1. MODELING REACTIVE TRANSPORT IN NUCLEAR WASTE GEOLOGICAL DISPOSAL - glass/iron/clay interactions - atmospheric carbonation of concrete SeS BENCH – NOVEMBER 11.-13. 2013 O. Bildstein, P. Thouvenot, J.E. Lartigue, I. Pointeau CEA (French Alternative Energies and Atomic Energy Commission) B. Cochepin, I. Munier ANDRA (French Radioactive Waste Management Agency) 14 octobre 2015 | PAGE 1 CEA | 10 AVRIL 2012 S. Bea (CONICET, Argentina) J. Corvisier, L. De Windt (Mines Paristech, France) D. Jacques (CEN.SCK, Belgium) N. Leterrier (CEA Saclay, France) N. Marty, F. Claret (BRGM, France) C. Steefel (LBNL, USA) D.Y. Su, U. Mayer (UBC, Canada)

2. DISPOSAL CONCEPT IN A CLAYSTONE FORMATION AT 500 m DEPTH Current design of deep underground repository for high and intermediate level long-lived waste S.S.BENCH - November 16-18. 2011 SeS BENCH – Leipzig | NOV. 2013 | PAGE 2

3. Update on glass/iron/clay benchmark S.S.BENCH - November 16-18. 2011 DRD/EAP/11-0219

4. HLW DISPOSAL CELL 14 octobre 2015 | PAGE 4 different types of material in physical contact, technological gaps  long term calculations of geochemical evolution (100 000 years) Vitrified waste packages Cross section 3 cm gap steel liner disposal package 0.8 cm gap 3 cm gap scale

5. 1D radial domain transport: diffusion only water saturated, constant porosity isothermal conditions H 2 (g) from anoxic corrosion pH 2(max) = 60 bar glass Φ = 0.42 m, H = 1 m porosity = 0.12 metallic components total thickness = 0,095 m, porosity = 0.25 connected fractured zone 0.4 * excavation diameter = 0.268 m porosity = 0.20; D eff (25°C) = 5.2 10 -11 m 2 /s undisturbed claystone (50 m) porosity = 0.18; D eff (25°C) = 2,6 10 -11 m 2 /s GEOMETRY AND TRANSPORT PROPERTIES | PAGE 5 Major challenges come from: -highly reactive system (producing pH and redox perturbation) -complex geochemical system (15 chemical elements, 80 aqueous species, 60 minerals)

6. BENCHMARK SUB-COMPONENTS 14 octobre 2015 | PAGE 6 Problem 1: iron corrosion only (45 000 yrs) magnetite, Ca-siderite, and greenalite dominate (oxide) (carbonte) (silicate) also smaller amounts of aluminosilicates (nontronites and saponites) POROSITY CLOGGING modeling vs. experimental results iron/claystone at 90°C for 1 year small amount of magnetite siderite(-Ca), Fe-silicates  more phenomenological model for corrosion Canister zone 0,1 µm Problem 2: iron corrosion + glass alteration (100 000 yrs) (Schlegel et al. 2007)

7. RESULTS IN THE BASE CASE (2) 14 octobre 2015 | PAGE 7 A very good agreement is obtained between MIN3P and Crunchflow… in the iron zone

8. RESULTS IN THE BASE CASE (3) 14 octobre 2015 | PAGE 8 in the glass zone

9. RESULTS IN THE BASE CASE (4) 14 octobre 2015 | PAGE 9 in the clay zone

10. RESULTS IN THE BASE CASE (5) 14 octobre 2015 | PAGE 10 But other codes (Hytec, PhreeqC, PHAST,…) failed at this point to run these cases (timestep too small, CPU time too high,…) A change in the set up of the benchmark case is under way in order to get more codes to run: -progress with Hytec -PhreeqC-based codes…?? -Anyone else…?

