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Made available in DSpace on 2014-10-09T12:35:14Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:36Z (GMT). No. of bitstreams: 0 / Para elaborar um programa de proteção radiológica, as instalações radiativas brasileiras devem considerar normas, diretrizes e recomendações nacionais e internacionais que encontram-se em documentos de diferentes organizações publicados nas últimas décadas: Comissão Internacional de Proteção Radiológica (CIPR), Organismo Internacional de Energia Atômica (OIEA) e Comissão Nacional de Energia Nuclear (CNEN). Visando a proporcionar a essas instalações o acesso às informações pertinentes de forma rápida, integrada e eficiente, este projeto propõe informatizar e disponibilizar em um só documento os programas de otimização da proteção radiológica unificados, inter-relacionados e em português, fornecendo ao público usuário um veículo completo para fins de pesquisa, consulta e informação. A partir do discernimento do que deve conter cada programa e seu real dimensionamento, foi trabalhado o inter-relacionamento das informações de maneira a satisfazer as normas e recomendações nacionais e internacionais. O projeto inclui conceitos, definições e teoria necessários, além da pesquisa detalhada do conteúdo do programa de otimização, das técnicas de ajuda para tomada de decisão, das doses de radiação e detrimento e das informações relacionadas aos custos de proteção. O conteúdo permite responder a todas as questões que devem ser colocadas na elaboração de um programa de otimização de forma a possibilitar montagem do plano de Proteção Radiológica conforme a situação específica do usuário. Para a informatização dos programas de otimização foram estudadas as possibilidades de acesso à Tecnologia da Informação e Comunicação nas empresas brasileiras, possibilitando identificar o perfil de utilização do sistema e definir a estrutura funcional adequada para a criação das melhores interfaces de ferramentas e recursos, bem como de um projeto de navegabilidade eficaz facilitando a busca de informações. O poder de processamento dos servidores aliado à tecnologia dos bancos de dados relacionais permite correlacionar informações advindas de diferentes fontes, possibilitando consultas complexas com tempo de resposta reduzido. O sistema segue o padrão WEB 2.0, que possibilita a estrutura organizacional necessária para a adequada informatização da proteção radiológica e considera os corretos critérios de indexação da informação para garantir seu reconhecimento pelos motores de busca da internet. O projeto conta com a combinação de várias tecnologias, potencializando os recursos disponíveis em cada uma delas para alcançar os objetivos propostos. Este trabalho experimental lança um cerne inicial para a informatização dos programas de proteção radiológica, informatizando inicialmente os programas de otimização. A investigação do perfil de utilização durante um período de cinco meses possibilitou o levantamento de dados importantes que apontam novas possibilidades para o desenvolvimento da informatização dos programas de proteção radiológica. Pretende-se, a partir dos resultados deste projeto, aprofundar o trabalho de investigação e completar a execução do sistema de informatização. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Light water reactors (LWRs) are the world’s dominant nuclear reactor system. Uranium (U)-fuelled LWRs produce long-lived transuranic (TRU) isotopes. TRUs can be recycled in LWRs or fast reactors. The thermal neutron spectrum in LWRs is less suitable for burning TRUs as this causes a build-up of TRU isotopes with low fission probability. This increases the fissile feed requirements, which tends to result in a positive void coefficient (VC) and hence the reactor is unsafe to operate. Use of reduced-moderation LWRs can improve TRU transmutation performance, but the VC is still severely limiting for these designs. Reduced-moderation pressurized water reactors (RMPWRs) and boiling water reactors (RBWRs) are considered in this study. Using thorium (Th) instead of U as the fertile fuel component can greatly improve the VC. However, Th-based transmutation is a much less developed technology than U-based transmutation. In this thesis, the feasibility and fuel cycle performance of full TRU recycle in Th-fuelled RMPWRs and RBWRs are evaluated. Neutronic performance is greatly improved by spatial separation of TRU and 233-6U, primarily implemented here using heterogeneous RMPWR and RBWR assembly designs. In a RMPWR, the water to fuel ratio must be reduced to around 50% of the normal value to allow full actinide recycle. If implemented by retrofitting an existing PWR, steady-state thermal-hydraulic constraints can still be satisfied. However, in a large break loss-of-coolant accident, the emergency core cooling system may not be able to provide water to the core quickly enough to prevent fuel cladding failure. A discharge burn-up of ~40 GWd/t is possible in RMPWRs. Reactivity control is a challenge due to the reduced worth of neutron absorbers in the hard neutron spectrum, and their detrimental effect on the VC, especially when diluted, as for soluble boron. Control rods are instead used to control the core. It appears possible to achieve adequate power peaking, shutdown margin and rod-ejection accident response. In RBWRs, it appears neutronically feasible to achieve very high burn-ups (~120 GWd/t) but the maximum achievable incineration rate is less than in RMPWRs. The reprocessing and fuel fabrication requirements of RBWRs are less than RMPWRs but more than fast reactors. A two-stage TRU burning cycle, where the first stage is Th-Pu MOX in a conventional PWR feeding a second stage continuous burn in a RBWR, is technically reasonable. It is possible to limit the core area to that of an ABWR with acceptable thermal-hydraulic performance. In this case, it appears that RBWRs are of similar cost to inert matrix incineration in LWRs, and lower cost than RMPWRs and Th- and U-based fast reactor recycle schemes.

No description available.

This thesis is focused to the economic analysis of the nuclear fuel strategy change at nuclear power plant Temelin, where the change to 18 months fuel cycle is considered. The introduction of theses is aimed to the identification of direct economic aspects for the financial analysis. Nuclear fuel strategy change affects operation of power plant as a whole and affects production of spent nuclear fuel. Therefore the economic analysis is needed for include all social costs of the change. The conclusion of thesis is aimed to the risk analysis of the nuclear fuel strategy change. Risk analysis is performed by Monte Carlo simulation.

This Master’s thesis deals with optimization of loading patterns of nuclear reactors VVER. In the thesis is described the process of both types of fuel cycle – the closed and the open one. The middle part of fuel cycle containing the optimization process represents the crucial part of the thesis. The thesis is focused on the fuel cycles of the nuclear power plant Dukovany. The problem of the optimization is solved by using different programs. In the final part of the thesis, the program Athena for the loading patterns optimation is explained by a practical calculation for different versions of Moby-Dick macrocode and the calculated values for the optimization of the third unit of the nuclear power plant Dukovany are compared.

The Master's thesis focuses on loading patterns of nuclear reactors VVER. It describes the whole process of fuel cycle, since production to storage or reprocessing. The author puts emphasise on the middle part of fuel cycle in Czech nuclear power plants - Dukovany and Temelín and he also explains which fuels are used in both power plants now and which were used in history. The thesis also contains a basic overview of approaches to loading patterns optimisation in foreign countries. The final part of the thesis discusses practical calculation of loading patterns in the Block III of Nuclear power plant Dukovany, by using optimisation programme Athena and Moby-Dick macrocode.