abstract: The operating temperature of photovoltaic (PV) modules is affected by external factors such as irradiance, wind speed and ambient temperature as well as internal factors like material properties and design properties. These factors can make a difference in the operating temperatures between cells within a module and between modules within a plant. This is a three-part thesis. Part 1 investigates the behavior of temperature distribution of PV cells within a module through outdoor temperature monitoring under various operating conditions (Pmax, Voc and Isc) and examines deviation in the temperature coefficient values pertaining to this temperature variation. ANOVA, a statistical tool, was used to study the influence of various factors on temperature variation. This study also investigated the thermal non-uniformity affecting I-V parameters and performance of four different PV technologies (crystalline silicon, CdTe, CIGS, a-Si). Two new approaches (black-colored frame and aluminum tape on back-sheet) were implemented in addition to the two previously-used approaches (thermally insulating the frame, and frame and back sheet) to study temperature uniformity improvements within c-Si PV modules on a fixed latitude-tilt array. This thesis concludes that frame thermal insulation and black frame help reducing thermal gradients and next best viable option to improve temperature uniformity measurements is by using average of four thermocouples as per IEC 61853-2 standard. Part 2 analyzes the temperature data for two power plants (fixed-tilt and one-axis) to study the temperature variation across the cells in a module and across the modules in a power plant. The module placed in the center of one-axis power plant had higher temperature, whereas in fixed-tilt power plant, the module in north-west direction had higher temperatures. Higher average operating temperatures were observed in one-axis tracking as compared to the fixed-tilt PV power plant, thereby expected to lowering their lifetime. Part 3 focuses on determination of a thermal model coefficients, using parameters similar to Uc and Uv thermal loss factors used in PVsyst, for modules of four different PV technologies experiencing hot-desert climate conditions by statistically correlating a year-long monitored data. Thermal models help to effectively quantity factors influencing module temperatures to estimate performance and energy models. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2016

Made available in DSpace on 2014-10-09T12:51:02Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:20Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

A priorização da implantação de usinas hidrelétricas no Brasil deve-se, primordialmente, ao vasto potencial hidrelétrico existente no país e à competitividade econômica que esta fonte apresenta. PPara atender à crescente demanda, foram implantados ao longo dos anos, diversos empreendimentos hidrelétricos por todo o país. Apesar do inequívoco sucesso quanto ao objetivo central de tais empreendimentos - fornecer energia para o desenvolvimento econômico tais empreendimentos causam impactos com diferentes níveis de severidade aos sistemas físico-biótico, sócio-econômico e cultural das regiões em que as instalações são realizadas. O presente trabalho objetivou identificar problemas e impactos ambientais nos ecossistemas aquáticos do Rio Tocantins relacionados com o desenvolvimento do seu potencial hidroelétrico, de forma a contribuir com a compatibilização de geração de energia e conservação da biodiversidade e manutenção dos fluxos gênicos. O cenário considerado contemplou os empreendimentos em operação e aqueles em instalação, com estudos de viabilidade aprovados e licenças prévias obtidas. A metodologia de Análise de Cadeia Causal (ACC) foi utilizada para que a partir da identificação dos problemas e impactos ambientais prioritários, a relação dos mesmos com diferentes causas imediatas, setoriais e raízes pudesse ser estabelecida. A hierarquização dos impactos foi feita através de matriz de caracterização, tendo as comunidades íctias como principais indicadores. Os impactos considerados como mais relevantes foram: (i) queda na qualidade dos recursos hídricos, (ii) perda e alteração de habitats, (iii) mudanças na estabilidade dos ecossistemas, (iv) redução de recursos pesqueiros, (v) interferência com as comunidades de bentos e de microorganismos, (vi) alteração nas cadeias alimentares e (vii) interferência na dispersão de comunidades íctias e de mamíferos. O conhecimento sobre a biodiversidade existente e a identificação dos principais impactos existentes e em potencial nos ecossistemas aquáticos do Rio Tocantins, representam um passo importante