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HSI for monitoring the critical safety functions status tree of a NPP
Get PDFCritical safety function (CSF) is the most significant design concept for prioritize operator actions based on the
potential threat to the three barriers (fuel cladding, primary coolant system boundary, and containment) and allows the operator to respond to these threats prior to event diagnosis. CSF has a hierarchical information structure that organizes the system variables affecting the plant safety in terms of goal-means relations. It is important that the operator should be aware of various success paths associated with each CSF in order to respond to unanticipated system failures quickly. When an emergency occurs in NPPs, the operator should monitor CSFs periodically and identify possible success paths as necessary, and try to stabilize or safely shut down the plant using emergency operating procedure (EOP) that includes steps to check the CSFs. This implies that safety function status check may become a cognitively burdensome task that needs to be supported by proper information display. The advanced human-system interface (HSI) in nuclear power plants provides an information environment that supports the operators’ burdensome cognitive tasks. This paper describes a CSFs interface design for supporting the operator’s tasks to monitor and identify the associated success path for Westinghouse 3-loops NPP
Estabilization Time for Subcritical System with Different External Neutron Source
Get PDFThis work aims at studying one dimensional spatial kinetics equations for ADS (Accelerator Driven System) type reactors, through computational simulations. Where the neutrons diffusion equations are discretized espatially by the finite differences cell centered mesh scheme and time discretized using the Crank-Nicolson method. Discretized equations used with fixed source problem are programmed in FORTRAN and used to simulate the system behavior, with different neutron source types. In this way, we can analyse the instant of time when the subcritical system becomes stationary, or the time interval corresponding to the stationary flux, for different external sources. The result shows that, it is always possible to reach system stability where no oscillation is detected, even for pulsed sources
Numerical Simulation Of Ultrasonic Wave Propagation In Elastically Anisotropic Media
Get PDFThe ultrasonic non-destructive testing of components may encounter considerable difficulties to interpret some inspections results mainly in anisotropic crystalline structures. A numerical method for the simulation of elastic wave propagation in homogeneous elastically anisotropic media, based on the general finite element approach, is used to help this interpretation. The successful modeling of elastic field associated with NDE is based on the generation of a realistic pulsed ultrasonic wave, which is launched from a piezoelectric transducer into the material under inspection. The values of elastic constants are great interest information that provide the application of equations analytical models, until small and medium complexity problems through programs of numerical analysis as finite elements and/or boundary elements. The aim of this work is the comparison between the results of numerical solution of an ultrasonic wave, which is obtained from transient excitation pulse that can be specified by either force or displacement variation across the aperture of the transducer, and the results obtained from a experiment that was realized in an aluminum block in the IEN Ultrasonic Laboratory. The wave propagation can be simulated using all the characteristics of the material used in the experiment evaluation associated to boundary conditions and from these results, the comparison can be made
Simulação computacional da homogeneização do ácido bórico em pressurizador de um reator nuclear avançado
No full textPrograma: Ciência e Tecnologia Nucleares – IEN/CNEN
A reatividade de um reator refrigerado a água é controlada utilizando-se barras de controle ou diluição de boro na água do refrigerante do circuito primário. O boro 10 (10B) é considerado um absorvedor de nêutrons eficiente, principalmente quando utilizado na absorção de nêutrons térmicos. Estudos transitórios com deficiência na homogeneização de boro em reatores PWR tornam-se importante, pois a solução de ácido bórico é adicionada ao refrigerante do circuito primário auxiliando no controle das taxas de fissão no núcleo do reator. Após desligamento do reator, o boro presente no refrigerante tem a função de manter o reator no estado de subcriticalidade. Caso haja a introdução de água borada com baixa concentração no circuito primário, torna-se necessário fazer um aumento da concentração desta solução e assegurar que o refrigerante esteja bem homogeneizado, evitando que água com pouca quantidade de boro atinja o núcleo. O objetivo deste trabalho é simular a homogeneização do boro no pressurizador de um reator nuclear avançado. É utilizada uma seção de testes, que representa ¼ de um pressurizador de um reator nuclear modular. Através da utilização do código CFX, programa computacional que permite análises termohidráulica de diferentes tipos de escoamento, foram simulados três exemplos em diferentes condições de operação. A partir destes resultados foram analisados parâmetros que podem influenciar nesta homogeneização. Estudos de casos como variação das dimensões da tubulação de entrada e saída, variação da vazão e mudança de posicionamento das entradas e saídas, foram feitos com o objetivo de encontrar parâmetros que podem auxiliar na otimização da homogeneização do boro. Os resultados encontrados mostram que os fatores analisados podem ser alterados no projeto a fim de se obter melhores condições de