Thermophysical properties of molten core materials: Zr–Fe alloys measured by electrostatic levitation

In order to investigate the progression of a core meltdown accident, it is necessary to understand the behavior of molten core materials. Zr–Fe alloys are one of the low-melting-temperature liquid phases that are thought to form in the early stages of bundle degradation. The objective of this study is to measure the thermophysical properties of Zr–Fe liquid alloys. Alloy samples with a composition of Zr_{1 − x}Fe_x (x = 0.12, 0.24, and 0.50) were synthesized by arc melting, and their density, viscosity, and surface tension were measured using an electrostatic levitation technique. The results indicate that the density of Zr–Fe liquid alloys can be estimated by a linear combination of the measured or extrapolated densities of pure Zr and Fe. The viscosities of the Zr–Fe liquid alloys can be roughly estimated by extrapolating those of Zr to lower temperatures, although this method tends to underestimate the viscosity of alloys, especially for eutectic compositions. The values of the Zr–Fe liquid alloys’ surface tensions are close to those of pure Zr.