Computational analysis for wax detection in deepwater pipelines using nuclear techniques

Wax deposition along the extensive oilfield pipelines is a problem that affects the flow assurance. To solve it, one must monitor the wax formation in its initial stage. In this light, nuclear techniques are an effective alternative solution, as they can detect characteristics of materials or substances in an indirect and non-invasive manner. The present work shows a computational model using the MCNP6 (Monte Carlo N-Particle 6) code and the gamma radiation transmission profiling technique to detect different wax thickness. This fact is directly related to the attenuation of the gamma radiation beam when crossing the wax thicknesses

Artificial neural network used in the study of sensitives in iris reactor pressurizer

In general, the technique of sensibility analysis studies the behavior of the ratio between the variation of output results and the variation of input parameters. This study performed in the reactor pressurizer, which is a component responsible for control of the pressure inside the vessel, has fundamental importance in designing the security of any concept of advanced reactor. Above all, 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 large computational effort. Unlike this method, Artificial Neural Networks (ANN), beyond faster, do not require a typical linear behavior of the system. Moreover, they can also use experimental data for their training and learning. If the ANN are satisfactory in this theoretical case may be used for future mapping and forecasting of the behavior of various phenomena in both plant operation and small-scale experiment to be installed in CRCN-NE. Based on the results obtained in this study, one can conclude that the artificial neural networks are presented as an alternative to MODPRESS code, as well as a great tool to calculate the sensitivity coefficient

Simulação Neutrônica do Núcleo de um Reator Nuclear do Tipo iPWR Usando o Código SERPENT

Nuclear energy is one of the main alternatives for future energy sources without greenhouse gas emissions. Small modular nuclear reactors have great potential for future development. And among them, due to their safety characteristics and similarity to current reactors, the integral pressurized water reactors (iPWR) stand out. In the work, a neutronic computational model based on the Monte Carlo Serpent code is presented for the design of a four-year extended fuel cycle. The main results of the core neutronic behavior for the extended fuel cycle are offered.A energia nuclear é uma das principais alternativas para futuras fontes de energia sem emissões de gases contribuintes ao efeito estufa. Neste contexto os reatores nucleares modulares de pequeno porte têm grande potencial de desenvolvimento. Nesta categoria, por suas características de segurança e semelhanças com os reatores atuais em operação, destacam-se os reatores integrais de água pressurizada (iPWR). Neste trabalho, é apresentado um modelo computacional neutrônico baseado no código Monte Carlo Serpent para o projeto e análise de um ciclo de combustível estendido de quatro anos em um reator de tipo iPWR. Os principais parâmetros do comportamento neutrônico do núcleo são calculados e comparados com as recomendações para retores refrigerados a água

Sensor capacitivo para medição do nível de água

A water level sensor, based on a varnished copper wire, was developed. Water and copper are the plates of the capacitor, and the varnish, the dielectric. Nine sensors with wires of different diameters were individually calibrated. For each wire, a linear regression was calculated between the water levels and their respective capacitances. All of the determination coefficients showed values near to the unity. Capacitance of wire ranges from 37.3 to 84.3 pF/cm.Um sensor de nível de água, baseado em um fio esmaltado, foi desenvolvido. A água e o cobre são as placas dos capacitores e o esmalte o dielétrico. Nove sensores, com fios de vários diâmetros e tipos de isolantes foram calibrados individualmente. Para cada fio foi calculada uma regressão linear entre os níveis de água e as respectivas capacitâncias. Todos os coeficientes de determinação tiveram valores próximos da unidade. A capacitância do fio variou entre 37,3 e 84,3 pF/cm

GAMMA RADIATION AS A METHOD FOR STERILIZATION OF ALL-IN-ONE ADMIXTURES BAGS FOR CLINICAL USE: A STUDY OF STABILITY

Objective: The aim of this work was to evaluate the stability of all-in-one (AIO) admixtures exposed to gamma irradiation sterilization.Methods: The samples were divided into four groups with 10 bags each: a) Group I: control samples (bags without sterilization or inoculation with microorganisms); b) Group II: bags sterilized by gamma irradiation; c) Group III: bags inoculated and then irradiated and, d) Group IV: bags only inoculated. The following studies were performed: macroscopic analysis of admixtures; physicochemical stability; degree of lipoperoxidation (LPO), and microbiological tests.Results: Gamma irradiation sterilization was 100% effective, since no irradiated sample showed growth of microorganisms. All groups exhibited similar particle size distribution, but a longer storage time led to a smaller percentage of large particles. In general, irradiated samples showed reduced LPO.Conclusion: Gamma irradiation sterilization of these admixtures can be extended to clinical practice, as it results in physicochemically stable admixtures

