Liquid immiscibility in a (O,U,Zr) model corium

• Published in: Journal of nuclear materials 1998-04, Vol.254 (2), p.158-174
• Main Authors: Guéneau, C., Dauvois, V., Pérodeaud, P., Gonella, C., Dugne, O.
• Format: Article
• Language: English
• Subjects: Applied sciences; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Installations for energy generation and conversion: thermal and electrical energy
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/S0022-3115(98)00002-6

New data on the miscibility gap in the liquid state in both O–U and O–U–Zr phase diagrams are reported. Mixtures are melted by electron bombardment. Tie-lines are determined in the O–U miscibility gap at 3090 K as well as in the O–U–Zr ternary system at 3223 K. `Metallic' and `oxide' liquids are immiscible in a large range of temperature and composition in both systems. The miscibility gap extent is extrapolated by thermodynamic calculations. The quenched microstructures of the different liquid phases are described and interpreted using a solidification path calculation. For the (O,U,Zr) alloys entering the miscibility gap, the minor oxide liquid phase is in the form of droplets in the metallic parent liquid. The droplets seem to segregate at the ingot surface. This leads to a layer formation in the case of the O–U system where there is the greatest difference between the two liquid compositions.