Orientador: Prof. Dr. Pedro Carajilescov / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Energia, 2016. / Os estudos sobre transitórios em bombas de refrigeração de um reator são importantes para a análise de segurança de uma central nuclear. Uma análise precisa do decaimento da vazão de refrigerante no circuito primário durante uma eventual falha das bombas principais de refrigeração, evento conhecido como coastdown, é requerida tanto para pelos critérios de segurança estabelecidos como para a especificação e fabricação das bombas. Neste trabalho, o estudo é realizado utilizando um modelo matemático para simular transiente de vazão durante o período de coastdown em reatores nuclear do tipo PWR, no qual a equação de conservação da quantidade de movimento linear é utilizada de uma forma adimensional. Informações detalhadas sobre as características da bomba centrífuga não são necessárias. Como resultado, o decaimento da vazão é determinado a partir da razão entre dois parâmetros: a energia cinética do fluido refrigerante no circuito e a energia cinética armazenada nas partes rotativas da bomba. Em estudos anteriores, essa razão, denominada razão de energia efetiva, é mantida constante durante todo o evento de coastdown. Neste trabalho, foram propostas três correções para a melhoria dos resultados, a saber: a consideração de uma razão de energia efetiva variável durante o transitório, das variações na eficiência da bomba durante o transitório e das perdas mecânicas internas devido ao atrito e viscosidade no interior da bomba para baixas rotações. Para implementação do modelo proposto foi desenvolvido um programa, denominado de COREP-flow, cujos resultados foram comparados com dados experimentais obtidos na literatura. As comparações mostraram uma melhoria na reprodução desses resultados em relação aos modelos de referência. No Modelo 5 desenvolvido neste trabalho, os resultados obtidos apresentaram menor discrepância quando comparados com os dados experimentais. Para vazões superiores a 20 % da vazão inicial, a vazão de refrigerante calculada pelo Modelo 5 apresentou uma discrepância relativa média de 1,8 %, enquanto que o modelo proposto por Gao et al. (2011) apresentou uma discrepância relativa média de 4 %. Para vazões de refrigerantes inferiores a 20 % da vazão inicial, a discrepância relativa média para a vazão de refrigerante do Modelo 5 foi de 10,3 %, enquanto que a de Gao et al. (2011) foi de 50,6 %. / The transient studies in reactor cooling pumps (RCPs) are important for the nuclear power plant security analysis. An accurate analysis of flow coastdown in the primary cooling loop system during an eventual failure of the RCPs is required both for the established security criteria, and for the pumps specification and manufacturing. In this work, the study is performed using a mathematical model to simulate the flow rate transient in PWR reactor type during flow coastdown period, in which the conservation of linear momentum equation is non-dimensional. The detailed information of the centrifugal pump characteristics are not required. As result, the coastdown is determined from the ratio between two parameters: the kinetic energy of the coolant in the circuit and the kinetic energy stored in the rotating parts of the pump. In previous studies, the ratio, known as energy ratio, is kept constant during the whole coastdown period. In this work, it was proposed three corrections aiming the improvement of the results, to know: the consideration of an energy ratio variable during the transient, of the efficiency variations of the pumps during the transient and of the internal mechanical losses due to friction and viscosity inside the pump for low rotations. For the model implementation, a program was developed, the COREP-flow, whose results were compared to the experimental data obtained in the literature. The comparison showed an improvement in the reproduction of the results in relation to the reference models. In Model 5, developed in this work, the obtained results presented less discrepancy when compared to the experimental data. For flow rates higher than 20% of the initial flow, the coolant flow calculated by Model 5 presented a mean relative discrepancy of 1.8%, while the model proposed by Gao et al. (2011) presented a mean relative discrepancy of 4%. For coolant flow rates less than 20% of the initial flow, the mean relative discrepancy for the coolant flow of Model 5 was of 10.3%, while the one from Gao et al. (2011) presented a mean relative discrepancy of 50.6%.

