Este trabalho é baseado nos estudos das reações nucleares da Pt, como outras reações já observadas na literatura atual. Trata-se de reação de transmutação, onde o eletrodo de Pt em uma célula eletroquímica passa a apresentar traços de Au. Este estudo tem como finalidade a obtenção de dados que irão contribuir para o entendimento de algumas reações já estudadas como Reações Nucleares de Baixa Energia (LENR) ou Reações Nucleares Quimicamente Assistidas (CANR). Nestes estudos foram utilizados uma célula eletroquímica simples e alguns equipamentos de medida. Usou-se como eletrólito KOH em concentração de 0,17 M, embora a maioria dos trabalhos da literatura tenha usado LiOD ou hidróxido de Lítio com água pesada. Usou-se tensões mais elevadas do que é usual em eletrólise alcalina da água. Foram usadas tensões de 7 a 15 V, de forma a se obter uma densidade de corrente da ordem de 100mA /cm2. Além destas modificações, usou-se uma eletrólise convencional. Os resultados obtidos por estas eletrólises produziram micrografias com aspecto indicativos de Ouro, ou seja regiões amarelas sobre um metal branco. As análises realizadas por EDX e por chapas radiográficas confirmaram a presença de Au e seus radioisótopos. A análise microscópica realizada na superfície destes eletrodos mostraram pontos amarelos que após um tempo longo a cor é modificada visivelmente. Outro fato sugestivo dessas mudanças é o que foi encontrado por estudos radiográficos sensíveis à radiação gama, onde foi confirmada esse tipo de emissão ao longo do tempo. Os dados experimentais sugerem que as reações químicas acontecem na superfície do eletrodo e não como mostra a literatura, no interior da grade cristalina. / This paper is based on studies of nuclear reactions of Pt, as well as other reactions already observed in current literature. It is a transmutation reaction where the Pt electrode in an electrochemical cell begins to present traces of Au. The purpose of this study is to obtain data that will contribute towards an understanding of some reactions already studied, such as Low Energy Nuclear Reactions (LENR) or Chemically Assisted Nuclear Reactions (CANR). These studies used a simple electrochemical cell and some measuring equipment. A KOH electrolyte was used at a concentration of 0.17 M, although most studies found in literature had used LiOD or Lithium Hydroxide with heavy water. Higher voltages than normal were used in this alkaline electrolysis of the water. Voltages from 7 to 15 V were used in order to obtain a current density of 100 mA/cm2. Besides these modifications, conventional electrolysis was used. The results obtained from such electrolysis produced micrographs which indicated Gold, that is, yellow areas on a white metal. Analyses made by EDX or radiographs confirmed the presence of Au and its radioisotopes. The micrographic analysis conducted on the surface of these electrodes revealed yellow spots. The color changed visibly over a long period of time. Another suggestive fact regarding these changes is what was found by radiograph studies sensitive to gamma radiation, where this type of emission was confirmed over time. The experimental data suggest that the chemical reactions occur on the surface of the electrode and not, as shown in literature, within the crystal structure.

In this thesis, the feasibility to use sodium cooled fast reactors loaded with MOX, metallic and nitride fuels for efficient transmutation of americium is investigated by performing transient analysis for cases with different americium contents in fuels, using safety parameters obtained with the SERPENT Monte Carlo code. It was then demonstrated that there is no solid limit for the Am introduction into oxide, metallic and nitride fuels that were loaded into sodium fast reactors. Instead, higher Am contents could be permitted if specific levels of power penalty were accepted. Transient analysis of a new Accelerator Driven System design with higher neutron source efficiency than the reference EFIT-400 design, was also performed. Based on simulation results, the suggested ADS design was proved to survive the full set of transients, preserving 130 K margin to cladding rupture during the most limiting transient. After comparing Am transmutation performances in SFRs and the suggested ADS, it can be concluded that: 1. Nitride fuel could provide the highest Am transmutation efficiency, when loaded into SFRs; 2. One SFR loaded with nitride fuel is sufficient to transmute Am inventory produced by more than 15 commercial LWRs within the same time period, which is three times higher than the supporting ratio reported for the suggested ADS; 3. The total fraction of ADS power in the power park is half of cases for critical reactors. / QC 20120201

