ADONIS MARCELO SALIBA SILVA

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  • Artigo IPEN-doc 24335
    Analysis of slag formation during UF4 magnesiothermic reduction
    2017 - DURAZZO, MICHELANGELO; SALIBA-SILVA, ADONIS M.; GARCIA, RAFAEL H.L.; CARVALHO, ELITA F.U. de; RIELLA, HUMBERTO G.
    Metallic uranium is a fundamental raw material for producing nuclear fuel elements for research reactors and irradiation targets for producing 99Mo, as U3Si2, UMo alloy, UAlx, and uranium thin foils. Magnesiothermic reduction of UF4 is a possible route in the nuclear fuel cycle for producing uranium as a metal ingot. The main concern about the reducing scale to produce low-enriched (metallic) uranium (LEU) (around 1 kg) is the relatively low yield compared to calciothermic reduction. Nevertheless, the magnesiothermic reduction has the advantages of having lower cost and being a safer method for dealing with uranium processing. The magnesiothermic process, as a batch, is closed inside a sealed crucible. In the present study, in order to have a qualitative idea of the kinetics during the ignition moment, the slag projected over the lateral inner face of the crucible was used to sketch the general magnesiothermic evolution. The methods used were metallographic observation and X-ray diffraction followed by Rietveld refinement. The results of these analyses led to the conception of a general reaction development during the short time between the ignition of the reducing reaction and final settlement of the products. Relevant information from this study led to the conclusion that uranium is not primarily present in the lateral slag projection over the crucible during the reaction, and the temperature level may reach 1500°C or more, after the ignition.
  • Artigo IPEN-doc 19901
    The role of Gdsub(2)Osub(3) phase transition on UOsub(2)-Gdsub(2)Osub(3) fuel sintering
    2013 - DURAZZO, MICHELANGELO; LEAL NETO, RICARDO M.; SALIBA SILVA, ADONIS M.; URANO de CARVALHO, ELITA F.; RIELLA, HUMBERTO G.