Abstract: There is a great demand for phantoms by many areas of knowledge to be used for teaching or daily work. However, commercial phantoms are expensive and hard to obtain, especially in countries going through development. As an alternative, 3D printing can be the way to produce less expensive and reliable 3D phantoms. The goal of this study is to evaluate 14 available commercial filaments, in order to find if and how they can be used in 3D printed phantoms in computed tomography. Each material was printed as a 2 cm edge cube with rectilinear pattern and 60, 80 and 100% infill. The 80% infill of five other patterns were also printed and compared. Each 100% infill cube was weighted and had its density calculated. After that, the cubes were scanned in a Philips CT Brilliance 6 with 120 kVp, 200 mA, 2 mm slices and standard reconstruction. At the center of each cube, a ~120 mm2 region of interest was set to measure the mean Hounsfield Unit (HU) and its standard deviation. The software Origin was used to plot HU results for rectilinear pattern, determine linear trends with its R2 and compare achieved values with HU tissue range from literature. To confirm the response of HU values of selected tested materials in CT imaging as a function of percentage infill, a phantom prototype of a finger was 3D printed. The HU of the tested materials ranged from −516.2 ± 7.3 to 329.8 ± 18.9. All human tissues could be mimicked making use of these materials, except cortical bone above ~350 HU and tooth parts. The most promising filament was PLA + Cu, due to the multiple infill configuration that allows the resulting HU range to represent from adipose and skin tissue to marrow bone.

Palavras-Chave: 3d printing; phantoms; fabrication; filaments; radiology; computerized tomography

SAVI, MATHEUS; ANDRADE, MARCO A.B.; POTIENS, MARIA P.A. Commercial filament testing for use in 3D printed phantoms. Radiation Physics and Chemistry, v. 174, p. 1-7, 2020. DOI: 10.1016/j.radphyschem.2020.108906. Disponível em: http://repositorio.ipen.br/handle/123456789/31424. Acesso em: $DATA.

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Abstract: The incorporation of gadolinium as burnable poison directly into nuclear fuel is important for reactivity compensation, which enables longer fuel cycles. The function of the burnable poison fuel is to control the neutron population in the reactor core during its startup and the beginning of the fuel burning cycle to extend the use of the fuel. The implementation of UO2-Gd2O3 poisoned fuel in Brazil has been proposed according to the future requirements established for the Angra-2 nuclear power plant. The UO2 powder used is produced from the Ammonium Uranyl Carbonate (AUC). The incorporation of Gd2O3 powder directly into the AUC-derived UO2 powder by dry mechanical blending is the most attractive process, because of its simplicity. Nevertheless, processing by this method leads to difficulties while obtaining sintered pellets with the minimum required density. The cause of the low densities is the bad sintering behavior of the UO2-Gd2O3 mixed fuel, which shows a blockage in the sintering process that hinders the densification. This effect has been overcome by microdoping of the fuel with small quantities of aluminum. The process for manufacturing the fuel inevitably generates uranium-rich scraps from various sources. This residue is reincorporated into the production process in the form of U3O8 powder additions. The addition of U3O8 also hinders densification in sintering. This study was carried out to investigate the influence of both aluminum and U3O8 additives on the density of fuel pellets after sintering. As the effects of these additives are counterposed, this work studied the combined effect thereof, seeking to find an applicable composition for the production process. The experimental results demonstrated the effectiveness of aluminum, in the form of Al(OH)3, as an additive to promote increase in the densification of the (U,Gd)O2 pellets during sintering, even with high additions of U3O8 recycled from the manufacturing process.

Palavras-Chave: sintering; gadolinium oxides; uranium oxides; nuclear fuels; fabrication; burnable poisons; aluminium oxides

SANTOS, LAURO R. dos; DURAZZO, MICHELANGELO; CARVALHO, ELITA F.U. de; RIELLA, HUMBERTO G. Effect of Al(OH)3 on the sintering of UO2–Gd2O3 fuel pellets with addition of U3O8 from recycle. Journal of Nuclear Materials, v. 493, p. 30-39, 2017. DOI: 10.1016/j.jnucmat.2017.05.050. Disponível em: http://repositorio.ipen.br/handle/123456789/27863. Acesso em: $DATA.

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Abstract: This paper presents a study on biocidal effect of polymer nanocomposite films of gamma irradiated polypropylene (PP) and silver nanoparticles. The modified polypropylene was obtained from isotactic polypropylene (iPP) in pellets form by irradiation with gamma rays in the presence of acetylene. A new morphology with long chain branching of PP and distinct rheology is obtained by this process. The blend of 50/50 wt neat PP and PP modified by gamma radiation were further mixed using a twin screw extruder. The AgNPs were infused into this polymer blend at different concentrations of: 0.1%; 0.25%; 05%; 1.0%; 1.0% (PVP), 2.0% and 4.0% by wt%. These polymer nanocomposites were characterized by Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TG), differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), cytotoxicity test and Kirby-Bauer disk diffusion techniques. The bactericidal effect of Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) were assessed in detail.

Palavras-Chave: nanocomposites; polypropylene; acetylene; branching ratio; calorimetry; concentration ratio; fabrication; films; gamma radiation; transmission electron microscopy; x-ray diffraction; nanoparticles; pseudomonas; pvp; raman spectroscopy; scanning electron microscopy; silver; staphylococcus; thermal gravimetric analysis; x radiation

OLIANI, WASHINGTON L.; PARRA, DUCLERC F.; KOMATSU, LUIZ G.H.; LINCOPAN, NILTON; RANGARI, VIJAYA K.; LUGAO, ADEMAR B. Fabrication of polypropylene/silver nanocomposites for biocidal applications. Materials Science and Engineering C, v. 75, p. 845-853, 2017. DOI: 10.1016/j.msec.2017.02.109. Disponível em: http://repositorio.ipen.br/handle/123456789/27883. Acesso em: $DATA.