para o desenvolvimento de opções políticas eficazes com vistas à minimização da degradação ambiental decorrente do setor hidroelétrico. / The priority given to the construction of hydropower plants in Brazil is mostly due to the large hydroelectric potential available in the country and the economic advantages that this energy source presents. In order to meet the increasing demand, during the years many plants have been constructed allover the country. Regardless the obvious success concerning the main objective of such facilities to supply energy for economic development these plants have caused environmental and social impacts with different levels of severity to the aquatic ecosystems and the human communities living in the region. The objective of this work was to identify environmental problems and impacts to the aquatic ecosystems in Tocantins River related to the development of its hydropower potential in order to contribute to the target of making compatible energy generation and biodiversity protection.. The scenario considered included those powerplant in operation and those to be constructed, with feasibility studies and environmental licenses already approved. The Causal Chain Analysis methodology was used, in order to starting with the main environmental problems, to be able to identify the environmental impacts and their immediate, sectoral and root causes. The impacts were ranked according to the characterization matrix, having the fish communities as the main indicators. The impacts considered the most relevant were: (i) degradation of water resources, (ii) loss and changes in habitats, (iii) changes in the ecosystems stability, (iv) reduction of fish stocks, (v) interference with benthic communitites and microorganisms populations, (vi) changes in the food-chain and (vii) interference with the dispersion of fishes and mammals. The knowledge about the existing biodiversity and the identification of the main existing and potential impacts on the aquatic ecosystems of Tocantins River represents an important step for development of effective policy options to minimize the environmental degradation associated to the electric sector.

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.

A pesquisa trata do poder da comunicação na implantação de projetos originados em políticas públicas, com elevado impacto socioambiental, colocados pelo Estado à sociedade na condição de interesse público. Constitui o objeto os processos de comunicação vinculados à Usina Hidrelétrica Foz do Chapecó, no Rio Uruguai (SC/RS - Brasil). O recorte temporal é o “tempo da obra”, entre novembro de 2006 e outubro de 2010. A reflexão teórica assenta-se na teoria da esfera pública e nas tensões entre comunicação pública e estratégica. O estudo de caso está sediado numa abordagem qualitativa, com análise crítica de discurso. A identificação das organizações que participaram dos contenciosos revelou uma extensa e complexa rede, mas concentrada em torno da Foz do Chapecó Energia (concessionário), do Ibama, do Ministério de Minas e Energia e do Movimento dos Atingidos por Barragens (MAB). A comunicação dessas organizações foi extremamente assimétrica. A comunicação do Estado adotou uma matriz desenvolvimentista, visibilidade restrita, ausência de discussão e accountability superficial e funcional. Na sociedade civil, o MAB foi a única organização a produzir comunicação de forma sistemática (e sob uma matriz crítica), embora com baixos níveis de visibilidade. Centro da matriz cognitiva desenvolvimentista, a comunicação da Foz do Chapecó Energia foi de ordem muito superior à dos demais, marcada por alta visibilidade, ausência de debate e níveis de accountability estrategicamente selecionados. A cobertura dos meios de comunicação aderiu à comunicação da FCE e tendeu a silenciar outras vozes. No centro dessa assimetria estão questões que emergem na transferência da concessão pública para aesfera privada, sem levar consigo requisitos inerentes a um bem público. O trabalho concluiu que a comunicação é elemento central e constitutivo das negociações sobre o espaço a ser ocupado pelas barragens e fator estratégico nas relações entre atingidos e não atingidos e as organizações do Estado, do mercado e da sociedade civil. É nos espaços criados pela comunicação que estão as opções de acesso à informação e participação na esfera pública e midiática, por meio das quais opera a própria representação, se configuram simbolicamente os contenciosos e se constroem ou não espaços para a participação e avanços democráticos. / The research is about the power of communication towards the implementation of projects derived from public policies, with a high socio-environmental impact, set by