operação.The reactivity of a water cooled reactor is controlled using control rods or boron dilution in water of the primary circuit. The boron-10 (10B) is an efficient neutron absorber, especially when used in the absorption of thermal neutrons. Transient studies with disabilities in the homogenization of boron in PWR reactors become important as the boric acid solution is added to the primary circuit coolant in order to help control the rate of fission in the reactor core. After the reactor shutdown, the boron present in the coolant has the function of maintaining reactor subcriticality. If low concentrated boron solution enters in the primary circuit, it becomes necessary to inject boron and to assure that the coolant will be well homogenized in order to increase the concentration and thus preventing water with small amounts of boron to reach the core. The aim of this study is to simulate the boron homogenization in the pressurizer of an advanced nuclear reactor. It is used a test section, which represents a quarter of a modular nuclear reactor pressurizer. By using the CFX code, a computer program that allows thermal hydraulic analysis of different types of flow, three examples were simulated using different operating conditions. With the results, it was analyzed the parameters that could influence this homogenization. Case studies such as variation of the dimensions of the water inlet and outlet tubes, flow variation and change in positioning of entrances and exits were made with the goal of finding parameters that could help the optimization of the homogenization of boron. The results confirm that the issues analyzed can be changed in the project in order to obtain the best operating condition
Solução da equação de difusão de nêutrons para o estudo da distribuição de potência em 3D, aplicado a reatores nucleares
No full textEmpregando a equação de difusão de nêutrons em estado estacionário multidimensional para simular o fluxo de nêutrons em reatores refrigerados água, e fazendo uso do Método de Diferenças Finitas, o presente trabalho tem por objetivo apresentar um estudo sobre o comportamento da distribuição de potência num reator tipo PWR, considerando a intensidade e a migração dos picos de potência à medida que ocorre a inserção das barras de controle no núcleo. Além disso, tomando como ponto de partida a distribuição axial de potência ao longo da vareta de maior fluxo de calor, realiza-se a análise térmica dessa vareta e do canal refrigerante associado. Para tal é empregado o código Fuel_Rod_3D, que usa o Método dos Elementos Finitos para modelar uma vareta combustível e seu canal refrigerante, possibilitando a simulação do comportamento termohidráulico de uma única vareta discretizada em três dimensões, considerando o fluxo de calor a partir do interior da pastilha combustível, passando pelo "gap" e pelo revestimento até alcançar o fluido refrigeranteThis Work aims to present a study about the power distribution behavior in a PWR type reactor, considering both intensity and migration of power peaks due to insertion of control rods into the core. Employing the multidimensional steady-state neutron diffusion equation in order to simulate the neutron flux, and using the Finite Difference Method. Furthermore, based on the axial power distribution on the largest heat flux rod, is carried out thermal analysis of this rod and associated coolant channel. For this purpose is employed the Fuel_Rod_3D code, it uses the Finite Element Method to model the fuel rod and the associated coolant channel, allowing the thermohydraulics simulation of a single rod discretized in three dimensions, considering the heat flux from the pellet, crossing the gap and the cladding until it reaches the coolant
O impacto da aposentadoria no processo de transferência do conhecimento sob a ótica da ARSO (Análise de Redes Sociais e Organizacionais)
Get PDFThe organizational environment has been learning continuously generate knowledge and its main form of transfer is through contact between people, so understanding how is this interaction is essential. One way to get this understanding is with the help of the technique of social network analysis. This paper presents the applicability of the technique within the context of Knowledge Management, showing its value for understanding the flow of tacit knowledge within an organization, pointing out the critical actors and demonstrating the impact caused by the exit of the servers by granting retirement. Therefore, we carried out an exploratory, descriptive literature and case study conducted through a questionnaire that was designed to obtain data on social networks organizational information, trust and friendship between the servers CNEN, headquartered in the city of Rio de Janeiro, with activities related to Human Resources, selected through non-probabilistic method due to its accessibility. The data were processed in software Ucinet for Windows 6 for Windows - version 6.483 in parallel to the program Netdraw 2134, which allowed the mapping and analysis of informal social networks showing the location and view more clearly who are actors and critical paths driven by organizational knowledge, facilitating the sharing of knowledge. The main findings expose the analyzed networks suffer significant declines, jeopardizing the flow of knowledge.O ambiente organizacional vem aprendendo continuadamente a gerar conhecimento e sua principal forma de transferência é por meio do contato entre as pessoas, portanto o entendimento de como se dá esta interação é essencial. Uma forma de ter esse entendimento é com a ajuda da técnica de análise de rede social. Esse trabalho apresenta a aplicabilidade da técnica dentro do contexto da Gestão do Conhecimento, mostrando seu valor para o entendimento do fluxo de conhecimento tácito dentro de uma