Measurements of thermal conductivity for near stoichiometric (U0.7-zPu0.3Amz)O2 (z = 0.05, 0.10, and 0.15)

Abstract

• The thermal conductivity of (U , Pu, Am)O 2 solid solution has been studied. • The O/M ratio during measurement was controlled near the stoichiometric composition. • Effect of the addition of Am on thermal conductivity has been investigated. • The thermal conductivity decreased with increasing Am content. The thermal conductivities of near stoichiometric (U 0.7-z Pu 0.3 Am z )O 2 solid solutions (z = 0.05, 0.10, and 0.15) have been measured between room temperature (RT) and 1473 K under oxygen partial pressure controlled atmosphere. Thermal conductivities were obtained from the thermal diffusivity measured by the laser flash method. From the oxygen partial pressures during the thermal diffusivity measurements, the oxygen to metal ratios of the specimens were maintained between 1.999 and 2.000. The thermal conductivities decreased with increasing Am content, and could be expressed by the classical phonon transport model ( λ = 1 / ( A + B T ) ) up to about 1473 K. In this equation, Coefficient A values increased linearly with increasing Am content while B values were independent of Am content. The coefficients obtained from experiments could be described by the phonon scattering model theoretically, assuming cations of U 4+ , U 5+ , Pu 4+ , and Am 3+ in the stoichiometric composition.