viscosity is poorlydependent on the gaz nature contrary to the Klikenberg parameter or Knusdsen diffusion coefficient.Differents gases (Helium and Nitrogen) are used to discriminate between the microscopic transferphenomena.The hollow cylinder being unconfined it is possible that, at some water content, the gas entry pressureovercome the tensile unconfined sample strength, making impossible a permeability measurement : tensilestress of 2 to 5MPa have been measured in this study whereas gaz entry pressure as high than 10MPa maybe expected (Thomas et al. 1968, Marcshall et al 2005) Confined axial permeability tests in a triaxial cellhave been performed to investigate this issue.RESULTSPermeability tests have been tests have been performed on samples cored at 1m to 4m and at 12m fromthe well wall which is 6.3m in diameter. The following partial conclusions can been drawn :– Samples cored at 1m to 4m were initially fractured. Because the preferential pathways are individualfractures at the sample scale we cannot deal with a sample permeability, but in-situ testing would bemore relevant to identify the fracture network.INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENTPage 497
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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
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P/MTPM/11n t (mol)as received8 10 -
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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 74 and 75: P/MTPM/36200Bq/g1801601401201008060
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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
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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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