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Processamento de placas de circuito impresso de equipamentos eletroeletrônicos de pequeno porte
Get PDFDesenvolvimento e aplicação de código de fluidodinâmica computacional para análise transiente 3D de mecânica de fluidos e transferência de calor com transporte e decaimento de material radioativo
No full textA Fluidodinâmica Computacional (CFD) oferece ferramentas eficientes para o estudo de dispersão de radionuclídeos, inclusive em problemas onde há decaimento radioativo. Este trabalho apresenta um tratamento via fluidodinâmica computacional da dispersão de radionuclídeos, aplicável tanto na dispersão em ambientes internos quanto na dispersão externa e, em ambos os casos, tanto por via atmosférica quanto aquática. A primeira situação é de fundamental importância para a otimização do projeto de salas que abrigam material radioativo visando à segurança e minimização da dose em caso de dispersão. A segunda situação diz respeito à dispersão para o exterior de instalações nucleares ou radiativas, sendo de grande relevância para oferecer subsídios para a análise de segurança e de impacto ambiental no entorno da instalação. Neste trabalho as equações de quantidade de movimento, energia e transporte com decaimento de material radioativo são discretizadas para obtenção de soluções numéricas. O programa desenvolvido emprega simulação das grandes escalas de turbulência (LES) combinadas com técnicas de computação paralela e distribuídaThe computational fluid dynamics (CFD) offers efficient tools for the study of dispersion of radionuclides, including problems where radioactive decay needs to be considered. This work presents a CFD approach for the analysis of radionuclides dispersion, applicable both for internal and external environments, either through air or aquatic ways. The first case is relevant for the optimization of the design of rooms that keep or store radioactive material and is also important for safety and the minimization of doses in the event of dispersion. The second case concerns external dispersion from nuclear and radioactive installations and is essential for safety analysis and the evaluation of environment impact of such installations. In this work the equations governing momentum, energy and transport with decay of radioactive materials are discretized in order that numerical solutions can be obtained. Additionally, the code developed employs Large Eddy Simulation (LES) of turbulence combined with techniques of parallel distributed computin
Evaluation of Cross Correlation Technique to Measure Flow in Pipes of the Oil Industry
Get PDFThe present work is concerned with the use of the cross correlation technique to measure delay time between two simulated signals displaced with respect to time, in order to develop a cross correlator system that will be used to measure the water and oil pipes flowrate in which the detection system is composed by two external low intensity radiation sources located along the tube and two NaI(Tl) gamma-ray detectors. The final purpose of the correlator system is to use the natural disturbances, as the turbulence in the own flow rather than to inject radioactive tracers to the fluid flow as usually is carried out. In the design of this correlator is evaluated the point-by-point calculation method for the cross correlation function in order to produce a system accurate and fast. This method is divided at the same time in three modes of operation: direct, relay and polarity
Priority of areas for agricultural radiovulnerability mapping
Get PDFThe methodology for classifying areas according to soil properties for the vulnerability to a 137Cs contamination is of high importance to the preparedness related to nuclear and/or radiological accidents that lead to release of radionuclides to the environment with the consequent contamination of agricultural areas. The priority of research for agricultural areas should then focus on the surrounding areas of nuclear power plant that have higher probability of public exposure through the ingestion pathway. The objective of this work was to create a rank order for priority of areas to be mapped based on EMBRAPA database on soil properties. The 16 municipalities previously selected to define parameters for dose assessment simulations related to the Brazilian Nuclear Power Plants, located in the district of Angra dos Reis, Rio de Janeiro, have been investigated in order to create this rank order to direct the research on radiovulnerability mapping, considering their relevance to public exposure based on their agricultural productivity. The two aspects selected in this study account for the maximum loss of income and to the collective doses that can be averted due to the banning of agricultural INAC 2013, Recife, PE, Brazil. products. These quantities are inputs to optimization analysis. The priority defined shall then guide research on both the adequate values for the transfer factors and on the agricultural countermeasures suitable to each area according to the cause(s) of their vulnerability and their typical agricultural crops
