Study of Worker’s Exposure to Tantalum-bearing Particles in a Mining and Metallurgical Plant

The objective of this study was to assess worker exposure to mineral dust particles and a metabolic model, based on the model adopted by ICRP, was applied to assess human exposure to Ta, and predicted values of Ta concentrations in excreta. The occupational exposure to Th, U, Nb, and Ta bearing particles during routine tasks to obtain Fe-Nb alloys was estimated using air samplers and excreta samples. Ta concentrations in food samples and in drinking water were also determined. The results support that workers were occupationally exposed to Ta bearing particles, and also indicate that a source of Ta exposure for both workers and the control group was the ingestion of drinking water containing soluble compounds of Ta. Therefore, some Ta compounds should be considered soluble compounds in gastrointestinal tract. Consequently the metabolic model based on ICRP metabolic model and/or the transfer factor f1 for Ta should be reviewed and the solubility of Ta compounds in gastrointestinal should be determined.

Avaliação do padrão de resposta de imunoglobulinas em diferentes linhagens de camundongos frente à infecção por T.cruzi

Dissertação (Mestrado)

Residence Time Distribution (Rtd) Associated with Statistical Weighted Moments to Fit Mathematical Models Using In Industrial Systems Diagnosis

This work presents a computational, called MOMENTS, code developed to be used in process control to determine a characteristic transfer function to industrial units when radiotracer techniques were been applied to study the unit´s performance. The methodology is based on the measuring the residence time distribution function (RTD) and calculate the first and second temporal moments of the tracer data obtained by two scintillators detectors NaI positioned to register a complete tracer movement inside the unit. Non linear regression technique has been used to fit various mathematical models and a statistical test was used to select the best result to the transfer function. Using the code MOMENTS, twelve different models can be used to fit a curve and calculate technical parameters to the unit.

Estudo do efeito da radiação ionizante por feixe de elétrons sobre o polietileno de ultra alto peso molecular virgem e reciclado industrial

Dissertacao (Mestrado)

Production of Gaseous Radiotracers Ch3i and I2 Through Na123i Salt

The objective of the present work was to develop, separately, methodology for production of two gaseous tracers through the sodium iodide NaI marked with 123I. Found in the nature in form different, the iodine has been used in diverse works in the area of the industry and health. These two forms of the gaseous iodine, the methyl iodide, CH3I, and molecular iodine, I2, are very unstable and volatile in the ambient temperature and presents different problems in clean-up and monitoring systems. The syntheses were processed with sodium iodide (NaI) 1M aqueous solution marked with 123I. The production of gas I2 was realized with in chlorine acid (HCl) and sodium iodate salt (NaIO3) and the CH3I was used, the salt of NaI and the reagent (CH3)2SO4. The production of gases was initially realized through in unit in glass with an inert material and the purpose was to study the kinetic of reaction and to determine the efficiency of production. The two synthesis occurs in the reaction bottle and after of produced, the gas is stored in the collect bottle that contains a starch solution for fixed the I2, and in syntheses of CH3I contains a silver nitrate solution for your fixation. To determine the efficiency of production of gases, analytic tests were realized, where the consumption of iodide ions of the bottle of reaction are measured. The optimization of production of the each gaseous tracer was studied varying parameter as: concentration of iodide, concentration of acid and temperature. After, the syntheses of the radiotracers were realized in the compact unit, having been used as main reagent the salt radiated of sodium iodide, Na123I. The transportation of elementary iodine and methyl iodine was studied by a scintillation detector NaI (2 x 2)” positioned in the reaction bottle.

Modelo organizacional de ensino a distancia para instituicoes tecnologicas

Tese (Doutoramento)

Specific Filters Applied in Nuclear Medicine Services

In Nuclear Medicine, radioiodine, in various chemical forms, is a key tracer used in diagnostic practices and/or therapy. Due to its high volatility, medical professionals may incorporate radioactive iodine during the preparation of the dose to be administered to the patient. In radioactive iodine therapy doses ranging from 3.7 to 7.4GBq per patient are employed. Thus, aiming at reducing the risk of occupational contamination, we developed a low cost filter to be installed at the exit of the exhaust system where doses of radioactive iodine are fractionated, using domestic technology. The effectiveness of radioactive iodine retention by silver impregnated silica [10%] crystals and natural activated carbon was verified using radiotracer techniques. The results showed that natural activated carbon is effective for I2 capture for a large or small amount of substrate but its use is restricted due to its low flash point (150º C). Besides, when poisoned by organic solvents, this flash point may become lower, causing explosions if absorbing large amounts of nitrates. To hold the CH3I gas, it was necessary to increase the volume of natural activated carbon since it was not absorbed by SiO2 + Ag crystals. We concluded that, for an exhaust flow range of (306 4) m3/h, a double stage filter using SiO2 + Ag in the first stage and natural activated carbon in the second is sufficient to meet radiological safety requirements.

