INSTITUTO DE PESQUISAS ENERGÉTICAS E NUCLEARES
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Navegação Periódicos - Artigos por Agências de fomento "Comissão Nacional de Energia Nuclear (CNEN)"

Navegação Periódicos - Artigos por Agências de fomento "Comissão Nacional de Energia Nuclear (CNEN)"

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  • IPEN-DOC 27577

    ALMEIDA, G.F.C. ; SUGAHARA, T.; ARBEX, A.A.; COUTO, A.A. ; MASSI, M.; MONTORO, F.E.; REIS, D.A.P.. Analysis of the surface treatments effect on the creep behavior of Ti-6Al-4V alloy. Materials Research, v. 23, n. 6, p. 1-9, 2020. DOI: 10.1590/1980-5373-MR-2020-0314

    Abstract: This paper compares the creep behavior of Ti-6Al-4V alloy after different surface treatments, the plasma nitriding using Plasma Enhanced Chemical Vapor Deposition (PECVD), and the deposition of SiC thin films with Cr interlayer using High Power Impulse Magnetron Sputtering (HiPIMS). A microstructural characterization was performed with Scanning Electron Microscopy (SEM), Scanning and Transmission Electron Microscopy (STEM), and Energy Dispersive Spectroscopy (EDS) techniques. The creep test was performed at a constant load from 500 to 600 °C and 125 to 319 MPa, and a fractographic analysis was performed. The EDS analysis of the plasma nitrided layer indicated the nitrogen presence of the compounds TiN and Ti2N and an increase in the iron concentration. Creep test results in both conditions indicated an increase in the creep resistance. Plasma nitrided condition indicated the lowest creep rate and lesser elongation, making it the most suitable in applications that require a low dimensional distortion.

    Palavras-Chave: titanium alloys; thin films; sputtering; magnetrons; plasma; nitridation; creep; surface treatments

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  • IPEN-DOC 27360

    ALVARENGA, TALLYSON S. ; POLO, IVON O. ; PEREIRA, WALSAN W.; MAYHUGH, MICHAEL R.; CALDAS, LINDA V.E. . Application of the Reduced-Fitting Method to determine neutron scattering. Radiation Physics and Chemistry, v. 179, p. 1-8, 2021. DOI: 10.1016/j.radphyschem.2020.109207

    Abstract: As the number of techniques using neutron radiation has grown, the number of neutrons detectors has increased along with need for their calibration. In Brazil this substantial demand for neutron detector calibration falls on a single laboratory located in Rio de Janeiro. One of the major problems in the calibration of neutron detectors is neutron scattering, which varies depending on the size and configuration of the laboratory. This is due to the neutrons that interact with the experimental setup and the surrounding, walls, floor and ceiling. This scatter influences the reading of the instrument to be calibrated and causes systematic errors in the calibration of neutron detectors. ISO 8529-2 recommends the following methods to correct these effects: The Semi-Empirical Method (SEM), the Reduced-Fitting Method (RFM), the Shadow-Cone Method (SCM) and the Generalized Fit Method (GFM). In this study, the neutron scattering characterization was performed in the Neutron Calibration Laboratory (LCN) of IPEN/CNEN, using the RFM method. The neutron source used was 241AmBe, which was positioned in the center of the calibration room. Neutron spectra were obtained using a scintillation detector based on 6Lil(Eu) in combination with a Bonner sphere spectrometer (BSS) at source-detector distances from 30 cm to 258 cm.

