ABSTRACT
Three series of real time experiments have been undertaken concerned with the disintegration of UO2 during oxidation in air at temperatures in the range 225 to 550°C. Gravimetric measurements, using a controlled atmosphere microbalance, have established the time at which powdering first occurred and the rate of subsequent continuing spallation. In-situ observations have been made also using environmental cells with hot stages fitted respectively to an X-ray diffractometer and an optical microscope. The former have examined the chemical and the latter the topographical changes during UO2 oxidation. The results have both confirmed and extended current understanding of the mechanisms of the chemical and physical processes involved.