Event and fault tree model for reliability analysis of the greek research reactor
Get PDFFault trees and event trees are widely used in industry to model and to evaluate the reliability of safety systems. Detailed analyzes in nuclear installations require the combination of these two techniques. This work uses the methods of fault tree (FT) and event tree (ET) to perform the Probabilistic Safety Assessment (PSA) in research reactors. The PSA according to IAEA (International Atomic Energy Agency) is divided into Level 1, Level 2 and level 3. At Level 1, conceptually safety systems act to prevent the accident, at Level 2, the accident occurred and seeks to minimize the consequences, known as stage management of the accident, and at Level 3 are determined consequences. This paper focuses on Level 1 studies, and searches through the acquisition of knowledge consolidation of methodologies for future reliability studies. The Greek Research Reactor, GRR - 1, was used as a case example. The LOCA (Loss of Coolant Accident) was chosen as the initiating event and from there were developed the possible accident sequences, using event tree, which could lead damage to the core. Furthermore, for each of the affected systems, the possible accidents sequences were made fault tree and evaluated the probability of each event top of the FT. The studies were conducted using a commercial computational tool SAPHIRE. The results thus obtained, performance or failure to act of the systems analyzed were considered satisfactory. This work is directed to the Greek Research Reactor due to data availability
Applying human factors to the design of control centre and workstation of a nuclear reactor
Get PDFHuman factors is a body of scientific factors about human characteristics, covering biomedical, psychological and psychosocial considerations, including principles and applications in the personnel selection areas, training, job performance aid tools and human performance evaluation. Control Centre is a combination of control rooms, control suites and local control stations which are functionally related and all on the same site. Digital control room includes an arrangement of systems, equipment such as computers and communication terminals and workstations at which control and monitoring functions are conducted by operators. Inadequate integration between control room and operators reduces safety, increases the operation complexity, complicates operator training and increases the likelihood of human errors occurrence. The objective of this paper is to present a specific approach for the conceptual and basic design of the control centre and workstation of a nuclear reactor used to produce radioisotope. The approach is based on human factors standards, guidelines and the participation of a multidisciplinary team in the conceptual and basic phases of the design. Using the information gathered from standards and from the multidisciplinary team, an initial sketch 3D of the control centre and workstation are being developed
Virtual dosimetry applied to the physical security of a nuclear installation
Get PDFAn important activity to be held in radiation protection is the location of radioactive sources. The present work was devoted to the development of a virtual dosimetry tool for locating and detecting such sources. To this end, was created a three-dimensional virtual model of the Instituto de Engenharia Nuclear – IEN, endowed with virtual characters (avatars), capable of move and interact with the environment, radiation detectors (fixed and mobile) and radioactive sources. Aiming to assist in planning physical security of nuclear installations, the tool developed allows the detection simulation of individuals carrying radioactive sources through detectors installed at strategic points of the site. In addition, it is possible to detect and locate sources by handling portable detectors, operated by characters within the virtual environment. The results obtained show the behavior of the radiation detectors on continuous profile of radioactive sources, allowing calculate the dose rate at any position of the virtual environment. Thus, this work can assist in the training of security officers, as well as in evaluating the radiological safety of the nuclear site
Quantitative analysis of thorium in the presence of rare earth by x-ray fluorescence spectrometry
Get PDFThe occurrence of Thorium in ores is normally associated to other elements such as Uranium and Cerium, as
well as some Rare-Earths (RE). The separation of these elements by traditional analytic chemistry techniques is both time and reagent consuming, thus increasing the analysis cost. The hereby proposed method consists in the direct determination of Thorium in rare earths ores and compounds by X-ray fluorescence spectroscopy without any prior chemical separation from other matrix elements. This non-destructive technique is used to determine which elements are present in solid and liquid samples, as well as their concentrations. The studied matrix contains Lanthanum, Cerium, Praseodymium, Neodymium, Samarium, Gadolinium and Yttrium. This study evaluated the analytical lines of radiation emission for each rare earth contained in the matrix, comparing it to the Thorium main analytical line. The Thorium quantification was measured through the Th L line, where
