LUCAS STANO JUNQUEIRA
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Dissertação IPEN-doc 29737 Determinação da atividade de emissores beta e gama em rejeitos radioativos operacionais da central nuclear de Angra2023 - JUNQUEIRA, LUCAS S.Todo rejeito radioativo precisa ser caracterizado para que seu repositório final seja definido conforme os critérios de segurança apresentados nas normas CNEN 6.06 e CNEN 6.09. Neste trabalho foram adaptadas metodologias para analisar os rejeitos radioativos de concentrado de evaporador e resinas de troca iônica das usinas nucleares de Angra dos Reis e determinar a concentração de atividade dos seguintes radionuclídeos de difícil medição: 63Ni, 59Ni, 90Sr, 129I e 135Cs, que apresentaram rendimento de separação, em média de 93, 40, 97 e 73% respectivamente. O 63Ni e o 59Ni foram separados por cromatografia de troca iônica em coluna de Ni resin da Eichron Technologies, o 63Ni foi medido por cintilação líquida e o 59Ni por espectrometria gama. O 90Sr foi separado por cromatografia de troca iônica em coluna Sr-spec e precipitação com oxalato. O 135Cs foi separado por cromatografia de troca iônica em coluna com resina Dowex 50W-X12 e coprecipitação com molibdato de amônio e o 129I foi separado por precipitação com PdCl2. As concentrações de atividade em Bq/g encontradas para o 59Ni ficaram entre 123 e 1685, para o 63Ni entre 40 e 6,53X105, para o 129I entre 0,61 e 535, para o 90Sr entre 0,35 e 58,04 e o 135Cs teve todas as suas medidas abaixo dos limites de detecção que variaram de 2,7 a 349. A metodologia desenvolvida para a separação do iodo não foi encontrada na literatura e apresenta melhorias significativas quando comparada com os métodos atuais para a mesma determinação.Artigo IPEN-doc 26154 Determination of I-129 on radioactive waste from Angra 1 and 2 Power Plants2019 - JUNQUEIRA, LUCAS S.; ANGELINI, MATHEUS; ZAHN, GUILHERME S.; SILVA, PAULO S.C. daRadioactive waste must be characterized in order to be deposited in a suitable place for its confinement, avoiding any contamination of the environment. This study determined 129I, one of the difficult-to-measure nuclides that make up the radioactive waste from Angra 1 and 2 nuclear power plants. The methodology used a 129-I (1Bq/mL) liquid certified standard and consisted on guarantying that all the iodine was converted into iodide before the addition of PdCl2 for the precipitation of PdI2. After the separation procedure the 129I was quantified by gamma spectrometry by measuring its X-ray emissions with energies of 29.7 keV and 33.8 keV, as well as the gamma-ray emission of 39.6 keV. The chemical yield of the procedure was 74.4% (0,2).Artigo IPEN-doc 26149 Activity determination of the difficult to measure radionuclide 55Fe in operational radioative waste from the Angra Nuclear Power Plant2019 - ANGELINI, MATHEUS; SILVA, PAULO S.C. da; JUNQUEIRA, LUCAS S.Pressurized Water Reactors, PWR, are responsible for converting nuclear energy from the nuclear reactions, in the core, into thermal energy by heat exchange with the water in the primary system and then into mechanical energy by the pressure increase from the heat exchange and at last, electrical energy, from the turbine rotation due to the resultant pressure. In a reactor such as described, cool water must flow through the Primary System (where the nuclear core is located) in order to allow heat exchange for electrical energy generation and also to refrigerate the core, providing it will not to be melted or causing any acci dent. Materials that make up the internal part of the primary system such as the walls or core coating may suffer effects like drag force due to the high water pressure or neutron activation due to the high l evels of radiation. Therefore some of these nucl ides that compose these materials are expected to be present in the core water and so, a filtration system is required to reduce these nuclides concentrations. At Angra Nuclear Power Plant two types of filtration systems are used , ion exchange resin, respo nsible for adsorbing these nuclides and a polymer type filter responsible for withholding solid particles in suspension. After a while, these filters become saturated and must b e replaced; once replaced , the old ones become Radioactive Waste of Low or Medi um Activity. This study has evaluated the chemical yield of different procedures for 55 Fe determination by using anion exchange chromatography, to be further applied to determine the activity concentration in nuclear waste samples. The activity concentrati ons were determined by Liquid Scintillation Counting (LSC) and Gamma Spectrometry (GS). This project is part of a bigger objective that aims to fulfill several regulations from the Brazilian National Nuclear Energy Commission (CNEN) and the development of a repository for proper storage of radioactive waste materials