organização, apontando os atores críticos e demonstrando o impacto causado pela saída dos servidores mediante a concessão de aposentadoria. Para tanto, realizou-se uma pesquisa exploratória, descritiva, bibliográfica e de estudo de caso realizada por meio de aplicação de questionário que visava obter dados a respeito das redes sociais organizacionais de informação, confiança e amizade entre os servidores da CNEN, sediados no município do Rio de Janeiro, com atividades ligadas a área de Recursos Humanos, selecionados através do método não-probabilístico em função da sua acessibilidade. Os dados obtidos foram tratados no software Ucinet para Windows 6 for Windows - versão 6.483 em paralelo ao programa Netdraw 2.134, que permitiram o mapeamento e análise das redes sociais informais demonstrando a localização e visualização de forma mais clara de quem são atores críticos e dos caminhos percorridos pelo conhecimento organizacional, facilitando o compartilhamento do conhecimento. Os principais resultados encontrados expõem que as redes analisadas sofrerão quedas significativas, comprometendo o fluxo de conhecimento
Fast and epithermal neutron radiography using neutron irradiator
Get PDFThe neutron radiography technique (NR) with neutrons in the energy range fast to epithermal is a powerful tool used in non-destructive inspection of bulky objects of diverse materials, including those rich in hydrogen, oxygen, nitrogen and carbon. Thus, it can be used to identify, inclusions, voids and thickness differences in materials such as explosive artifacts and narcotics. Aiming at using NR with fast and epithermal neutrons, an Irradiator was constructed composed by: a 241Am-Be source, with 5 Ci activity; a collimator with adjustable collimation rate, L/D; and a shielding device composed by plates of borated paraffin and iron. The test specimens chosen were a Beam Purity Indicator (BPI) and an Indicator of Visual Resolution (IVR). The neutron radiography images obtained had a resolution of 444.4 m and 363.6 m respectively when registered in: 1) the sheet of the nuclear track solid detector, CR-39 type, through X(n,p)Y nuclear reaction; and 2) Kodak Industrex M radiographic film plate in close contact with a boron converter screen, both stored in a Kodak radiographic cassette
Evaluation of the mobility of 123CS in soil profiles of the pantanal region
Get PDFRadioactive pollutants can cause impact on the environmental quality of soils and represent a risk to human health. Radioecological studies have shown that soils with low pH, low organic matter content and low fertility are more vulnerable to contamination by 137Cs, since the transfer to plants is high. In this study, some surface horizons of soils from Jaraguari, situated at Brazilian Pantanal were assessed in order to map their vulnerability to contamination by 137Cs. It was also proposed some mitigation measures adapted to the regional scenario in order to optimize radiological protection for rural areas. A conceptual model established to detect the vulnerability of radioactively contaminated soils was applied for soils located in the municipality of Jaraguari (Mato Grosso do Sul). This conceptual model was established based on the relationship between reference values of the soil-to-plant transfer factor (TF) for 137Cs and critical pedological parameters for each radiovulnerability category (pH, CTC and exchangeable K). The application of this conceptual model to a soil databank using Geographic Information System (GIS) tools generated vulnerability soils maps. This result identified that most of Pantanal soils presented very low radiovulnerability, but it was possible to detect some small areas presenting extreme radiovulnerability. It was possible to conclude that these small areas is not indicated for activities that presents a potential risk for 137Cs contamination and also it must receive priority actions for remediation in the case of accident, since a superficial contamination with 137Cs in these areas can lead to a contamination of subsoil and to a significant spread of contamination via groundwater
Selectivity and structural integrity of a nanofiltration membrane for treatment of liquid waste containing uranium
No full textUtilização da realidade virtual na contagem do detector de bolhas
No full textForam estudados os principais atributos do detector de bolhas (sua propriedade e características) com objetivo de desenvolver um ambiente virtual para suporte à sua leitura (contagem de bolhas). Para o detector obtido para testes foi feita sua coleta de imagens digitais sequenciais em apenas uma dimensão, utilizando um aparato, que dispões de uma base giratória, o qual é possível obter variações de grau em grau, de O (zero) a 360 (trezentos e sessenta) graus e máquina fotográfica digital. A partir de então foi feita a modelagem de uma ambiente virtual, utilizando OpenGl, calibragem das imagens junto ao ambiente virtual e desenvolvimento da interação do usuário com o ambiente virtual. O resultado final obtido foi uma interface computacional que permitiu, para o caso específico do detector obtido para testes, fazer uma contagem de forma virtual, em ambiente de visão estéreo, da quantidade de bolhas do detectorThis work examines some attributes of the bubble detector aiming to develop a virtual environment to support its reading (counting bubbles). To the used detector, this work took sequential digital images, with help of a bench graduated in degrees (form 0 to 180 degrees) and a digital camera. At this point, using OpenGLm this work modelled a virtual environment, calibrated images in the virtual environment, and developed the user´s interaction in the virtual environment. The final result is a computational interface which allowed the count of the detector´s bubbles in a virtual manner, using Stereo Vision