Photopeak efficiency response function of an underwater gamma ray NaI(TI) detector using MCNP X

This work presents a study to calculate the response function of a 1.5”x 1” NaI(Tl) scintillation detector when it is used in the marine environment in the energy range from 20 keV to 662 keV. The method takes into account both the scattering of photons in the water and the detection mechanism of the detector. In addition, the calculation of the response function of the whole system is essential for suppressing the background of the measurement and for estimating the concentration of the involved radionuclides, especially given the greater probability of primary gamma photons undergoing multiple scattering events before they interact with the detector. The experimental photopeak efficiency measurements for point sources were compared with the simulated results under the same conditions of the experimental setup to validate the simulation of the detector. Monte Carlo simulations were performed using the MCNP-X code for the investigation of gamma-ray absorption in water in different brines. The energy resolution curve was used to improve the response of the mathematical simulation of the detector. The detector’s simulation was based on information obtained from the gammagraphy technique. Both dimensions and materials were used for the calculation with the MCNP-X code. The photopeak efficiency of a NaI(Tl) detector for different radionuclides in the aquatic environment with different salinities was calculated

Development of counting system for wear measurements using thin layer activation and the wearing apparatus

This paper focus on developing a counting system for the Wearing Apparatus, which is a device previously built to generate measurable wear on a given surface (Main Source) and to carry the fillings from it to a filter (second source). The Thin Layer Activation is a technique used to produce activity on one of the Wearing Apparatus' piece, this activity is proportional to the amount of material worn, or scrapped, from the piece's surface. Thus, by measuring the activity on those two points it is possible to measure the produced wear. The methodology used in this work is based on simulations through MCNP-X Code to find the best specifications for shielding, solid angles, detectors dimensions and collimation for the Counting System. By simulating several scenarios, each one different from the other, and analyzing the results in the form of Counts Per Second, the ideal counting system's specifications and geometry to measure the activity in the Main Source and the Filter (second source) is chosen. After that, a set of previously activated stainless steel foils were used to reproduce the real experiments' conditions, this real experiment consists of using TLA and the Wearing Apparatus, the results demonstrate that the counting system and methodology are adequate for such experiments

Study of gas pipelines cracks using transmission and scattering measures with nuclear technique

Most of the natural gas production is transported through pipelines that require periodic inspections to evaluate the structural integrity of the pipelines due to possible defects caused by degradation that can rupture causing leakage of the fluid causing major disasters. Based on this, the project presents a methodology for predicting cracks in pipe used in gas pipelines. The approximation is based on the principles of gamma densitometry to calculate the density of the pipe wall in order to investigate possible cracks. The natural gas fluid is found in such systems and interferes in the density calculations and therefore will be considered in the simulations. The detection system uses a narrow beam geometry appropriately, comprising gamma ray source (137Cs) and NaI(Tl) 3"x3" detectors for calculating transmitted and scattered photons. Different positioning angles of the detector are investigated. In this study, the MCNP-X code is used to perform the simulations, in order to develop a counting geometry. Simulations of different thicknesses of the crack were also used to determine the minimum thickness detected by the two NaI(Tl) detectors. Having equipment that can estimate cracks present in pipes used in gas pipelines, in addition to predicting their location can reduce costs and make a major contribution to this sector

Use of transmission gamma for study of calculation of incrustation thickness in oil pipelines

Incrustation can be defined as chemical compounds organic, inorganic and mixed, initially insoluble, and which precipitate accumulating in the internal wall of pipes, surface equipment and/or parts of components involved in the production and transport of oil. These compounds, when precipitating, cause problems in the oil industry and consequently result in losses in the optimization of the extraction process. Although the importance and impact of the precipitation of these compounds in the technological and economic scope, there is still the difficulty in determining methods that enable the identification and quantification of the incrustation at an initial stage. The use of the gamma transmission technique may provide support for a better understanding of the deposition of these compounds, making it a suitable tool for the non-invasive determination of their deposition in oil transport pipelines. The geometry used for the incrustation detection include a 280 mm diameter steel pipe containing barium sulphide incrustation (BaSO4) ranging from 5 to 80 mm, a gamma radiation source with divergent beam and as NaI(Tl) 2x2” scintillation detector. The opening size of the collimated beam was evaluated (2 to 7 mm) to also quantify the associated error in calculating the incrustation. The study was realized with computer simulation, using the MCNP-X code and validated by means of analytical equations that indicate the possibility of using this study for this purpose

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

Estudo de método de transferência de eficiência usando detectores NaI(Tl)