11. Update on concrete carbonation benchmark S.S.BENCH - November 16-18. 2011 DRD/EAP/11-0219

12. DESIGN: ILLW CELLS, SHAFTS (AND SEALS), ILLW DISPOSAL OVERPACK Atmospheric carbonation of overpack during the operating period S.S.BENCH - November 16-18. 2011 | PAGE 12 Bitumized waste Compacted metallic waste Organic waste SeS BENCH – Leipzig | NOV. 2013

13. DRYING AND CARBONATION PROCESSES OF ILLW OVERPACK S.S.BENCH - November 16-18. 2011 | PAGE 13 SeS BENCH – Leipzig | NOV. 2013 Major challenges come from: -Fast gaseous CO 2 transport and highly reactive with portlandite -Coupling capability with « multiphase » flow and transport

14. GEOMETRY 1D Cartesian – 5.5 cm divided in 11 cells (5 mm) for concrete 1 extra cell for “atmosphere” Boundary conditions (EOS 4) S.S.BENCH - November 16-18. 2011 Symmetry axis Dry air Package thickness 110 mm | PAGE 14 SeS BENCH – Leipzig | NOV. 2013 concrete

15. CASE 1/3 DRYING OF CONCRETE OVERPACK S.S.BENCH - November 16-18. 2011 DRD/EAP/11-0219

16. DRYING PHENOMENON : PARAMETERS IN REFERENCE CASE BHP CEM I S.S.BENCH - November 16-18. 2011 ROCK1 Density (kg/m 3 )2700 Porosity0.12 Intrinsic permeability to liquid (m ² ) 1e-19 Intrinsic permeability to gas (m ² ) 1e-17 Relative permeability m – Slr – Sls - Sgr 0.424 – 0.0 – 1.0 – 0.0 Capillarity pressure m – P 0 (MPa) – Pmax (MPa) 0.424 – 15 - 1500 Molecular diffusion coefficient in gaseous phase (m ² /s) 2.4e-5 Molecular diffusion coefficient in aqueous phase (m ² /s) 1.9e-9 Millington-Quirk a parameter2 Millington-Quirk b parameter4.2 Klinkenberg parameter (MPa)0.45 | PAGE 16 SeS BENCH – Leipzig | NOV. 2013

17. DRYING RESULTS S.S.BENCH - November 16-18. 2011 | PAGE 17 SeS BENCH – Leipzig | NOV. 2013 TOUGH2 Full multiphase (EOS4) Richards (EOS9)  OK to use Richards’ equation for benchmarking exercise Hytec (Richards’ equation)

18. CASE 2/3 CARBONATION WITH CONSTANT SATURATION S.S.BENCH - November 16-18. 2011 DRD/EAP/11-0219

19. PHENOMENOLOGY Constant saturation but unsaturated + diffusion of gas S.S.BENCH - November 16-18. 2011 | PAGE 19 SeS BENCH – Leipzig | NOV. 2013 S liq = 0.36

20. CHEMICAL PARAMETERS Primary phases Secondary phases Kinetics of dissolution / precipitation Phase Volume % Calcite72.12 Portlandite5.73 CSH 1.613.76 Monocarboaluminate2.26 Ettringite3.60 Hydrotalcite0.39 Hydrogarnet-Fe (C3FH6)2.05 Phase typePhases OxidesMagnetite, Amorphous silica HydroxidesBrucite, Gibbsite, Fe(OH) 3 Sheet silicatesSepiolite Other silicatesCSH 1.2, CSH 0.8, Straetlingite, Katoite_Si Sulfates, chlorides, other saltsGypsum, Anhydrite, Burkeite, Syngenite, Glaserite, Arcanite, Glauberite, Polyhalite CarbonatesCalcite, Nahcolite OtherHydrotalcite-CO 3, Ettringite, Dawsonite

21. CHEMICAL PARAMETERS Primary and Secondary phases kinetics parameters | PAGE 21 SeS BENCH – Leipzig | NOV. 2013 ! Precipitation of secondary minerals using a specific surface area : involves a « nucleus » volume fraction: 10 -4 in Toughreact (see discussion below)

22. REACTION TRANSPORT RESULTS AT CONSTANT S L Making sure the same effective diffusion coefficient is used… | PAGE 22 SeS BENCH – Leipzig | NOV. 2013 For Crunchflow, b = 3.2 has to be used (instead of b= 4.2 for Toughreact)

23. REACTION TRANSPORT RESULTS AT CONSTANT S L | PAGE 23 TOUGHREACT MIN3P CRUNCHFLOWHYTEC Carbonation front is similar

24. REACTION TRANSPORT RESULTS AT CONSTANT S L | PAGE 24 Calcite precipitation front is similar TOUGHREACTMIN3P CRUNCHFLOW HYTEC

25. REACTION TRANSPORT RESULTS AT CONSTANT S L | PAGE 25 Timing not the same for all codes Straetlingite more persistent with Crunchflow TOUGHREACT HYTEC MIN3P CRUNCHFLOW

