Thermophysical Properties of Zr-O Liquid Alloys Measured by Electrostatic Levitation

Abstract

To understand behavior of molten core materials is an urgent issue to investigate the progression of a core meltdown accident in nuclear power plants. Zirconium (Zr) based alloys have been widely used as nuclear fuel claddings and structural materials in the nuclear power plants. Since the typical atmosphere during most accident scenarios is steam, Zr liquid containing significant amount of O (Zr-O liquid alloys) will be generated in the case of the core meltdown accident. In this study we aim to provide thermophysical properties of Zr-O liquid alloys. To avoid a difficulty in measurement due to high melting point and high reactivity of Zr liquid, electrostatic levitation technique was employed for the measurement. Zr-O alloys with nominal compositions of Zr0.9O0.1 and Zr0.8O0.2 were prepared from powder Zr and ZrO2 by solid-state reaction. The oxygen composition was evaluated by thermogravimetric analysis. The measured viscosities of Zr-O liquids are higher than those of Zr liquid (experimental) and ZrO2 liquid (calculated), which indicates that the composition-dependent viscosity may have maxima in Zr-O liquids.