Some of the important technical issues involved in the implementation of a spent fuel storage regime under international auspices are discussed. In particular, we consider: the state of the art as far as the different possible storage modes are concerned, the relevant accident, sabotage, and transportation considerations, and the impact of recent technical spent fuel safeguards initiatives on the nonproliferation rationale for international spent fuel management. / Prepared for the U.S. Dept. of Energy under Contract no. EN-77-S-02-4571.A000.

abstract: The objective of this project was to evaluate human factors based cognitive aids on endoscope reprocessing. The project stems from recent failures in reprocessing (cleaning) endoscopes, contributing to the spread of harmful bacterial and viral agents between patients. Three themes were found to represent a majority of problems: 1) lack of visibility (parts and tools were difficult to identify), 2) high memory demands, and 3) insufficient user feedback. In an effort to improve completion rate and eliminate error, cognitive aids were designed utilizing human factors principles that would replace existing manufacturer visual aids. Then, a usability test was conducted, which compared the endoscope reprocessing performance of novices using the standard manufacturer-provided visual aids and the new cognitive aids. Participants successfully completed 87.1% of the reprocessing procedure in the experimental condition with the use of the cognitive aids, compared to 46.3% in the control condition using only existing support materials. Twenty-five of sixty subtasks showed significant improvement in completion rates. When given a cognitive aid designed with human factors principles, participants were able to more successfully complete the reprocessing task. This resulted in an endoscope that was more likely to be safe for patient use. / Dissertation/Thesis / M.S. Applied Psychology 2011

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Made available in DSpace on 2014-07-29T15:04:28Z (GMT). No. of bitstreams: 1 dissertacao-jackeline-maciel.pdf: 555827 bytes, checksum: e5c0f7c6020e05758b2a38bfe2ab0aa0 (MD5) Previous issue date: 2008-04-24 / SUMMARY: This is a descriptive research carried out in twenty digestive endoscopy services at the municipality of Goiânia. We aimed at characterizing the endoscope reprocessing through the use of glutaraldeide in upper digestive endoscopy services. The sample was constituted by endoscopes used for upper digestive endoscopy and professionals performing these endoscope reprocessing. We observed ethical legal aspects of human research. Data was collected through direct observation of the physical structure of the place used for endoscope reprocessing and the individuals performing such reprocessing and recorded in a check list. In each service we obtained samples of three endoscopes, able to be chosen the first, the second, and the last endoscope used in that period. Samples were collected in the border, biopsy channel, and aspiration channel of each endoscope right after the use and at the end of reprocessing. Samples were processed in the Laboratório de Bacteriologia Médica of the Instituto de Patologia Tropical e Saúde Pública of the Universidade Federal de Goiás. Microorganisms were identified concerning the form through Gram coloring technique. For isolated bacteria we performed the susceptibility profile. We carried out twenty observations regarding physical structure, one in each service. Sixty endoscope reprocessing were observed, three in each service. The outcomes showed that reprocessing is carried out in the same screening room without proper flow of service. All reprocessing stages showed failure. Errors were observed during the cleansing stage due to the use of enzyme detergent and brushing only the biopsy tubes. Disinfection was identified in all reprocessing, however it was not observed at 2 % concentration of germicide, there was no aspiration of the product in the internal channels and total immersion of the endoscopes, and exposure time to glutaraldeide was lower than the recommended one. Rinsing was most of the time with unfiltered water. The internal channels drying was improper due to the nonuse of compressed air. Adequate conditions to endoscope storage were identified. Microbial range of contaminated endoscopes was low, between 101 a 104 ufc/mL. Performing the precleansing stage, the use of enzyme detergent, cleansing of internal endoscope tubes, and the filling of these tubes with glutaraldeide were the significant variables, < 0.005 for the efficiency of endoscope reprocessing. These stages were crucial to reduce microbial burden. Chemical disinfection through the use of glutaraldeide was efficient in the endoscope reprocessing in eight services which is evidenced through the elimination of initial microbial range, however failures in the reprocessing of those were identified. We isolated from decontaminated endoscope: S. aureus, Staphylococcus coagulase negative, Enterobacter agglomerans, Enterobacter sp., E. coli. These microorganisms were susceptible to antimicrobials tested, except for azitromycin-resistant Gram-negative bacteria. This study shows that despite the low microbial range of contaminated endoscopes, disinfection has not been achieved in all services due to reprocessing failures, mainly in the cleaning stage. We consider