    Palavras-Chave: scattering; neutrons; radiations; neutron detectors; calibration; calculation methods; bonner sphere spectrometers; neutron spectra

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  • IPEN-DOC 27553

    MILAGRE, MARIANA X. ; FRANCO, MARGARETH ; GENEZINI, FREDERICO ; WIMPORY, ROBERT C.; YOKAICHIYA, FABIANO; COSTA, ISOLDA . A correlation between microstructure and residual stress in the 6061 Al–Mg–Si alloy with different thermomechanical process. SN Applied Sciences, v. 2, n. 12, 2020. DOI: 10.1007/s42452-020-03945-y

    Abstract: Depending on the nature of the loading during service, the level and nature of residual stress can contribute to the lower service-life of a component. In this study the internal level of the residual stress of a 6061 Al–Mg–Si alloy with different thermomechanical processes was evaluated by residual stress neutron diffraction (RSND). Commercial tempers such as T6 (peak aged) and O (annealed) were compared with the 6061 alloy after different steps of a thermomechanical processing used for the manufacturing of nuclear fuel plates, R3 and R9H60. The results showed that the lowest level of residual stress was found for the peak age, T6 condition. This was associated with the highest microhardness value (highest density of "β″ phase) and lowest grain size. The O temper was the only condition which showed compressive residual stress and the most coarsened precipitates. The nuclear thermomechanical processes, R3 and R9H60, resulted in increased level residual stress related to the T6 and showed a tensile nature in relation to its parent material (6061-O). Moreover, the RSND technique allows observing that the texture is also higher for the samples processed by the nuclear thermomechanical process due the hot rolling stage.

    Palavras-Chave: microstructure; residual stresses; aluminium alloys; neutron diffraction; thermomechanical treatments; magnesium alloys; silicon alloys; friction welding

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  • IPEN-DOC 28851

    MILAGRE, MARIANA X. ; ARAUJO, JOAO V. de S. ; MACHADO, CARULINE de S.C.; PEREIRA, MARCO S. ; ANTUNES, RENATO A.; GENEZINI, FREDERICO ; COSTA, ISOLDA . Corrosion behavior of the 6061 Al–Mg–Si alloy in different soils extracts. Metallography, Microstructure, and Analysis, v. 11, n. 2, p. 327-340, 2022. DOI: 10.1007/s13632-022-00848-9

    Abstract: In this work, the corrosion behavior of the 6061 Al-alloy in different temper conditions was studied in different soil extracts using electrochemical and surface monitoring techniques. The results showed that the corrosion behavior of the 6061 alloy depends on the soil extract composition, with the highest electrochemical activities related to the soil extracts with the lowest nitrate and sulfate concentrations. The 6061-T6 condition was more susceptible to corrosion than the 6061-HCR one. The results were related to the higher amounts of MgSi particles in the 6061-T6 alloy compared to the 6061-HCR. Sulfate and nitrate ions acted as corrosion inhibitor reducing the corrosion kinetics of the 6061 alloy in solutions with high concentration of chloride ions.

    Palavras-Chave: corrosion; aluminium alloys; soils; corrosion resistance

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  • IPEN-DOC 29131

    ALMEIDA JUNIOR, J.N. ; POTIENS, M.P.A. ; RODRIGUES JUNIOR, O. . Development of an additional filtration system by 3D printing for the implementation of new X-ray beam qualities used in diagnostic radiology. Brazilian Journal of Radiation Sciences, v. 10, n. 3B, p. 1-7, 2022. DOI: 10.15392/2319-0612.2022.1992

    Abstract: The Calibration Laboratory (LCI) of the Nuclear and Energy Research Institute (IPEN-CNEN) offers calibration services for radiation measurements instruments used in radiation protection, diagnostic radiology and radiotherapy. LCI produces radiation qualities and irradiation conditions which are in accordance with the national and international standard requirements. In order to establish the recommended radiation qualities for diagnostic radiology, X-ray beams generated in laboratory are modified for the irradiation conditions found in equipment routinely used in healthcare services. In this work, a new additional filtration system was developed to be adapted to the existing filter system at LCI. The new filter support can be coupled to the PTW Bench Control installed at the LCI X-ray system. Using a FDM 3D printer, a support model and a set of drawers were developed for the placement of additional filters. The models were also developed to fit each specific drawer of each filter to be used in the laboratory routine, coupled to the specific sensors that fit the spaces of the support part. Additionally, a microcontroller based on Arduino, micro switches, low- and high-level programming, allow checking of drawer status and integration of information with the laboratory control system. The system allows the recognition of the filter inserted in the drawer from sensors attached to the support. Tests were carried out to verify the usability of the system in the routine, adding Ag (silver) and Cu (copper) filters, for the characterization of attenuated radiation beams of interest in diagnostic radiology.

