Mass Transfer & Porous Media (MTPM) - Andra

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P/MTPM/10Figure 1: Horizontal cross section of the norm of the Darcy velocity for the RTN (left) and KR (right)mixed finite elements..References:[1] D.N Arnold, D.Boffi and R.S.Falk : Approximation by quadrilateral finite elements, Mathematics ofcomputation, Vol. 71, Number 239, pp. 909-92, 2002.[2] D.N Arnold, D.Boffi and R.S.Falk : Quadrilateral H(div) finite elements, SIAM J.Numer. Anal. Vol.42, No. 6, pp.2429-2451, 2005.[3] Yu. Kuznetzov and S. Repin : New mixed finite element method on polygonal and polyhedral meshes,Russ. J. Numer. Anal. Math. Modelling, Vol. 18, pp. 261-278, 2003.[4] Yu. Kuznetsov and S. Repin : Convergence analysis and error estimates for mixed finite elementmethod on distorted meshes, Russ. J. Numer. Anal. Math. Modelling, Vol. 13, pp. 33-51, 2005.[5] R. L. Naff, T. F. Russell, and J. D. Wilson : Shape functions for velocity interpolation in generalhexahedral cells. Comput. Geosci. Vol 6(3-4), pp. 285-314, 2002.[6] A. Sboui, J.E. Roberts and J. Jaffré : A mixed finite macroelement for distorted hexahedral grids, inpreparation.[7] J.Shen : Mixed Finite Element Methods on Distorted Rectangular GridsTechnical report Institute forScientific Computation, Texas A\&M University, College Station, 1994.Page 442INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENT
P/MTPM/11DIFFUSIVE PROPERTIES OF STAINLESSSTEEL FILTER DISCS BEFOREAND AFTER USE IN DIFFUSIONEXPERIMENTS WITH COMPACTED CLAYSM.A. Glaus, R. Rossé, L.R. Van LoonLaboratory for Waste Management, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.INTRODUCTIONPorous stainless steel filters are frequently used for the purpose of confining compacted samples ofexpanding clays in diffusion studies. The typical sandwich-type of arrangement applied, viz. filter–clay–filter, allows for an even contact to be made between the liquid phase and the clay. For a proper evaluationof the diffusion coefficients of the clay it is important to know the diffusive properties of these filters.Depending on the geometrical differences in the pore structure of the filters and the clays, the diffusiveresistance of the filters may be negligible in some cases. However, if the permeability of the filter discs isof similar order of magnitude as the one of the clay, the filter disc has a significant impact on the tracerconcentration at the clay boundaries. Neglecting this effect may lead to an underestimation of diffusioncoefficients of the clay.In recent work (Glaus et al., 2007) we described diffusion measurements, where the diffusive resistanceof the clay was a function of the salt concentration in the liquid phase contacting the clay. Such casesrequire a sufficient knowledge of the diffusive properties of the filters and a careful optimisation of thedimensions of clay and filters. Otherwise such experiments may not be carried out in reasonable time andwith adequate accuracy.In the present contribution measurements of the diffusive properties of porous stainless steel filters arereported for a series of diffusants before and after use of the filters for diffusion experiments with differentclay minerals. The results are discussed in the light of optimisation of the experimental setup and theimpact of the uncertainties in the filter properties on the overall uncertainties involved in the calculationof the diffusion parameters of the clays.EXPERIMENTALThrough-diffusion measurements were carried out using in-house manufactured acrylic glass two-chamberdiffusion cells, in which the chambers were separated by the filter disc. The filter discs were laterallysupported with FKM-elastomer flat seals in order to prevent advective transport along the filters or liquidloss from the diffusion cells. Filters were either used as received from the manufacturer or taken from thediffusion experiments with the various clays as described in Glaus et al . (2007) after being in contact withthe Na-montmorillonite ( Na-mom), Na-illite ( Na-ill), or kaolinite ( kao ) for a minimum of 50 days up to400 days at a dry density of ~1950 kg m -3 . Diffusion was started by adding a concentrated solution of thediffusant under study to one of the chambers. HTO and 22 Na were used as radioactive tracers, whereas thediffusion of Sr and Cs was measured using stable isotopes.RESULTS AND DISCUSSIONFigure 1 shows a comparison of breakthrough curves for the through-diffusion of Sr through a filter used asreceivedand others after being previously used in diffusion experiments with various clays. For the filterused as received an effective diffusion coefficient for diffusion in the filter, D f , of (1.1 ±0.1)·10 -10 m 2 s -1 wascalculated, whereas this value was reduced to (0.61 ±0.02)·10 -10 m 2 s -1 for Na-mom, (0.50 ±0.04)·10 -10 m 2 s -1for Na-ill and (0.79 ±0.02)·10 -10 m 2 s -1 for kao . Two explanations are feasible for the increased diffusiveresistance of used filter discs: (i) the mechanical stress of the expanding clay or (ii) small clay particlesINTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENTPage 443
Page 1: Poster [MTPM]Mass Transfer & Porous
Page 4 and 5: P/MTPM/1The free energy cost of for
Page 7 and 8: P/MTPM/3DIFFUSION OF IONS IN UNSATU
Page 9: P/MTPM/4POROUS MEDIA CHARACTERIZATI
Page 12 and 13: P/MTPM/5Oxalate ionsQuartzQuartz +P
Page 14 and 15: P/MTPM/6borehole was capped with a
Page 16 and 17: P/MTPM/7Initial state with glass an
Page 18 and 19: P/MTPM/8The mesh of the elementary
Page 20 and 21: P/MTPM/9Moreover, using another sam
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
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P/MTPM/350.50η R ()0.400.300.200.1
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P/MTPM/36200Bq/g1801601401201008060
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P/MTPM/37Argilite (ionic strength 0
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P/MTPM/38-Samples cored at 12m were
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P/MTPM/39APPLICATIONSCORE 2D has be
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P/MTPM/40Figure 1: Sketch drawing o
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P/MTPM/41Figure 1: Thermal conducti
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P/MTPM/42Figure 2: Model of pore st
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P/MTPM/43The available data are con
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P/MTPM/44Figure 1: Spatial extensio
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P/MTPM/45Relative concentration / (
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P/MTPM/46Figure 2: Swelling pressur
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P/MTPM/47then used in the transport
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P/MTPM/4820181614121086Gas pressure
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