Thermophysical properties of molten FeO1.5, (FeO1.5)(0.86)-(ZrO2)(0.14) and (FeO1.5)(0.86)-(UO2)(0.14)

FeO1.5 is a promising candidate for a sacrificial material to lower the liquidus temperature of molten corium while keeping the viscosity as low as possible in order to mitigate the molten core-concrete interaction. Phase diagrams of such systems as FeO1.5-ZrO2 and FeO1.5-UO2 indicate that the FeO1.5 addition would significantly lower the liquidus temperature of corium, but how it would affect the viscosity has not been investigated. Thus, the viscosity of FeO1.5, (FeO1.5)(0.86)-(ZrO2)(0.14), and (FeO1.5)(0.86)-(UO2)(0.14) was measured using the aerodynamic-levitation technique coupled with the droplet-oscillation method. It was found that the viscosity of (FeO1.5)(0.86)-(ZrO2)(0.14) at approximately 2100 K is almost identical to that of ZrO2 at around 3200 K, and that (FeO1.5)(0.86)-(UO2)(0.14) maintains a low viscosity at a temperature well below the melting temperature of UO2, owing to the low viscosity of FeO1.5. These results indicate that the iron oxide addition would not only lower the liquidus temperature of the molten corium but also keep its fluidity as high as possible.