Thermophysical properties of rock-like oxide fuel with spinel-yttria stabilized zirconia system

Thermal expansion, thermal diffusivity, melting temperature, Vickers hardne ss and creep rate of the rock-like oxide (ROX) fuel were measured with the MgAl2O4(spinel)-ZrO2(Y,Gd) (YSZ: stabilized zirconia) system and the MgAl2O 4-YSZ-UO2 system in the temperature range between room temperature and 1800 K in order to evaluate thermophysical properties. Thermal expansion coeffi cients of MgAl2O4-YSZ composites increased with increasing YSZ content and the values were well represented by the Turner's equation. Addition of UO2 to MgAl2O4-YSZ composite resulted in an increase of thermal expansion. Ther mal conductivity values of the MgAl2O4-YSZ composites decreased with increa sing YSZ content and agreed with predictions of the Maxwell-Eucken equation . The eutectic temperature of MgAl2O4-YSZ and MgAl2O4-YSZ-UO2 systems was f ound to be 2200 K. High temperature hardness of the composites was higher t han that of YSZ or MgAl2O4. The hardness of ROX fuel was considerably highe r than that of UO2. The creep rate of MgAl2O4-YSZ composite was controlled by the lattice diffusion of YSZ. (C) 1999 Elsevier Science B.V. All rights reserved.