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Master's Dissertation
DOI
10.11606/D.54.1983.tde-24062008-160115
Document
Author
Full name
Dayse Iara dos Santos
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1983
Supervisor
Committee
Aegerter, Michel Andre (President)
Craievich, Aldo Felix
Zanotto, Edgar Dutra
Title in Portuguese
Vidros porosos de de alto teor de sílica para armazenamento de rejeitos nucleares. Solidificação, caracterização e lixiviação
Keywords in Portuguese
Armazenamento de rejeitos nucleares
Lixivação
Separação de fases
Testes soxlet
Vidro poroso de sílica
Abstract in Portuguese
Apresentamos um estudo de solidificaçaõ e lixiviacão de matrizes de vidros porosos de alto teor de sílica armazenando 20% em peso de solução aquosa simuladora de rejeitos nucleares de alto nível de radioatividade do tipo Savanah River Labratory. A matriz porosa foi preparada após o tratamento térmico de um vidro de 65% SiO2-27%B2O3-8%Na2O, que sofreu separação de fase à 560°C por 20 horas e lixiviado em HCl - 3N à 90°C. O tamanho dos poros (tipicamente de 100 à 250Å de diâmetro) , foi determinado utilizando o método BET. Após sinterização à 1300°C em ar, as amostras foram caracterizadas física e quimicamente através de testes de lixiviação padronizados MCC1, Soxhlet (MCC5) e Estagnante durante cerca de 28 dias. Determinamos a perda de peso total, o pH, as taxas de lixiviação diferencial e as concentrações acumuladas para os seguintes elementos: Si, Na, B, Ca, Mn, Al, Fe e Ni com técnicas de ICP e espectroscopia de chama para o caso do Na. Os resultados são comparados com os obtidos com vidros borosilicatos de referência, fabricados por fusão convencional (SRL 131, PNL 76-68, MCC 76-68, SRL TDS 131, AVM-Ml à M7), vidros fabricados pela técnica sol-gel (TDS 211), vidros de alto teor de sílica (CU PGM), synroc-D, cerâmicas manufaturadas, concreto FUETAP e matrizes metálicas. Os valores obtidos são similares àqueles obtidos com os melhores vidros borosilicato presentemente usados.
Title in English
High content silica porous glass for nuclear waste storage. Solidification, characterization and leaching
Keywords in English
Corrosion of waste storage
Leaching
Nuclear waste storage
Phase separation
Silica porous glass
Soxlet tests
Abstract in English
We present a study of the sinterization and of the leaching behavior of a high silica porous glass matrix containing 20 weight % of simulated solution of high level liquid nuclear waste of the type Savanah River Laboratory. The porous matrix has been prepared after heat treatment of a 65% SiO2-27%B2O3-8%Na2O glass, phase separate at 560°C for 20 hours and leached in 3N HCl at 90°C. The pore size (typically 100-250Å in diameter) has been determined by the BET method. After sinterization in air at 1300°C, the samples have been physically and chemically characterized during 28 days using the MCC1, Estagnant and Soxhlet (MCC5) standard tests. We have determined thetotal weight loss, the pH, the diferential leaching rate and the cumulative concentrations for the following elements: Si, Na, B, Ca, Mn, Al, Fe and Ni by ICP technique, for Na flames spectroscopy. The results are compared with these obtained with other reference borosilicate glasses made by conventional fusion techniques (SRL 131, PNL 76-68, MCC 76-68, SRL TDS 131, AVM-M1 to M7), glasses made by sol-gel technique (TDS-211), porous glasses matrix (CU PGM), synroc-D, tailored ceramics, FUETAP concrete and metallic matrix. The values obtained are similar to those found for the best borosilicate glass presently used.
 
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DayseSantos_M.pdf (4.03 Mbytes)
Publishing Date
2008-07-04
 
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