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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

slide-1
SLIDE 1

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 1

Radiation damages in vitreous wasteforms

| PAGE 1 CEA | 10 AVRIL 2012

slide-2
SLIDE 2

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 2

G   

Viscosity Shear Modulus Relaxation time

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 Tg. Glass properties depend on:

  • Chemical composition
  • Thermal historyduring elaboration process

Glassy state

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SLIDE 3

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 3

SiO4 BO4 BO3 AlO4

  • Short Range Order, SRO : Yes

Polyhedra

  • Medium Range Order, MRO : Yes

Angle, Ring statistic

  • Long Range Order, LRO : No

Glassy state

slide-4
SLIDE 4

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 4

Complex oxides glasses : French Nuclear Glass

Oxide glass with around 30 oxides Sodium alumino-borosilicate glass Si O Na B

Fission product / Actinide in an octahedric site

Monographie DEN : Le conditionnement des déchets nucléaires

  • L. Cormier, J.M. Delaye, D. Ghaleb, G. Calas, PRB 61 (2001) 14495
slide-5
SLIDE 5

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 5

Nuclear Glass or GCM: What type of radiation?

Fission products: mainly β decays Actinides: mainly α decays

Spontaneous fission

Most of alpha and beta decays

slide-6
SLIDE 6

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 6

Interaction with matter

e- e- e- Ion M1, Z1 Sputtered atom Solid M2, Z2 hn ionization

  • f target

atoms Ionization of incident ion electronic capture Displacment cascade Implanted ion V=0

Due to the various decays: Emission of particles with high amount of energy

Se = (dE/dx)elec = Electronic energy loss due to collisions with electrons Sn = (dE/dx)nucl = Nuclear energy loss due to collisions with atoms Sn Se>Se threshold Se<Se threshold

slide-7
SLIDE 7

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 7

Mainly nuclear collisions Ballistic damage Displacement cascade

244Cm 240Pu

97 keV 5,8 MeV Recoil nuclei (~100 keV)

a

(4-5 MeV) 30-40nm 20-30 mm Mainly electronic collisions

0.1 1 10 100 1000 10000 1E-4 1E-3 0.01 0.1 1

dE/dx (kev/nm) Energy (KeV) Pu dE/dx elec Pu dE/dx nucl He dE/dx elec He dE/dx nucl

Pu He e- e- e- Ion M1, Z1 Sputtered atom Solid M2, Z2 hn ionization

  • f target

atoms Ionization of incident ion electronic capture Displacment cascade Implanted ion V=0

Interaction with matter

slide-8
SLIDE 8

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 8

  • 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)

Interaction with matter

Important parameters to consider:

10 10

1

10

2

10

3

10

4

10

5

10

6

10

5

10

6

10

7

10

8

10

9

10

10

electronic collision, a decay electronic collision,  decay,  transition electronic collision nuclear collision

Absorbed Dose (Gy) Waste Storage Time (years)

10 10

1

10

2

10

3

10

4

10

5

10

6

10

  • 2

10

  • 1

10 10

1

10

2

10

3

10

4

10

5

electronic collision, a decay electronic collision,  decay,  transition electronic collision nuclear collision

Dose rate (Gy/h) Waste Storage Time (years)

Up to 10 GGy 104 to 10 Gy/h Up to 0.1 GGy

slide-9
SLIDE 9

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 9

  • Nuclear collisions, dpa = displacements per atom

Interaction with matter

TD=Energy available for damage production E0=Energy of the particle FD,e=Energy lost to electronic stopping Ed=Threshold displacement energy

10

1

10

2

10

3

10

4

10

5

10

6

1E-3 0,01 0,1 1

He (at%)

Time (years)

0,01 0,1 1 10

HLW glass HLW glass with higher MA HLW glass + 10%

239PuO2

dpa

All the atoms have been displaced

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SLIDE 10

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 10

Glass Long Term Behavior – complex ageing scenario

Glass Metallic containers Near-field materials

time

Containers corrosion Leaching RN release Dose rate Activity Temperature Water resaturation Irradiation dose dpa, He Lithostatic stress Hundreds to thousands years Thousands to hundreds of thousands years

slide-11
SLIDE 11

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 11

Focus on the results of the research program started in 2001 at CEA USA (NLs) 70’s-90’s <3 x 1018 a/g UK (AERE) 70’s-80’s <3 x 1018 a/g France (CEA) 70’s- 80’s <3 x 1018 a/g EU (ITU) 70’s-90’s <5 x 1018 a/g JAPAN (JAERI) 90’s <1019 a/g

Main laboratory studies of alpha decay impact

Macrosocpic behavior in a limited level of dose but no data on the glass structure ! 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

Glass Long Term Behavior: main past studies?

slide-12
SLIDE 12

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 12

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

  • 1. Curium doped glasses
  • 2. External irradiation with light and heavy ions
  • 3. In pile irradiation : 10B(n,a)7Li
  • 4. Molecular dynamic modeling of ballistic effects

Atalante DHA, CEA OSIRIS, CEA IPN Orsay Lyon, Ganil DM, CEA

slide-13
SLIDE 13

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 13

Methodology: Cm doping

  • SON68 glasses doped with 0.04, 0.4, 1.2, 3.25wt% of 244CmO2
  • International Standard Glass (ISG) doped with 0.7wt% of 244CmO2

