Thermodynamic functions for plutonium rich (U,Pu)O2

Enthalpy increments of U1-yPuyO2 solid solutions with y = 0.45, 0.55 and 0.65 were measured using a high-temperature differential calorimeter by employing the method of inverse drop calorimetry in the temperature range 993-1803 K, 960-1782 K and 956-1797 K respectively. From the fit equations for the enthalpy increments, heat capacity data were computed in the temperature range 298-1800 K. The results indicate that the enthalpies of U1-yPuyO2 solid solutions with y = 0.45, 0.55 and 0.65 obey the Neumann-Kopp's molar additivity rule. (author)