wasteforms CEA | 10 AVRIL 2012 | PAGE 1 Joint ICTP-IAEA Workshop - PowerPoint PPT Presentation

Radiation damages in vitreous wasteforms CEA | 10 AVRIL 2012 | PAGE 1 Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 1

Glassy state A glass (or vitreous solid) is a solid formed by rapid melt quenching. A glass is an amorphous solid that exhibits a glass transition phenomena at T g. Viscosity    Relaxation time G Shear Modulus Glass properties depend on: - Chemical composition Thermal historyduring elaboration process - Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 2

Glassy state • Short Range Order, SRO : Yes Polyhedra • Medium Range Order, MRO : Yes Angle, Ring statistic • Long Range Order, LRO : No BO 3 BO 4 SiO 4 AlO 4 Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 3

Complex oxides glasses : French Nuclear Glass Oxide glass with around 30 oxides Sodium alumino-borosilicate glass L. Cormier, J.M. Delaye, D. Ghaleb, G. Calas, PRB 61 (2001) 14495 Si Na B O Fission product / Actinide in an octahedric site Monographie DEN : Le conditionnement des déchets nucléaires Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 4

Nuclear Glass or GCM: What type of radiation? Actinides: mainly α decays Fission products: mainly β decays Spontaneous fission Most of alpha and beta decays Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 5

Interaction with matter Due to the various decays: Emission of particles with high amount of energy Solid Implanted ion M 2 , Z 2 electronic h n V=0 capture e - e - Ion ionization M 1 , Z 1 e - Ionization of of target Sputtered incident ion atoms Displacment atom cascade Se = (dE/dx) elec = Electronic energy loss due to collisions with electrons Sn = (dE/dx) nucl = Nuclear energy loss due to collisions with atoms S e >S e threshold S e <S e threshold S n Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 6

Interaction with matter Solid Implanted ion M 2 , Z 2 electronic h n V=0 capture e - e - Ion ionization e - M 1 , Z 1 Ionization of of target Sputtered incident ion atoms Displacment atom cascade Pu dE/dx elec Pu dE/dx nucl He dE/dx elec He dE/dx nucl 5,8 MeV 244 Cm 240 Pu 1 Pu dE/dx (kev/nm) 97 keV 0.1 He Mainly nuclear collisions Recoil nuclei Ballistic damage (~100 keV) 0.01 Displacement cascade 30-40nm 1E-3 a 20-30 m m (4-5 MeV) 1E-4 Mainly electronic collisions 0.1 1 10 100 1000 10000 Energy (KeV) Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 7

Interaction with matter Important parameters to consider: • Dose rate : absorbed energy per unit of mass of material per unit of time (Gy/s) • Dose : absorbed energy per unit of mass of material (Gy = J/kg) 5 10 electronic collision, a decay Up to 10 GGy electronic collision,  decay,  transition 10 10 4 10 electronic collision nuclear collision 3 10 9 10 Absorbed Dose (Gy) 10 4 to 10 Gy/h Up to 0.1 GGy Dose rate (Gy/h) 2 10 8 10 1 10 7 10 0 10 electronic collision, a decay 6 10 electronic collision,  decay,  transition -1 10 electronic collision nuclear collision 5 -2 10 10 0 1 2 3 4 5 6 0 1 2 3 4 5 6 10 10 10 10 10 10 10 10 10 10 10 10 10 10 Waste Storage Time (years) Waste Storage Time (years) Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 8

Interaction with matter • Nuclear collisions, dpa = displacements per atom All the atoms have been displaced 1 HLW glass 10 HLW glass with higher MA 239 PuO 2 HLW glass + 10% 0,1 1 He (at%) dpa 0,01 T D =Energy available for damage 0,1 production E 0 =Energy of the particle 1E-3 F D,e =Energy lost to electronic stopping 0,01 1 2 3 4 5 6 10 10 10 10 10 10 E d =Threshold displacement energy Time (years) Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 9

Glass Long Term Behavior – complex ageing scenario Metallic Lithostatic Containers Leaching containers stress corrosion RN release Glass Hundreds to Thousands to hundreds of Near-field materials thousands years thousands years Temperature Dose rate Activity Irradiation dose dpa, He Water resaturation time Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 10

Glass Long Term Behavior: main past studies? Main laboratory studies of alpha decay impact <3 x 10 18 a /g 70 ’ s-90 ’ s USA (NLs) <3 x 10 18 a /g 70 ’ s-80 ’ s Macrosocpic UK (AERE) behavior in a limited <3 x 10 18 a /g level of dose 70 ’ s- 80 ’ s France (CEA) but no data on the <5 x 10 18 a /g glass structure ! 70 ’ s-90 ’ s EU (ITU) <10 19 a /g 90 ’ s JAPAN (JAERI) Need to improve the understanding of alpha decays effects To predict long term behavior To explore nuclear glass limits To optimize the future glass or glass ceramics composition Focus on the results of the research program started in 2001 at CEA Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 11