the government for society in the condition of public interest. The object is the communication process linked to the Hydroelectric Power Plant Foz do Chapecó, on Uruguay River (SC/RS – Brazil). The time stretch is the “duration of the works”, between November 2006 and October 2010. The theoretical aspect is based on the importance given to communication by the theory of public sphere. The case study has a qualitative approach with a critical analysis of speech. Identifying the organizations that took part in the contentious process has revealed an extensive and complex network, but only a few, such as Ibama (the federal environmental agency), the Ministry of Mines and Energy, Foz do Chapecó Energia – FCE (concessionary enterprise) and the Movement of People Affected by Dams - MAB, had the power to interfere with them. These organizations communicated in a very asymmetric way. The government communicated adopting a developmental matrix, restricted visibility, absence of discussion and a superficial and functional accountability. On civil society, MAB has been the only organization to produce communication in a systematic way (and under a critical matrix), although with low levels of visibility. Communication undertaken by Foz do Chapecó Energia, as the center of the developmental cognitive matrix, was of a much higher magnitude than that carried out by the other organizations, marked by visibility, absence of debate and strategically selected levels of accountability. Coverage of the communication media joined the FCE communication, silencing other voices. At the center of such asymmetry are certain issues that arise from the transfer of concessionfrom the public to the private sphere, without bringing with it the requirements inherent to a pu The conclusion of this work was that communication is a central and constitutive element of negotiations regarding the space to be occupied by the dams and a strategic factor on the relations between those affected and those not affected and the governmental, market and civil society organizations. The options of access to information and participation in the public arena and the media are found in the space created by communication, which is also where representation is operated, where the contentious are symbolically shaped and where spaces are, or aren’t, created for participation and democratic advances.

Reinjection of spent geothermal fluids has become common practise in geothermal power plants. Reinjection can, despite being mostly beneficial, have unwanted effects such as cooling of nearby production wells and injection-induced earthquakes. Tracer tests, along with their modeling and interpretation, are important tools for monitoring the flow paths of the injected water and to predict reservoir cooling. Knowledge of flow paths in the system allows for better resource management and a more sustainable utilization. A simulation model of the Húsmúli reinjection zone in the Hellisheiði Geothermal Power Plant in SW-Iceland was developed using the TOUGH2 program. Its hydrological parameters, porosity and permeability, were calibrated using results from an extensive tracer test carried out in the area in 2013-2015. The aim of the simulations was to obtain better understanding of the flow paths in Húsmúli since, despite fast tracer recovery in production wells in the area, hardly any cooling has been observed in those production wells. The results show that the tracer recovery can be modelled by means of permeable flow channels within the medium. Good results for tracer arrival and concentration peaks were obtained both by assuming a single wide channel and several narrower ones. The parameters that gave the best fit for the single channel model were permeability of 5·10-12 m2 and porosity ranging from 0.2%–3%. For the multi-channel model they were 1·10-12 m2 and 0.2%–3.5%, respectively. The high permeability and low porosity in the channels make for an abstract representation of fractured zones within the medium. Greater cooling was seen with the single-channel modelling approach than with the multiple narrower channel approach, the latter showing hardly any cooling in the production elements during the simulation time. This indicates that the flow paths are more likely multiple channels consisting of fracture networks. The simulations show that the flow paths are lengthened by sinking of the fluid to greater depth because of the higher density of the colder injected water. This implies that the injected fluid is warmed up by contact with a larger volume of rock, causing a limited and delayed cooling effect. / Geotermisk energi anses vara en förnybar och miljövänlig energikälla. Som sådan, kan den spela en