    Palavras-Chave: magnesium base alloys; biological materials; biodegradation; decomposition; fluorescence spectroscopy; x radiation; specifications

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  • IPEN-DOC 27572

    CONTATORI, C. ; DOMINGUES JUNIOR, N.I.; BARRETO, R.L. ; LIMA, N.B. de ; VATAVUK, J.; BORGES, A.A.C. ; ALMEIDA, G.F.C. ; COUTO, A.A. . Effect of Mg and Cu on microstructure, hardness and wear on functionally graded Al-19Si alloy prepared by centrifugal casting. Journal of Materials Research and Technology, v. 9, n. 6, p. 15862-15873, 2020. DOI: 10.1016/j.jmrt.2020.11.050

    Abstract: This paper aims to investigate the copper and the magnesium effects on the microstructure, on the hardness, and on the resistance to micro-abrasive wear of the alloy Al–19Si. Early findings could show that the hypereutectic Al–Si alloys fabricated by centrifugal casting exhibited the possibility of obtaining a Functionally Graded Material (FGM), as well as the less-dense particles tended to be concentrated in the region close to the tube inner surface. It was observed that the wear resistance in this region was increased by the concentration of primary Si and Mg2Si particles due to their smaller densities than that of the Al. Also, the Cu and Mg were added in contents of 2.5 and 5% by weight. Moreover, this study focused on understanding the radial β-Si and Mg2Si particles migration in the Al–19Si alloy tubes and their effect on hardness and wear resistance. Firstly, a large quantity of primary Si and Mg2Si particles were concentrated in the inner layer of the tubes produced by centrifugal casting in the alloys Al–19Si, Al–19Si–2.5Cu–2.5Mg and Al–19Si–5Cu–5Mg. After that, the hardness increase was related to the number of primary particles presented in this tube region. Therefore, the segregation of the primary particles towards the inner surface of the tube was more pronounced in the casting end region and the wear resistance was also related to the presence of the primary particles. However, an excessive number of primary particles accumulated near this region could lead to higher wear due to the higher particles tearing.

    Palavras-Chave: microstructure; magnesium; copper; aluminium alloys; casting; silicon; centrifugation; wear resistance; functionals; chemical composition

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  • IPEN-DOC 27390

    MILAGRE, MARIANA X. ; DONATUS, UYIME; MOGILI, NAGA V.; MACHADO, CARULINE S.C. ; ARAUJO, JOAO V.S. ; KLUMPP, RAFAEL E. ; FERNANDES, STELA M.C. ; SOUZA, JOSE A.B. de ; COSTA, ISOLDA . Effects of Picture Frame Technique (PFT) on the corrosion behavior of 6061 aluminum alloy. Journal of Nuclear Materials, v. 539, p. 1-13, 2020. DOI: 10.1016/j.jnucmat.2020.152320

    Abstract: The 6061 Al–Mg–Si alloy is used in nuclear fuel plates of nuclear research reactors which are fed with fuel in plate shapes. The production of these plates is based on the picture frame technique (PFT). The picture frame technique (PFT) is a manufacturing process for the fabrication of nuclear fuel plates where the nuclear fuel is encapsulated by Al alloy plates and thermomechanically processed to generate a set with reduced thickness. The effects of PFT on the corrosion resistance of the 6061 aluminum alloy were evaluated in this study by immersion and electrochemical tests in 0.005 mol L−1 NaCl solution. The results showed that the PFT fabrication process increases the corrosion resistance of the 6061 alloy in relation to the conventional 6061-T6, due phase dissolution and lower content of β’’ phase. Also, corrosion propagation gradually changes, with an increasing number of processing steps, from intergranular to intragranular corrosion attack.

