CHEMICAL EVOLUTION IN THE NEAR FIELD OF HLW CELLS: INTERACTIONS BETWEEN GLASS, STEEL, AND CLAYSTONE IN DEEP GEOLOGICAL CONDITIONS 5 TH ANDRA INTERNATIONAL

CHEMICAL EVOLUTION

IN THE NEAR FIELD OF HLW CELLS:

INTERACTIONS BETWEEN GLASS, STEEL,

AND CLAYSTONE IN DEEP GEOLOGICAL

CONDITIONS

5TH ANDRA INTERNATIONAL MEETING – MONTPELLIER | 22 OCT. 2012

O. Bildstein, J.E. Lartigue, I. PointeauCEA, DEN, Cadarache, 13108 Saint Paul lez Durance, France

B. Cochepin, I. Munier, N. MichauANDRA, 92298 Châtenay-Malabry Cedex, France

20 avril 2023 | PAGE 1CEA | 10 AVRIL 2012

OUTLINE PLAN

20 avril 2023 5th 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

HLW DISPOSAL CELL

5th Andra International Conference - Montpellier | 22 Oct 2012 | PAGE 3

• different types of material in physical contact, technological gaps

HLW DISPOSAL CELL



Vitrified wastepackages

Cross section

3 cm gap steel liner

disposal package

0.8 cm gap

3 cm gap

scale

HLW DISPOSAL CELL



long term calculations of geochemical evolution (100 000 years)

Vitrified wastepackages

Cross section

3 cm gap steel liner

disposal package

0.8 cm gap

3 cm gap

scale

• Perform predictive calculations of HLW disposal cell geochemical evolution in the long term (~100 000 a)

OBJECTIVES



• 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



• 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


• 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; Deff(25°C) = 5.2 10-11 m2/s

• undisturbed claystone (50 m)

porosity = 0.18; Deff(25°C) = 2,6 10-11 m2/s

GEOMETRY AND TRANSPORT PROPERTIES

argilites (50 m – 183 cells)

glass (21cm – 21 cells)

overpack + lining + gaps

(13,8cm – 14 cells)


• 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; Deff(25°C) = 5.2 10-11 m2/s

• undisturbed claystone (50 m)

porosity = 0.18; Deff(25°C) = 2,6 10-11 m2/s

GEOMETRY AND TRANSPORT PROPERTIES

argilites (50 m – 183 cells)

glass (21cm – 21 cells)

overpack + lining + gaps

(13,8cm – 14 cells)


Non-isothermal calculations: thermodynamical parameters, kinetics, and diffusion coefficients = function of temperature

- reactive-transport codes: Crunch/Hytec

- H2(g) produced from anoxic corrosion p(H2)max = 60 bar considered unavailable for chemical reactions after corrosion phase

-

• Water composition from Lartigue & Bildstein 2011 (mineral equilibrium + pH, Al and SO4)

• 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 elements277 aqueous spieces3 gas82 minerals

362 reactions


Claystone

Steel: Fe0

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 = r0 - After 700 yrs: glass alteration rate = rres - Complete alteration in ~ 2 Myrs (~ 0.1 µm/yr)

t = 700 aglass alterationstarts with r0

t = 710 a: glass alteration with rres

t = 100 000 years

5thAndra International Conference - Montpellier | 22 Oct 2012 | PAGE 12

GLASS ALTERATION




• 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 = 100 000 yearst = 45 000 anscorrosion completed


CORROSION

GLASS ALTERATION




• 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 = 100 000 yearst = 45 000 anscorrosion completed


Base case: no sulphate/sulphide reactions

no ion exchange/surface complexation

CORROSION

GLASS ALTERATION

RESULTS IN THE BASE CASE (1)

pH and H2 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

(pyritepyrrhotite)

extension ~ 15 cm




Claystone:



(pyritepyrrhotite)

extension ~ 15 cm


20 avril 2023



Claystone:



(pyritepyrrhotite)

extension ~ 15 cm

production of H2 gas

extension : ~10 m

vanishes after end of corrosion


20 avril 2023



Claystone:



(pyritepyrrhotite)

extension ~ 15 cm

production of H2 gas

extension : ~10 m

vanishes after end of corrosion

Eh drops during corrosion, then slowly rises

Eh init

Eh solution (mV)



