Mass Transfer & Porous Media (MTPM) - Andra

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P/MTPM/142.5Energy (M eV)1.6 1.7 1.8 1.9 2.02.5Energy (MeV)1.6 1.7 1.8 1.92.0l1.5l1.0MtTerri ReferenceMtTerri +Eu 1dayMtTerri +Eu 3daysMtTerri +Eu 4daysMtTerri +Eu 7daysSimulationsNormalized Yield2.01.51.0MtTerri ReferenceMtTerri +Sr 5minutesMtTerri +Sr 2hoursMtTerri +Sr 4hoursMtTerri +Sr 1day0.50.50.0700 750 800 850 900Channel0.0700 750 800 850ChannelFigure 1: (Left) RBS spectra of MtTerri clay: (• ) untreated and after contact with Eu solution ( ) 1 day,( ) 3 days, ( ) 4 days and ( ) 7 days. (Right) RBS spectra of MtTerri clay: ( ) untreated and after contactwith Sr solution ( ) 5 minutes, ( ) 2 hours, ( ) 4 hours and ( ) 1 day. Simulations are plotted ascontinuous lines.SrThe time dependence of the Eu peak height and tail was in agreement with a diffusion process. Similarbehaviour was observed for Eu and for the 2 nm Au colloids, but in comparison, the gold signal was lowerthan that of Eu and its profile thinner, suggesting slightly slower diffusion. However, different behaviouris observed for Sr in Figure 1 (right). In this case, even after 5 minutes, the Sr signal is plane, overlappingits tail with the signal of lighter elements, indicating faster Sr diffusion than that of Eu (Figure 1) or 2 nmAu colloids.From the RBS spectra simulation, considering an average clay composition, and introducing aconcentration gradient of the selected element (Eu, Au or Sr), diffusion lengths were determined, and itwas possible to evaluate apparent diffusion coefficients for Eu, Sr and Au colloids. Diffusion coefficientswere measured for Eu (D a 2.5E-16 m 2 /s) and Au colloids, being 10 -17 m 2 /s. Since Sr presented fasterdiffusion, the signal was plane even after only 5 minutes (Figure 1 right), so it was only possible toevaluate an inferior limit for diffusion coefficient (D a > 4E-14 m 2 /s). Through the porosity values, effectivediffusion coefficients (D e ) were calculated and the values are compared to that reported in the literature.Experimental times required with the methodology presented here are clearly shorter (days) than thoserequired with conventional experiments (months-years). The applicability and (or) limitations of this newmethodology to other relevant solutes are also discussed.Page 450INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENT
P/MTPM/15NUMERICAL INTERPRETATIONOF IN SITU DIR DIFFUSION EXPERIMENTSON C-OX CLAY AT BURE SITEJ. Samper 1 , S. Dewonck 2 , L. Zheng 1 , Q. Yang 1 , A. Naves 11. Universidade da Coruña. Campus de Elviña s/n, 15192 A Coruña, Spain (jsamper@udc.es).2. ANDRA, Bure, France (Sarah.Dewonck@andra.fr).The Callovo-Oxfordian argillite is under investigation as a potential host rock for high-level wasterepository at Andra Underground Research Laboratory in Meuse/Haute Marne (France). DIR (DIffusionand Retention) is an experimental program which aims at characterizing diffusion and retention ofradionuclides in clay rock. Several boreholes were drilled to perform in situ diffusion experiments in orderto determine diffusion and retention properties of radionuclides such as tritium ( 3 H), iode ( 125 I - ), chloride( 36 Cl - ), sodium ( 22 Na + ), and cesium ( 134 Cs + ). DIR diffusion experiments were performed in vertical boreholesdrilled perpendicular to bedding. Bure clay exhibits mild diffusion anisotropy due to stratification. In situdiffusion experiments DIR2001, DIR2002 and EST208 were interpreted using data on the decrease oftracer activity in the testing interval. All the analysis were perfomed by CEA DPC Saclay. Theseexperiments could not be interpreted with analytical solutions because they do not account for the presenceof the filter, the gap between the casing and the borehole wall and an excavation disturbed zone which herewill be denoted as EdZ.DIR experiments were interpreted using numerical inverse models with INVERSE-CORE (Dai andSamper, 2004). Numerical interpretation of DIR experiments requires the use of 3-D models due todiffusion anisotropy. However, symmetry with respect to borehole axis allows the use of 2-D axisymmetricmodels. Comparison of the results of a 2-D anisotropic model with those of a 1-D modelindicates that concentrations at the testing interval computed with both models are similar and are notsensitive to the diffusion anisotropy ratio. Therefore, 1-D axisymmetric models were used to interpretDIR diffusion experiments. Numerical models were used to: 1) Compute numerical sensitivities ofconcentrations to model parameters; 2) Analyze parameter identifiability and parameter estimation errorswith synthetic experiments and 3) Interpret real DIR experiments. Here we report on the results of thenumerical interpretation of real DIR experiments.Real diffusion experiments relied on results of sensitivity runs and identifiability analysis of synthetic data.They were interpreted using a systematic approach according to which: 1) De filter and De gap were estimatedfirst using mostly early-time 2) De filter and De gap were fixed to the estimated values and De EDZ and φ EDZwere estimated using mostly concentration data measured and 3) De clay and φ clay were estimated using allconcentration date while De filter , De gap , De EDZ and φ EDZ were fixed at the values estimated in precious steps.This sequence of steps led to excellent fits to measured data. In addition, this approach worked well forall tracers and all experiments, providing robust results in all cases.Model results indicate unambiguously that a model without EdZ cannot fit measured data with values ofDe clay and φ clay within the range of values determined in lab experiments. In fact, measured concentrationdata can only be fitted with values of De clay and φ clay much larger than measured values. Therefore, HTOdata allow us to conclude that data are clearly affected by an EdZ and such data cannot be explainedwithout resorting to such hypothesis. Several sources of parameter uncertainty have been evaluated. Byadopting a volume of water in circulation system 5% smaller than the reference value, data can be fitequally well as with the reference volume, but with slightly smaller values of De clay , φ clay and φ EDZ . Thismeans that a small (5%) error in the volume of water in the circulation system has no major effect onINTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENTPage 451
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 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 82 and 83:
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
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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