1.00E+16 1.00E+17 1.00E+18 1.00E+19 1.00E+20

2001 2003 2005 2008 2010 2012 2014 2017 2019

time Alpha decay dose (a/g)

0.04wt% CmO 0.4wt% CmO 1.2wt% CmO 3.25wt% CmO

244 244 244 244

1020 1019 1018 1017 1016

2 2 2 2

  • Initial characterizations of the glasses

(homogeneity, chemical composition)

  • Periodical characterizations of the glass

properties

~ 10000 to 100000 years of storage

Mol% SiO2 Na2O B2O3 Al2O3 CaO ZrO2 Other

  • xides

ISG/CJ4 60.1 12.6 16.0 3.8 5.7 1.7 R7T7 52.8 11.3 14.1 3.4 5.0 1.6 11.8

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SLIDE 14

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 14

Methodology: Ion beam irradiation experiment Jannus Saclay,Orsay, Ganil Alpha particles Heavy ions (RN) Alpha + Heavy ion Heavy ion + Alpha Simultaneous

a

R a

R Mono beam Double beam

slide-15
SLIDE 15

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 15

D1 D2 D3 D4 E (MeV) He(1.47) + Li(0.84) Fluence (neutron cm-2) 5.9 ×1018 1.2 ×1019 3.5 ×1019 5.2 ×1019 Number of events (ion cm-3) 3.5 ×1019 7.0 ×1019 2.1 ×1020 3.1 ×1020 dE/dxnucl (keV nm-1) dE/dx(He) <0.03 dE/dx(Li) <0.06 dE/dxelec (keV nm-1) dE/dx(He) <0.33 dE/dx(Li) <0.56 Enucl (GGy) 0.06 0.13 0.39 0.57 Eelec (GGy) 5.16 10.45 30.69 45.71 Dpa 0.27 0.54 1.6 2.38

Glass Fuse Aluminum sample holder in contact with cooling water

Thermal modeling and fuses

  • bservations after irradiation:

T<70°C

Neutron detectors

Glass samples : polished disks thickness 0.5 mm

OSIRIS reactor, CEA SACLAY

Methodology: In pile irradiation : 10B(n,a)7Li

Mol% SiO2 Na2O B2O3 Al2O3 CaO ZrO2 Other

  • xides

CJ1 67.7 14.2 18.1 SON68 52.8 11.3 14.1 3.4 5.0 1.6 11.8

slide-16
SLIDE 16

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 16 Mol% SiO2 Na2O B2O3 Al2O3 CaO ZrO2 Other

  • xides

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

  • Simplified borosilicate glasses (CJ1, CJ7)

Methodology: Molecular dynamic modeling s

  • 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)

6

exp ) (

ij ij ij ij ij ij j i ij

r C r B r q q r             

Initial Glass

slide-17
SLIDE 17

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 17

Light ions irradiations (He) : mainly electronic interactions Heavy ions irradiations (Kr, Au) : mainly nuclear interactions Doped glasses and OSIRIS irradiation : electronic and nuclear interactions Molecular Dynamics : only nuclear interactions

10

18

10

19

10

20

10

21

10

22

10

19

10

20

10

21

10

22

10

23

10

24

10

19a/g

10

18a/g

Deposited electronic energy (KeV.cm

  • 3)

Deposited nuclear energy (KeV.cm

  • 3)

Cm doped glass Au (1 to 7) MeV Kr (400 KeV) He (1.7MeV) Osiris

10B(n,a) 7Li

10

17a/g

Molecular dynamic simulation

Alpha decay dose scale or time scale ~ 100000 years of storage

  • f nuclear glass

5 to 10 years of storage of

244Cm glass

Methodology: Materials and irradiation conditions

Simulation of at least 100000 years

  • f disposal by

various methods !

slide-18
SLIDE 18

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 18

Homogeneous microstructure, without bubbles, phase separation or crystallization Stability of the glassy state

244Cm SON 68 glass : SEM (CEA Marcoule), alpha decay dose 2x1019a/g

1 mm 100 µm 5 µm

Creuset Pt Creuset Pt Creuset Pt Verre Verre Verre

244Cm SON 68 glass : TEM (ITU Karlsruhe), alpha decay dose 8x1018a/g

(Around 100000 years of storage)

Stability of the metastable glassy state ? Effect on the glass microstructure

  • S. Peuget et al. JNM 44 (2014)
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SLIDE 19

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 19

Slight decrease of the glass density (0.5%) No effect of the dose rate Stabilization of the evolution at around 4x1018 a/g Evolution according to an exponential law (direct impact model) ✓Variations correclty simulated by external irradiations wih heavy ions and MD simulation ✓Swelling level is lower under α decays irradiation (0,5% compared to 1,2% Au irradiation)

0.0 2.0x10

18 4.0x10 18 6.0x10 18 8.0x10 18 1.0x10 19 1.2x10 19 1.4x10 19 1.6x10 19 1.8x10 19 2.0x10 19

  • 0.8
  • 0.7
  • 0.6
  • 0.5
  • 0.4
  • 0.3
  • 0.2
  • 0.1

0.0 0.1

0.04CmSON68 0.4CmSON68 1.2CmSON68 3.25CmSON68 exponential law

Density variation (%) Alpha decay dose (a/g)

  • S. Peuget et al. J. Nucl. Mat. 354 (2006) 1
  • S. Peuget et al. J. Nucl. Mat. 354 (2014) 1

Stability of the metastable glassy state ? Effect on the macroscopic properties ?