viktig roll för att minska utsläppen av växthusgaser från energisektorn över hela världen och genom det bekämpa antropogena klimatförändringar. Geotermiska kraftverk extraherar het vätska från berggrunden, separerar ångan från vätskan och använder sedan ångan för att driva turbiner som genererar elektricitet. Injektion av använd geotermisk vätska från kraftverk har blivit vanligt i den geotermiska industrin för att kassera använd geotermisk vätska, upprätthålla systemtrycket och öka produktionseffektiviteten. Återinjektion av nedkyld vätska kan, trots att den är mestadels fördelaktig, ha oönskade effekter, såsom kylning av närliggande produktionsbrunnar och injektionsinducerad seismisk aktivitet. Spårprov, som möjliggör spårning av en kemikalie inom systemet, tillsammans med modellering, är viktiga verktyg för att förstå flödesvägarna för det injicerade vattnet samt att kunna förutsäga nedkylningar av vattenmagasin. Kunskap om flödesvägar i systemet möjliggör bättre resurshantering och ett mer hållbart användande. En simuleringsmodell av återinjektionszonen för det geotermiska kraftverket Hellisheiði på sydvästra Island, Húsmúli, utvecklades med hjälp av simuleringsprogrammet TOUGH2. Dess hydrologiska parametrar, permeabilitet och porositet, kalibrerades med hjälp av resultat från ett omfattande spårtest som utfördes i området 2013-2015. Syftet med simuleringarna var att få en bättre förståelse av flödesvägarna i Húsmúli. Detta er inressant eftersom trots en snabb återhämtning av spårämne i produktionsbrunnar, har knappt någon kylning observerats i området. Resultaten visar att återhämtningen av spårämnet inte kan modelleras med ett homogent medium, men kan istället modelleras genom att bygga permeabla strömningskanaler inom mediet. Goda resultat för spårämnesankomst och koncentrationstoppar erhölls både genom att använda en enda bred kanal och flera smalare. Kanalerna ger en abstrakt representation av sprickzoner inom mediet. Större kylning observerades för modelleringsmetoden med en enkel bred kanal än med flera smalare kanaler. Detta indikerar att flödesvägarna i området troligtvis går genom flera sprickzoner. Flödesvägarna förlängs genom att vätskan sjunker till ett större djup på grund av den högre densiteten hos det injicerade vattnet. Detta innebär att den injicerade vätskan värms upp genom kontakt med en större volym berg, vilket medför en begränsad och fördröjd kylningseffekt.

A construção de reservatórios modifica drasticamente a paisagem transformando um ambiente lótico em lêntico e criando uma nova linha de margem com características muitas vezes diferentes. Estes novos habitats são passíveis a utilização e colonização por diversas espécies. Com relação aos crocodilianos existem registros de ocorrência para três espécies nesta região Caiman crocodilus, Paleosuchus palpebrosus e Melanosuchus niger. O presente estudo verificou abundância, densidade, taxa entre os sexos e o uso de habitat para as espécies C. crocodilus e P. palpebrosus, encontradas no reservatório em um período de dez meses de monitoramento pós-represamento. Para efetuar as observações e capturas de indivíduos, focagens noturnas em barco a motor foram realizadas ao longo de cinco campanhas bimestrais. Foram visualizados 659 jacarés sendo 259 C. crocodilus, 102 P. palpebrosus e 298 indeterminados. Nenhum exemplar da espécie M. niger foi observado. O número de crocodilianos por campanha não variou de forma significativa, sendo C. crocodilus mais freqüente. Foram efetuadas 75 capturas, sendo 43 C. crocodilus (21 ♀ e 22 ♂ ) e 32 P. palpebrosus (10 ♀ e 22 ♂). A eficiência de captura foi de 16,60% para C. crocodilus, 31,37% para P. palpebrosus e 11,38% para ambas as espécies considerando também os indeterminados. A captura de exemplares de P. palpebrosus foi mais eficiente se comparada a de C. crocodilus. Foram capturados 29 filhotes entre o final da estação chuvosa e o pico da estação seca, nas três últimas campanhas, evidenciando reprodução pós-represamento, sendo 26 C. crocodilus e 3 P. palpebrosus. Os filhotes de C. crocodilus foram observados agrupados em três regiões diferentes sendo que um destes agrupamentos se manteve no mesmo local pelas três últimas campanhas apresentando redução paulatina do número de filhotes. Os três filhotes agrupados de P. palpebrosus só foram observados na quinta campanha. A classificação não-supervisionada de imagens LANDSAT – TM, resultou em oito classes (manchas de habitats) representando 93% da área. Tais manchas foram caracterizadas a partir de anotações de campo e interpretação da imagem. A macha 1, caracterizada como um buritizal alagado próximo ao aeroporto, foi a que apresentou as maiores densidades 60 e 110 ind/km2 para C. crocodilus