1. CHEMICAL EVOLUTION IN THE NEAR FIELD OF HLW CELLS: INTERACTIONS BETWEEN GLASS, STEEL, AND CLAYSTONE IN DEEP GEOLOGICAL CONDITIONS 5 TH ANDRA INTERNATIONAL MEETING – MONTPELLIER | 22 OCT. 2012 O. Bildstein, J.E. Lartigue, I. Pointeau CEA, DEN, Cadarache, 13108 Saint Paul lez Durance, France B. Cochepin, I. Munier, N. Michau ANDRA, 92298 Châtenay-Malabry Cedex, France 16 octobre 2015 | PAGE 1 CEA | 10 AVRIL 2012

2. OUTLINE PLAN 16 octobre 20155 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 2 Context of the study Objectives of the simulations Phenomenology and parameters Simulations of the evolution of the High Level Waste (HLW) cell in the base case Sensitivity calculations:  ion exchange and surface complexation Conclusion

3. HLW DISPOSAL CELL 5 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 3 different types of material in physical contact, technological gaps

4. HLW DISPOSAL CELL 16 octobre 20155 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 4 different types of material in physical contact, technological gaps Vitrified waste packages Cross section 3 cm gap steel liner disposal package 0.8 cm gap 3 cm gap scale

5. HLW DISPOSAL CELL 16 octobre 20155 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 5 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

6. Perform predictive calculations of HLW disposal cell geochemical evolution in the long term (~100 000 a) OBJECTIVES 5 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 6

7. Perform predictive calculations of HLW disposal cell geochemical evolution in the long term (~100 000 a) Robustness of the predictions can be achieved through different approaches and in different steps: - using different codes  benchmarking (e.g. SeS-benchmarking workshop) - comparison with experiments, archeological analogues, natural analogues - sensitivity calculations (e.g. parameters or scenarios assumptions for redox, assumptions for ion exchange) OBJECTIVES 5 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 7

8. Perform predictive calculations of HLW disposal cell geochemical evolution in the long term (~100 000 a) Robustness of the predictions can be achieved through different approaches and in different steps: using different codes  benchmarking (e.g. SeS-benchmarking workshop) comparison with experiments, archeological analogues, natural analogues - sensitivity calculations (e.g. parameters or scenarios assumptions for redox, assumptions for ion exchange) Indicators: pH and redox perturbation fronts inducing changes - in mineralogy affecting the ion exchange capacity - in mineralogy affecting transport properties (porosity) - on RN migration (redox sensitive) OBJECTIVES 5 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 8

9. 1D radial domain transport: diffusion only water saturated, constant porosity 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 5 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 9

10. 1D radial domain transport: diffusion only water saturated, constant porosity 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 5 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 10 Non-isothermal calculations: thermodynamical parameters, kinetics, and diffusion coefficients = function of temperature - reactive-transport codes: Crunch/Hytec - H 2 (g) produced from anoxic corrosion p(H 2 )max = 60 bar considered unavailable for chemical reactions after corrosion phase -

11. Water composition from Lartigue & Bildstein 2011 (mineral equilibrium + pH, Al and SO 4 ) Mineralogical composition (glass/iron/claystone) Choice of secondary minerals (see Appendice) List established in collaboration with Andra simulation units and experimental laboratory groups (Glass/Iron/Clays, Thermochimie) Kinetics of minerals dissolution/precipitation processes dissolution: from Palandri & Kharaka with BET surfaces/100 kinetics constant: precipitation = dissolution WATER AND MINERALOGICAL COMPOSITION 27 elements 277 aqueous spieces 3 gas 82 minerals 362 reactions 5 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 11 Claystone Steel: Fe 0 Glass composition: Si, B, Na, Al, Ca, Fe, Cs, Rb, Ba, Ni, Zr, Tc, Np, U, I, Se, Eu (oxides)

12. SOURCE TERMS FOR GLASS AND IRON glass alteration scenario - Time lag = 700 yrs (for temperature to drop < 50°C) - Starting at 700 yrs: glass alteration rate = r 0 - After 700 yrs: glass alteration rate = r res - Complete alteration in ~ 2 Myrs (~ 0.1 µm/yr) t = 700 a glass alteration starts with r 0 t = 710 a: glass alteration with r res t = 100 000 years 5 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 12 GLASS ALTERATION

13. SOURCE TERMS FOR GLASS AND IRON glass alteration scenario - Time lag = 700 yrs (for temperature to drop < 50°C) - Starting at 700 yrs: glass alteration rate = r 0 - After 700 yrs: glass alteration rate = r res - Complete alteration in ~ 2 Myrs (~ 0.1 µm/yr) Iron corrosion - Corrosion rate from Foct & Gras (2003): 2 µm/yr at 25°C - Complete corrosion in ~ 45 000 yrs t = 0: corrosion starts t = 700 a glass alteration starts with r 0 t = 710 a: glass alteration with r res t = 100 000 years t = 45 000 ans corrosion completed 5 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 13 CORROSION GLASS ALTERATION

