Determination of the region of sensitivity of a scintillator detector NaI(Tl) (2 X 2)” submerged in water

This paper presents the development of a methodology used to calculate the region of sensitivity of a scintillator detector NaI(Tl) (2 x 2)” submerged in water. The procedure was based in the simulation of a radioactive cloud (radiotracer), emitting anisotropy photons, that approximate of the submerged detector. This detector will be fixed into large industrial mixing. The detector registers the increase of the number of photons, because the solid angle and concentration of radiotracer also increase. Considering the absence of data in the literature, the methodology presented has your adequacy verified indirectly with a simple geometry that consists in a circular detector and one disk source in front of the detector. The theoretical and experimental tests were used for the determination of the region of sensitivity. The Simpson integration Method was used for the solid angle calculations and Monte Carlo Method was used for the validation of the employed geometry. The two methods were compared showing an error between 1.5% and 5%. In the experimental test was employed one disk source of the 137Cs, with radius of 1.2 cm and a collimated and not collimated scintillator detector NaI(Tl) (2 x 2)”. The counts were registered in three different plans enabling to determine the region of sensitivity of the detector

Study of the source-detector system geometry using the MCNP-X code in the flowrate measurement with radioactive tracers

The use radioactive tracers for flow rate measurement is applied to a great variety of situations, however the accuracy of the technique is highly dependent of the adequate choice of the experimental measurement conditions.To measure flow rate of fluids in ducts partially filled, is necessary to measure the fluid flow velocity and the fluid height. The flow velocity can be measured with the cross correlation function and the fluid level, with a fluid level meter system. One of the error factors when measuring flow rate, is on the correct setting of the source-detector of the fluid level meter system. The goal of the present work is to establish by mean of MCNP-X code simulations the experimental parameters to measure the fluid level [3]. The experimental tests will be realized in a flow rate system of 10 mm of diameter of acrylic tube for water and oil as fluids. The radioactive tracer to be used is the 82Br and for the detection will be employed two 1” NaI(Tl) scintillator detectors, shielded with collimators of 0.5 cm and 1 cm of circular aperture diameter

Study of volume fractions on biphasic stratified regime using gamma ray

In the oil industries, interconnected pipelines are used to This modal has an advantage because they are more economical, eliminate a need for stocks and, in addition, great safety in operation minimizing a possibility of loss or theft when transported another way. In many cases, especially in the petrochemical industry, the same pipeline is used to carry more than one type of product. They are called poliduct. In the operation of a poliduct there is a sequence of products to be transported and during the exchange of the product, there are still fractions therefore important to identify precisely this region in order to reduce the costs of reprocessing and treatment of discarded products. In this way, this work presents a methodology to evaluate the sensitivity of the gamma densitometry technique in a study of the calculation of volume fractions in biphasic systems, submitted to the stratified flow regime. Using computational simulations using the Monte Carlo Method with the MCNP-X code measurement geometry was proposed that presented a higher sensitivity for the calculation of volume fractions. The relevant technical data to perform a simulation of the scintillator detectors were based on information obtained from the gammagraphy technique. The study had a theoretical validation thought analytical equations, and the results show that it is possible to identify volume fractions equivalent to 3%

Radiosterilization of historical documents: the potential effects of gamma irradiation on paper and printing inks

The controlled exposition to gamma radiation is a physical process which can be used for the preservation and recovery of historical documents. Depending on the intrinsic characteristics of the material to be treated, it is necessary to research and stablish, from time to time, the optimum dose rate and total dose, the conditions to eliminate or reduce the biological threat, the equipment and its logistics, the economic aspects and any other impact caused by radiation on the material to be treated. The references indicate that through research it is possible to consolidate the knowledge about gamma radiation emitted from 60Co in order to completely remove or at least greatly reduce infestation by insects or biodeterioration microorganisms. On this work we have used a MDS Nordion self-contained 60Co research irradiator, model Gamacell Excel 220, at Postgraduate Institute of Engineering and Research Alberto Luiz Coimbra, in Rio de Janeiro Federal University. The analysis of the samples submitted to controlled thermal dry aging and to gamma radiation made possible to verify the differences between treated and untreated samples. The results of the chromatic measures indicate that, with the optimum total dose, the gamma radiation treatment does not significantly alter the properties of paper or printing inks. This way, it is possible to conclude that even though the gamma irradiation of historical documents is a complex procedure which demands a detailed study in order to assure its safe application, it is environmentally safer than the use of chemical pesticides

Characterization of electrochemical cell for production of radiotracer in organic medium

In a petrochemical plant, precise knowledge of the flow of the compounds that flow inside the pipelines that carry oil and these derivatives is crucial. To perform these controls a series of flow meters are installed inside ducts in direct contact with the fluid to be monitored. This invasive method presents a great limitation because the oil aggressive proprieties that require these measurement devices are subjected to frequent calibrations which, in turn, cause the stoppage of the plant and low productivity. In this sense, radiotracers has been used in conjunction with the time transient method, by configuring a precise and non-invasive measurement technique. This work presents the study of the characterization of an electrolytic cell model for the production of petroleum derivatives labeled with Iodine-123 for use as radiotracer in the measurement of flow in ducts and the time transient method. Labelling of organic compounds usually a sequence of solvent separation and extraction steps which, when used for labeling oil and oil derivatives it causes high gamma exposition for the operator at considerable dose rates due to the need for direct interaction with the marking system. The objective of this work is to develop a cell model that is part of a compact, automatically operated labelling system with physics and chemistry parameters defined to optimize the organic phase labelling processes of petroleum derivatives. The labelling cell is composed of a cylindrical reaction vessel where the aqueous medium containing the iodine-123 in the form of sodium iodide (NaI-I123) is inserted with about 2 mCi of activity and the organic medium. In the system are introduced, two Platinum electrodes where a voltage of 0. 8 V is applied. This system allows the production of radiotracer for a rapid pulse injection. The results show that there was no significant variation of the stability of the system in the temperature range of 25 °C to 40 °C and showed a labelling efficiency around 85%