This thesis deals with the influence of the discharges of the Dukovany Nuclear Power Plant ("Dukovany NPP") and the assessment of impacts on the population and the vicinity of the power plant. The thesis summarizes the issues of tritium 3H discharges into waterways and partially deals with the 14C discharges. Attention is paid especially to the radioisotope of hydrogen 3H, due to its chemical and physical form and its presence in the cooling medium (light water) used by that type of nuclear power reactor. The thesis also contains a description of the current state of the Dukovany NPP, especially the existing discharges of the radioactive substances to the surroundings of the nuclear power plant, both to the air and into the waterway. Also was discussed the issue of the new planned blocks of the Dukovany NPP and impacts of the projected discharges on the population during the simultaneous operation of the existing blocks and the planned blocks, again in relation to the 3H discharged into the waterway. The application ESTE AI was used for the determination of individual groups of inhabitants who are most exposed to the radioactive discharges (also called representative person). Based on the current discharges of the Dukovany NPP and the planned blocks discharges were determined the annual effective doses for a representative person. The doses were compared with the legislation on the conditions for the peaceful use of nuclear energy requirements and then with the water management legislation. In order to avoid exceeding these limits were set up recommendations how to dispose of radioactive substances optimally. The thesis answer to the research question: What impacts on the population will have discharges of the Dukovany NPP after the construction of a new nuclear source, especially in relation to the discharges of the 3H into the waterway and which measures will must be applied on the optimization of the inhabitants doses.

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Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-06-22T14:12:07Z No. of bitstreams: 0 / Made available in DSpace on 2016-06-22T14:12:07Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

A presente dissertação discute as questões relacionadas à intensificação das mudanças climáticas por causas antrópicas conforme a evolução no uso dos recursos naturais, inovações nos processos produtivos, transformações econômicas, sociais, culturais, políticas e, especialmente ambientais. Aborda a comercialização dos créditos de carbono através de projetos de Mecanismo de Desenvolvimento Limpo (MDL), um dos mecanismos de flexibilização criados pelo Protocolo de Kyoto. No contexto de mudanças climáticas, uma matriz energética que utilize fontes de energia que não emitam gases causadores do efeito estufa (GEE) se mostra uma importante estratégia de desenvolvimento sustentável. Sob essa perspectiva, a energia nucleoelétrica é apresentada como uma alternativa viável aos combustíveis fósseis, considerando que esta é uma energia limpa e compatível com a perspectiva de desenvolvimento sustentável. A Fábrica de Combustível Nuclear (FCN), localizada em Resende (Rio de Janeiro), pertencente às Indústrias Nucleares do Brasil (INB), é um conjunto de sofisticadas fábricas nas quais se processam etapas importantes do ciclo do combustível nuclear. Na FCN, o Centro Zoobotânico realiza a gestão das atividades voltadas para a conservação da natureza tais como o Programa de Recuperação de Mata Ciliar, Reflorestamento e Fauna. O Relatório de inventário das emissões diretas e indiretas de GEE da FCN, elaborado pela INB para o ano de 2008, permite a auto-avaliação da empresa, retratando a preocupação corporativa com as questões relativas às mudanças climáticas. Segundo este Relatório, o total de emissões de GEE quantificado corresponde a 12,14% da capacidade total de sequestro de dióxido de carbono, no período de Janeiro a Dezembro de 2008. A proteção de florestas e a plantação de árvores são componentes essenciais de qualquer estratégia global para mitigação da mudança climática, e a participação da INB no mercado de crédito de carbono pode proporcionar externalidades positivas, tais como ganhos de imagem, adequação a padrões ambientais e melhoria do relacionamento com a sociedade. / This dissertation discusses issues related to intensification of climate change by anthropogenic causes for the evolution in use of natural resources, innovations in production processes, economic, social, cultural, political and especially environmental. Approaches marketing of carbon credits through projects of Clean Development Mechanism (CDM), one of the flexible mechanisms created by the Kyoto Protocol. In context of climate change, an energy matrix that uses energy sources that do not emit greenhouse gases (GHG) proves an important strategy for sustainable development. From this perspective, the nuclear-electric energy is presented as a viable alternative to fossil fuels, considering that this is a clean energy and compatible with sustainable development perspective. The Nuclear Fuel Factory (FCN), located in Resende (Rio de Janeiro), belonging to the Nuclear Industries of Brazil (INB), is a sophisticated set of factories where important steps of nuclear fuel cycle are processed. In FCN, the Zoobotanical Center performs the management of activities for conservation of natures, as the Recovery Program of Riparian Vegetation, Forestry and Wildlife. The report of inventory of direct and indirect emissions of greenhouse gases from FCN, produced by INB for the year 2008, allows the self-assessment of the company,portraying the corporate preoccupation with issues related to climate change. According to the report, total GHG emissions measured corresponds to 12.14% of the total capacity of sequestration of carbon dioxide in the period January to December 2008. Protecting forests and planting trees are essential components of any comprehensive strategy for mitigating climate change and the share of INB in the carbon credit market can provide positive externalities, such as earnings picture, fitness for environmental standards and improving the relationship with society.

