Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-11-11T09:45:23Z No. of bitstreams: 0 / Made available in DSpace on 2016-11-11T09:45:23Z (GMT). No. of bitstreams: 0 / Um desafio recorrente em processos produtivos é o desenvolvimento de sistemas de monitoração e diagnóstico. Esses sistemas ajudam na detecção de mudanças inesperadas e interrupções, prevenindo perdas e mitigando riscos. Redes Neurais Artificiais (RNA) têm sido largamente utilizadas na criação de sistemas de monitoração. Normalmente as RNA utilizadas para resolver este tipo de problema são criadas levando-se em conta apenas parâmetros como o número de entradas, saídas e quantidade de neurônios nas camadas escondidas. Assim, as redes resultantes geralmente possuem uma configuração onde há uma total conexão entre os neurônios de uma camada e os da camada seguinte, sem que haja melhorias em sua topologia. Este trabalho utiliza o algoritmo de Otimização por Colônia de Formigas (OCF) para criar redes neurais otimizadas. O algoritmo de busca OCF utiliza a técnica de retropropagação de erros para otimizar a topologia da rede neural sugerindo as melhores conexões entre os neurônios. A RNA resultante foi aplicada para monitorar variáveis do reator de pesquisas IEA-R1 do IPEN. Os resultados obtidos mostram que o algoritmo desenvolvido é capaz de melhorar o desempenho do modelo que estima o valor de variáveis do reator. Em testes com diferentes números de neurônios na camada escondida, utilizando como comparativos o erro quadrático médio, o erro absoluto médio e o coeficiente de correlação, o desempenho da RNA otimizada foi igual ou superior ao da tradicional. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2017-11-01T17:02:12Z No. of bitstreams: 0 / Made available in DSpace on 2017-11-01T17:02:12Z (GMT). No. of bitstreams: 0 / Este trabalho apresenta um estudo prático da aplicação do conceito Leak Before Break (LBB), usualmente aplicado em usinas nucleares, em uma tubulação fabricada a partir de aço AISI 316LN soldada com a utilização de eletrodo revestido AISI 316L. O LBB é um critério fundamentado em análises de mecânica da fratura, que considera que um vazamento proveniente de uma trinca, presente em uma tubulação, possa ser detectado por sistemas de detecção de vazamento, antes que esta trinca alcance um tamanho crítico que implique na falha da tubulação. Na tubulação estudada, foram realizados ensaios mecânicos de tração e análises de Ramberg-Osgood, bem como ensaios de tenacidade à fratura para a obtenção da curva de resistência J-R do material. Os ensaios foram realizados considerando o metal base, a solda e a zona termicamente afetada (ZTA), nas temperaturas de operação de uma planta nuclear. Para as propriedades mecânicas encontradas nos ensaios foram realizadas análises de carga limite para se determinar o tamanho da trinca que cause um vazamento detectável e, também, o seu tamanho crítico que cause a falha por colapso plástico. Para o tamanho crítico de trinca encontrado na solda, região que apresentou a menor tenacidade, foram realizadas análises de Integral J e de módulo de rasgamento T, considerando falha por rasgamento dúctil. Os resultados demonstram um comportamento bem definido entre o metal base, a ZTA e a solda, onde o metal base apresenta um comportamento altamente tenaz, a solda um comportamento pouco tenaz e a ZTA apresentou propriedades mecânicas intermediárias entre o metal base e a solda. Utilizando o software PICEP, foram determinadas as curvas de taxa de vazamento versus tamanho de trinca e também o tamanho crítico da trinca, considerando análise por carga limite. Observou-se que, após certo tamanho de trinca, a taxa de vazamento do metal base é muito maior do que para a ZTA e solda, para um mesmo comprimento de trinca. Isso ocorre porque é esperado que a trinca cresça de forma mais arredondada no metal base, devido à sua maior tenacidade. O menor tamanho crítico de trinca foi encontrado para o metal base para trincas circunferenciais. Para as análises de Integral J realizadas na solda, foi demonstrado que a falha por rasgamento dúctil não ocorrerá nas condições consideradas e essa hipótese foi sedimentada pela análise de mecânica da fratura elasto-plástica (MFEL) com o uso do diagrama J/T. Dessa forma, pode-se concluir que a tubulação estudada estaria apta a ser empregada em um circuito primário de um reator que utilizasse o critério de LBB, nas condições de carregamento e geometria consideradas. Adicionalmente, concluiu-se que nessas condições apenas o modo de falha por colapso plástico é esperado. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