    Palavras-Chave: aluminium alloys; corrosion; fuel elements; pitting corrosion; differential thermal analysis; magnesium; silica; fuel plates

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  • IPEN-DOC 29505

    KOMATSU, LUIZ G.H. ; CAJADO, GIUSEPPE M. ; PARRA, DUCLERC F. . Effects of silver addition in zinc oxide nanoparticles on films of HMSPP/SEBS against Staphylococcus aureus and Escherichia coli contamination. Journal of Materials Science and Engineering B, v. 12, n. 7-9, p. 108-116, 2022. DOI: 10.17265/2161-6221/2022.7-9.004

    Abstract: In this research we decided to analyze the addition of silver (Ag°) on zinc oxide (ZnO) utilizing two nanoparticles: the synthesized zinc oxide-doped-silver nanoparticles (ZnO/Ag_Lab) utilizing the zinc nitrate as metal precursor for ZnO and silver nitrate as metal precursor for Ag°; and the commercial nanoparticle ZnO/Ag. For the study of application of the nanoparticles, they were processed in the form of films and the polymer utilized was the blend of HMSPP (high melt strength polypropylene) and styrene-ethylene/butadiene-styrene. For the study of nanoparticles, they were submitted to biocide tests against Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC8739) and XRD (X-Ray Diffraction). The XRD analysis results indicated, in both of nanoparticles, with the presence of wurtzite phase of ZnO, being that on the commercial nanoparticles the intensity of peak was higher than that of synthesized one, on other hand, the peaks attributed to Ag°, were more intense in the synthesized nanoparticle.

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  • IPEN-DOC 28692

    BARROS, L.F. ; DIAS, M.S. ; KOSKINAS, M.F. . Experimental determination of k0 and Q0 values for 121Sb, 123Sb and 130Ba targets applying covariance analysis. Applied Radiation and Isotopes, v. 184, p. 1-7, 2022. DOI: 10.1016/j.apradiso.2022.110122

    Abstract: This work consists of an experimental determination of k0 and Q0 for 121Sb, 123Sb and 130Ba targets. Covariance analysis has been introduced to supply not only the overall uncertainties in these parameters but also their correlations. The irradiations were performed near the core of the IEA-R1 4.5 MW swimming-pool nuclear research reactor of the Nuclear and Energy Research Institute (IPEN-CNEN/SP), in São Paulo, Brazil. The epithermal neutron flux shape parameter, alpha, at the irradiation position is very close to zero, which favors to obtain Q0 values more accurately. Two irradiations were carried out in sequence, using two sets of samples: the first with bare samples and the second inside a Cd cover. The activity measurements were carried out in a previously calibrated HPGe gamma-ray spectrometer. The measurements were corrected for: saturation, decay time, cascade summing, geometry, self-attenuation, measuring time and mass. Standard sources of 152Eu, 133Ba, 60Co and 137Cs traceable to a 4πβ−γ primary system were used to obtain the HPGe gamma-ray peak efficiency as a function of the energy. The experimental efficiency curve was performed by a fourth-degree polynomial fit, in the energy range of the standard sources, 121–1408 keV, it contains all correlations between points. For energies above 1408 keV, the efficiencies were obtained by the Monte Carlo Method. The covariance matrix methodology was applied to all uncertainties involved. The final values for k0 and Q0 were compared with the literature.

    Palavras-Chave: gamma spectroscopy; monte carlo method; monte carlo method; antimony isotopes; barium 130; reactors; antimony 123; antimony 121

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  • IPEN-DOC 27391

    MILAGRE, MARIANA X. ; DONATUS, UYIME; SILVA, REJANE M.P. ; BETANCOR-ABREU, ABENCHARA M.; RAMIREZ, OSCAR M.P.; MACHADO, CARULINE S.C. ; ARAUJO, JOAO V.S. ; SOUTO, RICARDO M.; COSTA, ISOLDA . Galvanic coupling effects on the corrosion behavior of the 6061 aluminum alloy used in research nuclear reactors. Journal of Nuclear Materials, v. 541, p. 1-11, 2020. DOI: 10.1016/j.jnucmat.2020.152440