adherence to endoscopes reprocessing protocols eliminates the major failures identified in the reprocessing / Pesquisa descritiva realizada em vinte Serviços de Endoscopia Digestiva do Município de Goiânia. Objetivou caracterizar o reprocessamento dos endoscópios pelo uso do glutaraldeído em serviços de endoscopia. A amostra constituiu-se de endoscópios utilizados para Endoscopia Digestiva Alta, e de profissionais que realizavam os reprocessamentos. Foram observados os aspectos ético-legais de pesquisa, em seres humanos. Os dados foram obtidos mediante observação direta da estrutura física do local utilizado para o reprocessamento dos endoscópios, e dos sujeitos que realizaram este reprocessamento, e registrados em um check-list. Em cada serviço foram obtidas amostras de três endoscópios, sendo elegíveis o primeiro, o segundo e o último endoscópio utilizados, no período. As amostras foram coletadas na ponta, canal de biópsia e canal de aspiração, de cada endoscópio, logo após o uso, e ao término do reprocessamento. As amostras foram processadas no Laboratório de Bacteriologia Médica do Instituto de Patologia Tropical e Saúde Pública da Universidade Federal de Goiás. Os microrganismos foram identificados quanto à forma, pela técnica de coloração de Gram. Para as bactérias isoladas foi realizado o perfil de suscetibilidade. Foram realizadas 20 observações referentes à estrutura física, uma em cada serviço. Foram observados 60 reprocessamentos de endoscópios, sendo três em cada serviço. Os resultados mostraram que o reprocessamento é realizado na mesma sala de exames, sem atendimento de um fluxo adequado. Houve falhas em todas as etapas do reprocessamento. Foram constatadas deficiências, durante a etapa de limpeza, por uso inadequado do detergente enzimático e escovação apenas do canal de biópsia. A desinfecção foi executada em todos os reprocessamentos, contudo verificada concentração inferior a 2% do germicida, não houve aspiração do produto nos canais internos, e imersão total do endoscópio, e o tempo de exposição ao glutaraldeído inferior ao recomendado. O enxágüe, na maioria das situações, ocorreu com o uso de água sem filtrar. Secagem dos canais internos é inadequada pela falta de uso de ar comprimido. Condições adequadas para o armazenamento do endoscópio foram confirmadas. A carga microbiana dos endoscópios contaminados foi baixa, entre 101 e 104 ufc/mL. A realização da pré-lavagem, o uso do detergente enzimático, a limpeza dos canais internos do endoscópio, e o preenchimento destes canais com o glutaraldeído foram variáveis significativas, < 0,005 para a eficácia do reprocessamento dos endoscópios. Estas etapas foram determinantes para a redução da carga microbiana. A desinfecção química pelo glutaraldeído foi eficaz no reprocessamento dos endoscópios em oito serviços evidenciada pela eliminação da carga microbiana inicial, embora houvesse falhas no reprocessamento. Para os endoscópios reprocessados isolamos: S. aureus, Staphylococcus coagulase negativa, Enterobacter agglomerans, Enterobacter sp., E. coli. Estes microrganismos foram suscetíveis aos antimicrobianos testados, com exceção das bactérias Gram-negativas resistentes à azitromicina. O estudo mostra que apesar da baixa carga microbiana dos endoscópios imediatamente após o uso, a desinfecção não foi alcançada, em todos os serviços, por falhas no reprocessamento, especialmente na etapa de limpeza. Consideramos que, a adesão aos protocolos de reprocessamento dos endoscópios eliminaria as principais falhas identificadas.

Le réacteur à sels fondus rapides (MSFR) est un des six concepts de réacteur nucléaire retenu lors du Forum Génération IV en 2001. La particularité de ce concept est d'utiliser un combustible liquide constitué d'un sel fondu, LiF-ThF₄-UF₄/UF3₃ (77-19-4 mol%) et d'intégrer un procédé de traitement du sel usé. Ce traitement est constitué d'étapes successives de séparation chimiques basées sur les propriétés redox et acido-basiques des éléments produits dans le réacteur par des réactions nucléaires : produits de fission solubles et gazeux, éléments métalliques et actinides mineurs solubles. L'une des étapes majeures du procédé de traitement est une extraction réductrice qui consiste à mettre en contact le sel fondu et un métal liquide, le bismuth, contenant un élément réducteur, le lithium. Cette étape permet notamment de séparer les actinides mineurs des lanthanides. Les actinides mineurs sont réintroduits dans le réacteur nucléaire afin d'y être brûler alors que les lanthanides seront confinés en stockage profond.Le travail réalisé au cours de cette thèse avait deux objectifs : (i) vérifier la faisabilité de l'extraction réductrice des actinides et des lanthanides, étape qui avait été validée au préalable uniquement sur la base de calculs thermodynamiques et (ii) étudier la chimie des sels fluorures fondus (et notamment le sel combustible LiF-ThF₄-UF₄) en développant une méthodologie pour la détermination de données fondamentales telles que les coefficients d'activité dans les milieux fluorures, coefficients qui quantifient les propriétés de solvatation.La première étape pour réaliser expérimentalement une extraction réductrice consiste à préparer une nappe métallique de Bi-Li liquide de composition pré-définie. Une technique d'électrolyse en milieu LiCl-LiF fondu à 550°C a été retenue pour réaliser ces solutions métalliques. Nous avons montré que seul ce milieu fondu