Volume fraction prediction in biphasic flow using nuclear technique and artificial neural network

The volume fraction is one of the most important parameters used to characterize air-liquid two-phase flows. It is a physical value to determine other parameters, such as the phase’s densities and to determine the flow rate of each phase. These parameters are important to predict the flow pattern and to determine a mathematical model for the system. To study, for example, heat transfer and pressure drop. This work presents a methodology for volume fractions prediction in water-gas stratified flow regime using the nuclear technique and artificial intelligence. The volume fractions calculate in biphasic flow systems is complex and the analysis by means of analytical equations becomes very difficult. The approach is based on gamma-ray pulse height distributions pattern recognition by means of the artificial neural network. The detection system uses appropriate broad beam geometry, comprised of a (137Cs) energy gamma-ray source and a NaI(Tl) scintillation detector in order measure transmitted beam whose the counts rates are influenced by the phases composition. These distributions are directly used by the network without any parameterization of the measured signal. The ideal and static theoretical models for stratified regime have been developed using MCNP-X code, which was used to provide training, test and validation data for the network. The detector also was modeled with this code and the results were compared to experimental photopeak efficiency measurements of radiation sources. The proposed network could obtain with satisfactory prediction of the volume fraction in water-gas system, demonstrating to be a promising approach for this purpose

Produção do traçador radioativo CH3Br marcado com 82 Br

O crescente desenvolvimento da indústria de petróleo tem motivado a aplicação de novas tecnologias e metodologias para o estudo da avaliação de unidades industriais. Atualmente, a disponibilidade de uma grande diversidade de métodos de produção de traçadores radioativos proporcionou um avanço no emprego de técnicas nucleares para o monitoramento e a avaliação dessas unidades. O objetivo do trabalho foi estudar a produção de um gás orgânico radioativo para monitorar sistemas com fluxo de material gasoso empregado em diversas indústrias. O gás orgânico brometo de metila, CH3Br, foi escolhido como radiotraçador e sua produção se realizou através da irradiação do sal de brometo de potássio, através do isótopo 82Br, metanol e ácido sulfúrico 9M (catalisador). Um sistema de vidraria foi montado para se produzir o gás CH3Br. A identificação do gás halogenado foi feita, através de uma mistura contendo acetona/NaI, colocada no frasco de coleta. O transporte do brometo de metila foi estudado por dois detectores cintiladores de NaI (2 x 2)”, que foram posicionados no frasco de reação e no final do sistema de produção do gás

Flow measurements in hydrotransport units using gamma scattering and cross-correlation techniques

The proposal of this research was to develop a methodology using gamma radiation and cross-correlation techniques to measure the speed of ore pellets in a hydrotansport duct. An experimental unit was designed and built to be used in a two-phase flows transport simulation It was used to measure the velocity of the solid pellets. The flowmeter system consists in two independent systems, each one composed by a NaI (1x1”) scintillators detector- 241Am gamma source, installed outside the tube, both systems were located in the same vertical plane and separated by 18.0 cm. As pellets, were produced a variety of specimens with different compositions in order to verify the methodology. Using this flowmeter was possible to calculate the solid phase velocity

Unidade de produção de traçador radioativo gasoso

O objetivo do trabalho foi o desenvolvimento de uma unidade compacta para a produção do radiotraçador gasoso chamado brometo de metila, CH3Br, que foi marcado com 82Br, a partir do sal irradiado de KBr. O gás é produzido e empregado próximo do sistema inspecionado, minimizando a possibilidade de contaminação radiológica e garantindo um transporte seguro para o material irradiado. O gás foi produzido através de dois métodos de síntese: etanol/ácido sulfúrico e sulfato de dimetila com rendimento médio de extração de 70 % e 88 %, respectivamente

Fluid flow profile in a packed bead column using residence time curves and radiotracer techniques

Filling columns are extremely important in the chemical industry and are used for purification, separation and treatment processes of gas or liquid mixtures. The objective of this work is to study the hydrodynamics of the fluid for a characterization of aqueous phase flow patterns in the filling column, associating with the methodology of the Curves of Residence Time Distribution (RTD) to analyze and associate theoretical models that put as conditions column operating. RTD can be obtained by using the pulse-stimulus response technique which is characterized by the instantaneous injection of a radiotracer into the system input. In this work, 68Ga was used as radiotracer. Five shielded and collimated NaI (Tl) 1x1" scintillator detectors were suitably positioned to record the movement of the radiotracer's path in the conveying line and filling column. Making possible the analysis of the RTD curve in the regions of interest. With the data generated by the NaI (Tl) detectors with the passage of the radiotracer in the transport line and inside the column, it was possible to evaluate the flow profile of the aqueous phase and to identify operational failures, such as internal conduit and the existence of a retention zone in the inside the column. Theoretical models were used for different flow flows: the piston flow and perfect mixing