• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 9
  • 8
  • 7
  • 6
  • 5
  • Tagged with
  • 91
  • 91
  • 52
  • 29
  • 28
  • 20
  • 18
  • 13
  • 11
  • 10
  • 10
  • 10
  • 10
  • 9
  • 9
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Análise e gerenciamento dos efluentes gerados no processo produtivo do combustível nuclear / Analysis and management of effluents generated in the nuclear fuel production process

Mayara Costa de Castro Becca Sakai 05 December 2017 (has links)
O Brasil com o propósito de se tornar autossuficiente na produção de radioisótopos e fontes radioativas usados na medicina nuclear, na agricultura e no meio ambiente desenvolveu o projeto de um reator multipropósito de 30 megawatts de potência para atender a demanda nacional. No Instituto de Pesquisas Energéticas e Nucleares (IPEN), o Centro de Combustível Nuclear (CCN) é responsável pela fabricação dos combustíveis para o reator IEA-R1 e, possivelmente, pelos combustíveis do reator multipropósito. Com o intuito de atender a demanda para os reatores foi projetada uma nova planta de fabricação com a capacidade máxima de 60 combustíveis por ano, o qual atualmente é de dez. O aumento da produção consequentemente aumentará o volume de efluentes gerados. A atual preocupação com o meio ambiente faz-se necessário elaborar um plano de gestão para tornar o processo sustentável, o qual ocasionará em benefícios ambientais, econômicos e sociais. O processo produtivo do combustível gera vários tipos de efluentes, contendo urânio ou não, sendo sólidos, líquidos e gasosos com características físicas e químicas variadas. Esse estudo tem como objetivo identificar, caracterizar e segregar os efluentes gerados em todo o processo produtivo de obtenção do combustível nuclear do tipo MTR (Materials Testing Reactors). No desenvolvimento do presente trabalho foram utilizadas como base a Resolução n° 357, de 17 de março 2005, e a Resolução n° 430, de 13 de maio de 2011 do Conselho Nacional do Meio Ambiente CONAMA. Com os resultados obtidos foi possível determinar que os efluentes líquidos são os principais aspectos que podem causar contaminação ao meio ambiente, e a atual situação do CCN mostra que 30% do efluente líquido possui tratamento de recuperação de urânio; 20% dos efluentes líquidos são reutilizados na composição química em que foi gerado; 35% descartado diretamente ao meio ambiente de acordo com a legislação. O restante dos efluentes líquidos, cerca de 15%, estão em fase de desenvolvimento do processo de tratamento. / Brazil with the purpose of becoming self-sufficient in the production of radioisotopes and radioactive sources used in nuclear medicine, agriculture and the environment has developed the project of a multipurpose reactor of 30 megawatts of power to meet the national demand. At the Instituto de Pesquisas Energéticas e Nucleares (IPEN), the Centro de Combustível Nuclear (CCN) is responsible for manufacturing fuels for the IEA-R1 reactor and, possibly, the multipurpose reactor fuels. In order to meet the demand for the reactors, a new manufacturing plant with a maximum capacity of 60 fuels per year has been designed, which is currently ten. The increase in production will consequently increase the volume of effluents generated. The current concern with the environment makes it necessary to elaborate a management plan to make the process sustainable, which will lead to environmental, economic and social benefits. The production process of the fuel generates several types of effluents - containing uranium or not - being solid, liquid and gaseous with varied physical and chemical characteristics. This study aims to identify, characterize and segregate the effluents generated in the entire production process of obtaining the nuclear fuel type MTR (Materials Testing Reactors). In the development of this paper, Resolution 357 of March 17, 2005, and Resolution No. 430 of May 13, 2011 of the National Environmental Council - CONAMA, were used. With the results obtained it was possible to determine that the liquid effluents are the main aspects that can cause contamination to the environment, and the current situation of the CCN shows that 30% of the liquid effluent has uranium recovery treatment; 20% of the liquid effluents are reused in the chemical composition in which it was generated; 35% discarded directly to the environment according to the legislation. The rest of the liquid effluents, about 15%, are in the development phase of the treatment process.
32

Um estudo sobre o efeito dominó em instalações do ciclo do combustível nuclear / A STUDY ON DOMINO EFFECT IN NUCLEAR FUEL CYCLE FACILITIES

