G EOLOGICAL REPOSITORY OF F RENCH HLW C IGO P ROJECT : T HE - PowerPoint PPT Presentation

G LASS FORMULATION H IGH ACTIVITY STUDIES P ROCESS DEVELOPMENT DE LA RECHERCHE À L’INDUSTRIE L ONG TERM BEHAVIOR Leila Galai L ABORATORY OF L ONG TERM BEHAVIOR OF VITREOUS MATRICES J OINT ICTP-IAEA I NTERNATIONAL S CHOOL ON N UCLEAR W ASTE V ITRIFICATION Commissariat à l’énergie atomique et aux énergies alternatives - www.cea.fr J OINT ICTP-IAEA I NTERNATIONAL S CHOOL ON N UCLEAR W ASTE V ITRIFICATION Commissariat à l’énergie atomique et aux énergies alternatives 1

G EOLOGICAL REPOSITORY OF F RENCH HLW C IGÉO P ROJECT : T HE GEOLOGICAL STORAGE OF HLW DEVELOPED BY ANDRA A MULTI - BARRIER CONCEPT : N ATIONAL A GENCY FOR R ADIOACTIVE W ASTE M ANAGEMENT G LASS MATRIX POURED IN STAINLESS STEEL L OW - ALLOYED STEEL OVERPACK CANISTER 500- METER DEEP DISPOSAL C ALLOVO -O XFORDIAN (COX) CLAYSTONE  Demonstrating the enviromental safety of the concept : Assessing the long term behaviour of the nuclear glass Understand the physical and chemical mechanisms that determine glass behavior under repository conditions J OINT ICTP-IAEA I NTERNATIONAL S CHOOL ON N UCLEAR W ASTE V ITRIFICATION Commissariat à l’énergie atomique et aux énergies alternatives 2

M ETHODOLOGY 1 Description of repository condition key parameters  Callovo-Oxfordian claystone fluid composition and its renewal  Surrounding materials: clay, metal, cement 2 Quantification of the effect of these parameters on glass matrices life-time  Parametric alteration experiments 3 Identification of glass alteration mechanisms 4 Modeling lab experiments SON68 glass composition in oxide wt% The inactive reference material is SON68 glass. This glass contains neither radioactive 3 elements, which are instead simulated by other elements. (Jollivet, 1995) J OINT ICTP-IAEA I NTERNATIONAL S CHOOL ON N UCLEAR W ASTE V ITRIFICATION Commissariat à l’énergie atomique et aux énergies alternatives 3

I DENTIFICATION OF GLASS ALTERATION MECHANISMS  Water: main cause of corrosion of the glass packages  Leaching experiments in aqueous solutions, in  Identify the nature and the properties contact with enviromental materials of the alteration products  Solution analysis and solid characterization • HLW French reference glass rates r 0 100 ° C ~ 1 µm/d r 0 50 ° C ~ 10 nm/y Maximum dissolution rate r 0 r r 90 ° C / r 0 90 ° C ~ 10 000 (Alteration resumption) Rate drop Residual rate r r 2 µm Pristine glass Hydrated Alteration regimes glass Macroporous Crystalline phases alteration layer Quasi steady state alteration Precipitation of Experimental evidence of Precipitation of secondary specific secondary a dense layer acting as a phase phases Formation of the And/or evolution of the diffusion barrier and a passivating layer passivating layer hydrated glass that Glass dissolution conserves glass structure Interdiffusion Time J OINT ICTP-IAEA I NTERNATIONAL S CHOOL ON N UCLEAR W ASTE V ITRIFICATION 4 Commissariat à l’énergie atomique et aux énergies alternatives

M ODELING AND EXPERIMENTAL MULTI - SCALE APPROACH Atomistic Models Geochemical Model Macroscopic scientific Detailed mechanistic models : • models : understand coupling at microscopic scale • Justify assumptions of understand elementary mechanisms operational models  Monte Carlo  Molecular dynamics  Ab initio  GRAAL Model validations : Natural and archaeological Accounts for the diffusion and solubility in the gel, integrated with the reactive transport model HYTEC analogues of glasses attempt to answer the question of time scale - (Frugier et al. 2008) (Verney-Carron 2008) To describe macroscopic properties… 5 H 2 O … from atomic to mesoscopic scale J OINT ICTP-IAEA I NTERNATIONAL S CHOOL ON N UCLEAR W ASTE V ITRIFICATION Commissariat à l’énergie atomique et aux énergies alternatives

DE LA RECHERCHE À L’INDUSTRIE S TUDY OF REACTION MECHANISMS GOVERNING IRON - GLASS INTERACTION IN HLW DISPOSAL CONTEXT Leila Galaï  L ABORATORY OF L ONG - TERM BEHAVIOR OF VITREOUS MATRICES Commissariat à l’énergie atomique et aux énergies alternatives - www.cea.fr J OINT ICTP-IAEA I NTERNATIONAL S CHOOL ON N UCLEAR W ASTE V ITRIFICATION Commissariat à l’énergie atomique et aux énergies alternatives

Context C IGÉO P ROJECT : T HE GEOLOGICAL STORAGE OF HLW DEVELOPED BY ANDRA Lid Stainless stell primary Glass Impact the long-term package Matric In presence of water behavior of nuclear vitrified glass/steel Interaction waste Low alloyed stainless steel overpack Pantin de céramique Bring new insights into mechanisms governing the interaction between glass matrix and the stainless steel over-pack for a better prediction of the long term behavior of the nuclear glass under repository conditions 7 J OINT ICTP-IAEA I NTERNATIONAL S CHOOL ON N UCLEAR W ASTE V ITRIFICATION Commissariat à l’énergie atomique et aux énergies alternatives 1

