2383 research outputs found
Sort by
I0904 - Imagem de carvão ativado
No full textDimensão: 18,5x25 cmFoto colorida de conjunto para teste de vazamento de agulhas de rádio, composto por carvão ativado, no Instituto de Engenharia Nuclear, na Ilha do Fundão, Rio de Janeiro
I0929 - Imagem do Reator Argonauta
No full textDimensão: 9x12 cmFoto P&B da fachada do prédio do Reator Argonauta, no Instituto de Engenharia Nuclear, na Ilha do Fundão, Rio de Janeiro
I0936 - Imagem do Reator Argonauta
No full textDimensão: 10x15 cmFoto colorida com vista em diagonal do lado direito do Reator Argonauta, no Instituto de Engenharia Nuclear, na Ilha do Fundão, Rio de Janeiro
I0941 - Imagem do Reator Argonauta
No full textDimensão: 10x15 cmFoto colorida com vista superior em diagonal do lado direito do Reator Argonauta, no Instituto de Engenharia Nuclear, na Ilha do Fundão, Rio de Janeiro
Sorption study of u+6 in brazilian soils
Get PDFThe uranium mining is one of the main activities of the nuclear fuel cycle that can contribute to the increased exposure to radioactive materials and is one of the main routes of contamination of soil by natural radionuclides. This study investigated the sorption of uranium in brazilian soils, through sorption isotherms performed in batch. In this study, two types of soils were selected: Ferralsols Red and Nitosol. The adjustment of the experimental data to the kinetic models were evaluated by two approaches: the traditional, based on the coefficient of determination (R2); and the theoretical and informative, based on Corrected Akaike Information Criteria (AICC). The coefficient of determination (R2), revealed that, although empirical, both the kinetic model, Freundlich and Langmuir, describes satisfactorily the experimental data, showing R2 values higher than 0.9, while the partition constant model was not suitable for describe these sorption data. The AICC model analysis showed that the Langmuir model fit the U sorption curve well for Ferralsols Red, while the Freundlich model fits better to Nitosol. This study has highlighted the role of organic matter on the sorption of uranium in highly weathered soils, rich in oxyhydroxides and low activity clays. The Kd values reported in this study differ from those recommended by the United States Environmental Protection Agency, therefore must be considered as reference values for highly weathered soils, since it refers to Brazilian pedoenvironmental conditions. The low Kd values obtained in this study allowed us to evaluate the high vulnerability of highly weathered soils to uranium contamination
A methodology for nuclear power plant operational events evaluation
Get PDFOperational events are normal occurrences in industrial plants and in nuclear power plants. The evaluation of operational events gains importance when it comes specifically to nuclear power plants due to the proportions that the impact and the consequences of these events may cause to the installation itself, their workers, the external area of the nuclear installation, the environment and to the public in general. These consequences, for the operation of these facilities can range from very little, until the consequences that lead to accidents and can cause significant impacts. Operational events may be associated or have influence in many fields of knowledge, such as operation, maintenance, engineering, Radiological Protection, physical protection, chemistry, Human or Organizational Factors and external events, among others. The accident at the Fukushima Daichi nuclear power plant, shows the importance of exhausting all the studies concerning operational events in order to improve the operational safety of nuclear plants, considering all the causes and possible consequences. In this context, the evaluation of operational events discipline emerges as an important and relevant tool to contribute to the maintenance and/or improvement of the operational safety of nuclear installations. Not without reason the nuclear industry actively participates in programs of exchange of operational experience, where relevant events are thoroughly evaluated and discussed in specific forums, such as power plant operators, regulators and/or joint technical meetings, always with the purpose to prevent, minimize or mitigate its consequences. Any evaluation of operational events passes necessarily by an in-depth study of the circumstances of the event, culminating with the identification of your cause and proposition of corrective actions to prevent recurrence of similar events. Additionally, the events should not be studied individually, but evaluated within a temporal context in order to identify trends that might pass unnoticed. There