Jean Claude Bozzolan 28 November 2006 (has links)
Os acidentes causados pelo efeito dominó são dos mais graves ocorridos na indústria química e de processo. Mesmo sendo o potencial destrutivo desses eventos acidentais bastante conhecido, pouca atenção tem sido dada a este problema pela literatura técnica e uma metodologia completa e aprovada para a avaliação quantitativa da contribuição do efeito dominó ao risco industrial ainda não está plenamente desenvolvida. O presente estudo propõe um procedimento sistemático para a avaliação quantitativa do efeito dominó em plantas químicas do ciclo do combustível nuclear. O trabalho é baseado em avanços recentes feitos na modelagem de danos a equipamentos de processo causados por incêndios e explosões devido aos vetores de propagação (radiação de calor, sobrepressão e projeção de fragmentos). Dados disponíveis na literatura técnica e novos modelos de vulnerabilidade deduzidos para diversas categorias de equipamentos de processo foram utilizados no presente trabalho. O procedimento proposto é aplicado a uma área de tancagem típica de uma planta de reconversão situada em um sítio que abriga varias outras instalações do ciclo do combustível nuclear. São analisados os vários eventos iniciadores, seus vetores de propagação, as conseqüências desses eventos e as freqüências associadas ao efeito dominó. / Accidents caused by domino effect are among the most severe accidents in the chemical and process industry. Although the destructive potential of these accidental scenarios is widely known, little attention has been paid to this problem in the technical literature and a complete methodology for quantitative assessment of domino accidents contribution to industrial risk is still lacking. The present study proposed a systematic procedure for the quantitative assessment of the risk caused by domino effect in chemical plants that are part of nuclear fuel cycle plants. This work is based on recent advances in the modeling of fire and explosion damage to process equipment due to different escalation vectors (heat radiation, overpressure and fragment projection). Available data from literature and specific vulnerability models derived for several categories of process equipment had been used in the present work. The proposed procedure is applied to a typical storage area of a reconversion plant situated in a complex that shelters other nuclear fuel cycle facilities. The top-events and escalation vectors are identified, their consequences estimated and credible domino scenarios selected on the basis of their frequencies.
33

Diretrizes para implantação de um sistema de gestão ambiental no ciclo do combustível nuclear: estudo de caso da USEXA - CEA / Guidelines for implementation of an environmental management system in the nuclear fuel cycle: a case study of USEXA-CEA

Mattiolo, Sandra Regina 29 November 2012 (has links)
As normas de gestão ambiental têm por objetivo prover as organizações dos elementos necessários para implantação de Sistemas da Gestão Ambiental (SGA) que possam ser integrados a outros requisitos da gestão, e auxiliá-las a alcançar seus objetivos ambientais e econômicos. A Unidade de Produção de Hexafluoreto de Urânio USEXA, do Centro Tecnológico da Marinha em São Paulo - CTMSP, será a primeira planta industrial da etapa de conversão do ciclo do combustível nuclear (produção de hexafluoreto de urânio UF6) do Brasil, permitindo que seja agregado valor ao minério de urânio. Neste trabalho, o SGA proposto para a USEXA, permite disciplinar suas interfaces com o meio ambiente, uma vez que as Normas da CNEN Comissão Nacional de Energia Nuclear e da AIEA Agência Internacional de Energia Atômica para instalações nucleares, na sua grande maioria, visam a atender a critérios de segurança para o público e o meio ambiente, apenas nos quesitos envolvendo radiações ionizantes. O modelo de SGA desenvolvido preenche as lacunas das normas da CNEN e da AIEA, por considerar os impactos ambientais decorrentes do uso de substâncias químicas no processo de fabricação de UF6 e os aspectos gerais de sustentabilidade. Isso pode ser considerado uma contribuição original dentro das complexas atividades que abrangem o processamento de urânio no ciclo do combustível nuclear. Como resultado, esta pesquisa propõe, para avaliação de impactos ambientais, a adoção de um filtro de significância, relacionado à localização do empreendimento, apresenta um Manual do Sistema de Gestão para a USEXA e sugere modelos de treinamentos em gestão de pessoal, como o coaching e a programação neurolinguística, e que poderão ser aplicados em qualquer Sistema de Gestão. Os treinamentos podem ser considerados como uma ação preventiva, por contribuírem para diminuir os incidentes relacionados à manutenção de equipamentos e consequentemente a ocorrência de impactos ambientais. / The environmental management standards are intended to provide to the organizations the elements needed for the implementation of an Environmental Management System (EMS) that can be effectively integrated to another management requirements and assist them to achieve their environmental and economic goals. The Uranium Hexafluoride Production Unit - USEXA, located at the Navy Technological Center in São Paulo, will be the first Brazilian industrial plant responsible for the conversion stage in the nuclear fuel cycle (production of uranium hexafluoride UF6), allowing added-value to the uranium ore. The EMS proposed to USEXA in this project allows to regulate its interfaces with the environment, since the Standards of CNEN - National Commission of Nuclear Energy and of the IAEA - International Atomic Energy Agency for Nuclear Installations, aim, mostly, to attend the security criteria for the population and the environment, concerning ionizing radiation. This model of EMS fills the gaps in standards of IAEA and CNEN, since it takes into account the environmental impacts from the use of chemicals in the manufacturing process of UF6, and general aspects of sustainability. It can be considered an original contribution within the complex activities that includes the uranium processing in the nuclear fuel cycle. This research proposes, as result, the use of a filter of significance to evaluate the environmental impacts depending on the installation location. It is also presented the Management System Manual for USEXA and models for training in personnel management are suggested, such as coaching and neurolinguistic programing, which can be applied to any Management System. The trainings can be considered a preventive action as they considerably decreased incidents related to equipments maintenance and thus the occurrence of environmental impacts.
34

