1. 1 Experimental study and thermodynamic assessment of the Er-Zr-H ternary system A. MascaroCalphad XLI – Berkeley - USA8th June 2012 A. Mascaro 1,2, C. Toffolon-Masclet 1, J.-M. Joubert 2 and C. Raepsaet 3 1 CEA-Saclay, Nuclear Energy Division, Nuclear Materials Department, SRMA, LA2M, 91191 Gif-Sur-Yvette, France 2 Chimie Métallurgique des Terres Rares, Institut de Chimie et des Matériaux Paris-Est, CNRS, Université de Paris XII, 2-8 rue H. Dunant, 94320 Thiais, France 3 CEA-Saclay, DSM, IRAMIS, SIS2M, LEEL, 91191 Gif-Sur-Yvette, France

2. Pressurized Water Reactor: PWR 2

3. 3 Assembly and cladding Cladding: L ~4 m Ø ~1 cm thickness ~570 µm Zr alloy based IFBA Integral Fuel Burnable Absorber Fuel bundle Nuclear fuel cladding

4. Three layers cladding : triplex → CEA Patent Cladding manufacturing (melt spinning on needle) then lamination (CEZUS) by Pilger rolling Solid burnable poisons [1] C. Chabert et al., Proc. of ICAPP 08, Paper 8159, 2008 Neutronic solid burnable poison: reactivity control Captures extra neutrons The heavier isotope formed do not react with neutrons →Into the cladding, CEA concept [1,2] [2] J.-C. Brachet et al., CEA French Patent: BD 1725 (October 2006) Fuel + High neutron absorption cross section Low neutron absorption cross section Regular Zr alloy Zr-6 wt% Er 4

5. Interactions with the surrounding environment Zr + 2 H 2 O → ZrO 2 + 2 H 2 Oxidation Hydrogenation 5 → If Er into the cladding: In nominal and accidental conditions, interaction with the pressurized water surrounding the cladding Two effects: oxidation and hydrogenation Nominal: Pressurized water (350°C, 155 bars) Accidental: T vapor >600°C (ex. LOCA) Thus, it is of high interest to study the Er-Zr-H ternary system. Experimentally and modelled Fuel Regular Zr alloyZr 6 wt% Er H2OH2O ZrO 2

6. 6 Study and modelling the Er-Zr-H ternary system Er-Zr >Fully re- determined experimentally and modelled by J. Jourdan [2] Er-H >Uncertainties >1958 phase diagram, Mulford [3] >Measurements have been made on the system but not taken into account The 3 associated binary systems have to be known and modelled Zr-H >Experimentally determined and modelled in the Zircobase P=1 bar [5] J. Jourdan et al., JNM, vol 402, 102-107, 2010 [4] N. Dupin et al., JNM, vol 275, 287-295, 1999[6] R. N. R. Mulford, AECU 3813, 1958

7. Er-H binary system: modelling with the Calphad method 7 Use of sublattice model to describe hypo and hyper stoechiometry HCP_A3: (Er)(H, □)(H, □) 2 FCC_C1: (Er)(H, □)(H, □) 2 LIQ : (Er) GAS : H 2 Use of the Redlich-Kister polynomia α Er : (Er)(H, □) (□) 2 γ-ErH 3 : (Er)(H) (H, □) 2 β-ErH 2 Data α Er β-ErH 2 γ-ErH 3 Space groupP6 3 /mmc Phase prototypeMgCaF 2 HoH 3

8. 8 [4] Joubert, J.M. and J.C. Crivello, Int. J. Hydrog. Energy, vol 37(5), 4246-4253, 2012 Measurement of PCT curves Ab-initio calculations made by J.-M. Joubert and J.-C. Crivello: enthalpies of formation were added Lundin Beaudry Etc. Er-H binary system: modelling with the Calphad method P=1 bar

9. 9 Er Er-Zr binaries samples were cut and hydrogenated at different contents → Several ternary samples are obtained 500µm 25µm 10µm 100µm Er-Zr-H ternary system: experimental determination

10. Er-Zr-H ternary system 10 37 samples have been synthesized and characterized by XRD, ERDA… Let’s explain what ERDA is.

11. ERDA: Elastic Recoil Detection Analysis ERDA RBS PIXE Er 35.8 Zr 1.5 H 62.7 Er 78.85 Zr 4.15 H 17

12. 12 Er Zr H Er-Zr-H ternary system: experimental isothermal section at 350°C No ternary compound have been found experimentally P=1 bar

13. Er-Zr-H ternary system: modelling Zr-H: from Zircobase HCP_A3 : (Zr)(H, □) Tet BCC_A2 : (Zr)(H, O, □) 3 FCC_C1 : (Zr)(H, O, □) 2 ZRH2_EPSILON : (Zr)(H, O, □) 2 Er-Zr: from J. Jourdan BCC_A2 : (Er, Zr)(□) 3 HCP_A3 : (Er, Zr)(□) Oct LIQ : (Er, Zr) Er-H: this work HCP_A3 : (Er)(H, □) Oct (H, □) Tet 2 FCC_C1 : (Er)(H, □) (H, □) 2 LIQ : (Er) GAZ : H 13

14. About the HCP_A3 phase… Octahedral, 2 per conventional cell Tetrahedral, 4 per conventional cell 2 Zr atoms per conventional cell Multiplicities octa: 1 and tetra: 2 14 HCP_A3 Zr-H: (Zr) (H, □) Er-H: (Er) (H, □) (H, □) 2 In Er-H, the γ-ErH 3 component exists, we NEED 3 sites accepting the hydrogen. H is going only in interstitial sites. The HCP_A3 phases were not consistent. Zr-H modelling has been adapted to the new sublattice multiplicity. New end-members have been generated with new model in Zr-H and their enthalpies of formation have been calculated by J.-M. Joubert and J.-C. Crivello. Then implemented into the modelling. x2 add

15. Comparison of the 2 Er-Zr-H ternary systems 15 Same equilibrium shown The extensions of the solid phases have to be improved No ternary compound found T=350°C P=1 E 5 Pa Modelling still under process

16. Conclusions Experimental study and modelling of the Er-H binary system: New phase diagram Experimental study and modelling of the Er-Zr-H ternary system: No ternary compound but very large extensions of the two di-hydrides instead Very important stability of the erbium di-hydride β-ErH 2 Into the cladding concept: Precipitation of δ-ZrH 2 even if β-ErH 2 is more stable But the chemical properties of δ-ZrH 2 are modified due to Er substitution 16

17. Thank you for your attention! 17

18. L’idée de l’erbium combustible Erbium : Poison Neutronique consommable Capte le surplus de neutrons selon la réaction L’isotope plus lourd formé ne réagit plus avec les neutrons [1] J.-C. Brachet et coll., Brevet CEA: BD 1725 (16 Octobre 2006) Isotope σ a en barn3567128 Abondance naturelle de l'élément en % 33.6122.9326.79 Début de cycleTemps d’exploitation Puissance « potentielle du réacteur » Aujourd’hui (réacteurs 1000 MWe) Demain? (réacteurs 1600 MWe) 1 an Réactivité de l’erbium 18

19. Réacteur à Eau Bouillante 19