are several methodologies for evaluation of operational events, specifically, for the determination of the causes of the event, where the concepts of root cause, direct cause and causal factors, among others. However, the most recent methodology in use in Brazil, date of 2003. The subject is so important that there is national legislation dealing with the theme, also it need of update. The actual regulations establishes criteria for notification of the occurrence of events considered significant for safety and establishes criteria and deadlines for the issuance of the report. Is also discussed the relationship between occurrence of operational events and a potential application for the life extension of the nuclear power plants, considering the regulatory focus, theme quite present in the international field. The present study intends to present a modern, appropriate methodology for evaluation of operational events, focusing on regulatory aspects and verify its applicability to nuclear power plants. Will also be presented a study of the occurrence of events, focusing on the last five years of operation. Finally will be also presented to international trends in development on this area
Development of a test facility for analyzing supercritical fluid blowdown
Get PDFThe generation IV nuclear reactors under development mostly use supercritical fluids as the working fluid because higher temperatures improve the thermal efficiency. Supercritical fluids are used by modern nuclear power plants to achieve thermal efficiencies of around 45%. With water as the supercritical working fluid, these plants operate at a high temperature and pressure. However, experiments on supercritical water are limited by technical and financial difficulties. These difficulties can be overcome by using model fluids, which have more feasible supercritical conditions and exhibit a lower critical pressure and temperature. Experimental research is normally used to determine the conditions under which model fluids represent supercritical fluids under steady-state conditions. A fluid-to-fluid scaling approach has been proposed to determine model fluids that can represent supercritical fluids in a transient state. This paper presents an application of fractional scale analysis to determine the simulation parameters for a depressurization test facility. Carbon dioxide (CO2) and R134a gas were considered as the model fluids because their critical point conditions are more feasible than those of water. The similarities of water (prototype), CO2 (model) and R134a (model) for depressurization in a pressure vessel were analyzed
Estudo experimental do movimento de bolhas alongadas individuais em tubos vertical e ligeiramente inclinados usando uma técnica de visualização
Get PDFEste trabalho apresenta um estudo experimental de bolhas de Taylor ascendentes em tubos vertical e ligeiramente inclinados contendo um liquido estagnado, utilizando uma técnica de visualização. Foi utilizada uma montagem experimental que consistiu de um tubo de acrílico de seção circular com 2 m de comprimento e 24 mm de diâmetro interno, com as extremidades vedadas e contendo diferentes misturas de água destilada e glicerina (água pura, 80% de água, 50% de água, 20% de água e glicerina pura). Durante o enchimento do tubo com as misturas, foram deixados bolsões de ar com comprimentos de 10 cm e 20 cm para geração das bolhas de Taylor, que foram obtidas invertendo-se o tubo até a posição desejada. O tubo foi fixado em um dispositivo que permitiu variar os ângulos de inclinação em 0º/2,5º/5º/7,5º/10º/15º em relação à vertical. O estudo experimental consistiu na verificação da influência da inclinação e das propriedades do fluido, em especial a viscosidade, nas velocidades e nos comprimentos das bolhas de Taylor, empregando-se uma câmera de vídeo de alta velocidade para a medição destes parâmetros. O processamento das imagens foi realizado utilizando-se um software comercial e um programa desenvolvido no Laboratório de Termo-Hidráulica Experimental do Instituto de Engenharia Nuclear (LTE/IEN). Os resultados obtidos indicaram que as velocidades de ascensão das bolhas diminuíram com o aumento da viscosidade do líquido, e aumentaram com o aumento da inclinação do tubo
I0130 - Imagem do Ciclotron
No full textDimensão: 9x12,1 cmFoto P&B do quadro de controle elétrico da refrigeração do Ciclotron Compacto de Energia Variável, no Instituto de Engenharia Nuclear, na Ilha do Fundão, Rio de Janeiro
I0136 - Imagem do Ciclotron
No full textDimensão: 9x12,3 cmFoto P&B de vista superior dos tanques de decaimento do Ciclotron Compacto de Energia Variável, no Instituto de Engenharia Nuclear, na Ilha do Fundão, Rio de Janeiro