Subirrigation of land bordering small reservoirs in the semi-arid region in the Northeast of Brazil: monitoring and water balance

International audienceIn Northeast Brazil, more than 70,000 small dams retain superficial runoff and underground water flow, creating small reservoirs. Recession agriculture consists of cropping the margins of the reservoirs, on slight slopes, while the water level progressively decreases, and it is a widespread cropping system in this area. The water balance for this particular system was quantified on two contiguous plots, one with “Marreca” grass (Paspalum conjugatum Berg.), a forage crop, and the other one on bare soil, in the recession zone of the basin of Flocos dam, municipality of Tuparetama, PE (7°36′S and 37°18′W). The soil, classified as Fluvent, consists of a superficial clay textured layer overlying a sandy layer. Next to the dam, a meteorological station was installed, equipped with automatic sensors for recording rainfall, air temperature and wind speed, and pan evaporation. In the reservoir, the water level was recorded. The plots were instrumented with one neutron probe access tube, one piezometer and tensiometers at different soil depths. Water retention and hydraulic conductivity characteristics were determined through field and laboratory measurements. The water balance was determined for the cropped and the bare soil plots, during 67 days. Average values for the actual evaporation and evapotranspiration rate, were respectively 5.0 and 8.0 mm day−1, with an average reference evaporation rate of 8.7 mm day−1. The contribution of the aquifer recharge to evaporative demand was estimated and found to be very important. Field observation and the estimated aquifer recharge from the reservoir suggest the presence of preferential flow. The study of water dynamics in this system is fundamental for establishing a basis for the sustainable development of agriculture in this area

Desenvolvimento de um modelo fractal para a estimativa da condutividade hidráulica de solos não saturados A fractal model to estimate the unsaturated hydraulic conductivity of soils

Baseado nos conceitos da geometria fractal e nas leis de Laplace e de Poiseuille, foi criado um modelo geral para estimar a condutividade hidráulica de solos não saturados, utilizando a curva de retenção da água no solo, conforme representada por um modelo em potência. Considerando o fato de que este novo modelo da condutividade hidráulica introduz um parâmetro de interpolação ainda desconhecido, e que, por sua vez, depende das propriedades dos solos, a validação do modelo foi realizada, utilizando dois valores-limite fisicamente representativos. Para a aplicação do modelo, os parâmetros de forma da curva de retenção da água no solo foram escolhidos de maneira a se obter o modelo de van Genuchten. Com a finalidade de obter fórmulas algébricas da condutividade hidráulica, foram impostas relações entre seus parâmetros de forma. A comparação dos resultados obtidos com o modelo da condutividade e a curva experimental da condutividade dos dois solos, Latossolo Vermelho-Amarelo e Argissolo Amarelo, permitiu concluir que o modelo proposto é simples em sua utilização e é capaz de predizer satisfatoriamente a condutividade hidráulica dos solos não saturados.<br>From a conceptual model based on fractal geometry and Laplace's and Poiseuille's laws, a versatile and general fractal model for the hydraulic conductivity to be used in the soils was developed. The soil-moisture retention curve is derived from a power model. Due to the fact that the proposed model of hydraulic conductivity introduces a still unknown interpolation parameter, which in turn is a function of soil properties, its limiting values were considered for the analysis. To apply the model in the soil, the form parameters of the soil-moisture retention curve were chosen so as to reproduce van Genuchten's equation. In order to obtain a closed-form equation for the hydraulic conductivity, relationships between the form parameters were imposed. The comparison between the predicted and experimental hydraulic conductivity from two soils, Oxisol and Yellow Utilsol, demonstrated that the proposed model is flexible and that it can be used to predict the unsaturated hydraulic conductivity of soils with good accuracy