Mass Transfer & Porous Media (MTPM) - Andra

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P/MTPM/40Figure 1: Sketch drawing of hyperfiltration-induced precipitates in the pore spaces at the high pressureside of samples of low hydraulic conductivity (flow direction is from bottom to top).Figure 2: Sketch drawing of hyperfiltration-induced precipitates in the pore spaces at the high pressureside of samples of low hydraulic conductivity (flow direction is from bottom to top).mass and the conductivity damage strongly increase (Fig. 1). Full reversibility of the hydraulic conductivitydamage was only obtained at low saturations (10 %). This indicates that precipitating minerals cancompletely clog pores. The clogged pores are then inaccessible to solution and the minerals containedwithin are protected from re-dissolution, except from very slow diffusion controlled processes (Fig. 2).Hyperfiltration is thus considered a process which potentially limits the transport of contaminants awayfrom the near-field of leaky radioactive waste containers through mineral precipitation and lowering ofhydraulic conductivity. Experiments with clay membranes are currently under way.Page 502INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENT
P/MTPM/41ARGILLITES THERMAL CONDUCTVITYVARIATIONS INDUCED BY SEDIMENTARY /DIAGENETIC PROCESSESAND BY MECHANICAL DECOMPRESSIONY. Géraud 1 , L. Esteban 1234 , J.L. Bouchez 2 , A. Trouiller 31. Institut de Physique du Globe de Strasbourg, UMR 7516, Université Louis Pasteur-CNRS andGdR CNRS FORPRO, 1 rue Blessig, F-67089 Strasbourg cedex ( ygeraud@illite.u-strasbg.fr )2. Univ. Toulouse, LMTG, 14 Ave E. Belin, 31400-Toulouse and GdR CNRS FORPRObouchez@lmtg.obs-mip.fr3. Andra, Parc de la Croix Blanche, 1-7 rue J. Monnet, 32290-Châtenay-Malabry(alain.trouiller@andra.fr)4. Now at Geological Survey of Canada-Pacific, 9860 West Saanich Road, Sidney, B.C., Canada,V8L 4B2 lesteban@nrcan.gc.caINTRODUCTIONAccepting the hypothesis of diffusive heat transport, thermal conductivity (TC) is a decisive parameterthat controls the geometry of the deep underground laboratory of Andra, namely the spacing between“alveoles” and the total storage volume. The optical scanning technique, initially developed by Y.Popov from the University of Moscow ( Popov et al., 1999), is used to perform thermal conductivitymeasurements. Examples obtained from argillites will be presented, showing the effect of (1)diagenetic process with calcite cementation using the mapping technique, and (2) mechanicaldecompression of samples cored at the wall of an experimental gallery using the profile technique.DIAGENETIC PROCESS WITH CALCITE CEMENTATIONUsing the optical scanning technique, TC-maps were produced with a resolution of 1 mm 2 . Mapping wasoperated on samples cored at the wall of the descending shaft along two directions: perpendicular tobedding (dashed line on the circular section of figure 1) and parallel to bedding (rectangular section). TCvalues evolve from 1.3 to 2.4 W.m -1 .K -1 , the highest ones ( > 2) being induced by calcite cement. Thisdiagenitic process seems to be independent of bedding orientation. Hence, thermal conductivitymeasurement appears to be a good indicator of calcite distribution within the argillites. Parallel to thebedding plane, clay-enriched sectors under sedimentary control seem to parallel the small K 1 axis of themagnetic anisotropy ellipsoid (Esteban et al., 2006a and b ). K 1 seems to parallel low TC values and to beperpendicular to highest TC ones. These measurements point to a mineralogical and sedimentary controlof the TC properties of the argilites. As a consequence, TC-mapping can be used as an indicator ofsedimentary and diagenetic processes in mudrocks.MECHANICAL PROCESSESProfiles were performed along cores that were drilled from the walls of the underground laboratory. Ourmeasurements show that if a mean TC could be estimated, ranging from 1.2 to 1.5 W. m -1 .K -1 , largevariations were also observed as exemplified in figure 2. Three parallel-to-core profiles were obtained onthe core surfaces. On sides of a mean TC value of 1.3 W.m -1 .K -1 , large variations could be induced by anincrease in porosity or by mineralogical variations. A damaged zone was detected with a low TC (< 1unity) at the beginning of profile 1, attributed to a high porosity zone. At the end of profile 2, pyrite grains(or framboids) were detected with high TC values (3 W.m -1 .K -1 ).INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENTPage 503
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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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P/MTPM/1210,9Degree of saturation (
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P/MTPM/13RESULTSFirst, we estimated
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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
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
Page 84 and 85: P/MTPM/41Figure 1: Thermal conducti
Page 86 and 87: P/MTPM/42Figure 2: Model of pore st
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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Mass Transfer & Porous Media (MTPM) - Andra

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