The advanced fuels investigated in this thesis comprise fuels non− conventional in their design/form (TRISO), their composition (high content of plutonium and minor actinides) or their use in a reactor type, in which they have not been used before (e.g. nitride fuel in BWR). These fuels come with a promise of improved characteristics such as safe, high temperature operation, spent fuel transmutation or fuel cycle extension, for which reasons their potentialis worth assessment and investigation. Their possible use also brings about various challenges, out of which some were addressed in this thesis. TRISO particle fuels with their superior retention abilities enable safe, high−temperature operation. Their combination with molten salt in the Advanced High Temperature Reactor (AHTR) concept moreover promises high operating temperature at low pressure, but it requires a careful selection of the cooling salt and the TRISO dimensions to achieve adequate safety characteristic, incl. a negative feedback to voiding. We show that an AHTR cooled with FLiBe may safely operate with both Pu oxide and enriched U oxide fuels. Pu and Minor Actinides (MA) bearing fuels may be used in BWR for transmutation through multirecycling; however, the allowable amounts of Pu and MA are limited due to the degraded feedback to voiding or low reactivity.We showed that the main positive contribution to the void effect in the fuelswith Pu and MA content of around 11 to 15% consist of the decreased thermalcapture probability in Pu-240, Pu-239 and Am-241 and increased fast and resonance fission probability of U-238, Pu239 and Pu-240. The total void worthmoreover increases during multirecycling, limiting the allowable amount ofMA to 2.45% in uranium−based fuels. An alternative, thorium−based fuel allows for 3.45% MA without entering the positive voiding regime at any point of the multirecycling. The increased alpha−heating associated with the use of transmutation fuels, is at level 24−31 W/kgFUEL in the uranium based fuels and 32−37 W/kgFUEL in the thorium−based configurations. The maximum value of the neutron emission, reached in the last cycle, is 1.7·106 n/s/g and 2·106 n/s/g for uranium and for thorium−based fuels, respectively. Replacing the standard UO2 fuel with higher−uranium density UN orUNZrO2 fuels in BWR shows potential for an increase of the in-core fuelresidence time by about 1.4 year. This implies 1.4% higher availability of the plant. With the nitride fuels, the total void worth increases and the efficiency of the control rods and burnable poison deteriorates, but no major neutronics issue has been identified. The use of nitride fuels in the BWR environment is conditioned by their stability in hot steam. Possible methods for stabilizing nitride fuels in water and steam at 300◦ C were suggested in a recent patentapplication. / <p>QC 20121004</p>

CANDU (CANada Deuterium Uranium) reactor utilizes Pressure Tube (PT) fuel channel design and heavy water as a coolant. Fuel channel annulus gas acts as an insulator to minimize heat losses from the coolant to the moderator. Since fuel bundles are continuously under high neutron fluxes, annulus gas nuclides undergo different nuclear transformations generating new composition of the gas that might have different physical properties which are undesirable for the annulus system. In addition, gas nuclides become radioactive and lead to an increase of the radioactive material inventory in the reactor and consequently to an increase of radiation levels. Pressure Tube Reactor (PTR) and Pressure Tube Supercritical Water Reactor (PT SCWR) fuel channel models have been developed in Monte Carlo N-Particle (MCNP) code. Neutron fluxes in the fuel channel annulus gas have been obtained by simulating different types of neutron sources in both PTR and PT SCWR fuel channels. Transmutation rates of annulus gases have been calculated for different gases (CO2, N2, Ar and Kr) at different pressures and temperatures in both fuel channels. The variation of the transmutation rates, neutron fluxes and gas densities in the annulus gas have been investigated in PTR and PT SCWR fuel channels at constant pressures and different temperatures. MCNP code along with NIST REFPROP [14] and other software tools have been used to conduct the calculations. / UOIT

La loi française du 28 juin 2006, sur la gestion des déchets radioactifs, demande une évaluation pour définir la future stratégie industrielle. L'étude présentée ici, concerne plus spécifiquement l'axe de recherche sur la transmutation des actinides mineurs. Dans ce but, un concept d'ADS (Accelerator DrivenSystem) de haute puissance a été développé à SUBATECH. Dans ce réacteur sous-critique, un faisceau de protons de 1 GeV alimente trois cibles de spallation de plomb-bismuth. L'ADS MUST (MUltipleSpallation Target) peut ainsi atteindre une puissance thermique de plus de 1 GW avec une densité de puissance élevée. Une méthode de dimensionnement de ces réacteurs a été développée et appliquée pour différents scénarios double strate. Dans ces scénarios, des réacteurs électrogènes de type SFR (Sodium Fast Reactors) ou REP (Réacteurs à Eau Pressurisée) produisent des actinides mineurs destinés à être transmutés en ADS. Dans chaque cœur, un multi-recyclage du plutonium est réalisé et dans les réacteurs sous-critiques les éléments à transmuter le sont également. Pour limiter la réactivité du cœur et améliorer la conductivité thermique, le combustible contenant les actinides mineurs est mélangé à une matrice inerte de MgO. Des filières, avec des ADS à caloporteurs plomb et sodium, ont été étudiées pour différentes durées d'irradiation, et deux stratégies de transmutation : soit l'ensemble des actinides mineurs, soit seulement l'américium est incinéré. Le dimensionnement des ADS MUST de chaque filière et de leur combustible à l'équilibre est présenté dans cette thèse. Puis l'évolution du combustible et du coefficient de multiplication, sur un cycle, est réalisée et analysée. La radiotoxicité et la puissance thermique des déchets produits sont ensuite comparées. Enfin, l'étude de scénarios double strate est effectué afin d'analyser les inventaires d'actinides mineurs et de plutonium en cycle, ainsi que les déchets produits en fonction de la stratégie de transmutation adoptées et de l'évolution de la première strate.