there is no influence or interference from the rare earths analytical lines. The studied samples are certified
standards and the obtained results have been compared to Ethylenediaminetetraacetic acid (EDTA) titration
results, an already well-established and widely trusted method. We also measured the matrix effect thus using
complex rare earths liquor. This liquor contains also elements commonly found in monazites sands: phosphates, aluminum, iron. Obtained results state the efficience of X-ray Fluorescence to determine Thorium in the presence of rare earths without any prior chemical separation
Logistics for evaluation of doses received by IOE due to handling 18FDG-radiopharmaceutical during processing (IEN/CNEN) and in radiodiagnostic (clinical)
Get PDFThe objective of this study is to propose an improvement in radiological practices involving production, transportation and application of radiopharmaceutical 18F, by tracking the radiation doses received by occupationally exposed individuals (OEI) that develop production practices, transportation and application of some patients in hospitals and clinics in Rio de Janeiro, the radiopharmaceutical 18FDG. In light of the results and observations of how these practices are developed, it’s necessary to evaluate and suggest a logistics to minimize the doses received by OEI during these practices, seeking improvements in the actions and procedures for radiological protection. In practice the production of the radiopharmaceutical, the study focuses on the time of withdrawal of 18FDG cell processing, where the technician is exposed to higher dose rates. At this stage, we take to accomplish, yet two other reviews: the first is the placement of electronic dosimeters inside and outside the lead apron, whose objective is to assess the attenuation capacity of the apron. This last procedure refers to the use of a phantom cylindrical containing TLD 700 dosimeter in order to evaluate, using a mathematical model (MCNP), the doses ends (hand) of the technician, the process of removing the radiopharmaceutical of the cell and to compare the dosimetric dose recorded in the ring. Regarding the transport of 18FDG, we take into account the doses recorded in the cabin of the vehicle and the doses recorded in the dosimeter of the carrier. Finally, the doses received by health professionals who handle 18FDG are analyzed, since its withdrawal from the packing until administration to the patient
Introduction to the use of fram on the effectiveness assessment of a radiopharmaceutical dispatches process
Get PDFThis article aims to make an introduction to the use of Functional Resonance Analysis Method (FRAM) on the effectiveness assessment of a specific radiopharmaceutical dispatching process. The main purpose was to provide a didactic view of the method application to further in-depth analysis. The investigation also provided a relevant body of knowledge of radiopharmaceuticals dispatches processes. This work uses the term ‘effectiveness assessment’ instead of ‘risk assessment’ due to the broader meaning the former provide. The radiopharmaceutical dispatching process is the final task of a dynamic system designed to attend several medical facilities. It is comprised by functions involving mostly human activities, such as checking and
packaging the product and measuring the radiopharmaceutical nuclear activity. Although the dispatch process has well-known steps for its completion, the human factor is the fundamental mechanism of work and control, being susceptible of irregular and instable performance. As a socio-technical system, the risk assessment provided by FRAM may be of importance for safety and quality improvements, even more if considered the nuclear nature of the product, which makes risk assessment critical and mandatory. A system is safe if it is resistant and resilient to perturbations. Identification and assessment of possible risks is, therefore, an essential prerequisite for system safety. Although this seems obvious, most risk assessments are conducted under relative ignorance of the full behavior of the system. Such condition has lead to an approach to assess the risks of intractable systems (i.e., systems that are incompletely described or underspecified), namely Resilience Engineering. Into this area, the Functional Resonance Analysis Method has been developed in order to provide concepts, terminology and a set of methods capable of dealing with such systems. The study was conducted following the Functional Resonance Analysis Method. At first, the functions of the radiopharmaceutical dispatches process were identified and described as required for everyday performance to succeed, than for every function the essentials aspects for the function to be carried out were described. After that, some scenarios or instantiations of the model were analyzed in order to propose ways to monitor and dampen performance variability