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Determination of porosity into.supports for ceramic membranes of titanium dioxide by gamma spectroscopy
No full textMembrane separation process (MSP) have been widely used to fractionate, concentrate and purify solutions, such as: food industry, pharmaceutical, water desalination and for treatment of the radioactive liquid waste in the nuclear industry. The MSP are more economical than traditional methods because most of them are athermic. Increased membrane application has led nto expansion of the manufacturing technology knowledge base, resulting in membranes with high permeability, improved selectivity and long-term stability. The demand for high operating temperatures and chemical resistance have simulated the development of inorganic structures, mainly porous ceramics. The materials most used to obtain ceramic membranes are oxides like Al2O3, SiO2, ZrO2 and TiO2 or combination of these. Despite the favorable characteristics, ceramic membranes has not been applied extensively, mainly due to the difficulty of obtaining porous structures without cracks and with adequate pore size. /the objective of this work is obtain a support of titanium oxide using potato starch as a pore former. The titanium oxide used is commercial, with average particle size of 0.13µm. Three suspensions were prepared containing 0,5 and 10% of the potato starch and the drying in spray dryer, obtaining a homogeneous and granulated powder, with flowability suitable for compaction. The supports were uniaxial pressing with 1.5 kgf.cm-2 and sintering at temperatures of 1050, 1100 and 1150ºC for 1h in oven resistance. The results showed that the porosity obtained by gamma ray transmission method was approximately 502%. This value is within range for applications as membrane support
Study of the radioactive particle tracking technique using gamma-ray attenuation and MCNP-X code to evaluate industrial agitators
Get PDFAgitators or mixers are highly used in the chemical, food, pharmaceutical and cosmetic industries. During the fabrication process, the equipment may fail and compromise the appropriate stirring or mixing procedure. Besides that, it is also important to determine the right point of homogeneity of the mixture. Thus, it is very important to have a diagnosis tool for these industrial units to assure the quality of the product and to keep the market competitiveness. The radioactive particle tracking (RPT) technique is widely used in the nuclear field. In this paper, a method based on the principles of the RPT technique is presented. Counts obtained by an array of detectors properly positioned around the unit will be correlated to predict the instantaneous positions occupied by the radioactive particle by means of an appropriate mathematical search location algorithm. Detection geometry developed employs eight NaI(Tl) scintillator detectors and a Cs-137 (662 keV) source with isotropic emission of gamma-rays. The modeling of the detection system is performed using the Monte Carlo Method, by means of the MCNP-X code. In this work a methodology is presented to predict the position of a radioactive particle to evaluate the performance of agitators in industrial units by means of an Artificial Neural Network (ANN)
Virtual reality interactive simulator for training healthcare professionals in the use of ionising radiations
Get PDFThe application of ionizing radiation in medicine requires a rigorous attention to procedures in order to
minimize the risks to the healthcare professional and to the patient. Risk minimization involves the training of
the professional and the adequacy of the facilities. Virtual Reality (VR) is an already consolidated tool for training procedures, including those of the health sciences. In this context, an interactive VR simulator representing a radiotherapy room (bunker) for training healthcare professionals and the inspectors of such facilities was developed. This VR model allows the user to perform the normal activities on the operation and the inspection procedures of the facility. The model was based on the blueprints of a real radiotherapy clinic.