    Abstract: The 6061 alloy is used in different thermomechanical conditions in research nuclear reactors. Nuclear fuel plates are manufactured by the picture frame technique (PFT) and the 6061 alloy is used as cladding for the nuclear fuel “sandwiches”. After the PFT process, these nuclear plates are placed in a case made of 6061-T6 alloy. In this work, the galvanic effects of coupling the 6061 alloy in the T6 and PFT temper conditions were investigated in different chloride-containing solutions. The results showed that galvanic coupling was favored between the PFT and 6061-T6 alloy. A potential difference of about 50 mV was observed between the temper conditions. This was attributed to differences in β’’ phase density between the two conditions (T6 and PFT) which was indicated by microhardness results. The 6061 alloy in the PFT condition was cathodic in relation to the T6 one. Results from conventional electrochemical techniques were in agreement with the local measurements. Local electrochemical techniques such as the SVET, SECM and LEIS were useful in characterizing the electrochemical behavior of the galvanically coupled alloys.

    Palavras-Chave: corrosion; electrochemical corrosion; aluminium alloys; electrochemistry; scanning electron microscopy; research reactors; reactors; nuclear fuels

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  • IPEN-DOC 29783

    PRADO, FELIPE M. ; FRANCO, TOMAS J. ; VIEIRA, TARCIO de A. ; WETTER, NIKLAUS U. . High-power Nd:YLF four-level lasers with 68% slope efficiency. Applied Optics, v. 62, n. 8, p. C49 - C52, 2023. DOI: 10.1364/AO.476541

    Abstract: Three laser resonators are demonstrated emitting at 1053 nm and pumped at 797 nm by volume Bragg gratingequipped diodes, achieving the highest reported efficiencies for Nd:YLF in a four-level system, to the best of our knowledge. A peak output power of 880 W is achieved by pumping the crystal with a diode stack of 1.4 kW of peak pump power.

    Palavras-Chave: neodymium lasers; resonators; optical radar

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  • IPEN-DOC 29629

    MARCHIOLI, CARLOS A. ; ALMEIDA, GISELE F.C. ; GONCALVES, RODOLFO L.P.; XAVIER, MARCOS D.; SANTOS, GIVANILDO A. dos; COUTO, ANTONIO A. . Influência na microestrutura e propriedades mecânicas da liga de alumínio A380 fundida sob pressão pela variação nas velocidades de injeção / Influence in the microstructure and mechanical properties of the aluminum alloy A380 die casting by the injection speed steps. Tecnologia em Metalurgia, Materiais e Mineração, v. 20, p. 1-9, 2023. DOI: 10.4322/2176-1523.20222804

    Abstract: Na fundição sob pressão de ligas de alumínio, devido à alta velocidade de injeção do metal líquido no molde, obtém-se uma microestrutura com grãos refinados e possível ocorrência de defeitos como microporosidade e microrechupes. Esses defeitos podem ocorrer devido a deficiências no projeto do ferramental, na definição dos parâmetros de cálculo ou mesmo no controle dos parâmetros de injeção. O objetivo deste trabalho é analisar a influência das velocidades das fases de injeção (primeira e segunda fases) na microestrutura e propriedades mecânicas da liga de alumínio A380. Corpos de prova foram moldados sob pressão de matriz em uma máquina de injeção de câmara fria. A faixa de velocidade de injeção do processo foi de 0,10 m/s, 0,25 m/s e 0,50 m/s para a primeira fase, e 0,6 m/s, 1,5 m/s 3,0 m/s para a segunda fase. As propriedades mecânicas foram determinadas por meio de ensaios de tração e dureza e a caracterização microestrutural por microscopia óptica. Os resultados indicaram que a velocidade de injeção não influencia o limite de resistência tanto da primeira quanto da segunda fase de injeção. No entanto, o nível de porosidade e erros de execução mudaram em função das variações de velocidade, fatores que afetam o resultado do alongamento e limite de escoamento dos produtos de fundição sob pressão.

