Contribution to the study of the U---Cs---Mo---I---O system

The reaction in the U---Cs---Mo---I---O system at 1073 K have been studied as a function of oxygen potential. The chemical constitution and the morphology of the phases formed were examined by electron-probe microanalyzer and X-ray diffractometer. The existence of a two-phase field UO_2+x + Cs₂UO₄ was confirmed in the U---Cs---O system. The threshold oxygen potential was determined for the decomposition of CsI by UO_2+x to form Cs₂U₄O₁₂ and gaseous iodine. The effect of molybdenum on the UO_2+x?CsI reaction was also investigated. Predominance of Cs₂MoO₄ over Cs₂UO₄ was verified in a certain range of oxygen potentials. Some assessments and interpertations of the experimental results were made with the aid of thermodynamic calculations.