The virtual model of the radiotherapy bunker, developed at the Institute of Nuclear Engineering, was presented
to experts of the General Coordination of Medical and Industrial Facilities of CNEN and is in the process of
receiving small modifications to the specific needs for its adequateness, as a training tool, in a training course,
sponsored by the International Atomic Energy Agency (IAEA), for inspectors of radiotherapy installations. This work shows the possibility of using Virtual Reality in the development of training tools for professionals working in radioactive installations
Estudo do sistema passivo de remoção de calor residual de um Reator PWR pequeno modular
Get PDFEste trabalho apresenta um estudo sobre o sistema passivo de remoção de calor residual (PRHRS) de um reator nuclear modular de pequeno porte (SMR) de 75MW. Reatores nucleares mais avançados, como os da geração III+ e IV, possuem sistemas de segurança passivos que entram automaticamente em ação com o intuito de impedir acidentes. O PRHRS tem como objetivo a transferência do calor de decaimento do combustível nuclear do reator, mantendo o núcleo resfriado após o desligamento da usina. Ele começa a operar caso ocorra uma queda do fornecimento de energia elétrica para a estação nuclear, ou caso ocorra uma indisponibilidade do sistema de alimentação de água dos geradores de vapor. A remoção de calor de decaimento do núcleo do reator é realizada por meio do escoamento do refrigerante primário por circulação natural através de trocadores de calor situados em uma piscina cheia de água localizada acima no núcleo. A circulação natural é causada pelo gradiente de densidade entre o núcleo do reator e a piscina. Uma análise térmica e comparativa do PRHRS foi realizada consistindo da resolução das equações de conservação de massa, quantidade de movimento e energia e usando aproximações de fluido incompressível com a aproximação de Boussinesq. Os cálculos foram realizados com o auxílio do software Mathematica. Um dimensionamento do trocador de calor e do tanque de água de resfriamento foi feito de modo que o núcleo do reator se mantenha resfriado por 72 horas utilizando somente o PRHRS
Estudo de método de transferência de eficiência usando detectores NaI(Tl)
Get PDFA 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
HUMAN-CENTERED DESIGN OF THE HUMAN-SYSTEM INTERFACES OF MEDICAL EQUIPMENT: THYROID UPTAKE SYSTEM
Get PDFTechnology plays an important role in modern medical centers, making healthcare increasingly complex, relying on complex technical equipment. This technical complexity is particularly noticeable in the nuclear medicine. Poorly design human–system interfaces can increase the risks for human error. The human-centered approach emphasizes the development of the equipment with a deep understanding of the users activities, current work practices, needs and abilities of the users. An important concept of human-centered design is that the ease-of-use of the equipment can be ensured only if users are actively incorporated in all phases of the life cycle of design process. Representative groups of users are exposed to the equipment at various stages in development, in a variety of testing, evaluation and interviewing situations. The users feedback obtained is then used to refine the design, with the result serving as input to the next interaction of design process. The limits of the approach are that the users cannot address any particular future needs without prior experience or knowledge about the equipment operation. The aim of this paper is to present a methodological framework that contributes to the design of the human-system interfaces, through an approach related to the users and their activities. A case study is described in which the methodological framework is being applied in development of new human-system interfaces of the thyroid uptake system
A mobile dose prediction system based on artificial neural networks for NPP emergencies with radioactive material releases
Get PDFThis work presents the approach of a mobile dose prediction system for NPP emergencies with nuclear material release. The objective is to provide extra support to field teams decisions when plant information systems are not available. However, predicting doses due to atmospheric dispersion of radionuclide generally requires execution of complex and computationally intensive physical models. In order to allow such predictions to be made by using limited computational resources such as mobile phones, it is proposed the use of artificial neural networks (ANN) previously trained (offline) with data generated by precise simulations using the NPP atmospheric dispersion system. Typical situations for each postulated accident and respective source terms, as well as a wide range of meteorological conditions have been considered. As a first step, several ANN architectures have been investigated in order to evaluate their ability for dose prediction in hypothetical scenarios in the vicinity of CNAAA Brazilian NPP, in Angra dos Reis, Brazil. As a result, good generalization and a correlation coefficient of 0.99 was achieved for a validation data set (untrained patterns). Then, selected ANNs have been coded in Java programming language to run as an Android application aimed to plot the spatial dose distribution into a map.In this paper, the general architecture of the proposed system is described; numerical results and comparisons between investigated ANN architectures are discussed; performance and limitations of running the Application into a commercial mobile phone are evaluated and possible improvements and future works are pointed