    Palavras-Chave: castings; hardness; tensile properties; aluminium alloys; microstructure

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  • IPEN-DOC 29041

    BURIMOVA, ANASTASIA ; CARBONARI, ARTUR W. ; LIMA, NICOLE P. de ; MIRANDA FILHO, ARNALDO A. ; SOUZA, ALEXANDRE P. dos S. ; SALES, TATIANE da S.N. ; FERREIRA, WANDERSON L. ; PEREIRA, LUCIANO F.D. ; CORREA, BRUNO S. ; SAXENA, RAJENDRA N. . Local crystalline structure of doped semiconductor oxides characterized by perturbed angular correlations: experimental and theoretical insights. Crystals, v. 12, n. 9, p. 1-15, 2022. DOI: 10.3390/cryst12091204

    Abstract: Doping semiconductor oxides with trace amounts of non-native elements can improve their properties such as bandgap and conductivity. The lack of local techniques makes the precise characterization of these materials difficult. Among the few techniques capable of providing local characterization, those based on hyperfine interactions at probe nuclei have the advantage of being well established, probing the material homogeneously and completely, thus investigating different regions of material. Some of these techniques are also quite sensitive even at extremely low dopant concentrations. The perturbed angular correlation technique, combined with first-principles calculations, has recently been shown to be a powerful method for characterizing doped semiconductor oxides. In this paper, we present a brief review of the unique information extracted from the semiconductor investigation with such a complex approach, including semiconductor oxides doped with cadmium and other elements. A strong relationship between the local environment, including electronic structure, and the nature of the dopant and the native element of the doped oxides is also shown.

    Palavras-Chave: crystal doping; semiconductor materials; oxides; hyperfine structure; interactions; perturbed angular correlation

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  • IPEN-DOC 29909

    MORAIS, NATHANAEL W.S. ; MUCSI, CRISTIANO S. ; FABRIM, ZACARIAS E. ; SCHON, CLAUDIO G.; ROSSI, JESUALDO L. . Microstructural characterization of U-7.5Nb-2.5Zr alloy after ageing and constrained fatigue. Materials Research, v. 26, Suppl.1, p. 1-6, 2023. DOI: 10.1590/1980-5373-MR-2023-0039

    Abstract: U-7.5Nb-2.5Zr cladded in Zircaloy-4 is one of the most studied fuel prototypes. The Nb and Zrare added to the U to stabilize the body-centered cubic (BCC) gamma phase and grant mechanical and swelling resistance. The U-7.5Nb-2.5Zr undergoes the gamma to α′′ phase transformation, generating compressive stresses due to the volume reduction. The α′′ phase also can transform to a combination of α + γ2 phase (equilibrium phases), which are known to be hard and brittle. This work had the objective to test the effect of ageing the gamma to α′′ phase in thermal cycling of a U-7.5Nb-2.5Zr cladded in Zircaloy-4 part. A co-laminated specimen was aged and thermally cycled in a dilatometry experiment. The samples were characterized through X-ray diffraction and metallography. The results show that the gamma to α′′ phase transformations occur at the begin- ning of the initial ageing, followed by stress relief. During the cycling, the sample demonstrated non-equal thermal strains and presented fractures along with the U matrix.

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  • IPEN-DOC 28345

    HATTORI, C.S. ; ALMEIDA, G.F.C. ; GONCALVES, R.L.P.; SANTOS, R.G.; SOUZA, R.C.; SILVA JUNIOR, W.C. da; CUNALI JUNIOR, J.R.C.; COUTO, A.A. . Microstructure and fatigue properties of extruded aluminum alloys 7046 and 7108 for automotive applications. Journal of Materials Research and Technology, v. 14, p. 2970-2981, 2021. DOI: 10.1016/j.jmrt.2021.08.085