26. REACTION TRANSPORT RESULTS AT CONSTANT S L | PAGE 26 Dawsonite does not precipitate with Crunchflow and Hytec Straetlingite more persistent with Crunchflow TOUGHREACT HYTEC MIN3P CRUNCHFLOW

27. REACTION TRANSPORT RESULTS AT CONSTANT S L | PAGE 27 More precipitation of gypsum in the simulation with Crunchflow TOUGHREACT HYTEC MIN3P CRUNCHFLOW

28. REACTION TRANSPORT RESULTS AT CONSTANT S L | PAGE 28 Effect of the nuclei volume fraction (CRUNCHFLOW) V n = 10 -4 V n = 10 -3 V n = 10 -2 V n = 10 -1

29. CASE 3/3 FULLY COUPLED CARBONATION S.S.BENCH - November 16-18. 2011 DRD/EAP/11-0219

30. Input parameters Combination of parameters from the 2 previous cases: Flow and transport from case 1 Chemical reactions from case 2 Maximum time step: 20 s (limitation due to reactive diffusion of CO 2 ) Coupling limitations No dependence of reactivity with the saturation state No shielding effect (potential decrease of portlandite reactivity with calcite precipitation) Results only with Toughreact so far…

31. CARBONATION RESULTS pH decrease, portlandite dissolution and calcite formation over a thickness of about 2 cm after 100 years

32. CARBONATION RESULTS Dissolution of CSH 1.6, ettringite, monocarboaluminate and hydrotalcite on 2 cm after 100 years Precipitation of CSH 1.2, CSH 0.8, straetlingite, amorphous silica and gypsum on the same thickness Precipitation of small amounts of sepiolite, gibbsite and katoïte-Si is also predicted

33. CARBONATION: CPU CONCERNS… CO 2 diffusion (gas phase) and reactivity are very fast! No SIA  small time steps  CPU times go up (the roof)!

34. CONCLUSIONS Glass-iron-clay interactions exercise very demanding in terms of number of minerals with large domain of kinetics coupled with a strong pH and redox perturbation (desperately) looking for new teams to jump in! Concrete carbonation exercise highly reactive CO 2 diffusing rapidly in the gas phase emphasizing the coupling between transport and reactions (GI vs. OS) S liq -dependent diffusion coefficient [ another challenge: S liq -dependent reactivity? ]

35. Direction de l’Energie Nucléaire Département des Technologies Nucléaires Service de Modélisation des Transferts et de Mesures Nucléaires Commissariat à l’énergie atomique et aux énergies alternatives Centre de Cadarache | 13108 Saint Paul-lez-Durance T. +33 (0)4 42 25 37 24 | F. +33 (0)4 42 25 62 72 Etablissement public à caractère industriel et commercial | RCS Paris B 775 685 019 14 octobre 2015 | PAGE 35 CEA | 10 AVRIL 2012 THANK YOU FOR YOUR ATTENTION Acknowledgements: S. Bea (CONICET, Argentina) J. Corvisier, L. De Windt (Mines Paristech, France) D. Jacques (CEN.SCK, Belgium) N. Leterrier (CEA Saclay, France) N. Marty, F. Claret (BRGM, France) C. Steefel (LBNL) D.Y. Su, U. Mayer (UBC, Canada)

36. POSSIBLE EXTENSION: SATURATION-DEPENDENT CHEMICAL REACTIVITY Considerable reduction in the amplitude of carbonation (less dissolution of portlandite and CSH 1.6 and less precipitation of amorphous silica and other secondary CSH) Lower reactivity accompanied by a greater penetration of carbonation front due to lower consumption of CO 2 at the surface Effect of water content on reactivity (Bazant type function)

37. CONCLUSIONS Drying process of 11 cm thick waste packages depends strongly on the concrete nature and slightly on the flow model (Richards or full multiphase) Considering full multiphase model, carbonated depth is about 1 cm after 100 years for the High Performance Concrete.  degraded thickness is totally carbonated (total dissolution of primary mineral phases) If we consider a chemical reactivity depending on the liquid saturation (Bazant type function), a considerable reduction in the amplitude of carbonation and a greater penetration of carbonation front are observed. Progress areas include: taking into consideration a protective effect of secondary minerals improving knowledge on kinetics parameters and thermodynamic data, especially for CSH with low Ca/Si ratio coupling this system with corrosion of rebars