Dual phase magnesia-zirconia ceramics were developed, characterized, and evaluated as a potential matrix material for use in light water reactor inert matrix fuel intended for the disposition of plutonium and minor actinides. Ceramics were fabricated from the oxide mixture using conventional pressing and sintering techniques. Characterization of the final product was performed using optical microscopy, scanning electron microscopy, x-ray diffraction analysis, and energy-dispersive x-ray analysis. The final product was found to consist of two phases: cubic zirconia-based solid solution and cubic magnesia. Evaluation of key feasibility issues was limited to investigation of long-term stability in hydrothermal conditions and assessment of the thermal conductivity. With respect to hydrothermal stability, it was determined that limited degradation of these ceramics at 300^oC occurred due to the hydration of the magnesia phase. Normalized mass loss rate, used as a quantitative indicator of degradation, was found to decrease exponentially with the zirconia content in the ceramics. The normalized mass loss rates measured in static 300^oC de-ionized water for the magnesia-zirconia ceramics containing 40, 50, 60, and 70 weight percent of zirconia are 0.00688, 0.00256, 0.000595, 0.000131 g/cm2/hr respectively. Presence of boron in the water had a dramatic positive effect on the hydration resistance. At 300^oC the normalized mass loss rates for the composition containing 50 weight percent of zirconia was 0.00005667 g/cm2/hr in the 13000 ppm aqueous solution of the boric acid. With respect to thermal conductivity, the final product exhibits values of 5.5-9.5 W/(m deg) at 500^oC, and 4-6 W/(m deg) at 1200^oC depending on the composition. This claim is based on the assessment of thermal conductivity derived from thermal diffusivity measured by laser flash method in the temperature range from 200 to 1200^oC, measured density, and heat capacity calculated using rule of mixtures. Analytical estimates of the anticipated maximum temperature during normal reactor operation in a hypothetical inert matrix fuel rod based on the magnesia-zirconia ceramics yielded the values well below the melting temperature and well below current maximum temperatures authorized in light water reactors.

Thesis (Ph.D.)--McMaster University (Canada), 1989. / Source: Dissertation Abstracts International, Volume: 62-13, Section: A, page: 0000.