14. SOURCE TERMS FOR GLASS AND IRON glass alteration scenario - Time lag = 700 yrs (for temperature to drop < 50°C) - Starting at 700 yrs: glass alteration rate = r 0 - After 700 yrs: glass alteration rate = r res - Complete alteration in ~ 2 Myrs (~ 0.1 µm/yr) Iron corrosion - Corrosion rate from Foct & Gras (2003): 2 µm/yr at 25°C - Complete corrosion in ~ 45 000 yrs t = 0: corrosion starts t = 700 a glass alteration starts with r 0 t = 710 a: glass alteration with r res t = 100 000 years t = 45 000 ans corrosion completed 5 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 14 Base case: no sulphate/sulphide reactions no ion exchange/surface complexation CORROSION GLASS ALTERATION

15. RESULTS IN THE BASE CASE (1) pH and H 2 profiles Glass: pH up to 9 Iron: pH up to 9.5 during corrosion Claystone: pH value up to 9.5 close to interface and down to 6,5 in the first meters (pyrite  pyrrhotite) extension ~ 15 cm

16. RESULTS IN THE BASE CASE (1) pH and H 2 profiles Glass: pH up to 9 Iron: pH up to 9.5 during corrosion Claystone: pH value up to 9.5 close to interface and down to 6,5 in the first meters (pyrite  pyrrhotite) extension ~ 15 cm

17. RESULTS IN THE BASE CASE (1) 16 octobre 2015 pH and H 2 profiles Glass: pH up to 9 Iron: pH up to 9.5 during corrosion Claystone: pH value up to 9.5 close to interface and down to 6,5 in the first meters (pyrite  pyrrhotite) extension ~ 15 cm production of H 2 gas extension : ~10 m vanishes after end of corrosion

18. RESULTS IN THE BASE CASE (1) 16 octobre 2015 pH and H 2 profiles Glass: pH up to 9 Iron: pH up to 9.5 during corrosion Claystone: pH value up to 9.5 close to interface and down to 6,5 in the first meters (pyrite  pyrrhotite) extension ~ 15 cm production of H 2 gas extension : ~10 m vanishes after end of corrosion Eh drops during corrosion, then slowly rises Eh init Eh solution (mV)

19. RESULTS IN THE BASE CASE (2) 16 octobre 20155 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 19 Corrosion products (volume%, 45 000 yrs, end of corrosion) magnetite, Ca-siderite, and greenalite dominate (oxide) (carbonte) (silicate) also smaller amounts of aluminosilicates (nontronites and saponites) no significant changes after corrosion phase Canister zone

20. RESULTS IN THE BASE CASE (2) 16 octobre 20155 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 20 Corrosion products (volume%, 45 000 yrs, end of corrosion) magnetite, Ca-siderite, and greenalite dominate (oxide) (carbonte) (silicate) also smaller amounts of aluminosilicates (nontronites and saponites) no significant changes after corrosion phase modeling vs. experimental results (Schlegel at al. 2007) iron/claystone at 90°C for 1 year small amount of magnetite siderite(-Ca), Fe-silicates Canister zone 0,1 µm

21. RESULTS IN THE BASE CASE (3) 16 octobre 2015 | PAGE 21 Glass alteration products (volume%, 100 000 years) greenalite, vermiculite-Na and saponites dominate in the corrosion phase amorphous silica precipitates transiently (r 0 phase) siderite-Ca, dolomite, and chalcedony also precipitate during post-corrosion phase Glass zone 5 th Andra International Conference - Montpellier | 22 Oct 2012 Glass zone

22. RESULTS IN THE BASE CASE (3) 16 octobre 2015 | PAGE 22 Glass alteration products (volume%, 100 000 years) greenalite, vermiculite-Na and saponites dominate in the corrosion phase amorphous silica precipitates transiently (r 0 phase) siderite-Ca, dolomite, and chalcedony also precipitate during post-corrosion phase modeling vs. experimental results : silica gel Fe-silicates Mg-silicates Glass zone 5 th Andra International Conference - Montpellier | 22 Oct 2012 Burger et al. 2012 / M. Debure (this conference) glass grains iron powder glass

23. RESULTS IN THE BASE CASE (4) Claystone Claystone alteration (volume%, 100 000 years) 2 altered zones: extensive alteration (60 cm), H 2 reactivity (10 m) + undisturbed claystone zone zone 1: calcite, dolomite and illite precipitate; siderite- Ca disappears. Montmorillonites and kaolinite are destabilized (during corrosion phase)  most of secondary phases form in this zone zone 2: dissolution of pyrite (replaced by pyrrhotite), montmorilllonite-Na/-Ca and siderite-Ca dissolve, kaolinite precipitates (all in small amounts)

