Thermodynamic properties of ternary oxides of fission products from calorimetric measurements

Abstract

The alkaline earth elements barium and strontium, which are produced in a mixed oxide fuel during irradiation, can combine with other major fission products such as zirconium, molybdenum and cerium under favourable conditions of temperature and oxygen potential. As a part of our programme to investigate the thermodynamic properties of these fission product compounds, we have already reported thermodynamic data on BaZrO₃, SrZrO₃, BaMoO₄ and BaCeO₃. To complete the series, enthalpy increment measurements were carried out on SrCeO₃, SrMoO₄, CaZrO₃ and CaMoO₄ using a high temperature microcalorimeter. These data along with the derived thermodynamic functions are reported in this paper. The stabilities of the whole set of fission product compounds, under conditions of oxygen potentials and temperature prevalent in the mixed oxide fuel, are examined in the light of all the data mentioned above.