10

19

10

20

10

21

  • 4
  • 3
  • 2
  • 1

Au CJ1 MD CJ1 Au SON68 Density variation (%) Deposited nuclear energy dose (kev.cm

  • 3)

10

17

10

18

10

19

3.25CmSON68 exponential law Alpha decay dose (a.g

  • 1)
slide-20
SLIDE 20

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 20

Mechanical properties: example of hardness Decrease of hardness on curium doped glasses and ions irradiated glasses He induced lower changes Effect of electronic or nuclear interactions? No agreement versus Electronic dose ~ 60 GGy

10

19

10

20

10

21

10

22

10

23

10

24

  • 40
  • 30
  • 20
  • 10

0.4SON68 1.2SON68 3.25SON68 KrSON68 AuSON68 HeSON68 1.7

244CmO2 ITU

3.0 CmO2 JAERI AuCJ1 AuCJ3 AuCJ7 OSIRIS SON68

Hardness variation (%) Deposited electronic energy dose (keV.cm

  • 3)
  • S. Peuget et al, NIMB 246 (2006) 379
  • S. Peuget et al. JNM 354 (2014) 1

Mir et al. . JNM 469 (2016) 244

Stability of the metastable glassy state ? Effect on the macroscopic properties ?

slide-21
SLIDE 21

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 21

Mechanical properties: example of hardness Decrease of hardness on curium doped glasses and heavy ions irradiated glasses He induced lower changes Effect of electronic or nuclear interactions? Quite good agreement between doped glasses and heavy ions irradiated glasses Effect induced by nuclear interactions, rôle of RN ! 0.6 GGy

10

17

10

18

10

19

10

20

10

21

10

22

  • 40
  • 30
  • 20
  • 10

0.4SON68 1.2SON68 3.25SON68 KrSON68 AuSON68 HeSON68 1.7

244CmO2 ITU

3.0 CmO2 JAERI AuCJ1 AuCJ3 AuCJ7 OSIRIS SON68

Hardness variation (%) Deposited nuclear energy dose (keV.cm

  • 3)
  • S. Peuget et al, NIMB 246 (2006) 379
  • S. Peuget et al. JNM 354 (2014) 1

Mir et al. . JNM 469 (2016) 244

Stability of the metastable glassy state ? Effect on the macroscopic properties ?

slide-22
SLIDE 22

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 22

17/09/2018

Increase of BO3 (+7%)

192 195 198 201 204 207 4 8

Fluorescence Yield (a.u.) Energy (eV)

R7T7_sain R7T7_Au

Increase of BO3 units

244Cm ISG glass

4x1018a/g

CJ1 irradiated in OSIRIS reactor

RMN at ITU

11B MQMAS

Conclusion : Partial conversion BO4 into BO3 Complex and simplified glasses

ISG irradiated with Au et Xe

  • C. Mendoza et al. NIMB 325 (2014) 54-65

Xanes B K edge: R7T7 irradiated with Au

  • T. Charpentier et al. Scientific Reports 6:25499 (2016)
  • S. Peuget et al, NIMB 327 (2014) 22-28
  • G. Bureau, thesis, (2008)

Stability of the metastable glassy state ? Effect on glass structure : SRO around B

Increase of BO3 (+16%)

BO3 increase is lower under α decays irradiation

slide-23
SLIDE 23

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 23

Raman spectroscopy on Cm doped ISG (Atalante, DHA)

  • Increase of Q3 contribution in ISG glass : more NBO
  • Slight shift of the vibration band around 500cm-1

Decrease of the mean angle between silica tetrahedra

  • New D2 band on ISG Cm doped glass: 3 members silica rings
  • Stabilization of the silicon local environment after around 4 x 1018 a/g

200 400 600 800 1000 1200 1400 1600 3,07 10

16 a/g

3,75 10

17 a/g

2,05 10

18 a/g

Intensity Raman shif (cm

  • 1)

490 605 605 1070

540 560 580 600 620 640 660 680 700 720 Raman shift (cm

  • 1)

Cm3+ luminescence

  • C. Mendoza et al. Proc. Chem. 7 (2012) 581
  • S. Peuget et al. JNM 444 (2014)

Stability of the metastable glassy state ? Effect on glass structure : SRO around Si and MRO

J.-M. Delaye et al, J. Non-Cryst. Solids 357 (2011) 2763

1 2 3 4 5 6 7 4E+20 8E+20 1.2E+21 1.6E+21

__ CJ1 __ CJ7 Deposited nuclear energy (keV.cm-3) % NBO Raman ISG glass MD - CJ1 glass

1x10

18

2x10

18

3x10

18

4x10

18

5x10

18

6x10

18

7x10

18

  • 2

2 4 6 8 10 12 14 16

R band position (cm

  • 1)

Alpha decay dose (a.g

  • 1)

