Mass Transfer & Porous Media (MTPM) - Andra

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P/<strong>MTPM</strong>/15C/Co10.90.80.70.60.50.40.30.20.10experimental datamodle results for Cs EST2080 50 100 150 200 250 300Time (days)Figure 1: Comparison of model results and experimental data for 134 Cs + EST208 experiment.C/Co10.90.80.70.60.50.40.30.20.10experimental datamodle results for Cs EST2080.1 1 10 100 1000Time (days)estimates of De clay and φ clay . Our estimates of De clay for HTO in DIR2001, DIR2002 and EST208experiments are 30% larger than those obtained by CEA (Radwan et al., 2005) for DIR2001 and DIR2002.36 Cl - and 125 I - data from DIR2001 experiment and 36 Cl - data from EST208 experiment cannot be explainedwithout an EdZ. Several sources of parameter uncertainty were evaluated. By adopting a volume of waterin the injection system 5% smaller than the reference value, data can be fit equally well as with thereference volume, but with slightly smaller values of De clay , φ clay and φ EDZ . This means that a small (5%)error in the volume of water in the injection system has no major effect on estimates of De clay andaccessible φ clay for 36 Cl - and 125 I - .UDC estimates of D e clay for 36 Cl - are similar in DIR2001 and EST208 experiments. CEA D e clayestimates, however, show a rather large range for DIR2001 and DIR2002. Contrary to CEA who fixedaccessible porosity and estimated only D e clay we obtained estimates for both D e and porosity. Our estimateof D e clayfor 125 I - in experiment DIR2001 is within the range of CEA values.Model results indicate that 134 Cs + data can be fit equally well with several combinations of parameters: largeK d with a small De EDZ and small K d with a large De EDZ . Therefore, a model without EdZ can fit measureddata, but with values which are similar to those estimated for the EdZ. Several sources of parameteruncertainty were evaluated for 134 Cs + data including the volume of water in the injection system, theporosity of the gap and D e of filter. Numerical model fits data both at early times (which is best visualizedin a semilog c-logt plot) and late times (which is visualized in the c-t plot) (see Fig. 1). Parameter estimatesare consistent with parameter estimates obtained by CEA, except for the K d of 22 Na + for which our estimateis twice as large as CEA estimate.ReferencesDewonck, S. (2006): “Experimentation DIR. Synthese des resultats obtenus. Laboratoire de recherchesouterrain de Meuse/Haute-Marne”, ANDRA Rapport Technique, D.RP.ADPE.05.0719.Radwan J., Tevissen E., Descostes M. et Blin V. (2005) Premiers éléments d’interprétation et demodélisation des expériences de diffusion de traceurs inertes et réactifs en laboratoire souterrain deMeuse / Haute-Marne. Note technique CEA NT DPC/SECR 05-046/A.Samper, J., Zheng, L., Yang, Q., Naves, A. (2007): “Modelling and numerical interpretation of in situ DIRdiffusion experiments on C-Ox Clay at Bure site (Phase 1)”, UDC Technical Report.Page 452INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENT
P/<strong>MTPM</strong>/16IDENTIFICATION OF RELATIVECONDUCTIVITY MODELS FOR WATERFLOW AND SOLUTE TRANSPORT INUNSATURATED COMPACTED BENTONITEZhenxue Dai 1 , Javier Samper 2 *, Andrew Wolfsberg 1 , Daniel Levitt 11. Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos NM87545, USA (daiz@lanl.gov )2. Escuela Técnica Superior de Ingenieros de Caminos, Canales y Puertos, Universidad de A Coruña,A Coruña, Spain (* corresponding author, jsamper@udc.es )INTRODUCTIONUnderground facilities are being operated by several countries around the world for performing researchand providing demonstration of the safety of a deep geological high level radioactive waste (HLW)repository. The Grimsel test site at Swizerland is one of such facilities launched and operated by the SwissNuclear Waste Management Company (NAGRA) where various in situ experiments have been carried outin fractured granites. One of them is the FEBEX (F ull-scale E ngineered B arrier EXperiment) in situexperiment which is part of a larger demonstration and research project launched by ENRESA for theengineered barrier of a high level radioactive waste repository. FEBEX is based on the Spanish referenceconcept for radioactive waste disposal in crystalline rock according to which canisters are emplaced inhorizontal drifts and surrounded by a compacted bentonite clay barrier. This bentonite comes from theCortijo de Archidona deposit, exploited by Minas de Gádor, S. A., at Serrata de Níjar (Almería, Spain).This deposit was selected by ENRESA (Empresa Nacional de Residuos Radioactivos, S. A.) prior to theFEBEX project (Huertas et al., 2000) as the most suitable material for the backfilling and sealing of a HLWrepository. FEBEX bentonite has very high montmorillonite content, large swelling pressure, low hydraulicconductivity, good retention properties and is easy to compact for fabrication of blocks. Compactedbentonite is packaged as homogeneous as possible. Homogenization reduces model uncertainties (Huertaset al., 2000). Predictions of water flow and solute transport in the unsaturated compacted bentonite areessential for the repository of potentially hazardous chemicals to minimize the potential of groundwatercontamination. In order to establish an effective prediction model of water flow and solute transport inunsaturated bentonite, We developed an inverse methodology to estimate bentonite hydraulic parametersand identify its relative conductivity function from infiltration experiments using transient cumulativewater inflow and final water content data. Model identification criteria developed in the context ofinformation theory have been used to select the best relative conductivity function among four candidates,including that of Irmay (1954) and three proposed by van Genuchten (1980).RESULTS AND DISCUSSIONFive infiltration experiments were performed by CIEMAT on FEBEX compacted bentonite samples withthe steel cylindrical cells of 5 cm of inner diameter and 2.5 cm of length. Compacted bentonite sampleswere confined between two porous sinters. They were hydrated from the upper end under a constant waterpressure of 1 MPa. Infiltration rate was recorded with time. At the end of the test, the sample was takenout of the cell. Final water content (w) and dry density ( ρ d ) were measured at five sections located atdifferent distances to the hydration front.A 1-D numerical model was used to simulate the infiltration experiments and estimate unsaturated flowparameters. Four relative conductivity functions including that proposed by Irmay (1954) and three of vanGenuchten (1980) are tested with our inverse model INVERSE-CORE 2D (Dai and Samper, 2004) andcompared using model identification criteria. Table 1 summarizes the estimated parameters from the fiveexperiments. Mean, standard deviation (SD) and coefficient of variation (CV) of each estimated parameterINTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENTPage 453
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 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
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P/MTPM/40Figure 1: Sketch drawing o
Page 84 and 85:
P/MTPM/41Figure 1: Thermal conducti
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P/MTPM/42Figure 2: Model of pore st
Page 88 and 89:
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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