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



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


20 avril 2023 | PAGE 21

Glass alteration products(volume%, 100 000 years)

greenalite, vermiculite-Na and saponites dominate

in the corrosion phase amorphous silica precipitates transiently (r0 phase)

siderite-Ca, dolomite, and chalcedony also

precipitate during post-corrosion phase

Glass zone

5th Andra International Conference - Montpellier | 22 Oct 2012

Glass zone


20 avril 2023 | PAGE 22

Glass alteration products(volume%, 100 000 years)

greenalite, vermiculite-Na and saponites dominate

in the corrosion phase amorphous silica precipitates transiently (r0 phase)

siderite-Ca, dolomite, and chalcedony also

precipitate during post-corrosion phase

modeling vs. experimental results:

silica gel

Fe-silicates

Mg-silicates

Glass zone

5th Andra International Conference - Montpellier | 22 Oct 2012

Burger et al. 2012 / M. Debure (this conference)glass grains iron powder

glass


Claystone

Claystone

Claystone alteration(volume%, 100 000 years)

2 altered zones: extensive alteration (60 cm), H2

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)


Claystone alteration(volume%, 100 000 years)

Claystone

ClaystoneClaystone

2 altered zones: extensive alteration (60 cm), H2

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

OUTLINE PLAN


• 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

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, …)


RN Precipitation Exchange SorptionAm yes yes yesNp yes no no U yes no yesEu yes yes yesZr yes no yesTc yes no yesNi yes yes yesBa yes yes no Se yes no no Sr yes yes no Rb no yes no Cs no yes yesI no no no

retention by:

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)?


27 elements11 exchange reactions25 surf. complex. reactions277 aqueous spieces3 gas82 minerals

409 reactions

RN Precipitation Exchange SorptionAm yes yes yesNp yes no no U yes no yesEu yes yes yesZr yes no yesTc yes no yesNi yes yes yesBa yes yes no Se yes no no Sr yes yes no Rb no yes no Cs no yes yesI no no no

retention by:

DIFFERENT ASSUMPTIONS FORION EXCHANGE/SORPTION MODEL

Case 1

no explicite ion exchangedissolution/precipitation of Na- and Ca- montmorillonitesno 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)


Ca Na

Ca

RESULTS WITH ION EXCHANGE/SORPTION MODELS (1)


Evolution of pH in claystone at the interface with steel

Ca Na

Ca

CORROSION



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



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

GLASS ALTERATION

GLASS ALTERATION

GLASS ALTERATION



Evolution of minerals (mol/l) in claystone at the interface with steel

Similar amounts for secondary minerals

Ca Na

Ca

GLASS ALTERATION

GLASS ALTERATION

GLASS ALTERATION

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)



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



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


20 avril 2023

Impact on RN migration (mol/l) in claystone

at 8000 years

Ca


CONCLUSIONS

Evolution of the HLW cell in the base caseCorrosion 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

20 avril 2023

CONCLUSIONS





Ion exchangesome 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

20 avril 2023

CONCLUSIONS





Ion exchangesome 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

RedoxpH 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)

20 avril 2023

Glass :FeIII/FeII

Iron : FeIII/FeII/Fe0, H2/H2O(SIV/SII)

ArgilitesH2/H2O ?

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| PAGE 39

CEA | 10 AVRIL 2012

AcknowlegementANDRA for financial support

LBNL (C. Steefel, Crunchflow) and

Mines Paristech (PGT consortium, Hytec) for technical support on codes

THANK YOU FOR YOUR ATTENTION

APPENDICE: LIST OF SECONDARY MINERALS


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-CaSmectite(MX80)Mackinawite

codes apply different rules for the precipitation

of secondary phases (assumption for surface areas)!

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?


COCHEPIN Benoit

S'appuyer peut-être sur un diagramme Eh-pH avec les couples redox ?

Documents

CHEMICAL EVOLUTION IN THE NEAR FIELD OF HLW CELLS: INTERACTIONS BETWEEN GLASS, STEEL, AND CLAYSTONE IN DEEP GEOLOGICAL CONDITIONS 5 TH ANDRA INTERNATIONAL