Study of Ru released under accidental conditions by overheated nuclear fuel: the emission of Ru and U

The emission of uranium and ruthenium oxides from overheated nuclear fuel is a complex phenomenon which depends on the fuel matrix, on temperature, on the oxygen potential of the atmosphere in contact and on the emission sequence. All these factors influence the properties of particles before their dispersion in the reactor containment building and in the environment: these properties are, among others, surface composition, particle size, and, as a consequence, weathering rates in the environment. Emission in air increases the solubility of U-oxides mainly. This first paper describes the main physico-chemical characteristics of condensation particles released by overheated U and Ru oxides mixtures, in small-scale laboratory simulations. (orig.)