A strong trend of returning to nuclear power is evident in different places in the world. Forty-five countries are planning to add nuclear power to their grids and more than 66 nuclear power plants are under construction. Nuclear power plants that generate electricity and steam need to improve safety to become more acceptable to governments and the public. One novel practical solution to increase nuclear power plants' safety factor is to build them away from urban areas, such as offshore or underground. To date, Land-Based siting is the dominant option for siting all commercial operational nuclear power plants. However, the literature reveals several options for building nuclear power plants in safer sitings than Land-Based sitings. The alternatives are several and each has advantages and disadvantages, and it is difficult to distinguish among them and choose the best for a specific project. In this research, we recall the old idea of using the alternatives of offshore and underground sitings for new nuclear power plants and propose a tool to help in choosing the best siting technology. This research involved the development of a decision model for evaluating several potential nuclear power plant siting technologies, both those that are currently available and future ones. The decision model was developed based on the Hierarchical Decision Modeling (HDM) methodology. The model considers five major dimensions, social, technical, economic, environmental, and political (STEEP), and their related criteria and sub-criteria. The model was designed and developed by the author, and its elements' validation and evaluation were done by a large number of experts in the field of nuclear energy. The decision model was applied in evaluating five potential siting technologies and ranked the Natural Island as the best in comparison to Land-Based, Floating Plant, Artificial Island, and Semi-Embedded plant.

Cette thèse étudie le rôle des coûts de construction et de réglementation de la sécurité sur la compétitivité de l'énergie nucléaire. L'analyse des coûts de construction est basée sur l'utilisation de données réelles provenant des parcs nucléaires français et américains. En particulier, nous étudions différents canaux à partir de laquelle des réductions de coûts pourraient survenir. Nous montrons que la normalisation est un critère crucial pour la compétitivité économique de l'énergie nucléaire, d'abord parce que les effets d'apprentissage positifs sont conditionnels à la technologie, ce qui signifie que les réductions de coûts ne peuvent venir que si le même type de réacteur est construit à plusieurs reprises, mais aussi parce qu'elle permet de réduire le coût indirectement par l'intermédiaire de courts délais de construction. Dans l'analyse du rôle de réglementation de la sécurité, nous évaluons d'abord l'effet du dernier accident nucléaire majeur (c.-à Fukushima Dai-ichi) de la probabilité de survenance d'un tel événement, puis les effets de l'incertitude concernant la façon dont les soins de la sécurité à réduire la probabilité d'un accident nucléaire dans l'établissement de normes de sécurité en vertu de l'aléa moral et responsabilité limitée. Nous constatons que la norme sera la moins stricte lorsque le régulateur adopte une approche pire des cas, et plus stricte lorsque le régulateur adopte l'approche de la robustesse de regret et il est optimiste quant à l'efficacité des soins de la sécurité pour réduire le risque d'accident. Toutefois, cette norme pourrait induire le non-respect par les opérateurs les moins efficaces. / This thesis studies the role of construction costs and safety regulation on nuclear power competitiveness. The analysis of the construction costs is based on the use of the actual data coming from the american and french nuclear fleet. In particular, we study different channels from which cost reductions might arise. We show that standardization is a key criterion for the economic competitiveness of nuclear power, first because the positive learning effects are conditional to the technology, this means that cost reductions will arise only if the same type of reactor is built several times, but also because it allows to reduce the cost indirectly through shorter construction lead-times. In the analysis of the role of safety regulation, we first asses the effect of the latest major nuclear accident (i.e Fukushima Dai-ichi) in the probability of occurrence of such an event and then the effects of the uncertainty regarding how safety care reduce the probability of a nuclear accident in setting safety standards under moral hazard and limited liability. We find that the standard will be stricter when the regulator is optimistic in the safety care effectiveness to reduce the risk of an accident, but simultaneously this policy might induce no compliance of the most inefficient operators.