A utilização de detectores cintiladores NaI(Tl) para medições implica na determinação da eficiência de detecção em função da energia dos fótons incidentes. A curva de eficiência pode ser obtida experimentalmente com a utilização de várias fontes mono energéticas calibradas com energias de emissão que abranjam todo o intervalo de interesse ou utilizando o método de Monte Carlo. O Instituto de Engenharia Nuclear desenvolve diversas metodologias usando estes detectores, pois são robustos, baratos e não precisam de resfriamento para sua utilização. A montagem de um arranjo experimental costuma ser complexa, pois vários fatores influenciam no resultado afetando a reprodutibilidade nas medições, tais como: paralelismo entre a fonte e o detector, alinhamento entre fonte e detector e precisão na distância fonte-detector. Diante de tais dificuldades, desenvolveu-se um sistema automatizado de posicionamento para o conjunto fonte-detector controlado por um micro controlador baseado na linguagem ARDUINO visando garantir a reprodutibilidade nos arranjos experimentais.Na fase inicial deste estudo desenvolveu-se um modelo matemático no código MCNP-X utilizando um detector NaI(Tl). Uma validação teórica usando o Método de Transferência de Eficiência foi realizada em três diferentes posições no eixo axial do detector (10,6 cm; 11,3 cm e 12,0 cm). Este método baseia-se na razão dos ângulos sólidos efetivos. A validação experimental apresentou erros relativos máximos de 7,74% para a posição 11,3 cm

Morphological Features of the Acupuncture Points of Bladder Meridian in the Giant Anteater (Myrmecophaga tridactyla)

Background: The acupuncture points are considered a point in the skin of sensitivity to stimulation. The acupuncture meridians represent the communication between acupuncture points and internal organs. The giant anteater (Mirmecophaga tridactyla) is routinely attended in veterinary centers, and is pivotal to know its morphology and therapies such as acupuncture that, probably, can be used in medical practice. Thus, the aim of this study was to evaluate the morphological substrate in regions that correspond to the transposition of acupuncture points of the Bladder Meridian using radiography, ultrasonography, electrical impedance and histology in the giant anteater.Material, Methods & Results: Seven giant anteaters (six males and one female) were used. The animals were from the Center of Medicine and Research in Wild Animals (CEMPAS), School of Veterinary Medicine and Animal Science, UNESP, Botucatu, São Paulo. The acupoints of Bladder Meridian evaluated were Bladder 11 (B-11), Bladder 18 (B-18), Bladder 23 (B-23), Bladder 25 (B-25), and Bladder 28 (B-28). The locations of the acupoints were transposed based on the location of these acupuncture points in dogs. Four animals were live and were used for radiographic, ultrasonographic, and electrical impedance analysis. Three animals were died and the fragments of this acupoints were destined to histological routine with hematoxylin and eosin (HE) and Masson’s Trichrome stains. The giant anteaters studied had fifteen thoracic vertebrae, three lumbar vertebrae, and five sacral vertebrae fused in a single bone. The acupuncture points were characterized by presence of abundant connective tissue at the superficial and intermuscular level, muscular fascia, and many neurovascular bundles in the dermal layer. These bundles consisted of nerves, arteries and veins of various calibers. The spaces between the nerves and blood vessels were filled by loose connective tissue containing adipose cells, capillaries, and sweat glands.Discussion: The network of acupuncture points can be seen as a representation of a network formed by interstitial connective tissue. This hypothesis is supported by ultrasound imaging that demonstrated plans for cleavage of connective tissue at acupuncture points in normal humans. It seems that the anatomical relationship of acupoints and meridians with connective tissue planes is relevant to the mechanism of action of acupuncture and suggests an important integrative role for interstitial connective tissue. The presence of connective tissue was observed in the transposition areas studied in the giant anteater using ultrasound. The main histological structures found in the transposition regions of the acupoints in the giant anteater were the nerve and connective tissue, similar to other studies, who claimed that the nerve is the main histological component of an acupoint. Therefore, there are reports suggesting that the network of acupoints and meridians can be seen as a representation of a network formed by interstitial connective tissue and that this relationship is important for the therapeutic mechanism of acupuncture. Based on the results of this study, it is possible to infer that the studied regions present a morphological substrate that is consistent with the characteristics of an acupuncture point. Thus, it is suggested that there are probably acupuncture points in these regions in the giant anteater, which makes possible the use of this alternative medical therapy for the treatment of these animals

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

Conhecimento e uso de métodos anticoncepcionais entre os calouDa Rosdo 1 semestre - U.F.S.C. em 1995.

Trabalho de Conclusão de Curso - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Departamento de Tocoginecologia, Curso de Medicina, Florianópolis, 199