24. RESULTS IN THE BASE CASE (4) Claystone alteration (volume%, 100 000 years) Claystone 2 altered zones: extensive alteration (60 cm), H 2 reactivity (10 m) + undisturbed claystone zone zone 1: calcite, dolomite and illite precipitate; siderite- Ca disappears. Montmorillonites and kaolinite are destabilized (during corrosion phase)  most of secondary phases form in this zone zone 2: dissolution of pyrite (replaced by pyrrhotite), montmorilllonite-Na/-Ca and siderite-Ca dissolve, kaolinite precipitates (all in small amounts) secondary minerals: greenalite, Na-vermiculite, Na-and Ca-saponite

25. OUTLINE PLAN 16 octobre 20155 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 25 Context of the study Objectives of the simulations Phenomenology and parameters Simulations of the evolution of the High Level Waste (HLW) cell in the base case Sensitivity calculations:  ion exchange and surface complexation Conclusion

26. ION EXCHANGE / SURFACE COMPLEXATION Model from Grambow et al. (2006) for the claystones smectite fraction (based on MX80 bentonite) first choice because this model takes into account major cations (Na, Ca, Mg, K) and RN (Cs, Eu, Am etc…) [!! not equivalent to a claystone exchange model !!] this model is considered conservative since other minerals could be considered as exchanger in claystone ( illite, …) 16 octobre 20155 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 26

27. ION EXCHANGE / SURFACE COMPLEXATION Model from Grambow et al. (2006) for the claystones smectite fraction (based on MX80 bentonite) first choice because this model takes into account major cations (Na, Ca, Mg, K) and RN (Cs, Eu, Am etc…) [!! not equivalent to a claystone exchange model !!] this model is considered conservative since other minerals could be considered as exchanger in claystone ( illite, …) NOT PERFECT + conceptual difficulties: how to combine exchanger reactivity (dissolution/precipitation) with ion exchange reactions? conflict with montmorillonite-Na, -Ca, -Mg, -K? what about other potential secondary minerals as exchangers (saponites, vermiculites)? 16 octobre 20155 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 27 27 elements 11 exchange reactions 25 surf. complex. reactions 277 aqueous spieces 3 gas 82 minerals 409 reactions

28. DIFFERENT ASSUMPTIONS FOR ION EXCHANGE/SORPTION MODEL Case 1 no explicite ion exchange dissolution/precipitation of Na- and Ca- montmorillonites no surface complexation Case 2 explicite ion exchange model (Grambow et al. 2006) constant ion exchange capacity (montmorillonites non-reactive) surface complexation (protonation + RN) Case 3 explicite ion exchange model (Grambow et al. 2006) attached to reactive Montmorillonite-Ca (dissolution/precipitation) [Si-Al-Mg-Ca] surface complexation (protonation + RN) Case 4 explicite ion exchange model (Grambow et al. 2006) attached to reactive Si-Al exchanger (dissolution/precipitation) surface complexation (protonation + RN) 16 octobre 20155 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 28 Ca Na Ca

29. RESULTS WITH ION EXCHANGE/SORPTION MODELS (1) 16 octobre 20155 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 29 Evolution of pH in claystone at the interface with steel Ca Na Ca CORROSION

30. RESULTS WITH ION EXCHANGE/SORPTION MODELS (1) 16 octobre 20155 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 30 Evolution of pH in claystone at the interface with steel Only slight differences are observed: -pH fluctuates faster with reactive montmorillonites -intermediate behaviour with reactive exchanger - fluctuations slowter with non-reactive exchanger Ca Na Ca CORROSION GLASS ALTERATION

31. RESULTS WITH ION EXCHANGE/SORPTION MODELS (2) 16 octobre 20155 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 31 Evolution of minerals (mol/l) in claystone at the interface with steel Differences in evolution for: - primary silicates and alumino silicates minerals, kaolinite and illite in case 2 - carbonate minerals (calcite, Ca-siderite) for case 3 Similar evolution for: - partial quartz dissolution (especially in case 2 leading to more greenalite precipitation) - total dolomite dissolution (between 700-800 y) Ca Na Ca GLASS ALTERATION

32. RESULTS WITH ION EXCHANGE/SORPTION MODELS (2) 16 octobre 20155 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 32 Evolution of minerals (mol/l) in claystone at the interface with steel Similar amounts for secondary minerals Ca Na Ca GLASS ALTERATION Differences in evolution for: - primary silicates and alumino silicates minerals, kaolinite and illite in case 2 - carbonate minerals (calcite, Ca-siderite) for case 3 Similar evolution for: - partial quartz dissolution (especially in case 2 leading to more greenalite precipitation) - total dolomite dissolution (between 700-800 y)

