Academic Research for French Industrial Vitrification

Transcription

1 Academic Research for French Industrial Vitrification Olivier PINET, Sylvain PEUGET, Sophie SCHULLER, Stéphane GIN, Bruno LORRAIN CEA/DEN/DTCD/LCV/SECM F Bagnols-sur-Cèze, France 1

2 Choice of Glass for nuclear waste containment Excellent chemical durability, A wide range of chemical elements can be incorporated, Stability under radiation. silicium oxygène sodium Produits de fission 2

3 Industrial objective Find the best compromise Radioactive waste specification Composition, quantity, activity Waste loading Vitrification Incineration Process Optimal compromise Glass waste form Find the best process (robustness, maintainability, best elaboration conditions, low corrosion, volatility) Optimize the best containment matrice (glass feasibility, quality, long term behavior) 3

4 Industrial Challenges : material developed for cold and hot crucible Molten glass properties Glass feasibility Thermal conductivity Electric conductivity Redox Viscosity Chemical reactivity Glass waste form Si, B, Na, Al, Ca, Zr, Zn, Rb, Cs, Sr, Mo, Tc, Ru, Rh, Pd, Cd, Te, La, Ce, Pr, Nd, U, Np, Pu, Am, Cm, Radiation stability Glass structure Glass phenomenology Glass quality Solubility (Mo, Cr, Ru, S, ) Chemical durability Thermal stability Phase separation crystallization Glass containment properties Long term behavior 4

5 Glass phenomenology research topic Variability of radioactive waste Vitrification limits Mo Noble metals (Ru, Pd, Rh) Nd, La, Pr, Ce, P Fe, Ni, Cr Cl, S, Cd, Ag, I Phase separation and Molybdates crystallization Chemical reactivity, rheological, electrical conductivity modifications Apatite crystallization Spinel crystallization Volatility, crystallization Objective of Glass phenomenology research topic Increase the solubility (thermodynamic, structure of glass) Decrease the quantities of crystalline phases Control the microstructure and the composition of crystalline phases Increase the chemical reactivity (kinetic) Define the vitrification operating conditions 5

6 Chemical durability approach Understanding and modeling the mechanism of aqueous alteration to predict the long term behavior under geological repository Modeling and experimental approach Experimental Glass alteration, characterization Alteration layer morphology Performance Assessment Operational model Ex : MOP V 0 -> V r Natural analogues Validation of operational model hypothesis Mechanisms of the alteration layer formation m, Ma Macroscopic Mesoscopic GRAAL model, thermomechanic model mm, y µm, d Modeling Kinetic Monte Carlo Glass and alteration layer structure Elementary alteration mechanisms Atomistic nm, ps Ab initio calculation 6

7 Conclusion Academic research on glass material by experimental and modeling approaches is necessary to develop and optimize containment glass and vitrification processes Knowledge on glass elaboration Research topics generated by industrial issue Knowledge on glass containment properties Research topics generated by the final disposal Optimize the operating conditions of the vitrification furnace Support specification of new glass matrix Optimize glass quality Increase the solubility of elements Validation of long term modeling for performance calculations, Optimize glass composition to increase durability and radiation stability Optimize the geological disposal design An iterative processus of expertise and valorisation Support industrial process (Calcination-vitrification, gaz treatment) Support geological repository (design & safety) Generate a large field of expertise, innovation and large potential for the futur 7

8 Context : Agreement between CEA and BARC on development and characterization of high level radioactive vitreous waste forms Between 2007 and 2011 Two mains actions identified: 1. Methodology to study Glass Long Term Behavior (LTB) 2. Radiation effects on borosilicate glasses CEA : French Atomic Energy Commission BARC : Bhabha Atomic Research Center 8

9 MARCOULE / March 2007 The glass waste forms, fabrication and the concepts of disposal BARC / K. BANERJEE Methodology to study the LTB of glass: BARC / R.G. YEOTIKAR - CEA / S. GIN - Effects of radiations on glass long term behaviour BARC / R.G. YEOTIKAR - CEA / S. PEUGET - Effect of environment on glass alteration BARC / R.G. YEOTIKAR -CEA / N. GODON - The glass alteration mechanisms CEA / P. FRUGIER - Operational modelling of glass LTB CEA / I.RIBET - The natural analogs and glass LTB BARC / R.K. BAJPAI- CEA / S. GIN - Discussion about the methodology to evaluate the long term behaviour of glass - Define the main actions of cooperation 9