Desenvolvimento de um sistema eletronico com registro simultaneo de amplitude e instante de ocorrencias dos pulsos, aplicado ao metodo de coincidencias 4'pi''beta''gama'

Dissertacao (Mestrado)

Flow Regime Identification Methodology with Mcnp-X Code And Artificial Neural Network

This paper presents flow regimes identification methodology in multiphase system in annular, stratified and homogeneous oil-water-gas regimes. The principle is based on recognition of the pulse height distributions (PHD) from gamma-ray with supervised artificial neural network (ANN) systems. The detection geometry simulation comprises of two NaI(Tl) detectors and a dual-energy gamma-ray source. The measurement of scattered radiation enables the dual modality densitometry (DMD) measurement principle to be explored. Its basic principle is to combine the measurement of scattered and transmitted radiation in order to acquire information about the different flow regimes. The PHDs obtained by the detectors were used as input to ANN. The data sets required for training and testing the ANN were generated by the MCNP-X code from static and ideal theoretical models of multiphase systems. The ANN correctly identified the three different flow regimes for all data set evaluated. The results presented show that PHDs examined by ANN may be applied in the successfully flow regime identification.

Artificial Neural Network and Neutron Aplication in a Volume Fraction Calculation in Annular and Stratified Multiphase System

Multiphase flows, type oil–water-gas are very common among different industrial activities, such as chemical industries and petroleum extraction, and its measurements show some difficulties to be taken. Precisely determining the volume fraction of each one of the elements that composes a multiphase flow is very important in chemical plants and petroleum industries. This work presents a methodology able to determine volume fraction on Annular and Stratified multiphase flow system with the use of neutrons and artificial intelligence, using the principles of transmission/scattering of fast neutrons from a 241Am-Be source and measurements of point flow that are influenced by variations of volume fractions. The proposed geometries used on the mathematical model was used to obtain a data set where the thicknesses referred of each material had been changed in order to obtain volume fraction of each phase providing 119 compositions that were used in the simulation with MCNP-X –computer code based on Monte Carlo Method that simulates the radiation transport. An artificial neural network (ANN) was trained with data obtained using the MCNP-X, and used to correlate such measurements with the respective real fractions. The ANN was able to correlate the data obtained on the simulation with MCNP-X with the volume fractions of the multiphase flows (oil-water-gas), both in the pattern of annular flow as stratified, resulting in a average relative error (%) for each production set of: annular (air= 3.85; water = 4.31; oil=1.08); stratified (air=3.10, water 2.01, oil = 1.45). The method demonstrated good efficiency in the determination of each material that composes the phases, thus demonstrating the feasibility of the technique.

Evaluation of Gaseous Fluid Dispersion Through Packed Bed Using Radiotracers Technique

In this study, it was developed a methodology for the determination of the dispersion of a gaseous tracer in porous media using the radiotracer technique. In order to evaluate several porous media, a cylindrical filter was constructed in PVC and connected to a system with constant flow. Inside this unit silica crystals (16-20) mesh was used as porous media and CH3Br (Methyl Bromide) marked with 82Br was used as radiotracer. An instantaneous pulse of tracer was applied in the system entrance and registered by two NaI (3x3)” scintillation detectors located one before and the other after the filter. The curves produced by the radioactive cloud and recorded by the detector were analyzed statistically using the weighted moment method. The mathematical model one considered as great dispersion of tracer was used to evaluate the flow conditions inside the filter system. The results show us that the weight moment method associated with radiotracer techniques is useful to evaluated an industrial filter and allows to measure the residence time distribution, τ, and the axial dispersion, DAB, gas in a porous medium.

Desenvolvimento de Sistema de Aquisição e Análise de Dados para Aplicações de Traçadores Radioativos em Unidades Industriais

Desenvolveu-se no Instituto de Engenharia Nuclear um sistema de aquisição de dados para avaliação das condições operacionais de unidades industriais pelo estudo das curvas Distribuição do Tempo de Residência - RTD, composto de detectores cintiladores NaI (Tl) 3”x 3” conectados a analisadores monocanal cujos sinais são captados por uma interface acoplada a um microcomputador. Para a análise das informações coletadas desenvolveu-se o programa TRACER que efetua um tratamento matemático preliminar dos dados; apresenta na tela a curva RTD, e calcula valores como o tempo de residência médio e as funções resposta, tanto para estímulos instantâneos como para estímulos contínuos. As informações levantadas permitem a identificação de problemas como possíveis canalizações, fugas, zonas mortas e decréscimo na eficiência das unidades. Todo o conjunto é disposto em módulos compactos o que possibilita seu transporte e instalação em unidades industriais.

Ferramentas para adequação das linhas de pesquisa de intitutos de pesquisa: o exemplo do IPEN

Tese (Doutoramento)

Methodology for Labeling Oil Products with 123I

The objective was the development a methodology to label organic compounds with radioactive iodine (123I) from the reaction of organic compound with iodine nomochloride (ICL). The process begins with the production of 123ICl from the oxidation of potassium iodate in acid medium. The ICL labeled with 123I is extracted from aqueous phase using diethyl ether and then mixed with the organic compound to be labeled and the process is based on adding the radioactive iodine to the Carbon-Carbon double bonds of the organic compound. To measure the efficiency of the labeling process, in all stages samples were collected and the total activity of 123I was measure. The results show a production yield of 82% for lubricant oil and 85% for gasoline and diesel.

Desenvolvimento e validação de metodologia analítica para a determinação de fármacos em amostyras de água, superficial e tratada, utilizando a cromatografia líquida de ultra performance acoplada a espectrometria de massas tandem (UPLC-MS/MS)

Dissertação (Mestrado)