Étude de la réduction de UO₂F₂ à haute température sous air humide et sous dihydrogène humide

Abstract
The aim of this work was to clarify the reduction process of UO₂F₂ and to identify some intermediate compounds likely to be formed in the course of this process. Gravimetric studies have been carried out in water or molecular hydrogen atmospheres. Each compound isolated has been identified by X-Ray diffraction analysis. We first investigated the conversion of UO₂F₂ into U₃O₈ in a water partial pressure of 300 mbar at 700, 750 and 800°C. Thus, we have determinated the influence of the temperature on the reaction kinetics at a fixed vapor pressure. After identification of the two intermediates β-UO₃ and UO_2,9, we have proposed differents mechanims. As well, the reduction of UO₂F₂ in a dihydrogen atmosphere at 700°C was investigated. This reaction leads, in two steps, to the nuclear fuel by the way of U₃O₈.