Literature review Glass-iron system: study of the effect of iron on glass alteraction De Combarieu, 2007 Carrière, 2017 Burger et al., 2013 Arena, 2016 Frugier et al. 2007 Mc Vay et al., 1983 Michelin et al., 2013 Schegel et al., 2016 Godon et al., 2013 Brossel, 2017 Hypothesis Increasing of glass Highlight the presence of + Si-Fe formation leads to a delay in alteration in presence iron silicates the saturation of the solution of iron No adequate reference experience ? No unambiguous conclusion on the effect of  Si Na B iron on the alteration of glass Simultaneous degradation of glass and H + Iron/ iron / steel Glass Steel OH -  Difficulty in identifying mechanisms on the surface of each material ? Poor literature on the effect of Si on Fe  corrosion H 2 Fe 2+ Experimental systems too complex to allow a detailed understanding of the mechanisms governing the glass iron interaction J OINT ICTP-IAEA I NTERNATIONAL S CHOOL ON N UCLEAR W ASTE V ITRIFICATION Commissariat à l’énergie atomique et aux énergies alternatives 2

Scientific Strategy Glass-steel-water complex system Decomposition of the original system Better understanding of the complex into two simplified model-systems system Iron-Solution: Glass-Solution: Combined alteration Si effect on iron Fe 2+ effect on glass experiments corrosion alteration Glass/Iron/solution • V corr.Fer • V disso verre • V prec.Si-Fe • V prec.Si-Fe Understanding of the mechanisms Verification of the deduced and associated kinetics mechanisms transferability to a more complex system J OINT ICTP-IAEA I NTERNATIONAL S CHOOL ON N UCLEAR W ASTE V ITRIFICATION Commissariat à l’énergie atomique et aux énergies alternatives 3

First results Glass-Solution system Study of Fe 2+ effect on glass alteration kinetics  • Glove box • T= 90°C • S/V = 0,5 cm -1 • CJ2= Si, B, Na, Al 1. Free pH experiments  Increasing of glass H 2 O FeCl 2 alteration in presence of Need to work on the same pH to FeCl 2 pH 8,7 6,2 dissociate the effect of iron and % Va 20 40 pH on glass alteration 2. Buffered experiments: Buffer NH 3 /NH 4 Cl 0.3 CJ2-Tampon  Hides the possible Need to find an inert buffer NL(B) g/m² effect of Fe 2+ on glass 0.2 CJ2-FeCl2- towards glass alteration Tampon alteration 0.1 CJ2-FeCl2- H2O 0 0.0 20.0 40.0 Temps (Jours) J OINT ICTP-IAEA I NTERNATIONAL S CHOOL ON N UCLEAR W ASTE V ITRIFICATION Commissariat à l’énergie atomique et aux énergies alternatives 4

First results Iron-Solution system • Study of Si effect on iron corrosion kinetics • Iron Corrosion monitoring • 2 H + + Fe Fe(II) + H 2 Sealed reactors to avoid gaz leak P(H 2 ) monitoring H 2 O/OH - … Si(IV) In solution  XPS Characterization • Iron oxide and hydroxide formation on the surface • Oxide layer thickness Fe 2+ /Fe 3+ ratio • • Si-Fe formation • Iron oxide and • Monitoring of Si hydroxide formation in consumption solution Iron corrosion experiments   Fe 2+ In solution • 4, 9 et 30 days  • pH 8 • T 50  Fe-EP-4 Fe- 2p 3/2 Oxide layer Oxide layer formed on Duration thikness Fe- 2p 1/2 Experience the surface of Fe powder Intensity / a.u. name (Days ) (nm)  Fe 3+ contribution with little or no Fe- EP-4 4 5 evolution in terms of  Fe 2+ contribution Fe- EP-9 9 6 composition and  Fe 0 contribution Fe- EP-30 30 6 thickness 733 728 723 718 713 708 703 11 Binding energy / eV Study of iron corrosion kinetics possible only by solution analysis + characterization J OINT ICTP-IAEA I NTERNATIONAL S CHOOL ON N UCLEAR W ASTE V ITRIFICATION Commissariat à l’énergie atomique et aux énergies alternatives 6

Experimental approach Need to impose identical physicochemical conditions in all experiments Glass solution system : Iron solution System : T = 50 °C Fe effect on glass Si Effects on iron pH= 8,2 alteration corrosion Borate buffer: H 3 BO 3 ,NaOH Anoxic media (glove-box) PTFE container PTFE container Fe H 4 SiO 4 Fe Sheet (99,95%) Alterative solution Na Na B CJ1: Na, Si, B Fe B Glass powder Alterative solution • V corr.Fer • V disso verre Identical physicochemical conditions: • V prec.Si-Fe • V prec.Si-Fe Similar Si-Fe formed Modeling: Combined alteration experiments • Glass/Iron/solution Characterization: precipitated minerals nature and stoichiometry • Kinetics of formation, Fe corrosion kinetics, glass alteration kinetics J OINT ICTP-IAEA I NTERNATIONAL S CHOOL ON N UCLEAR W ASTE V ITRIFICATION Commissariat à l’énergie atomique et aux énergies alternatives 5