1

7 . 13

  cm RSat

Unitary damage volume=450nm

3

slide-24
SLIDE 24

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 24

17/09/2018

Effects on the glass structure? Summary

Modification of the Short Range Order Increase of trigonal boron, increase of NBO Modification of the Medium Range Order Ring statistic modification, increase of glass disorder and Si/B mixing Effects similar to those induced by thermal quenching of a molten glass

BO4 BO3 + NBO Decrease of the glass density

Wu and Stebbins JNCS 356 (2010)

11B NMR on quenched and annealed glass

BO4 BO3

T

slide-25
SLIDE 25

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 25 Pristine glass Tf Enthalpy Tf Enthalpy Tf Enthalpy Irradiated Glass T’f

10

16

10

17

10

18

10

19

520 530 540 550 560

Fictive Temperature, °C Cumulative Dose, a-decays g

  • 1

10

16

10

17

10

18

10

19

520 530 540 550 560

Fictive Temperature, °C Cumulative Dose, a-decays g

  • 1

10

16

10

17

10

18

10

19

520 530 540 550 560

Fictive Temperature, °C Cumulative Dose, a-decays g

  • 1

Irradiated zone has a higher fictive temperature

1. Balistic step : disordered state 2. Relaxation step : very important quenching rate

 

) exp( 1 D V Tf Tf Tf

c Sat

   

Understanding of glass behavior under alpha decays

Stabilization of a new glass structure when all the volume has been damaged once Model of accumulation of ballistic disordering fast quenching events: “supervitrification”

E Maugeri et al, J. Am. Ceram. Soc. 95 (2012) 2869

slide-26
SLIDE 26

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 26

5 10 15 20 25 30 2000 4000 6000 8000 10000

Local Temperature (K)

Time (ps)

10

12

10

13

10

14

10

15

10

16

10

17

10

18

Quenching Rate (K.s

  • 1)

Effects on the glass structure? Ballistic damage

Golden = Si Green = B Blue = Na Red = O Very high quenching rate of the disordered state induced by the displacement cascade Supervitrification

JM Delaye, PRB 61 (2000) 14481

What happen in the displacement cascade induced by a recoil nuclei?

1. Balistic phase 2. Thermal phase

slide-27
SLIDE 27

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 27

Main effects observed under alpha decay irradiation:

✓ A saturation effect with dose, a new glass structure is reached after around 4x1018 a/g (Nuclear dose ~30 MGy) ✓ No effect of the dose rate in the relevant range ✓ Changes at both Short Range Order and Medium Range Order

✓ Changes in boron coordination number and glass polymerization index ✓ Changes in ring statistic, angle distribution

✓ A higher fictive temperature after irradiation ✓ Stored energyof ~100J/g ✓ Complex glasses are less modified than simple glasses

1x10

18

2x10

18

3x10

18

4x10

18

5x10

18

6x10

18

7x10

18

  • 2

2 4 6 8 10 12 14 16

R band position (cm

  • 1)

Alpha decay dose (a.g

  • 1)

1

7 . 13

  cm RSat

Unitary damage volume=450nm

3

Characteristics of the irradiated glassy state? α irradiation

slide-28
SLIDE 28

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 28

Waste mechanical degradation? Can irradiation induce a cracking of the material?

  • Due to important swelling under irradiation?
  • Degradation of the mechanical properties?
  • Due to bubble formation (He bubbles generated by alpha decays)

Nuclear Glass or GCM under irradiation: What do we know?

slide-29
SLIDE 29

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 29

Waste mechanical degradation? Can irradiation induce a cracking of the material?

  • Due to important swelling under irradiation?
  • Degradation of the mechanical properties?
  • Due to bubble formation (He bubbles generated by alpha decays)

Nuclear Glass or GCM under irradiation: What do we know?

slide-30
SLIDE 30

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 30

Slight variation of the glass density Low swelling level, no microcraking

0.0 2.0x10

18 4.0x10 18 6.0x10 18 8.0x10 18 1.0x10 19 1.2x10 19 1.4x10 19 1.6x10 19 1.8x10 19 2.0x10 19

  • 0.8
  • 0.7
  • 0.6
  • 0.5
  • 0.4
  • 0.3
  • 0.2
  • 0.1

0.0 0.1

0.04CmSON68 0.4CmSON68 1.2CmSON68 3.25CmSON68 exponential law

Density variation (%) Alpha decay dose (a/g)

  • S. Peuget et al. J. Nucl. Mat. 354 (2014) 1

WASTE MECHANICAL DEGRADATION?

Important swelling of Homogeneous glass?

1 mm 100 µm 5 µm

Creuset Pt Creuset Pt Creuset Pt Verre Verre Verre

slide-31
SLIDE 31

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 31

Microcracking observed on some GCM

Waste form degradation ? GCM?

  • W. J. Weber and F. P. Roberts, Nuclear Technology, vol. 60.,178-198.

Amorphization of the crystalline phases: high swelling level of crystalline phase To go further in GCM development: Need to understand and master the origin of radiation induced cracking Evaluation of the impact of type of phase, density and size

  • f crystalline phases

WASTE MECHANICAL DEGRADATION?

slide-32
SLIDE 32

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 32

Waste mechanical degradation? Can irradiation induce a cracking of the material?