Diretrizes para implantação de um sistema de gestão ambiental no ciclo do combustível nuclear: estudo de caso da USEXA - CEA / Guidelines for implementation of an environmental management system in the nuclear fuel cycle: a case study of USEXA-CEA

Sandra Regina Mattiolo 29 November 2012 (has links)
As normas de gestão ambiental têm por objetivo prover as organizações dos elementos necessários para implantação de Sistemas da Gestão Ambiental (SGA) que possam ser integrados a outros requisitos da gestão, e auxiliá-las a alcançar seus objetivos ambientais e econômicos. A Unidade de Produção de Hexafluoreto de Urânio USEXA, do Centro Tecnológico da Marinha em São Paulo - CTMSP, será a primeira planta industrial da etapa de conversão do ciclo do combustível nuclear (produção de hexafluoreto de urânio UF6) do Brasil, permitindo que seja agregado valor ao minério de urânio. Neste trabalho, o SGA proposto para a USEXA, permite disciplinar suas interfaces com o meio ambiente, uma vez que as Normas da CNEN Comissão Nacional de Energia Nuclear e da AIEA Agência Internacional de Energia Atômica para instalações nucleares, na sua grande maioria, visam a atender a critérios de segurança para o público e o meio ambiente, apenas nos quesitos envolvendo radiações ionizantes. O modelo de SGA desenvolvido preenche as lacunas das normas da CNEN e da AIEA, por considerar os impactos ambientais decorrentes do uso de substâncias químicas no processo de fabricação de UF6 e os aspectos gerais de sustentabilidade. Isso pode ser considerado uma contribuição original dentro das complexas atividades que abrangem o processamento de urânio no ciclo do combustível nuclear. Como resultado, esta pesquisa propõe, para avaliação de impactos ambientais, a adoção de um filtro de significância, relacionado à localização do empreendimento, apresenta um Manual do Sistema de Gestão para a USEXA e sugere modelos de treinamentos em gestão de pessoal, como o coaching e a programação neurolinguística, e que poderão ser aplicados em qualquer Sistema de Gestão. Os treinamentos podem ser considerados como uma ação preventiva, por contribuírem para diminuir os incidentes relacionados à manutenção de equipamentos e consequentemente a ocorrência de impactos ambientais. / The environmental management standards are intended to provide to the organizations the elements needed for the implementation of an Environmental Management System (EMS) that can be effectively integrated to another management requirements and assist them to achieve their environmental and economic goals. The Uranium Hexafluoride Production Unit - USEXA, located at the Navy Technological Center in São Paulo, will be the first Brazilian industrial plant responsible for the conversion stage in the nuclear fuel cycle (production of uranium hexafluoride UF6), allowing added-value to the uranium ore. The EMS proposed to USEXA in this project allows to regulate its interfaces with the environment, since the Standards of CNEN - National Commission of Nuclear Energy and of the IAEA - International Atomic Energy Agency for Nuclear Installations, aim, mostly, to attend the security criteria for the population and the environment, concerning ionizing radiation. This model of EMS fills the gaps in standards of IAEA and CNEN, since it takes into account the environmental impacts from the use of chemicals in the manufacturing process of UF6, and general aspects of sustainability. It can be considered an original contribution within the complex activities that includes the uranium processing in the nuclear fuel cycle. This research proposes, as result, the use of a filter of significance to evaluate the environmental impacts depending on the installation location. It is also presented the Management System Manual for USEXA and models for training in personnel management are suggested, such as coaching and neurolinguistic programing, which can be applied to any Management System. The trainings can be considered a preventive action as they considerably decreased incidents related to equipments maintenance and thus the occurrence of environmental impacts.
35