10 Radiation effects on borosilicate glasses In pile irradiation using the 10 B(n, α) 7 Li to damage the glass and generate important helium content in the glass Simulation of alpha decay effects France - OSIRIS India - DHRUVA On both sides, irradiation in a reactor with to10 14 n/cm²/s thermal neutron flux Osiris Dhruva French glasses CJ1 R7T7 x x x Indian glasses AVS Tarapur WIP Trombay x x x x IR111 x 10

11 Radiation effects on borosilicate glasses Details of the OSIRIS irradiation (CEA Saclay Center): Glass samples : polished disks, diameter 5 and 11 mm, thickness 0.5mm Alpha dose : between and He/g More than years of glass disposal Neutron flux : 1,3x10 13 n.cm -2.s -1 thermal flux Adjusted to control de glass temperature during the irradiation (<70 C) and limit the helium diffusion Neutron dose measurement Glass samples Irradiation: november 2009 to march 2010 Temperature control 11

12 Radiation effects on borosilicate glasses Characterization of the R7T7 glass irradiated in OSIRIS Reactor : Density Density variation ρ/ρ (%) x x x x x Nuclear energy deposited, E nucl (kev cm -3 ) 0.04m doped glass (CEA) 0.4m doped glass (CEA) 1.2m doped glass (CEA) 3.25m doped glass (CEA) 1.5m doped glass (ITU) OSIRIS irradiated glass Decrease of density of around 0.6% Data in good agreement with results on Cm doped glasses Effect induced by nuclear interaction of recoil nuclei No effect of helium concentration Dpa 12

13 Radiation effects on borosilicate glasses Characterization of the R7T7 glass irradiated in OSIRIS Reactor : Hardness Nuclear energy deposited, E nucl (kev cm -3 ) Hardness variation, H v /H v (%) x x x x x % Cm doped glass (CEA) % Cm doped glass (CEA) 1.2% Cm doped glass (CEA) 3.25% Cm doped glass (CEA) -5 Cm doped glass (ITU) Cm doped glass (JAERI) Mod. Marples, dopés OSIRIS irradiated glass Dpa Decrease of hardness of around 35% Data in good agreement with results on Cm doped glasses Effect induced by nuclear interaction of recoil nuclei No effect of helium concentration 13

14 Radiation effects on borosilicate glasses Characterization of the R7T7 glass irradiated in OSIRIS Reactor: Helium release experiment, SEM examination Helium isothermal release fraction T=220 C T=280 C T=320 C F rel (-) t 1/2 (s 1/2 ) Release in agreement with the diffusion of a single population of helium atoms 1 µm Homogeneous microstructure No helium bubbles despite a helium concentration of 7x10 19 He/g 14

15 Radiation effects on borosilicate glasses Characterization of the R7T7 glass irradiated in OSIRIS Reactor: Helium release experiment Verres inactifs ( C) : E a = (0,61 ± 0,04) ev D (cm 2 s -1 ) R7T7 inf.: D nom R7T7 inf.: D max-min R7T7 inf.: D nom (25 C) R7T7 dopés 244 Cm: D nom R7T7 dopés irradiés réacteur R7T7 implanté 3 He + Verres irradiés en réacteur : E a = (0,67 ± 0,03) ev Verres dopés 244 Cm : E a = (0,61 ± 0,03) ev Verres inactifs (25 C) Verres implantés 3 He : E a = (0,55 ± 0,03) ev T -1 (K -1 ) No significant effect of the glass damage on the helium diffusion coefficient 15

16 End of the cooperation in July Characterization program is not finished Characterization of CJ1, AVS and WIP glasses - Raman analyses, - SEM examination - Density measurement - Helium concentration measurement - Some prospects was identified Radiation damage studies by external irradiations 16

17 Thank you for your attention 17