    Abstract: This work aimed to obtain by extrusion two aluminum alloys, 7108 and 7046. The microstructural characterized at each stage of the manufacturing process and the mechanical fatigue behavior of the extruded profile were evaluated. The aluminum alloys in the as-casted condition exhibited an interdendritic microsegregation inside the grains, with intermetallic phases precipitated on the grain boundaries. In the homogenization of the billets of the AA7108 and AA7046, the precipitated phases dissolved. The AA 7046, in the as-casted condition, displayed shrinkage microvoids throughout the length of the billet and a microstructure of heterogeneous grains, with the presence of a remelted layer at a maximum depth of 10 mm. The AA7046 displayed better tensile and fatigue properties than the AA7108. A higher surface roughness facilitated the initiation and propagation of cracks during the fatigue cycles. This effect was more pronounced with low levels of maximum stress and high number of cycles to failure. Deep secondary cracks perpendicular to the growth direction of the main crack were visible on all fracture surfaces. In the medium and high cycle fatigue tests of the AA7108 and AA7046, the cracks advanced in a perpendicular direction to the elongated grains resulting from the extrusion process. The fracture surfaces of the tested samples with a high number of cycles exhibited a region with a smaller crack propagation area and a larger region of rupture due to mechanical overload. The region of crack propagation is characterized by plastic deformation and the presence of striations perpendicular to the growth direction.

    Palavras-Chave: aluminium alloys; microstructure; extrusion; fracture mechanics; fatigue; automotive industry

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  • IPEN-DOC 28683

    VIEIRA, TARCIO de A. ; PRADO, FELIPE M. ; WETTER, NIKLAUS U. . Nd:YLF laser at 1053 nm diode side pumped at 863 nm with a near quantum-defect slope efficiency. Optics and Laser Technology, v. 149, p. 1-5, 2022. DOI: 10.1016/j.optlastec.2021.107818

    Abstract: Laser emission at the 1053 nm transition of Nd:YLF4 is demonstrated using diode-side-pumping at 863 nm directly into the emitting level. The laser configuration uses one total internal reflection at the pump face and provides the highest slope efficiency reported for the Nd:YLF4 medium, close to the quantum limit. In quasi-continuous mode, the laser operates with diffraction-limited beam quality and 78.2% slope efficiency with 14.4 W of output power. In continuous mode, 75.7% slope efficiency in both single-mode and multimode operation is achieved, with 13.5 W output power.

    Palavras-Chave: lasers; neodymium lasers; lithium fluorides; yttrium fluorides; crystal doping; optical pumping

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  • IPEN-DOC 28351

    SILVA, JOSE T. ; SOUZA, CARLA D. de ; ANGELOCCI, LUCAS V. ; ROSERO, WILMMER A.A. ; NOGUEIRA, BEATRIZ R. ; CORREIA, RUANYTO W. ; ZEITUNI, CARLOS A. ; ROSTELATO, MARIA E.C.M. . New model for an epoxy-based brachytherapy source to be used in spinal cancer treatment. Applied Radiation and Isotopes, v. 178, p. 1-7, 2021. DOI: 10.1016/j.apradiso.2021.109952

    Abstract: The present work described the cold fabrication of a P-32 radioactive source to be used in CNS cancer using epoxy resin. The epoxy plaque fabricated with Teflon mold presented better agreement. MCNP simulation evaluated the radiation dose. Special attention was given to factors that can impact dose distribution. Average dose was 16.44 ± 2.89% cGy/s. Differences of less than 0.01 cm in thickness within the plaque lead to differences of up to 12% in the dose rate.

    Palavras-Chave: epoxides; brachytherapy; neoplasms; central nervous system; monte carlo method; radiation doses

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  • IPEN-DOC 27144

    ARAUJO, LEANDRO G. de ; PRADO, EDUARDO S.P. ; MIRANDA, FELIPE de S.; VICENTE, ROBERTO ; SILVA SOBRINHO, ARGEMIRO S. da; PETRACONI FILHO, GILBERTO; MARUMO, JULIO T. . Physicochemical modifications of radioactive oil sludge by ozone treatment. Journal of Environmental Chemical Engineering, v. 8, n. 5, p. 1-8, 2020. DOI: 10.1016/j.jece.2020.104128