e P. palpebrosus respectivamente, explicada pela reduzida área ocupada por este habitat. A mancha 2 foi caracterizada como água com sedimento apresentando os maiores valores para área total e amostrada e conseqüentemente baixas densidades. A mancha 3 caracterizada como margem rasa apresentou a maior abundância para C. crocodilus. A mancha 5 caracterizada como solo arenoso não se destacou por elevadas densidades sendo porém a mais abundante para P. palpebrosus. As manchas 6, 7 e 8 se agrupadas mediante a caracterização como habitats de vegetação seca apresentam a segunda maior densidade com 27,55 ind/km2. A mancha 9 foi caracterizada como um habitat onde ocorria a presença de gramíneas (pasto e cerrado campo limpo) sendo C. crocodilus a espécie predominante neste habitat. Conclui-se com este trabalho que C. crocodilus e P. palpebrosus são as espécies de crocodilianos encontradas na região do reservatório e não se mostram relativamente vulneráveis, em um primeiro momento, devido ao represamento do rio. C. crocodilus é mais abundante do que P. palpebrosus no reservatório. C. crocodilus é mais seletivo quanto ao uso das manchas de habitats definidos A observação de grupos de filhotes corrobora para o fato destas espécies se adequarem ao novo ambiente. / The construction of river dams modifies drastically the local landscape, changing a lotic environment into a lentic one and, therefore, originating a new river edge, generally with quite different features. These new habitats could be used and occupied by a plenty of species. There are many projects, constructions and dams in most of its main rivers. Regarding the crocodilians, there are three species recorded in this region: Caiman crocodilus, Paleosuchus palpebrosus, and Melanosuchus niger. The present study verified the abundance, density, sex ratio, and habitat use of Caiman crocodilus and Paleosuchus palpebrosus. These species were found in the dam during a monitoring period of ten months carried out after flooding. Observations and captures were performed during nocturnal surveys using a motorboat. The surveys occurred in five campaigns with intervals of two months. 659 crocodilians, 259 C. crocodilus, 102 P. palpebrosus and 298 undetermined were visualized considering all campaigns. None specimens of M. niger were observed. The number of crocodilians by campaign did not show significant variation and C. crocodilus was the most frequent species. We captured 75 specimens, 43 C. crocodilus (21 ♀ and 22 ♂), and 32 P. palpebrosus (10 ♀ and 22 ♂). Capture effectiveness was 16.60% for C. crocodilus, 31.37% for P. palpebrosus, and 11.38% for both species considering the undetermined specimens. Capture of specimens of P. palpebrosus was more effective compared to C. crocodilus. Twenty nine hatchlings (26 C. crocodilus and 3 P. palpebrosus) were captured between the end of rainy season and the peak of dry season (during the last three campaigns), suggesting reproductive activity after flooding. Hatchlings of C. crocodilus were observed in groups in three different areas. One of these groupings was in the same place during the last three campaigns, showing a slight decrease in number of hatchlings. The three hatchlings of P. palpebrosus were observed only in the last campaign. The unsupervised classification of the LANDSAT – TM images, resulted in eight classes (habitat patches) which represented 93% of the dam. The patches were characterized based on field notes and image interpretation. Patch 1, characterized as a flooded “buritizal” near the airport, showed the highest density (60 and 110 individuals/km2 of the C. crocodilus and P. palpebrosus, respectively). Patch 2 was characterized by water with sediments, representing a great percentage of the sampled and total area and, consequently, showed the lowest density of crocodiles. Patch 3 represents shallow edges and showed the largest abundance of C. crocodilus. Patch 5 represents sandy grounds and, even though this habitat showed no high densities, P. palpebrosus was more abundant in this habitat. Patches 6, 7 and 8 were considered as dry vegetation, showing the second major density (27.55 individuals/km2). Patch 9 was characterized by the presence of grass (pasture and “cerrado campo limpo”) and C. crocodilus was the predominant species in this habitat. It can be concluded that C. crocodilus e P. palpebrosus are the species that occur in the dam and, apparently, they are not vulnerable due to the river modifications. C. crocodilus is more abundant than P. palpebrosus in the study area. C. crocodilus is more selective than P. palpebrosus in function of habitat patches. The presence of hatchlings corroborate to the species adaptation to the new habitats.