Thermal expansion of uraninm-plutonium dioxides

Abstract

Thermal expansions of PuyU1-yO2 (y=0-0.1) solid solutions were investigated in the temperature range from room temperature to 1273 K by a high temperature X-ray diffraction method. The lattice parameters of PuyU1-yO2 solid solutions for constant y value were given in polynomial expressions of temperature. The lattice parameters at constant temperature decreased linearly with increasing y, followed Vegard's law. High temperature heat capacities, Cp, of PuyU1-yO2 solid solutions were estimated from the thermodynamic relation using the measured thermal expansions and heat capacity data of UO2 and PuO2 at room temperature. The estimated error in the calculated Cp of PuyU1-yO2 solid solutions was less than 7%.