  • Due to important swelling under irradiation?
  • Degradation of the mechanical properties?
  • Due to bubble formation (He bubbles generated by alpha decays)

Nuclear Glass or GCM under irradiation: What do we know?

slide-33
SLIDE 33

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 33

Decrease of Hardness, Young Modulus, increase of fracture toughness No significant degradation of the mechanical properties Even slightly better, fracture toughness increase … Origin associated to structural changes under irradiation

Degradation of the mechanical properties?

10

17

10

18

10

19

10

20

10

21

10

22

  • 40
  • 30
  • 20
  • 10

0.4SON68 1.2SON68 3.25SON68 KrSON68 AuSON68 HeSON68 1.7

244CmO2 ITU

3.0 CmO2 JAERI AuCJ1 AuCJ3 AuCJ7 OSIRIS SON68

Hardness variation (%) Deposited nuclear energy dose (keV.cm

  • 3)

WASTE MECHANICAL DEGRADATION?

slide-34
SLIDE 34

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 34

Waste mechanical degradation? Can irradiation induce a cracking of the material?

  • Due to important swelling under irradiation?
  • Degradation of the mechanical properties?
  • Due to bubble formation (He bubbles generated by alpha decays)

Nuclear Glass or GCM under irradiation: What do we know?

slide-35
SLIDE 35

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 35

Is there any risk of formation of pressurized He bubbles in a nuclear glass?

  • Helium incorporation mechanism in the glassy network ?
  • Solubility limit ? Helium bubble formation?
  • Helium diffusion mechanism?
  • Impact of radiation damage on these mechanisms?

10 10

1

10

2

10

3

10

4

10

5

10

6

10

7

50 100 150 200 250 300 350 400 450

Stockage en profondeur Phase de stockage

Température (°C) Temps (années) Zone au coeur Zone intermédiaire Zone en surface

Phase d'entreposage

10

1

10

2

10

3

10

4

10

5

10

6

1E-3 0,01 0,1 1

He (at%) Time (years)

0,01 0,1 1 10

HLW glass HLW glass with higher MA HLW glass + 10%

239PuO2

dpa

WASTE MECHANICAL DEGRADATION?

slide-36
SLIDE 36

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 36

3He+ implantation :

[He]max: 4,3×1021 at./cm3 (local) dpa: 11 (local)

He Infusion (P , T) Equilibium gas/solid

[He]max: 3,5×1018 at./cm3 dpa: 0

CEA Marcoule CEMHTI Orléans, LEEL Saclay NRA d(3He,p)α) Jannus Orsay, MIAMI Huddersfield in-situ TEM Irradiation in OSIRIS reactor (10B(n,α)7Li)

[He]max: 2,2×1020 at./cm3 dpa: ~ 1-2

Cm doped glass (alpha decays)

[He]max : 4,4×1019 at./cm3 dpa: 1

WASTE MECHANICAL DEGRADATION?

He - METHODOLOGY

slide-37
SLIDE 37

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 37 Shackelford J. Appl. Phys. 43 (1972)

1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 4.0x10

15

6.0x10

15

8.0x10

15

1.0x10

16

1.2x10

16

1.4x10

16

1.6x10

16

Experimental data Simulation S (at. cm

  • 3 atm.)

1000T

  • 1 (K
  • 1)

T (K)

673 593 533 723 748 773

Density of solubility sites accessible to helium in R7T7 glass: Ns~3x1021 sites.cm-3 Ns~3 at% to confirm by high pressure infusion experiments at JRC-ITU He infusion experiments

  • T. Fares, J. Am. Cer. Soc. 95 (2012) 3854

RT E T k h T k h S B B

e e e N T k T mk h p C S

B B

/ ) ( 3 / 2 / 2 / 3 2

1 1 2

  

                  

n n

Glass LTB: He incorporation in nuclear glass

Incorporation of He in the glass free volume

slide-38
SLIDE 38

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 38

T (°C)

352°C 547°C 594°C

T< TG: No evolution of microstructure Helium inside the free volume ➢T<Tg: no glass deformation No bubbles (ø < 50 nm) ➢T>Tg: glass deformation is possible Bubble formation (ø > 50 nm) T~TG: Dark zones ➢ nucleation of He bubbles (1 µm < ø < 10 µm) T> TG: Formation of bubbles ➢ migration of bubbles ➢ release by bursts

520°C Tg 530°C 540°C

200 400 600 800 1000 5,0x10

  • 10

1,0x10

  • 9

1,5x10

  • 9

MS Signal / A Relative time / sec P 200

200 400 600 800 1000

Temperature / K

He release ITU QGames

Physical state of He ? Homogeneous generation with equilibrium gas/solide In-situ ESEM during thermal treatment on He infused nuclear glass ([He]=0.001at%)

T (K) [He]

Glass LTB: He incorporation in nuclear glass

No damage, dpa=0 (Ns=3 at%) ICSM, Marcoule

slide-39
SLIDE 39

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 39

Physical state of He ? Heterogeneous generation at -130oC with damage In-situ TEM during He implantation: Jannus Orsay, MIAMI Huddersfield

20 nm 20 nm

Ns (~3 at%)

F (He.cm-2)

