Mass Transfer & Porous Media (MTPM) - Andra

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P/MTPM/21490Pressure [bar]0 10 20 30 40 50PEP1001495PEP1002Depth [m bgl]500505510515PEP1003DIR1001DIR1002DIR1003SUG1106-001SUG1107Figure 1: 3D view of the measurement set-up and quasi-stabilized of the porewater pressures in boreholesPEP1001-PEP1003, DIR1001-1003, SUG1106-SUG1107.520The simulated transient vertical and horizontal pressure profiles over the first half year of monitoring areconsistent with the observed pressures. This indicates a good degree of consistency between thepermeability determined on the 10 cm scale and the one at metric to decametric scale, which determinesthe pressure response due to the drainage effect of the drift.However, at a later stage, a significant mismatch exists between the experimental data and the flowsimulation: the observed time evolution of the pressure profile after around 6 months observation followingthe excavation of the drift, presents a very slow increase or decrease (less than 1 bar in 6 months); on theother hand, the simulations results predict much larger decrease over time (several bar in 6 months). Thisindicates that the conceptual model should be enriched with additional processes in order to better explainthe observed pressures: several effects like mechanical compaction or perturbations in the nearfield of theboreholes might influence strongly the measurements and should be taken into account in a furtherinterpretation step.Globally, the results obtained in the study indicate that the permeability determined by the hydraulic testsin the boreholes on the several 10cm scale might represent an upper bound of the permeability at a largerscale in the Callovo-Oxfordian.References:Andra, 2005: Dossier 2005, synthesis, Evaluation of the feasibility of a geological repository in anargillaceous formationDelay, J., Vinsot, A., Krieguer, J.M., Rebours H., Armand, G. 2006. Making of the underground scientificexperimental programme at the meuse/Haute marne URL, North Eastern France. J. Phys. Chem. ofEarth, in pressDelay, Trouiller Lavanchy, 2006b: Propriétés hydrodynamiques du Callovo-Oxfordien dans l’Est du bassinde Paris : comparaison des résultats obtenus selon différentes approches, C.R. Geosciences, doi:10.1016/j.crte.2006.07.009.Page 464INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENT
P/MTPM/22IN SITU DIFFUSION TESTS PERFORMEDIN THE CALLOVO-OXFORDIAN MUDSTONEIN THE BURE URL: EXPERIMENTAL DATAAND NUMERICAL INTERPRETATIONSS. Dewonck 1 , M. Descostes 2 , V. Blin 2 , J. Radwan 2 , C.Poinssot 21. Andra - Bure URL - RD960 - 55290 Bure - France (sarah.dewonck@andra.fr)2. CEA – Saclay, DEN/DPC/SECR, 91191 Gif-sur-Yvette cedex (virginie.blin@cea.fr)INTRODUCTIONSeveral countries (Switzerland, Belgium, France,…) are studying deep argillaceous formations as potentialhost rocks for radioactive waste disposal due to their confinement properties (low permeability andretention capacity of the rock), that are favourable to limit the migration of radionuclides. In such anenvironment, the transport is dominated bydiffusion processes. To investigate andquantify the diffusion properties of theCallovo-Oxfordian argillite, studied in theFrench URL located at the limit of Meuseand Haute-Marne departments, sevenvertical boreholes have been drilled byAndra in geological layers with differentmineralogy (Illite/Smectite type R0 andIllite/Smectite type R1). Six short boreholeshave been performed from the drifts of theURL and one deep borehole (EST208) hasbeen carried out from the surface (Figure1).First, this paper presents the experimentaldata obtained from in situ tests that weremonitored over one year and more.Figure 1: Location of the diffusion experiments in the BureURLSecondly, it presents a first estimation of the diffusion coefficients that is based on the 1D radial modellingof the tracers’ concentrations decreases in the fluid circulating in contact with the rock.EXPERIMENTAL CONCEPTThe tests are carried out in vertical down boreholes in whose a packed off interval is initially filled withsynthetic water. To avoid a saline gradient, the composition of this synthetic water is close to that of thenatural pore water. At the bottom of the borehole, the circulating synthetic water is in contact with the rock.Tracers are added to the synthetic water when chemical and hydrostatic equilibrium are roughly reached. Thetracers injected are radioactive (HTO, 125 I, 36 Cl, 22 Na, 85 Sr, 134 Cs) and representative of the chemical andphysical behaviours of the different radionuclides in the waste. A circulation pump is maintaining ahomogeneous concentration of the tracers in the interval. Tracer contents in the circulating fluid are regularlymeasured by water sampling and analysing. The decrease of activities is monitored over time. At the end ofthe experiment, the rock around the injection chamber where tracers diffused, is retrieved by overcoring toanalyse tracers’ concentration profiles within the rock. This last step is not yet performed in the Bure URL.RESULTS AND INTERPRETATIONThe decrease of the relative tracers’ activities versus time is different from one tracer to another due to itschemical or physical behaviour. Compared to tritiated water, which is considered as a reference, therelative activity of anionic species decreases more slowly. At the opposite, the relative activity of cationicspecies decreases faster than that of tritiated water. This is in good agreement with results obtained byINTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENTPage 465
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 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
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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