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ARAÚJO, Júlio César Rosa de. Os chats: uma constelação de gêneros na internet. 2006. 341f. – Tese (Doutorado) – Universidade Federal do Ceará, Departamento de Letras Vernáculas, Programa de Pós-graduação em Linguística, Fortaleza (CE), 2006. / Submitted by Márcia Araújo (marcia_m_bezerra@yahoo.com.br) on 2014-08-25T10:57:19Z No. of bitstreams: 1 2006_tese_jcraraujo.pdf: 3695407 bytes, checksum: 7da489a27bf06a724a4705329ddc6d5b (MD5) / Approved for entry into archive by Márcia Araújo(marcia_m_bezerra@yahoo.com.br) on 2014-08-25T15:34:21Z (GMT) No. of bitstreams: 1 2006_tese_jcraraujo.pdf: 3695407 bytes, checksum: 7da489a27bf06a724a4705329ddc6d5b (MD5) / Made available in DSpace on 2014-08-25T15:34:21Z (GMT). No. of bitstreams: 1 2006_tese_jcraraujo.pdf: 3695407 bytes, checksum: 7da489a27bf06a724a4705329ddc6d5b (MD5) Previous issue date: 2006 / In the present research my objective was to create a concept to the phenomenon of the constellation of genres. Thus, to define that category, about which I developed my Thesis, the theoretical and philosophical formularizations of Bakhtin relative to the uses of the language were my support. The text which relates this research is organized in two great parts. In the first one, I present my theoretical and methodological construction for the study of the constellations of genres, bringing as proposal the choice of the strongest characteristic of the communication sphere where the grouping of genres is, the observation of the formative process of those genres and the identification of the social functions that they realize. In the second part, I present the chats like an example of constellation of genres and I illustrate my theoretical and methodological construction through of seven different types of chats, focusing the hypertextuality, the transmutation of genres and the communicative purpose as the operational categories to the analysis. In this research, I tried give an ethnographic character through an intense exercise of participant observation, accessing many chat rooms in the Internet during three years. For obtaining the data, besides the participant observation, I did small interviews with some chatters by e-mail. After the triangulation of the data and its posterior analysis, I arrived to the following results: the constellation of chats assumes a hypertextual nature because such characteristic is what brings chats closer as for the aspect of their communication sphere; chats are genres that share the same formative phenomenon, in other words, everyone of them is formed by the transmutation and the reinterpretation of oral genres from various communication spheres; finally, chats become distinct of each one because they build a web of communicative purposes inside of the constellation in order to serve to several social functions. / O objetivo da presente pesquisa foi desenvolver um conceito que desse conta do fenômeno de agrupamentos genéricos designado aqui de constelação de gêneros. Para o alcance deste objetivo, a investigação se inscreve na base epistemológica das formulações teórico-filosóficas de Bakhtin, relativas aos usos da linguagem. A Tese foi organizada em duas grandes partes. Na primeira, apresento a elaboração de um percurso teórico-metodológico que permitiu elaborar um constructo de constelação de gêneros a partir da eleição de pelo menos uma característica marcante da esfera de comunicação em que se ambienta o agrupamento constelar, do processo formativo de seus gêneros e das funções sociais que eles realizam. Na segunda parte, ilustro a elaboração do constructo com a análise de sete tipos de chats, elegendo a hipertextualidade, a transmutação e o propósito comunicativo dos bate-papos virtuais como as categorias operantes para caracterização do agrupamento constelar desses gêneros. Para a construção dos dados, foi realizada uma pesquisa de caráter etnográfico na Internet durante três anos. A partir de um exercício intenso de observação participante, em diversas salas de chat, e de pequenas entrevistas realizadas por e-mail com alguns chatters, a triangulação dos dados e a sua posterior análise apontam para os seguintes resultados: a constelação dos chats assume uma natureza hipertextual, pois tal característica aproxima os gêneros quanto a este aspecto; os chats são gêneros que compartilham o mesmo fenômeno formativo, uma vez que todos transmutam e reinterpretam gêneros orais de variadas esferas de comunicação; finalmente, esses gêneros se tornam distintos entre si graças à teia de propósitos comunicativos que eles formam dentro da constelação para atender às mais diversas funções sociais.

Made available in DSpace on 2016-08-03T12:30:41Z (GMT). No. of bitstreams: 1 Adalgisa Nunes.pdf: 2141385 bytes, checksum: 5e9eeccb31b83ce34a0e24c1b4a68798 (MD5) Previous issue date: 2008-04-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This essay is focused on the analysis of Dona Flor and her two husbands, miniseries produced by Rede Globo Television in 1997 to the time of 22 hours and presented in 20 chapters. With general direction of Mauro Mendonça Filho it was adapted by Dias Gomes, with co-authors Marcílio Moraes and Ferreira Gullar from the homonym romance of the Bahian writer Jorge Amado, published for the first time in May of 1966 by the publisher Bookstore Martins, with circulation of 75 thousand copies. Our goal is to ensure quality treatment given to a specific theme, present in the novel and miniseries, that is, cooking, in the passage of the novel for television product under the focus of eroticism. As methodology, we used the qualitative method, and as a technique, the analysis of content. It was evident that from the passage of the novel to the television, cooking was depicted on a less erotised, for the book, according to the requirement of support, as well as its insertion trying to highlight the regional character of the miniseries.(AU) / Este trabalho é centrado na análise de Dona Flor e seus dois maridos, minissérie produzida pela Rede Globo de Televisão em 1997, para o horário das 22 horas e veiculada na emissora, em 20 capítulos. Com direção geral de Mauro Mendonça Filho foi adaptada por Dias Gomes, com co-autoria de Marcílio Moraes e Ferreira Gullar a partir do romance homônimo do escritor baiano Jorge Amado, publicado pela primeira vez em maio de 1966 pela editora Livraria Martins, com tiragem de 75 mil exemplares. Nosso objetivo foi verificar qualitativamente o tratamento dado a um tema específico, presente no romance e na minissérie, qual seja, a culinária, na passagem do romance para o produto televisivo, sob o foco do erotismo. Como metodologia utilizamos o método qualitativo, e como técnica, a análise de conteúdo. Demonstrou-se que na passagem do romance para a televisão, a culinária foi retratada de forma menos erotizada, em relação ao livro, em função da exigência do suporte, bem como sua inserção tratou de evidenciar o caráter regional da minissérie.(AU)