~ 2 x 1016 (2 at%, ~2dpa) ~ 4 x 1016(4 at%)

➢ [He] < Ns: First bubbles observed at ~0,1 at% Weak evolution of size and density

  • R. Bes et al J. Nucl. Mater. 443 (2013) 544-554

Gutierrez et al., J. Nucl. Mater. 452 (2014) 565-568

20 nm

~ 9 x 1016 (9 at%)

➢ [He ] > Ns: Increase of the bubble size Increase of the bubble density

~ 1015 (0.1 at%, 0.1dpa) 10 keV, Jannus 6 keV, MIAMI

Glass LTB: He incorporation in nuclear glass

(Ns=3 at%)

slide-40
SLIDE 40

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 40

(~ 106 ans de stockage)

  • S. Peuget et al. NIMB 327 (2014) 22-28

Physical state of He ? Homogeneous generation at room temperature

244Cm and OSIRIS irradiated glass 10B(n,α)7Li : ~2x1020 He/cm3 ( 0.2 at%, ~1dpa)

Importance of the couple T/irradiation dammage

~ 1015 (0.1 at%, 0.1dpa)

Glass LTB: He incorporation in nuclear glass

(Ns=3 at%)

slide-41
SLIDE 41

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 41

Atome d‘He S : solubility constante PHe NS : density of solubility sites

  • Helium solubilized in the

glass free volume

  • Bubble formation for T>Tg

(~550oC)

594oC

  • 1. [He] < Ns
  • He solubilized in the free volume
  • Weak probability for He bubble formation
  • Importance of temperature and damage?
  • 2. [He] > Ns
  • Bubble formation
  • Stress state ?

Disposal conditions: in progress

Glass LTB: He incorporation in nuclear glass, summary

slide-42
SLIDE 42

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 42

100 200 300 400 500 600 700 800 900 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

T=423K T=523K T=623K T=698K

Helium release fraction Square root of time

(s 1/2)

40 80 120 160 200 240 280 320 360 400 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

T=220°C T=280°C T=320°C

Frel (-) t

1/2 (s 1/2)

244Cm doped glass

OSIRIS glass

Helium release experiment: determination of DHe

) , , , ( ) , , , ( ) , , , ( t z y x C D t z y x A t t z y x C     

 

 

 

t z y x A dt dN t z y x A

Cm Cm ) (

244 244

exp , , ) , , , (     

Only a solubilized helium population is needed to fit the data No need to introduce helium bubbles in the model …

  • T. Fares, Thèse Univ. Montpellier II (2011)
  • T. Fares, J. Nucl. Mater. 416 (2011) 236

DHA, Atalante

Glass LTB: He diffusion in nuclear glass

slide-43
SLIDE 43

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 43

T K H T K H

B B

e D e d D

 

 

_ _ 2 * 3 2

. . . . 6 1 n n All data are in quite good agreement Ea ~0.6 eV Diffusion through the glass free volume No significant effect of the glass damage on DHe

  • T. Fares, Thèse Univ. Montpellier II (2011)
  • F. Chamssedine J. Nucl. Mater. 400 (2010) 175

0,5 dpa 1 dpa 0 dpa 0 à 0,6 dpa 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 10

  • 15

10

  • 14

10

  • 13

10

  • 12

10

  • 11

10

  • 10

10

  • 9

10

  • 8

10

  • 7

10

  • 6

10

  • 5

3He implanted glass

Ea = (0,55 ± 0,03) eV OSIRIS glass Ea = (0,67 ± 0,03) eV He infused glass (25°C)

244Cm doped glass

Ea = (0,61 ± 0,03) eV

D (cm

2 s

  • 1)

1000T

  • 1 (K
  • 1)

He infused glass (280-460°C) Ea = (0,61 ± 0,04) eV

  • J. Shackelford J. Appl. Phys. 43 (1972)

Glass LTB: He diffusion in nuclear glass

slide-44
SLIDE 44

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 44

10 10

1

10

2

10

3

10

4

10

5

10

6

10

14

10

15

10

16

10

17

10

18

10

19

10

20

C (at.-He g

  • 1)

Temps (années)

He total généré R = 1 mm (ZP) R = 1 cm (ZI) R = 3 cm (ZC)

10 10

1

10

2

10

3

10

4

10

5

10

6

Temps (années)

Cmax (26000 a) = 5,0×1018 (He g-1) Cmax (300 a) = 1,5×1018 (He g-1) Cmax (300 a) = 1,7×1017 (He g-1)

[He]=f(t) is strongly dependent of bloc size Thermal diffusion can strongly reduce [He]max [He]max<Ns/100 He bubble formation is unprobable

  • T. Fares, Thèse Univ. Montpellier II (2011)

10 10

1

10

2

10

3

10

4

10

5

10

6

10

7

50 100 150 200 250 300 350 400 450

Stockage en profondeur Phase de stockage

Température (°C) Temps (années) Zone au coeur Zone intermédiaire Zone en surface

Phase d'entreposage

Glass LTB: modeling of He migration in a canister

0.1at%

slide-45
SLIDE 45

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 45 Open system

1E+05 1E+06 1E+07 1E+08 1E+09 10 100 1000 10000 100000 Time (years) 1E+17 1E+18 1E+19 Alpha activity Alpha decay dose Alpha specific activity (Bq.g -1) 109 108 107 106 105 1019 1018 1017 Alpha decay dose (g-1)

Closed system

Two main steps to study: 1. Impact on r0 2. Impact on residual rate, rr Experiments on radioactive and externally irradiated SON68 glasses

EFFECTS OF RADIATION ON THE LEACHING BEHAVIOR?

