Thermodynamic modelling of key metallic sub-systems for the treatment of mid-level wastes

L. Soldi (1) , S. Gossé (1) , J. Schorne Pinto (1) , C. Bonnet (1) , A. Laplace (1) , M. Roskosz (2)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 IMPMC - Institut de minéralogie, de physique des matériaux et de cosmochimie

The metallic waste resulting from the synthesis of mixed (U,Pu)O$_2$ oxides fuel is characterised by a mid-level contamination and needs to be treated before disposal. A possible process designed for this problem consists in melting such metals and then mixing them together with a SiO$_2$-Na$_2$O silicate melt in order to accommodate actinides into a stable glass matrix.Because of the large number of alloying elements involved in this process, the Calphad method is used to predict the thermodynamic behaviour of the metallic phase and the reactions between the metallic and oxide liquids at high temperature. This work focuses on the thermodynamic modelling of several metallic sub-systems of interest that may form during the processing of waste.A particular attention will be paid to the main elements present in the metallic waste Al-Cu-Fe-Si-U. Differential Thermal Analysis coupled with Electron Microscopy are used to better document a variety of binary and ternary sub-systems. These new data are also used to validate the database under development, which eventually will be representative of the entire metallic melt.

Keywords: Mid-level waste; Thermodynamic; Calphad

Domains: Nuclear Experiment [nucl-ex]; Nuclear Theory [nucl-th]

L. Soldi, S. Gossé, J. Schorne Pinto, C. Bonnet, A. Laplace, et al.. Thermodynamic modelling of key metallic sub-systems for the treatment of mid-level wastes. Calphad XLVI 2017, Jun 2017, Saint-Malo, France. ⟨cea-02434004⟩