GIOVANNI DE LIMA CABRAL CONTURBIA
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Artigo IPEN-doc 28149 Increasing productivity in the manufacture of UAl2–Al dispersion-plate targets for Mo-99 production2021 - DURAZZO, MICHELANGELO; CONTURBIA, GIOVANNI L.C.R.; CARVALHO, ELITA F.U. deMolybdenum-99 is the most important isotope because its daughter isotope, technetium-99 m, has been the most widely used medical radioisotope. The primary method employed to produce Mo-99 derives from the fission of U-235 incorporated in so-called irradiation targets. Pushed by the international Mo-99 crisis that occurred in 2009/2010, Brazil has decided to construct a new research reactor, the Brazilian Multipurpose Reactor (RMB), to produce this vital radioisotope to meet the Brazilian domestic demand. As part of this effort, it has been developed the process for manufacturing the target to be used in the production of Mo-99 by nuclear fission. The low enriched uranium (LEU) aluminide with the predominant phase UAl2 was the starting material. The picture-frame technique was used to clad UAl2–Al briquette with aluminum to obtain plate-type targets. It was developed an innovative method that allows increasing the productivity of this type of target based on multi-core rolling. A thermomechanical treatment was designed to get targets composed basically of a mixture of UAl3/UAl4 that are the required phases for a proper radiochemical dissolution after irradiation. The manufacturing process proved to be suitable for domestic production of targets, fulfilling the specification to produce Mo-99 in the Brazilian Multipurpose Reactor.Artigo IPEN-doc 25080 Phase quantification in UAlx-Al dispersion targets for Mo-99 production2018 - CONTURBIA, G.L.C.R.; DURAZZO, M.; CARVALHO, E.F.U. de; RIELLA, H.G.Uranium aluminide (UAlx) is a mixture of three distinct intermetallic compounds comprised of UAl2, UAl3 and UAl4, where the “x” is used to denote a mixture of those phases. Usually UAlx is formed during the target fabrication process by means of a solid state reaction between the uranium aluminide and aluminum. Quantitative techniques such as image analysis and X-ray diffraction using the Rietveld method were compared for their applicability in the determination of the UAl2, UAl3 and UAl4 concentrations, both in the UAl2 primary ingot and in the UAlx-Al dispersion. The UAlx composition was quantified in all stages of the target manufacturing. The image analysis method was shown to be useful for UAlx phase quantification in the primary UAl2 ingot, but was not applicable in the case of UAlx-Al dispersions. The X-ray diffraction method allowed the quantification of the existing UAlx phases in both the primary ingot and UAlx-Al dispersions. Possible sources of error are discussed. The method of quantification based on X-ray diffraction was shown to be appropriate to monitor the evolution of UAlx phases during the manufacturing process.Tese IPEN-doc 24291 Tecnologia de fabricação de alvos de aluminetos de urânio para produção de Mo-992017 - CONTURBIA, GIOVANNI de L.C.R.Neste trabalho os parâmetros de fabricação de alvos de dispersão UAlx-Al foram definidos aplicando-se a tecnologia de montagem e laminação de um conjunto núcleo-moldura-revestimentos tradicionalmente adotada na fabricação de placas combustíveis usadas em reatores de pesquisa. O uso das técnicas de dilatometria e difração de raios-x com refinamento de Rietveld contribuíram para desenvolver um processamento termomecânico para controle das fases presentes no núcleo do alvo. Um método inovador que permitiu o aumento da produtividade desse tipo de alvo também foi desenvolvido com base na laminação de múltiplos núcleos. O processo de fabricação mostrou-se adequado para produção de alvos com a especificação para produção de Mo-99 no Reator Multipropósito Brasileiro (RMB).Artigo IPEN-doc 23402 Study of thermomechanical treatment for manufacturing UAlx/Al dispersion targets2017 - CONTURBIA, GIOVANNI R.; DURAZZO, MICHELANGELOUranium aluminide/aluminum (UAlx-Al) targets are widely used in research reactors to produce 99Mo radioisotopes as a fission product of 235U. The 99Mo decays into 99mTc, which is the most suitable radionuclide for single-photon emission computed tomography image technique. The UAlx-Al targets were fabricated according to the picture frame technique, which employs hot rolling of such dispersion. The UAl2 is the starting uranium compound used as fissile material in the dispersion. During the manufacturing of targets some solid state reactions take place between UAl2 and Al matrix producing UAl3 and UAl4. The specification claims that the finished target must be free of UAl2 in its composition, because UAl2 is harder to dissolve in radiochemical processing. This work aims to develop a thermomechanical treatment that can consume all UAl2 initially presented in the dispersion. The dilatometry and x-ray diffraction with Rietveld refinement were used to obtain a final optimized thermomechanical treatment for the UAlx/Al dispersion targets.