Two parameters to study: 1. Dose rate 2. Dose

slide-46
SLIDE 46

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 46

EFFECTS OF RADIATION ON THE LEACHING BEHAVIOR?

Two parameters to study: 1. Dose rate 2. Dose 1. Impact on r0

slide-47
SLIDE 47

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 47

ALPHA DOSE RATE on initial rate R0?

Soxhlet-mode dynamic leach tests or short static tests (low SA/V ratio) on different α doped glasses1,2

No significant impact of a activity on R0

  • 1S. Peuget et al., JNM 362 (2007)
  • 2T. Advocat et al., JNM 298 (2001)
slide-48
SLIDE 48

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 48

ALPHA CUMULATIVE DOSE on initial rate R0?

Soxhlet-mode dynamic leach tests (100°C, 1 month) on1:

  • 244Cm-doped glasses
  • non radioactive glasses previously irradiated by Au ions

R0 determined from solution analysis

No significant ballistic impact of a cumulative dose on R0

  • 1S. Peuget et al., JNM 362 (2007)

In agreement with data from literature: no impact2 or less than factor two3

2D.M. Wellman et al., JNM 340 (2005) 3W.G. Burns et al., JNM 107 (1982)

slide-49
SLIDE 49

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 49

EFFECTS OF RADIATION ON THE LEACHING BEHAVIOR?

Two parameters to study: 1. Dose rate 2. Dose 2.Impact on residual rate, rr

slide-50
SLIDE 50

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 50

ALPHA DOSE RATE on residual rate ?

✓ Glass characteristics:

  • 2 SON68 doped glasses

10-2 10-1 1 10 102 103 104 105 1 10 100 1 000 10 000 100 000 1 000 000 Time (years) Dose rate (Gy/h) alpha bêta gamma total

water

239PuO2 doped glass 244CmO2 doped glass

a-doped glasses Dose rate (Gy/h) Dose cumulated before leach exp 0.85 wt% of 239PuO2 150  3.7x1016 a/g 0.4 wt% of 244CmO2 23,500  3x1018 a/g

slide-51
SLIDE 51

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 51

EXPERIMENTAL

✓ Glass samples ground & sieved  63 – 125 µm fraction powder ✓ SON68 reference glass powder  reference experiment ✓ Glass alteration

  • 10 g of glass powder
  •  300 mL of pure water
  • 4 Bar Ar overpressure
  • 90°C
  • > 3 years

✓ Analyses:

  • Regular leachate samples

(ICP-AES, ionic chromatography, pH, Eh, radiochemistry)

  • Solid analyses after leach test

(SEM, TEM, EDX)

17 SEPTEMBRE 2018

SBET ~ 645 cm2.g-1

S/V = 20-25 cm-1

slide-52
SLIDE 52

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 52

RESULTS: tracer evolution (B, Na, Li)

Time (days)

○ Congruence conserved between B, Na and Li  mobility not affected ~ similar  No « low » dose rate effect

slide-53
SLIDE 53

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 53

RESULTS: solid analyses

Alteration layer formed under radiation for

239Pu-doped glass:

  • Similar to non radioactive one
  • Thickness : similar to those calculated from solution releases (300 nm)

Pu-doped glass

SEM TEM TEM TEM

zoom

Inactive glass

a

TEM SEM

TEM at ITU (Karlsruhe, Germany)

slide-54
SLIDE 54

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 54

RESULTS: tracer evolution (B, Na, Li)

Time (days)

○ Congruence conserved between B, Na and Li  mobility not affected ~ similar  No « low » dose rate effect  « high » dose rate effect?  dose impact? Rate x 2.5 - 3

slide-55
SLIDE 55

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 55

200 400 600 800 1000 5x106 1x107 2x107 2x107

dE/dXnucl (keV/ion/cm) Depth (nm) 0.5 MeV 1.2 MeV 2.0 MeV 3.5 MeV Weighted sum Multi-ions (1000 ions)

Glasses and irradiation conditions

Simple glass composition

ISG (International Simple Glass)

Aluminium foil Glass monolith (polish surface) Non-irradiated zone Irradiated zone

Au

Multiple-energy gold ion irradiation

0.5 – 3.5 MeV → ≈ constant ballistic damage Energy deposition < ion track formation Wide range of fluences: 1.9x1012 → 5.5x1014 ions.cm-2

slide-56
SLIDE 56

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 56

200 400 600 800 1000 5x106 1x107 2x107 2x107

dE/dXnucl (keV/ion/cm) Depth (nm) 0.5 MeV 1.2 MeV 2.0 MeV 3.5 MeV Weighted sum Multi-ions (1000 ions)

Glasses and irradiation conditions

Simple glass composition

ISG (International Simple Glass)