[pt] Apresenta-se um estudo de avaliação dos critérios e métodos que são empregados atualmente na análise e projeto dos sistemas de tubulação nas usinas nucleares assim como a verificação da aplicação de alguns dos novos critérios apresentados pela comunidade técnico-científica internacional, dentro do método de análise modal-espectral. Estudam-se os tópicos da interação entre o sistema de tubulação e a estrutura que o suporta mediante o uso de espectros acoplados, a consideração do efeito do deslocamento relativo dos apoios da tubulação, usando-se espectros que o consideram ou uma excitação espectral múltipla, a introdução da combinação dos máximos modais dependendo da posição relativa das suas freqüências e a inclusão da resposta espectral correspondente aos modos de alta freqüência ou modos rígidos. A ferramenta básica de análise é constituída pelo programa computacional ANSYS. A avaliação é feita sobre parâmetros de esforços internos em trechos de um modelo de um sistema real de tubulações da usina nuclear brasileira, Angra 3. Os padrões são obtidos por análises no tempo de cada modelo sob o acelerograma de projeto. Conclusões são apresentadas sobre as atitudes mais convenientes para a atual conjuntura brasileira de projeto. / [en] The main concern of this work is with the application of the modal spectral seismic analysis to secondary structural systems of nuclear power plants, with the large amount of conservatism which is included in them, and, of course, with the consequences to the particular case of the plants under construction in Brazil. One considers the design analysis methods which have been used so far in Brazil, as well as the most recent developments in the area, in USA and in Europe, to conclude about the adequacy of those procedures and recommend eventual changes to them. One then studies the subjects of the coupling effect between the primary and secondary system responses, the influence of the piping support relative displacements, the contribution of the cross-correlation among response modal components and the participation in the overall response of the so-called rigid modes. The main computer program aid is taken from an ANSYS-2 version and one uses a reduced model of a piping system as the secondary system and a 3-D beam element model of a reactor building as the primary system. The spectral analysis results are compared to time domain solutions using the same structural models excited by a design accelerogram. Conclusions and recommendations are oriented to the present design practice in Brazil. / [es] En esta tesis se presenta un estudio de evaluación de los criterios y métodos que se emplean actualmente en el análisis y proyecto de los sistemas de tubulación en las plantas nucleares así como la verificación de la aplicación de algunos de los nuevos criterios presentados por la comunidad técnico-científica internacional, dentro del método de análisis modal-espectral. Se estudian los tópicos de la interacción entre el sistema de tubulación y la extructura que él soporta mediante el uso de espectros acoplados; la consideración del efecto de deslocamiento relativo de los apoyos de la tubulación, utilizando espectros que lo consideran o una excitación espectral múltipla; la introdución de la combinación de los máximos modales dependiendo de la posición relativa de las sus frecuencias y la inclusión de la respuesta espectral correspondiente a los modos de alta frecuencia o modos rígidos. La herramienta básica de análisis es el programa computacional ANSYS. La evaluación se realiza sobre parámetros de esfuerzos internos en trechos de un modelo de un sistema real de tuberías de la planta nuclear brasilera, Angra 3. Los padrones se obtienen por análisis en el tiempo de cada modelo bajo el acelerograma de proyecto. Se presentan conclusiones sobre las actitudes más convenientes para la actual conyuntura brasilera.

As the global energy crisis continues to have an impact on developing countries such as South Africa, stakeholders form an increasingly significant role especially around the concerns of development and the impact on the environment. Environmental conflicts have risen to the forefront in many areas in South Africa. Environmental conflicts fall under public disputes, which often occur as a result of human needs. This study is an attempt to explore the environmental conflict surrounding the proposed Nuclear Power station at Thyspunt, Oyster Bay in the Eastern Cape. Stakeholders are an integral part of environmental conflicts, and analyzing interests of stakeholders is vital in understanding environmental conflicts. This explorative study, seeks explore and to describe the interests of homeowners who are one of the key stakeholders involved the environmental conflict at Thyspunt, Oyster Bay in the Eastern Cape. The homeowners are represented by the St Francis Residents/ Ratepayers Association. The researcher conducted extensive face-face interviews with these homeowners. The organizations official documents, minutes of their meetings, letters to the media and various publications in which homeowners expressed their feelings were also made use of by the researcher in order to triangulate findings, as well as for data collection methods. The major themes were constructed from the study include: Security, Trust, Power and the various sources thereof, as well as a need for self-actualization based on values, and a final theme of the positive functions of conflict. The challenges facing the homeowners in terms of human security and environmental impact of the nuclear development are highlighted. Further recommendations for a more in-depth study are also made.