33. RESULTS WITH ION EXCHANGE/SORPTION MODELS (2) 16 octobre 2015 5 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 33 Evolution of Na and Ca (mol/l) in claystone at the interface with steel - Na: when more exchanger is dissolved at the interface, more Na in secondary phases (not the case when only montmorillonite are dissolving) Ca Na Ca

34. RESULTS WITH ION EXCHANGE/SORPTION MODELS (2) 16 octobre 2015 5 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 34 Evolution of Na and Ca (mol/l) in claystone at the interface with steel - Na: when more exchanger is dissolved at the interface, more Na in secondary phases (not the case when only montmorillonite are dissolving) - Ca: dissolution of exchanger at the interface, not true if only Ca- montmorillonite is dissolving Ca Na Ca

35. RESULTS WITH ION EXCHANGE/SORPTION MODELS (3) 16 octobre 2015 Impact on RN migration (mol/l) in claystone at 8000 years Ca 5 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 35

36. CONCLUSIONS Evolution of the HLW cell in the base case Corrosion products: magnetite, siderite-Ca, greenalite Glass alteration products: greenalite, saponite-Na, vermiculite-Na (+ nontronites and Ca- aluminosilicates) ALTERATION EXTENSION in claystone: ~15 cm Secondary phases in claystone : greenalite, vermiculite-Na, saponite-Na, saponite-Ca, pyrrhotite 16 octobre 2015

37. CONCLUSIONS Evolution of the HLW cell in the base case Corrosion products: magnetite, siderite-Ca, greenalite Glass alteration products: greenalite, saponite-Na, vermiculite-Na (+ nontronites and Ca- aluminosilicates) ALTERATION EXTENSION in claystone: ~15 cm Secondary phases in claystone : greenalite, vermiculite-Na, saponite-Na, saponite-Ca, pyrrhotite Ion exchange some differences are observed between the different conceptual models (essentially at the interface between claystone and steel)  more phenomenological model (Si-Al-Mg exchanger) no significant effect on mineralogical evolution (except at the interface between iron and connected fractured zone) and RN migration 16 octobre 2015

38. CONCLUSIONS Evolution of the HLW cell in the base case Corrosion products: magnetite, siderite-Ca, greenalite Glass alteration products: greenalite, saponite-Na, vermiculite-Na (+ nontronites and Ca- aluminosilicates) ALTERATION EXTENSION in claystone: ~15 cm Secondary phases in claystone : greenalite, vermiculite-Na, saponite-Na, saponite-Ca, pyrrhotite Ion exchange some differences are observed between the different conceptual models (essentially at the interface between claystone and steel)  more phenomenological model (Si-Al-Mg exchanger) no significant effect on mineralogical evolution (except at the interface between iron and connected fractured zone) and RN migration Redox pH are more acid without sulfates/sulfures (primary silicates and aluminosilicates are less reactive, carbonates are more reactive, and precitates concentrate at interfaces) the reducing front colonizes the whole domain in this model there is no redox buffer in the claystone (only H2/H2O is active) 16 octobre 2015 Glass : FeIII/FeII Iron : FeIII/FeII/Fe0, H 2 /H 2 O (SIV/SII) Argilites H 2 /H 2 O ?

39. 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 16 octobre 2015 | PAGE 39 CEA | 10 AVRIL 2012 Acknowlegement ANDRA for financial support LBNL (C. Steefel, Crunchflow) and Mines Paristech (PGT consortium, Hytec) for technical support on codes THANK YOU FOR YOUR ATTENTION

40. APPENDICE: LIST OF SECONDARY MINERALS 16 octobre 20155 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 40 Pyrrhotite Siderite GoethiteBvh Magnetite Greenalite SiO2(am) Chalcedony Chlorite(Cca-2) Gypsum Gibbsite Glauconite Strontianite List established in collaboration with Andra simulation units and experimental laboratory groups (VFA, Thermochimie) Brucite Lizardite Cronstedtite-Th Berthierine-Th Vermiculite-Na Vermiculite-Ca Saponite-FeNa Saponite-FeCa Saponite-Na Saponite-Ca Smectite(MX80) Mackinawite codes apply different rules for the precipitation of secondary phases (assumption for surface areas) !

41. REDOX CONTROL IN THE SYSTEM Base case without sulfate/sulfite reactions, but conceptual difficulty: hypothesis: no sufficient bacterial activity for this reaction but sulfate reduction is possible in the presence of iron surface what about the reactivity of hydrogen in the argilites? 16 octobre 20155 th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 41