Methodology to simulate alpha decays effects • Accelerate the time scale • Dissociate the effects of self-irradiation ( electronic / nuclear ) and helium generation • Evaluate the effects on the confinement properties • Evaluate the effects on the glass structure Propose some models to explain the glass behavior under alpha self-irradiation Atalante DHA, CEA 1. Curium doped glasses IPN Orsay Lyon, Ganil 2. External irradiation with light and heavy ions OSIRIS, CEA 3. In pile irradiation : 10 B(n, a ) 7 Li DM, CEA 4. Molecular dynamic modeling of ballistic effects Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 12

Methodology: Cm doping - SON68 glasses doped with 0.04, 0.4, 1.2, 3.25wt% of 244 CmO 2 - International Standard Glass (ISG) doped with 0.7wt% of 244 CmO 2 244 244 244 244 0.04wt% CmO 0.4wt% CmO 1.2wt% CmO 3.25wt% CmO 2 2 2 2 10 20 1.00E+20 ~ 10000 to 100000 years of storage Alpha decay dose ( a /g) 10 19 1.00E+19 10 18 1.00E+18 10 17 1.00E+17 10 16 1.00E+16 2001 2003 2005 2008 2010 2012 2014 2017 2019 time • Initial characterizations of the glasses Other Mol% SiO 2 Na 2 O B 2 O 3 Al 2 O 3 CaO ZrO 2 oxides (homogeneity, chemical composition) ISG/CJ4 60.1 12.6 16.0 3.8 5.7 1.7 • Periodical characterizations of the glass R7T7 52.8 11.3 14.1 3.4 5.0 1.6 11.8 properties Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 13

Methodology: Ion beam irradiation experiment Jannus Saclay,Orsay, Ganil Alpha particles Mono beam Heavy ions (RN) a R R Alpha + Heavy ion a Double beam Heavy ion + Alpha Simultaneous Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 14

Methodology: In pile irradiation : 10 B(n, a ) 7 Li OSIRIS reactor, CEA SACLAY D1 D2 D3 D4 E (MeV) He(1.47) + Li(0.84) Fluence (neutron cm -2 ) 5.9 ×10 18 1.2 ×10 19 3.5 ×10 19 5.2 ×10 19 Number of events (ion cm -3 ) 3.5 ×10 19 7.0 ×10 19 2.1 ×10 20 3.1 ×10 20 Glass samples : polished disks dE/dx(He) <0.03 thickness 0.5 mm dE/dx nucl (keV nm -1 ) dE/dx(Li) <0.06 dE/dx(He) <0.33 dE/dx elec (keV nm -1 ) Aluminum dE/dx(Li) <0.56 sample holder E nucl (GGy) 0.06 0.13 0.39 0.57 in contact with E elec (GGy) 5.16 10.45 30.69 45.71 cooling water Dpa 0.27 0.54 1.6 2.38 Neutron detectors Other Mol% SiO 2 Na 2 O B 2 O 3 Al 2 O 3 CaO ZrO 2 oxides CJ1 67.7 14.2 18.1 Glass SON68 52.8 11.3 14.1 3.4 5.0 1.6 11.8 Thermal modeling and fuses observations after irradiation: Fuse T<70 ° C Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 15

Methodology: Molecular dynamic modeling s Initial Glass - Simplified borosilicate glasses (CJ1, CJ7)   q q r C       i j ij ij ( r ) B exp    ij ij 6 r r   ij ij ij - Accumulation of displacement cascades caused by uranium atoms of energies from 700ev to 70keV - Characterization of the structural modifications induced by displacement cascades (SRO and MRO) Other Mol% SiO 2 Na 2 O B 2 O 3 Al 2 O 3 CaO ZrO 2 oxides CJ1 67.7 14.2 18.1 CJ7 63.8 13.4 17.0 4.1 1.8 SON68 52.8 11.3 14.1 3.4 5.0 1.6 11.8 Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 16

Methodology: Materials and irradiation conditions Cm doped glass Au (1 to 7) MeV Kr (400 KeV) Alpha decay dose 10 B(n, a ) 7 Li scale or time scale He (1.7MeV) Osiris 24 10 -3 ) Deposited electronic energy (KeV.cm ~ 100000 years of storage of nuclear glass 23 10 19 a /g 10 5 to 10 years of storage of 244 Cm glass 22 10 18 a /g 10 21 10 17 a /g 10 20 10 Molecular dynamic simulation 19 10 18 19 20 21 22 10 10 10 10 10 -3 ) Deposited nuclear energy (KeV.cm Simulation of at Light ions irradiations (He) : mainly electronic interactions least 100000 years Heavy ions irradiations (Kr, Au) : mainly nuclear interactions of disposal by various methods ! Doped glasses and OSIRIS irradiation : electronic and nuclear interactions Molecular Dynamics : only nuclear interactions Joint ICTP-IAEA Workshop – Trieste CEA/DEN/MAR/DE2D/SEVT C. Jegou 17