Management Tool for Assessment of Alternative Fuel Cycles

Preston, Jeffrey R 01 August 2010 (has links)
A new approach to fuel cycle uncertainty analysis and optimization is presented that combines reactor physics information, spent fuel management, and economic forecasting, which may be used to investigate effects of decisions in the design of advanced nuclear fuel cycles. The Matlab-based simulation includes isotopic mass and integral decay heat data produced by reactor physics codes in the SCALE package (SAS2, ORIGEN-ARP, and ORIGEN-S). Reactor physics data for Light Water Reactor (LWR), and metal- and oxide-fueled Liquid Metal-cooled Fast Burner Reactor (LMFBR) designs are stored in databases that the code uses as needed. Detailed models of the once through and hybrid LWR-LMFBR fuel cycles have been developed for repository decay heat analysis, determination of levelized unit electric cost (LUEC), and reprocessing of spent fuel into fast reactor fuel or targets as a means of isotopic inventory minimization. The models may be run for single estimates based on best estimates of model parameters as either a Monte Carlo uncertainty analysis or as an optimization using Genetic Algorithms (GA). Results from the LUEC calculations show the once through cycle has a bus bar cost of about $19.0mills/kWh (excluding repository and interim storage costs), and the hybrid cycle has a bus bar cost of about $26.5mills/kWh. Implementation of the hybrid cycle compared to the closed once through cycle yields an effective repository mass capacity increase by a percentage of about 30% to 60% through full reprocessing of LWR spent fuel compared to original mass definitions of the Yucca Mountain repository. The GA optimization routine allows the user to define any one of the variables present in the output structure as the fitness parameter; thus, optimization of any calculated value is possible, including economic cost, isotopic inventory, or required repository capacity. Optimization of the once through cycle with respect to LUEC gives a result of $19.2 mills/kWh when burn up approaches the upper limit of 60 GWd/t and delay time spent fuel cools after discharge approaches 200 years (including repository and interim storage costs).
36

Subcritical transmutation of spent nuclear fuel

Sommer, Christopher Michael 07 July 2011 (has links)
A series of fuel cycle simulations were performed using CEA's reactor physics code ERANOS 2.0 to analyze the transmutation performance of the Subcritical Advanced Burner Reactor (SABR). SABR is a fusion-fission hybrid reactor that combines the leading sodium cooled fast reactor technology with the leading tokamak plasma technology based on ITER physics. Two general fuel cycles were considered for the SABR system. The first fuel cycle is one in which all of the transuranics from light water reactors are burned in SABR. The second fuel cycle is a minor actinide burning fuel cycle in which all of the minor actinides and some of the plutonium produced in light water reactors are burned in SABR, with the excess plutonium being set aside for starting up fast reactors in the future. The minor actinide burning fuel cycle is being considered in European Scenario Studies. The fuel cycles were evaluated on the basis of TRU/MA transmutation rate, power profile, accumulated radiation damage, and decay heat to the repository. Each of the fuel cycles are compared against each other, and the minor actinide burning fuel cycles are compared against the EFIT transmutation system, and a low conversion ratio fast reactor.
37

Modeling energy consumption in the mining and milling of uranium

Tavrides, Emily Loree 16 February 2011 (has links)
A family of top-down statistical models describing energy consumption in the mining, milling, and refining of uranium are formulated. The purpose of the models is to estimate the energy-to-grade dependence for uranium extraction, while defining a minimum grade that can be feasibly mined and produced. The results serve as a basis for understanding the factors governing energy consumption in the production of U3O8. The models are applied to a considerably larger data set of operating mines than in any previous effort. In addition, the validity of the modeling approach is established by modeling energy for two other commodities, gold and copper, thereby showing it can be applied to other metals. Statistical measures of explanatory power show that the models the energy-to-grade relationship is well-described for both uranium and gold. For copper, there was insufficient data over a broad range of ore grades to obtain a model that passed statistical confidence measures. The results show that mining of lower-grade deposits of uranium is likely to be less energy-intensive than previous investigators concluded. It is shown that the uncertainty in the results is dominated by the contribution of the grade-independent component of energy consumption. / text
38

Analise multielementar e isotopica em compostos de uranio por espectrometria de massa com fonte de plasma induzido ( ICPMS )

OLIVEIRA JUNIOR, OLIVIO P. de 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:44:24Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:23Z (GMT). No. of bitstreams: 1 06890.pdf: 3271433 bytes, checksum: 57399ce5f630231a9b2741455ed096f0 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
39

Nova metodologia para o estudo da recuperacao do uranio nas escorias provenientes da producao do uranio metalico

FERRETO, HELIO F.R. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:43:12Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:02Z (GMT). No. of bitstreams: 1 06478.pdf: 3954633 bytes, checksum: a468f19b7b9160929a0d8d79444b6ed2 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
40

Analise de perigos em instalacoes de enriquecimento isotopico de uranio

LAURICELLA, CHRISTIANE M. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:25:33Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:38Z (GMT). No. of bitstreams: 1 06172.pdf: 5264843 bytes, checksum: a22f14e596334a88838be0798f8a00e9 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Page generated in 0.0579 seconds