Mass Transfer & Porous Media (MTPM) - Andra

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P/<strong>MTPM</strong>/25FIRST RESULTSPreliminary calculated sequences of cement/clay interaction is in fair agreement with the mineralogicalevolution observed in the upper part of the borehole with dissolution of quartz, massive precipitation ofboth calcite and dolomite, moderate formation of potassic feldspars and sodic zeolites. The last twominerals correspond to the first stages of the alkaline perturbation characterized by Na-K-OH fluids(though formation of calcic zeolites is also predicted by modelling). Calcite is by far the most commonsecondary phase, present as a crust at the cement/clay interface as well as deeper within the host rock. Theprecipitation of dolomite is thought to be specific to this situation since the water seeping through the EDZhas a Ca-Mg bicarbonate source. Kaolinite dissolution and CSH precipitation should also occur accordingto calculations but were not clearly pointed out by the first characterisation stage. Typical pyrite oxidationpatterns, yielding Fe-oxyhydoxide precipitation, were obtained both by analysis and calculation. Alkalineand oxidative perturbations did not seem to interfere between each others, that is to say without formingany mixed alteration products such as nontronites. This statement is still under investigation.In the lower part of the borehole, experimental characterisation of a typical argillite crack highlighted threesuccessive front zones: precipitation of crusty calcite close to the concrete (0.5 cm width), followed byneoformation of illite/smectite mixed-layers (1 cm), and finally calcite and feldspar overgrowths (1 cm).Preliminary modelling results seem to be significantly different from the experimental ones. Calciteprecipitation is spread all over the crack, the second and third mineralogical fronts seem to be switched bycomparison to the in situ observations and zeolites are found to be important secondary phases. Study isin progress to better understand the origin of the discrepancies between experimental and modelling results.ReferencesDe Windt, L., Pellegrini, D., van der Lee, J., 2004. Coupled modeling of cement/claystone interactions andradionuclide migration. J. Contam. Hydrol. 68 , 165–182.Savage, D., Noy, D., Mihara, M., 2002. Modelling the interaction of bentonite with hyperalkaline fluids.Appl. Geochem. 17 , 207– 223.Tinseau, E., Bartier, D., Hassouta, L., Devol-Brown, I., Stammose, D. (2006). Mineralogicalcharacterization of the Tournemire argillite after in situ interaction with concretes, Waste Manag . 26,789-800.Tinseau et al. (2007), this book of abstracts.van der Lee, J., De Windt, L., Lagneau, V., Goblet, P., 2003. Module oriented modeling of reactivetransport with HYTEC. Comput. Geosci. 29 , 265–275.Page 472INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENT
P/<strong>MTPM</strong>/26RESULTS ON PU DIFFUSION EXPERIMENTSIN THE OPALINUS CLAYA. Bauer , B. Fiehn, Ch. Marquardt, J. Römer, A. Görtzen, B. KienzlerForschungszentrum Karlsruhe, Institut für Nukleare Entsorgung, PO Box 3640, D-76021KarlsruheThe Opalinus Clay (OPA) is a potential host rock for a repository for spent fuel, vitrified high-level wasteand long-lived intermediate-level waste in Switzerland. Owing to its small hydraulic conductivity (10 -14 -10 -13 ms -1 ), it is expected that transport of solutes will be dominated by diffusion. Diffusion coefficients arevery sensitive parameters in performance assessment (PA). The diffusion process is well understood fornon-retarded solutes with simple chemistry, but little is known for retarded solutes such as strongly sorbingactinides. Therefore, the objective of this work is to understand the Pu diffusion in clay mineral-richgeological samples in order to provide support for improved representation of these processes in PA andto enhance safety case credibility.A sample cell - autoclave system (SCAS) was developed for carrying out actinide diffusion experimentsin clay stones under their natural, confining pressure (Fig. 1). To verify our SCAS we performed HTOdiffusion experiments. The effective diffusion coefficients of the OPA perpendicular to bedding was foundto be 1.6 x 10 -11 m 2 /s, which is in good agreement with the value determined by Van Loon et al., 2003.According to the results of batch sorption data, a strong 238 Pu sorption under the experimental conditionsof the diffusion experiment is expected. After termination of the diffusion experiments the clay core wascut for autoradiography in two pieces perpendicular to the bedding plane. Autoradiography revealed a veryINE Diffusion Cellstainless steelpipestainless steelconnection tothe PEEK tubesstainless steeldiffusion cellPEEK sampl e coatingclay sampl ePEEK filter diskPEEK distribution pl atestainless steelcapFigure 1: FZK-INE diffusion cell.INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENTPage 473
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 22 and 23: 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 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 82 and 83: P/MTPM/40Figure 1: Sketch drawing o
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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