ADONIS MARCELO SALIBA SILVA
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Artigo IPEN-doc 28427 Manufacturing LEU-foil annular target in Brazil2022 - DURAZZO, MICHELANGELO; SOUZA, JOSE A.B.; IANELLI, RICARDO F.; TAKARA, ERIKI M.; GARCIA NETO, JOSE S.; SALIBA-SILVA, ADONIS M.; CARVALHO, ELITA F.U. deMolybdenum-99 is the most important isotope because its daughter isotope, technetium-99m, has been the most used medical radioisotope. The primary method used to produce Mo-99 derives from the fission of U-235 incorporated in so-called irradiation targets. Two routes are being developed to make Mo-99 by fissioning with low enriched uranium (LEU) fuel. The first adopts UAlx-Al dispersion plate targets. The second uses uranium metal foil annular targets. The significant advantage of uranium foil targets over UAlx-Al dispersion targets is the high density of uranium metal. This work presents the experience obtained in the development of the uranium metal annular target manufacturing steps. An innovative method to improve the procedure for assembling the uranium foil on the tubular target was presented. The experience attained will help the future production of Mo-99 in Brazil through the target irradiation in the Brazilian Multipurpose Reactor (RMB).Artigo IPEN-doc 23040 Manufacturing low enriched uranium metal by magnesiothermic reduction of UF42017 - DURAZZO, M.; SALIBA-SILVA, A.M.; MARTINS, I.C.; CARVALHO, E.F.U. de; RIELLA, H.G.This work presents an experimental description of thermal and physical studies to attain a practical manufacturing process of uranium metal enriched to 20% U235 (LEU – Low Enriched Uranium) by metallothermic reduction of UF4, with nuclear purity, for reduced amounts (1000 g of uranium) and with radioactive safety. Uranium metal is needed to produce nuclear fuel elements based on uranium silicide (intermetallic U3Si2) and irradiation targets to produce Mo99. This process is a part of Brazilian efforts to fabricate the fuel elements for its research reactors, primarily aiming at the production of radioisotopes for nuclear medicine. The magnesiothermic reduction is influenced by variables which are related to the starting material UF4 and the thermal conditions for its reduction. These variables are investigated. The physical arrangement of the crucible/reduction reactor/furnace system and the management of the furnace thermal input in the reduction reactor during the heating were studied. Thermal simulation experiments provided delineation for the reactants’ thermal progress before the ignition of the metalothermic reaction. The heat input to the reduction system has proved to be the main variable that influenced the efficiency of the process. The levels of metallic yield and reproducibility have been improved, making the production process reproductive and economically viable. The typical yield in the production of uranium metal was above 80%. Unrecovered uranium metal is present in the MgF2 slag and can be recovered at the level of 96% yield. The process of recovering the uranium from the slag is also discussed.