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Abstract: A simple and highly efficient (shorter reaction time and almost no rework) method for production of iodine based radioactive silver seed cores for brachytherapy is described. The method allows almost quantitative deposition of iodine-131 on dozens of silver substrates at once, with even distribution of activity per core and insignificant amounts of liquid and solid radioactive wastes, allowing the fabrication of cheaper radioactive iodine seeds for brachytherapy.

Palavras-Chave: brachytherapy; deposition; fabrication; iodine 125; iodine 131; isotope production; liquids; radioactive wastes; radioisotopes; seeds; silver; substrates

CARDOSO, ROBERTA M.; SOUZA, CARLA D. de; ROSTELATO, MARIA E.C.M.; ARAKI, KOITI. Highly efficient method for production of radioactive silver seed cores for brachytherapy. Applied Radiation and Isotopes, v. 120, p. 76-81, 2017. DOI: 10.1016/j.apradiso.2016.11.023. Disponível em: http://repositorio.ipen.br/handle/123456789/27166. Acesso em: $DATA.

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Abstract: Molybdenum-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.

Palavras-Chave: radioisotopes; targets; plates; molybdenum 99; enriched uranium; fabrication

DURAZZO, MICHELANGELO; CONTURBIA, GIOVANNI L.C.R.; CARVALHO, ELITA F.U. de. Increasing productivity in the manufacture of UAl2–Al dispersion-plate targets for Mo-99 production. Progress in Nuclear Energy, v. 140, p. 1-9, 2021. DOI: 10.1016/j.pnucene.2021.103920. Disponível em: http://repositorio.ipen.br/handle/123456789/32381. Acesso em: $DATA.

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Abstract: 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.

Palavras-Chave: uranium; metals; nuclear fuels; materials recovery; enriched uranium; fuels; fabrication

DURAZZO, M.; SALIBA-SILVA, A.M.; MARTINS, I.C.; CARVALHO, E.F.U. de; RIELLA, H.G. Manufacturing low enriched uranium metal by magnesiothermic reduction of UF4. Annals of Nuclear Energy, v. 110, p. 874-885, 2017. DOI: 10.1016/j.anucene.2017.07.033. Disponível em: http://repositorio.ipen.br/handle/123456789/27736. Acesso em: $DATA.

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Abstract: We report the fabrication and characterization of double line waveguides directly written in tellurite and germanate glasses using a femtosecond laser delivering 30 mu J, 80 fs pulses at 4 kHz repetition rate. The double line waveguides produced presented internal losses inferior to 2.0 dB/cm. The output mode profile and the M-2 measurements indicate multimodal guiding behavior. A better beam quality for the GeO2 - Pbo waveguide was observed when compared with TeO2 - ZnO glass. Raman spectroscopy of the waveguides showed structural modification of the glassy network and indicates that a negative refractive index modification occurs at the focus of the laser beam, therefore allowing for light guiding in between two closely spaced laser written lines. The refractive index change at 632 nm is around 10(-4), and the structural changes in the laser focal region of the writing, evaluated by Raman spectroscopy, corroborated our findings that these materials are potential candidates for optical waveguides and passive components. To the best of our knowledge, the two double line configuration demonstrated in the present work was not reported before for germanate or tellurite glasses.

Palavras-Chave: lasers; waveguides; glass; fabrication; raman spectroscopy; laser radiation

SILVA, DIEGO S. da; WETTER, NIKLAUS U.; ROSSI, WAGNER de; KASSAB, LUCIANA R.P.; SAMAD, RICARDO E. Production and characterization of femtosecond laser-written double line waveguides in heavy metal oxide glasses. Optical Materials, v. 75, p. 267-273, 2018. DOI: 10.1016/j.optmat.2017.10.033. Disponível em: http://repositorio.ipen.br/handle/123456789/28846. Acesso em: $DATA.

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Abstract: Several fuel plants that supply nuclear research reactors need to increase their production capacity in order to meet the growing demand for this kind of nuclear fuel. After the enlargement of the production capacity of such plants, there will be the need of managing the new production level. That level is usually the industrial one, which poses challenges to the managerial staff. Such challenges come from the fact that several of those plants operate today on a laboratorial basis and do not carry inventory. The change to the industrial production pace asks for new actions regarding planning and control. The production process based on the hydrolysis of UF6 is not a frequent production route for nuclear fuel. Production planning and control of the industrial level of fuel production on that production route is a new field of studies. The approach of the paper consists in the creation of a mathematical linear model for minimization of costs. We also carried out a sensitivity analysis of the model. The results help in minimizing costs in different production schemes and show the need of inventory. The mathematical model is dynamic, so that it issues better results if performed monthly. The management team will therefore have a clearer view of the costs and of the new, necessary production and inventory levels.

Palavras-Chave: fabrication; uranium silicides; fuels; reactors; production; planning; control; mathematical models

NEGRO, MIGUEL L.M.; DURAZZO, MICHELANGELO; MESQUITA, MARCO A. de; CARVALHO, ELITA F.U. de; ANDRADE, DELVONEI A. de. Studies on production planning of dispersion type U3Si2-Al fuel in plate-type fuel elements for nuclear research reactors. World Journal of Nuclear Science and Technology, v. 6, p. 217-231, 2016. DOI: 10.4236/wjnst.2016.64023. Disponível em: http://repositorio.ipen.br/handle/123456789/27000. Acesso em: $DATA.

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