13 DECEMBRE 2012 | PAGE 1 Clays In Natural And Engineered Barriers For Radioactive Waste Confinement - march 23-25, 2015 27 juin 2022 | PAGE 1 CEA | 10 AVRIL 2012 GAINING INSIGHT INTO CORROSION PROCESSES AND SECONDARY MINERAL PARAGENESIS FROM NUMERICAL SIMULATIONS OF INTEGRATED IRON-CLAYSTONE EXPERIMENTS
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13 DECEMBRE 2012 | PAGE 1
Clays In Natural And Engineered Barriers For Radioactive Waste Confinement - march 23-25, 2015
21 avril 2023 | PAGE 1CEA | 10 AVRIL 2012
CEA (French Alternative Energies and Atomic Energy Commission)
B. Cochepin, I. Munier, N. Michau Andra (French Radioactive Waste Management Agency)
GAINING INSIGHT INTO CORROSION PROCESSES AND
SECONDARY MINERAL PARAGENESIS FROM NUMERICAL
SIMULATIONS OF INTEGRATED IRON-CLAYSTONE EXPERIMENTS
| PAGE 2
OUTLINE PLAN
- description of the « ArCorr » integrated experiment
- observations to be matched by the modeling
- numerical model implementation and parameters
- first results :
base case
sensitivity to kinetics parameters
sensitivity to transport parameters
- conclusions and perspectives
| PAGE 2
13 DECEMBRE 2012
| PAGE 3
THE « ARCORR » EXPERIENCE
| PAGE 3
CEA | 10 AVRIL 2012
EXPERIMENTAL CONDITIONS AND MODELING OPTIONS
21 avril 2023 | PAGE 4
Experimental conditions
Isothermal 90°CPressure 40 bars
2 interfaces :- iron/argilites- glass/argilites
Modeling options
- only the iron/argilites interface is treated in this presentation- « ThermoChimie V8 » thermodynamic database- kinetic parameters and diffusion coefficients at 90°C- dissolution kinetics parameters from Palandri & Kharaka (1984) - precipitation kinetics = kdiss/100 - use BET specific surface areas
13 DECEMBRE 2012 | PAGE 5
SIMULATION GEOMETRY AND PARAMETERS
| PAGE 5
• Geometry
• base case parameters• Iron zone
– porosity = 0.15
– Deff = 2,61 10-11 m2/s
• Argilites (38 mm)– porosity = 0.18 ;
– Deff = 8.10-11 m2/s
mailles de taille croissante
argilite (10m – 100 mailles)
verre(21cm – 10 mailles)
surconteneur + chemisage + vides
(13,8cm – 10 mailles)
6 mm – 6 nodes
µ-container + gapsthickness 0,3 + 0,04 mm
(34 nodes)
argilites 29 mm – 100 nodes
glass zone
REACTIVITY OF THE DIFFERENT MATERIALS
21 avril 2023 | PAGE 6
Argilites- no ion-exchange or surface complexation reactions
•modifying precipitation/dissolution kinetics affects only the amount of mineral precipitated, the mineral sequence remaining unchanged (unless a very high magnetite reactivity is used)
a low corrosion rate changes the nature of corrosion products: greenalite and sidérite instead of magnetite
a low diffusive barrier is necessary to avoid greenalite précipitation in the iron zone
high magnetite dissolution rate is required to allow for its redissolution at the interface with argilites
13 DECEMBRE 2012 | PAGE 20
PERSPECTIVES
21 avril 2023 | PAGE 20
•modify the tortuosity in the iron zone
•calculate the corrosion rate as controlled by the diffusion of reactants/products (H2) in the internal corrosion layer (magnetite)
13 DECEMBRE 2012
| PAGE 21
DEN
DTN
SMTA
LMTE
Commissariat à l’énergie atomique et aux énergies alternatives
Centre de Cadarache | 13108 Saint Paul lez Durance
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Etablissement public à caractère industriel et commercial | RCS Paris B 775 685 01921 avril 2023