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

The reactions 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 UO2+x+Cs2UO4 was confirmed in the U-Cs-O system. The threshold oxygen potential was determined for the decomposition of CsI by UO2+x to form Cs2U4O12 and gaseous iodine. The effect of molybdenum on the UO2+x-CsI reaction was also investigated. Predominance of Cs2MoO4 over Cs2UO4 was verified in a certain range of oxygen potentials. Some assessments and interpretations of the experimental results were made with the aid of thermodynamic calculations. (orig.)