The thesis deals with the issue of nuclear energy. Within thesis we focus on attitude of Germany, Japan, Czech Republic and Slovak Republic. We assess their energy policy and transition to renewable energy. The first chapter deals with importance of nuclear energy in European Union. The second chapter is focused on new opportunities in the energy sector and concept of smart cities. The third chapter analyzes the energy of Japan, the fourth chapter the energy of Germany and the fifth chapter is focused on energy of Czech Republic and Slovak Republic.

This master thesis has been conducted at Forsmark nuclear power plant. In nuclear power plants, safety is one of the most important tasks. After the Fukushima-accident, Forsmarks Kraftgrupp AB investigated the possibility to have additional emergency cooling systems. This thesis aims to investigate the use of cooling towers as mobile emergency cooling system for decay heat removal for the nuclear reactors at Forsmark NPP. The advantages and disadvantages of different cooling tower types were looked at. To achieve mobility, some restraints were considered such as dimensions and weight. In the design of cooling towers, experimental values are used. As these crucial data are missing, a backfitting from actual designs was done to derivate the missing data. The results of this thesis show that wet cooling towers are in this case more effective than dry cooling towers. The wet cooling towers cover in the best scenario up to 38MW which is 10 times higher than what can be achieved with the dry cooling tower. That covers the maximal decay heat released in the reactor F3 12 hours after a shutdown.

This paper uses a comparative focus group method to explore the conditions for risk communication after a hypothetical nuclear accident requiring decontamination. This is achieved by examining and comparing how older men and younger women express their deeper thoughts and ideas about risk and risk communication, and possible dilemmas they might face in the event of such an accident. Four focus groups were conducted with 18 residents of Örebro (eight younger women and ten older men). The discussions were recorded, transcribed and analyzed thematically. The results showed clear differences between the groups in terms of frames of reference and ideas about their own actions. Similarities were found in how the view of risks related to radiation was dominated by fear, uneasiness and worry, and especially in how the need for information was expressed. The conclusions show that more research is needed to better understand the conditions for risk communication about such complex and stigmatizing issues in a Swedish context. / Denna uppsats använder en komparativ fokusgruppmetod för att undersöka förutsättningarna för riskkommunikation efter en hypotetisk kärnteknisk olycka som kräver sanering. Mer specifikt görs detta genom att undersöka och jämföra hur äldre män och unga kvinnor uttrycker sina djupare föreställningar om risk och riskkommunikation, samt möjliga dilemman de kan ställas inför vid en dylik olycka . Fyra fokusgrupper genomfördes med 18 personer bosatta i Örebro (åtta yngre kvinnor och tio äldre män). Diskussionerna spelades in, transkriberades och analyserades tematiskt. Resultaten visade på tydliga skillnader mellan grupperna vad gäller referensramar och föreställningar om det egna agerandet. Likheter framkom i hur synen på risker med strålning dominerades av rädsla, obehag och oro, och framförallt vilket informationsbehov respondenterna uttryckte sig ha. Slutsatserna pekar på att vidare forskning behövs för att bättre förstå förutsättningarna för riskkommunikation om sådana komplexa och stigmatiserade frågor i en svensk kontext.

The Diploma thesis on the topic of Increased performance turbomachinery in EDU the NPR changing describes in detail some important devices of technology system of the secondary circuit of Dukovany Nuclear Power Plant together with their task in the thermal circulation. There is a computational model of secondary circuit according to the present thermal schema created in the main part of the thesis. At the end of the thesis, the possibilities of the increase of the terminal power of turbomachinery, specifically of the turbogenerator, by the exhange of low-pressure heaters (NPR) are stated. Obtained results are documented by drawings of the thermal schemes.