Viscosity models for corium melts Original Research Article

When a solid phase is in equilibrium with a liquid (partial crystalization), additional information is necessary to estimate the rheological behaviour of such a two-phase fluid. During the crystallization process it is possible to estimate the viscosity of the liquid phase by considering the evolution of its composition during the solid phase deposit. To estimate the increase of viscosity expected with the solid volume fraction and the mean ‘dimension’ of the solid particles must be known. The first part of this work consists of the application of Urbainʹs correlation developed for ternary SiO2–Al2O3–CaO mixtures. We calculated the viscosity of basalts and basalt with 18%wt. of UO2, and then, pending direct measurements of liquid corium viscosity, we tried to determine the range of applicability of this method to corium-concrete mixtures. In the second part, we looked for an apparent viscosity model which takes account of the increase of solid volume fraction when the temperature of the melt decreases. We observed that the viscosity of metallic or oxidic melts in the solidification range can be expressed as an exponential law versus the solid volume fraction.