This work deals with occupational professional exposures at Temelín Nuclear Power Plant. The introductory part is devoted to types of ionising radiation participating on radiation load of workers, values and units and to the essential legislation requests associated with individual monitoring. In the following part characteristics of methods used to measure individual doses of external exposures like film dosimetry, thermoluminescent do-simetry, radio-photoluminescent dosimetry and electronic dosimetry are described. For assessment of the committed effective dose from the internal exposures in vivo moni-toring or indirect measuring were used. The possibilities of the occupational dose optimisation were discussed Results of individual monitoring in 2005 and 2006 and layout of monitoring program are presented in this work. The new monitoring program is based on the active personal dosimeters (EPDs) rather than on the passive ones and covers the period of transformation between them. With respect to the passive dosimeters, EPDs offer some advantages which on one hand contribute to a better exposure control and on the other hand foster the development of a sound culture in radiation protection due to direct feedback of dose information.

In this work, which deals with problematics of releases from nuclear power plants, I tried to make an overview of various types of nuclear power plants and radioizotopes which are released through liquid and gasseous effluents. As a part of this comparison evaluation of czech and world nuclear power plants gaseous and liquid releases was made. Introductory part of this work contains information about different types of nuclear power plants and radioizotopes, which are produced in their reactors. It continues with today{\crq}s legislative and information about releasing levels and methods and systems used for measurement of radioactive gaseous and liquid effluents from nuclear power plants. Second part of this work describes the aim of this work and hypothesis. Third part explains the methods, which were used for completing of this work. Fourth part contains results in the form of tables and graphs. Fifth part represents discussion of the results. Last part is a summarization of the results.

This work deals with monitoring of the radiocarbon in the gaseous effluents from the Temelín nuclear power plant and its distribution in the environment. The reader should gain a comprehensive image about level of radiocarbon monitoring in ventilation systems in the Temelín nuclear power plant and in the surrounding environment. The work is divided into several parts. Some basic information of physics, chemistry and radiobiology relating to radiocarbon are given in the first part. The origin of radiocarbon in VVER reactor, its pathway to gaseous releases and then to carbon cycle in the environment are described there too. This introductory part continues with description of monitoring methods used in ventilation systems of the Temelín nuclear power plant and in the surrounding environment. Summary of Czech Republic legislation related to radiation protection is stated. The aim of the work and hypothesis are set in the second part. In the third part there are methods used to fulfil the aim of the work. The results in the form of tables and graphs are in the fourth part. In the following part there is a discussion of summarized data and results. Developed findings are summarized in the last part of this work.

At the nuclear power plant accident, the radionuclides with very short half-life come to enviroment, they decay the period from several second to several months. On the other sides come to enviroment radionuclides with long half-life. Their radionuclides occur in surrounding of the power plant for hundreds of years before they decay totally. Immediately after a nuclear power plant accident, radioiodine represents the most severe health hazard for population. Because it is a radionuclide with short half-life, it causes the danger during first months after the accident. Its health hazard lies in the fact, that it gets to food chains and irradiates a man, who consumed contaminated water and food. Radiocaesium and radiostrontiom are the next important radionuclides. They have long half-lifes, it means that will decay after hundred years after the accident and they endanger population a long time after the accident yet.

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