    Abstract: An experimental study on the degradation of organic compounds from radioactive oil sludge by the ozonation process is presented. The effects of different concentrations of ozone in the oil sludge degradation over time were investigated. The experiments were performed in a 0.125 L glass reactor with magnetic stirring and a diffuser plate at the bottom to feed the ozone. The ozone concentration varied from 13 to 53 mg L−1 and the total interaction time was 1 h. To investigate the physicochemical properties of the oil sludge (solid and liquid components) prior to and after the treatment, multiple analytical characterization methods were used: Thermal Gravimetric Analysis, X-ray diffraction, Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy, Fourier Transform Infrared spectroscopy, Spectrophotometer, and Residual Gas Analyzer. The most perceptive change is in the color of the liquid medium turned from dark brown to light yellow, especially under ozone concentrations higher than 33 mg L−1. Absorbance values decreased about 3.5 times after 30 min of treatment with [O3] =53 mg L−1. FTIR spectroscopy showed that the bands associated with the CH3 and CeH in CH2 disappeared during treatment. On the other hand, a greater presence of C]C aromatics was observed. By residual gas analysis, various organic and inorganic gases were identified during the treatment, such as CH4, H2, CO2, and H2S. Finally, the ozonation of the oil sludge proved to be effective, due to its high reaction capacity.

    Palavras-Chave: ozone; therapy; ozonization; radioactivity; sludges; oxidation; naturally occurring radioactive materials; fourier transformation; thermal gravimetric analysis

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  • IPEN-DOC 28413

    XAVIER FILHO, JOEL M. ; SILVEIRA, I.S. ; CALDAS, L.V.E. . Radiology and mammography standard X-ray spectra simulated with the Monte Carlo method. Brazilian Journal of Radiation Sciences, v. 9, n. 2C, p. 1-13, 2021. DOI: 10.15392/bjrs.v9i2C.1670

    Abstract: Six standard beams described in the TRS-457 (IAEA): RQR 5, 8, M1, M2, M3, M4 were simulated using the EGSnrc Monte Carlo code. Each spectrum was created by an X-ray tube simulated in BEAMnrc, and attenuation curves were obtained using the application egs_kerma. The quality of each beam was evaluated by the 1st and 2nd half-value layers, the homogeneity coefficients and the mean energies. All beams presented quality parameters compatible with those described in TRS-457 (IAEA).

    Palavras-Chave: x-ray spectra; mammary glands; biomedical radiography; monte carlo method; ionizing radiations

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  • IPEN-DOC 28529

    SCURO, N.L. ; ANGELO, G. ; ANGELO, E.; UMBEHAUN, P.E. ; TORRES, W.M. ; SANTOS, P.H.G. ; FREIRE, L.O. ; ANDRADE, D.A. . RANS-based CFD calculation for pressure drop and mass flow rate distribution in an MTR fuel assembly. Nuclear Science and Engineering, v. 195, n. 4, p. 349-366, 2021. DOI: 10.1080/00295639.2020.1825306

    Abstract: This work presents a Reynolds-averaged Navier Stokes–based computational fluid dynamics methodology for the calculation of pressure drop and mass flow rate distribution in a material test reactor flat-plate-type standard fuel assembly (SFA) of the IEA-R1 Brazilian research reactor to predict future improvements in newer SFA designs. The results improve the understanding of the origin of fuel plate oxidation due to high temperatures, and consequently, due to the internal flow dynamics. All numerical analyses were performed with the ANSYS-CFX® commercial code. The observed results show that the movement pin decreases the central channel mass flow due to the length of the vortex at the inlet region. However, the outlet nozzle showed greater general influence in the flow dynamics. It should have a more gradual cross-section transition being away from the fuel plates or a squarer-shaped design to get a more homogeneous mass flow distribution. Optimizing both regions could lead to a better cooling condition. The validation of the IEA-R1 numerical methodology was made by comparing the McMaster University’s dummy model experiment with a numerical model that uses the same numerical methodology. The experimental data were obtained with laser Doppler velocimetry, and the comparison showed good agreement for both pressure drop and mass flow rate distribution using the Standard k-ω turbulence model.

    Palavras-Chave: computer calculations; computerized simulation; fluid mechanics; materials testing; reactor materials

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