SCALE ANALYSIS OF DECAY HEAT REMOVAL SYSTEM BETWEEN HTR-10 AND HTR-PM REACTORS UNDER ACCIDENTAL CONDITIONS
Get PDFThe 10 MW high-temperature gas-cooled test module (HTR-10) is a graphite-moderated and helium-cooled pebble bed reactor prototype that was designed to demonstrate the technical and safety feasibility of this type of reactor project under normal and accidental conditions. In addition, one of the systems responsible for ensuring the safe operation of this type of reactor is the passive decay heat removal system (DHRS), which operates using passive heat removal processes. A demonstration of the heat removal capacity of the DHRS under accidental conditions was analyzed based on a benchmark problem for design-based accidents on an HTR-10, i.e., the pressurized loss of forced cooling (PLOFC) described in technical reports produced by the International Atomic Energy Agency. In fact, the HTR-10 is also a proof-of-concept reactor for the high-temperature gas-cooled reactor pebble-bed module (HTR-PM), which generates approximately 25 times more heat than the HTR-10, with a thermal power of 250 MW, thereby requiring a DHRS with a higher system capacity. Thus, because an HTR-10 is a prototype reactor for an HTR-PM, a scaling analysis of the heat transfer process from the reactor to the DHRS was carried out between the HTR-10 and HTR-PM systems to verify the distortions of scale and the differences between the main dimensionless numbers from the two project
VALIDATION OF A METHODOLOGY TO DEVELOP A TEST FACILITY IN REDUCED SCALE RELATED TO BORON DISPERSION IN A PRESSURIZER OF AN iPWR
Get PDFThe conception and the project of a 1:200 reduced scale test facility have been developed in earlier researches [1,2,3,4]. Such a facility aims to investigate boron homogenization process inside the pressurizer of an iPWR (integral PWR) by considering water mixing from this component with that coming from the reactor core. For this kind of reactor, the pressurizer is located at the top of the pressure vessel demanding the need of identifying the proper mechanisms in order to warrant an adequate homogenization for the water mixture. Once the installation of the experimental setup was concluded, its behavior has been analyzed by considering the concentration of a tracer diluted in the circulation water, whose measurements were obtained at the pressurizer outlet orifices. Two experiments representing boration(boron concentration increase)/deboration(boron concentration decrease) scenarios have been accomplished. Sample acquisition was carried out for every ten minutes during a total time equal to180 minutes. Results showed that the combination of Fractional Scaling Analysis with local Froude number consisted of an appropriate methodology to provide the reduced scale test facility parameters, inasmuch the measured concentrations from the experiments reproduced the theoretical behavior with sufficient accuracy
Parallel Computing in Cluster of GPU Applied to a problem of Nuclear Engineering
Get PDFCluster computing has been widely used as a low cost alternative for parallel processing in scientific applications. With the use of Message-Passing Interface (MPI) protocol development became even more accessible and widespread in the scientific community. A more recent trend is the use of Graphic Processing Unit (GPU), which is a powerful co-processor able to perform hundreds of instructions in parallel, reaching a capacity of hundreds of times the processing of a CPU. However, a standard PC does not allow, in general, more than two GPUs. Hence, it is proposed in this work development and evaluation of a hybrid low cost parallel approach to the solution to a nuclear engineering typical problem. The idea is to use clusters parallelism technology (MPI) together with GPU programming techniques (CUDA – Compute Unified Device Architecture) to simulate neutron transport through a slab using Monte Carlo method. By using a cluster comprised by four quad-core computers with 2 GPU each, it has been developed programs using MPI and CUDA technologies. Experiments, applying different configurations, from 1 to 8 GPUs has been performed and results were compared with the sequential (non-parallel) version. A speed up of about 2.000 times has been observed when comparing the 8-GPU with the sequential version. Results here presented are discussed and analyzed with the objective of outlining gains and possible limitations of the proposed approach