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

Abstract

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.

Density and viscosity of liquid ZrO2 measured by aerodynamic levitation technique

“…In the early stage of the accident, a metallic liquid phase is generated from zircaloy (Zr-based alloy), stainless steel (Fe-, Ni-, and Cr-based alloy), and B 4 C. The physical properties of Zr–Fe [2], Zr–Ni and Zr–Cr [3] liquid alloys have been reported. When the temperature of the fuels exceeds 2300 K, zircaloy claddings will react with UO 2 fuels, resulting in the formation of a U–Zr–O liquid phase.…”

Active disturbance rejection control of test sample in electrostatic suspension system

“…The electrostatic suspension system is used as a contactless detective technique of material testing by suspending the detected sample at the equilibrium position [1,2]. This technology is widely applied to the researches about the undercooling materials [3,4], the metastable materials [4,5] and other new functional materials [6][7][8] by avoiding the contact between the test sample and the container, and it could effectively restrain the heterogeneous nucleation. Compared to other suspension methods such as the electromagnetic suspension system [9,10], the aerodynamic suspension system [11] and the acoustic suspension system [12], the electrostatic suspension system could suspend the nonmetallic materials, realize the suspension in vacuum environment and separate the heating from the suspension.…”