Non-irradiated zone Irradiated zone

Multiple-energy gold ion irradiation

0.5 – 3.5 MeV → ≈ constant ballistic damage 1000 nm Energy deposition < ion track formation Wide range of fluences: 1.9x1012 → 5.5x1014 ions.cm-2 Ballistic dose: 0.7 → 215 MGy

slide-57
SLIDE 57

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 57

Leachate and characterizations

| PAGE 57 Non-irradiated zone Irradiated zone

Alteration protocol

Savillex, 200 cm-1, 90°C Glass monoliths sampled regularly

Leaching = alteration layer formation

Altered layer characterization

ToF-SIMS

Simple glass composition

ISG (International Simple Glass)

Multiple-energy gold ion irradiation

0.5 – 3.5 MeV → ≈ constant ballistic damage Energy deposition < ion track formation Wide range of fluences: Ballistic dose: 0.7 → 215 MGy

slide-58
SLIDE 58

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 58

Alteration layer thickness determination from boron profile

TOF-SIMS PROFILES

50 100 150 200 250 300 350 400 450 0,0 0,2 0,4 0,6 0,8 1,0

(B/Zr)/(B/Zr)glass not altered Depth (nm) ISG, 13 days of alteration, dose = 145 MGy

unaltered glass Alteration layer

Altered thickness ToF-SIMS profiles

Irradiated zone Non-irradiated zone

slide-59
SLIDE 59

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 59

Alteration layer thickness determination from boron profile

TOF-SIMS PROFILES

ToF-SIMS profiles

Irradiated zone Non-irradiated zone

slide-60
SLIDE 60

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 60

Altered thickness vs fluence

TOF-SIMS PROFILES

  • All non-irradiated zones in agreement
  • Increase of alteration layer thickness vs nuclear dose
  • « plateau » observed after ≈ 2-4.1020 keVbal/cm3

Non-irradiated zones (references)

On 244Cm-doped glass  higher Rr probably due to alpha cumulative dose

slide-61
SLIDE 61

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 61

SEM: ISG monolith altered 13 days (fluence = 3.34×1021 keV/cm3)

SEM & TEM CHARACTERIZATIONS

Irradiated zone Non-irradiated zone

Alteration layer Non-altered glass edge

slide-62
SLIDE 62

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 62

Alteration kinetics: 1 dose, thickness evolution versus time ×20

TOF-SIMS PROFILES

Apparent diffusion coefficient increases Diffusive mechanism

slide-63
SLIDE 63

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 63

Comparison with modifications of glass structure and properties Vickers hardness reduction & altered thickness: same tendency  Structural / properties & chemical durability similarly affected by the same cause

DISCUSSION

slide-64
SLIDE 64

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 64

Comparison with modifications of glass structure and properties

DISCUSSION

Increase of free volumes  increase of water or alkali migration? Increase of intern energy  increase of glass reactivity? Higher increase of alterability on glasses submitted to gold irradiation (x4.5) than on Cm-doped glass (x2.7)  Glass composition effect: complex compositions less sensitive to irradiation than simple glasses  Recovery effect of α particles in real alpha decay

slide-65
SLIDE 65

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 65

CONCLUSIONS & PROSPECTS

Initial alteration rate: no significant effect of alpha irradiation on complex glasses Residual alteration rate: increase of altered thickness on damaged glasses (x 4.5 max) and plateau reached for doses > 2-4.1020 keVbal/cm3 (few 1018 a/g) Chemical durability & glass structure / properties similarly affected by irradiation

  • Mechanisms: water access and/or increase of local reactivity
  • Long term chemical durability of glass sensitive to its initial structure

« simplifed » system vs 244Cm-doped glass, also taking into account:

  • Glass composition: simple glass more sensitive than complex glasses
  • Recovery effect of α particles in real alpha decay → « Dual Beam » irradiations

To increase mechanistic undertansding :

  • To explore very initial steps of alteration (water penetration in damaged glasses)
  • Atomistic modeling: create a damaged glass, explore water diffusion…
  • To study properties of alteration layer formed from damaged glasses
slide-66
SLIDE 66

CEA/DEN/MAR/DE2D/SEVT

  • C. Jegou

Joint ICTP-IAEA Workshop – Trieste 66

THANKS TO

17 SEPTEMBRE 2018 | PAGE 66 CEA | 10 AVRIL 2012

Funded by CEA and AREVA NC With the support of

J.M. Delaye, M. Tribet, A.H Mir, E.A. Maugeri, C. Mendoza,

  • R. Caraballo, O Bouty, C. Jégou

DEN/DTCD/SECM, CEA Marcoule, France

  • T. Charpentier, M. Moksura

DSM/IRAMIS, CEA Saclay, France

  • I. Monnet, M. Toulemonde, S. Bouffard, Ganil, Caen, France
  • J. DeBonfils, G. Panczer, D. DeLigny

LPCML – University Claude Bernard, Lyon

  • G. Calas, L. Galoisy

IMPMC - University Pierre et Marie Curie, France

  • G. Henderson

University of Toronto, Department of Geology, Toronto, Canada

  • T. Wiss, A. Jenssen, J.Y Colle, J. Somers, L. Martel, C. Selfslag,
  • D. Staicu, A. Zappia

EC JRC-ITU, Karlsruhe, Germany