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Costa S.P.,Federal University of Pernambuco | Lima F.R.D.A.,Federal University of Pernambuco | Lima F.R.D.A.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | Lapa C.M.F.,Brazilian Nuclear Engineering Institute (IEN) | And 2 more authors.
Progress in Nuclear Energy | Year: 2013

The technique of sensibility analysis studies the behavior of the ratio between the variation of output results and the variation of input parameters in general. This study performed in the reactor pressurizer, which is a component responsible for controlling of the pressure inside the vessel, has the fundamental importance in designing the security of any concept of an advanced reactor. In fact, for its feature of passive action of the pressurizer (there is no spray), this analysis becomes a necessary step for safety and performance of the plant. The direct method through code MODPRESS, which represents the pressurizer model of the International Reactor Innovative and Secure (IRIS), has required a huge computational effort. To solve this problem, artificial neural networks (ANNs), beyond faster, has been used to replace the MODPRESS in this article. The ANNs do not require linear behavior of the system and can use both, simulated or experimental data for their training and learning. In order this, we adopted a classical non-supervised training ANN for mapping and forecasting of the pressurized using initially simulated data. In next future, we will incorporate the experimental data from the operation of the CRCN-NE reduced-scale test facility mapping. Moreover, based on the results obtained in this study, one can conclude that the artificial neural networks are presented as an alternative to MODPRESS code, and artificial neural networks are actually a great tool to calculate the sensitivity coefficient. © 2013 Elsevier Ltd. All rights reserved. Source

Oliveira M.L.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | Maia A.F.,Federal University of Sergipe
Applied Radiation and Isotopes | Year: 2010

Tandem systems usually comprise two detectors with different radiation energy responses and are utilized to determine the effective energy of unknown radiation beams. The aim of this paper was to evaluate the influence of absorbed dose on tandem curves obtained for different TL materials. In the studied dose interval, the results demonstrate that there is no significant influence of dose on the tandem curves. Therefore, the reliability of these systems for the determination of radiation beam effective energy was confirmed. © 2010 Elsevier Ltd. All rights reserved. Source

Silva E.C.,Federal University of Minas Gerais | Khaidukov N.M.,RAS Kurnakov Institute of General and Inorganic Chemistry | Vilela E.C.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | Faria L.O.,Brazilian Nuclear Technology Development Center (CDTN)
Radiation Measurements | Year: 2013

Results of the investigation concerning thermoluminescence (TL) responses to X, gamma and neutron radiation fields for crystals of complex fluoride K 2GdF5 undoped and doped with varying concentrations of Dy3+ ions are presented. Crystals doped with 5.0 at% Dy3+ have shown the most efficient TL response, with a linear response to doses for all the radiation fields. In the X rays range, the maximum TL response has been found to be 15 times more than the response for gamma. The fast and thermal neutron TL outputs were evaluated for K2Gd0.95Y 0.05F5 and the contribution of the gamma component in the TL curve was estimated. © 2013 Elsevier Ltd. All rights reserved. Source

Menezes F.D.,Federal University of Pernambuco | Menezes F.D.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | Galembeck A.,Federal University of Pernambuco | Alves Jr. S.,Federal University of Pernambuco
Ultrasonics Sonochemistry | Year: 2011

Luminescent CdTe quantum dots (Qdots) have been produced at few minutes by using a new, simple and fast methodology in an aqueous medium by using ultrasound irradiation to accelerate the process of tellurium reduction. The structural and optical properties were characterized by TEM, XRD, absorption and fluorescence spectrocopy. The produced Qdots are in a strong quantum confinement regime and have only one fluorescence band. Moreover, the nanoparticles seem to be monodispersed, which is in accordance with the fluorescence results. We have developed a simple route for preparing monodispersed CdTe Qdots in an aqueous media. The use of ultrasound allows the morphology to be better controlled and the surfaces defects of Qdots to be reduced. © 2011 Elsevier B.V. All rights reserved. Source

Silva J.M.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | Villar H.P.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | Pimentel R.M.M.,Federal Rural University of Pernambuco
Radiation Physics and Chemistry | Year: 2012

Cells of the mesocarp of mango cultivar Tommy Atkins were analyzed by Transmission Electron Microscope-TEM to evaluate the effects of doses of 0.5 and 1.0. kGy applied immediately after the fruit and after storage for twenty days at a temperature of 12. °C followed by 5 days of simulated marketing at a temperature of 21. °C. No alteration was found in the structure of the cell wall, middle lamella, and plasma membrane of fruits when analyzed immediately after application of doses. The mesocarp cell structure of the cell wall, middle lamella, and the plasma membrane did however undergo changes after storage. Fruits that received a dose of 0.5. kGy displayed slight changes in cell wall structure and slight disintegration of the middle lamella. Fruits that received a dose of 1.0. kGy displayed more severe changes in the structure of the cell wall, greater middle lamella degradation, and displacement of the plasma membrane. © 2012 Elsevier Ltd. Source

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