pouvait être utilisé pour la fabrication de ces alliages métalliques. Des tests d'extraction ont ensuite été réalisés par contact entre LiF-ThF₄ (dans lequel sont introduits UF₄ et NdF ₃ pour simuler respectivement les actinides et les lanthanides) et Bi-Li à 650°C. Les principaux résultats montrent que l'extraction du néodyme et de l'uranium a été obtenue avec des rendements respectivement de l'ordre de 3% et 15% dans les meilleures conditions. Ces valeurs sont faibles comparées aux calculs thermodynamiques prévisionnels. On explique la faible efficacité de l'extraction par une extraction simultanée du thorium dans la nappe métallique liquide qui forme des composés intermétalliques à l'interface métal/sel et bloque le transfert interphasique. Des méthodes ont été développées pour atteindre des données fondamentales qui font défaut en milieu fluorures fondus, en particulier les propriétés de solvatation. La spéciation de plusieurs cations métalliques par les ions fluorures à haute température a notamment été étudiée et les constantes de complexation calculées par simulation des résultats expérimentaux. Réalisée pour deux lanthanides, le néodyme et le lanthane, deux actinides, le thorium et l'uranium et également pour un métal de transition, le nickel, cette étude permet d'atteindre les coefficients d'activité de ces éléments dans tous les sels fluorures fondus. En particulier, l'étude de la spéciation du thorium a été une étape importante dans la connaissance de la chimie du sel combustible LiF-ThF₄ puisque nous avons pu en déduire le coefficient d'activité de l'ion fluorure dans ce milieu à 650°C.Enfin, l'ensemble de ce travail a conduit à donner une première estimation de la réactivité de chaque élément de la classification périodique (présent dans le réacteur nucléaire après opération) à chaque étape du traitement du sel combustible usé. / The molten salt fast reactor (MSFR) is one of the six nuclear reactor concepts retained during the Forum GEN IV in 2001. The particularity of this concept is to use a liquid fuel consisting of a molten salt, LiF-ThF₄-UF₄ /UF ₃ (77-19-4 mol%) and to have an integrated spent fuel treatment process. This treatment consists of successive chemical separation steps based on redox and acid-base properties of the elements produced in the reactor by nuclear reactions: soluble and gaseous fission products, metals elements and soluble minor actinides. One of the major steps of the treatment method is a reducing extraction which consists to contact the molten salt and a liquid metal, bismuth, containing the reducing element, lithium. This step allows separating the minor actinides and lanthanides. Minor actinides are reintroduced in the nuclear reactor to be burned while the lanthanides are confined in deep storage.The work in this thesis had two objectives: (i) assess the feasibility of reducing extraction of actinides and lanthanides, a step that had previously only been validated on the basis of thermodynamic calculations and (ii) study the chemistry of molten fluoride salts (and especially the fuel salt) by developing a methodology for the determination of fundamental data such as the activity coefficients in fluorides media, coefficients activities which quantify the solvation properties.To experimentally realize a reducing extraction, the first step is to prepare a metal layer of liquid Bi-Li with predefined composition. An electrolysis technique in molten salt LiCl-LiF at 550°C was chosen to achieve these metal solutions. We have shown that only this molten medium could be used for the manufacture of such metal alloys. Extraction tests were then carried out by contact between LiF-ThF₄ (with UF₄ and NdF ₃ are introduced to simulate respectively the actinides and lanthanides) and Bi-Li at 650°C. The main results show that the extraction of neodymium and uranium was obtained with yields of around 3% and 15% respectively in the best conditions. These values are low compared to previous thermodynamic calculations. Low efficiency of the extraction is due to a simultaneous extraction of thorium in the liquid metal phase which forms intermetallic compounds at the metal/salt interphase and blocks the transfer.Methods have been developed to achieve fundamental data that are lacking in molten fluoride medium, in particularly the solvation properties. Speciation of some metallic cations by fluoride ions with high temperature was particularly studied and calculation of complexation constants by simulated experimental results was done. Carried out for two lanthanides, neodymium and lanthanum, two actinides, thorium and uranium, and also for a transition metal, nickel, this study achieves to calculate the activity coefficients of these elements in different fluoride molten salt. The study of the speciation of thorium was an important step to understand the chemistry of the fuel salt LiF-ThF₄. We were able to calculate the activity coefficient of the fluoride ion in this environment at 650°C.Finally, all of this work allows giving a first estimate of the reactivity of each element of the periodic table (present in the nuclear reactor after operation) at each stage of the treatment of the spent fuel salt.

The presence of group I/II fission products (Cs-137, Sr-90, and Ba-137) within molten salt nuclear processes degrades operational efficiencies by contributing to increased radiation levels in the case of material handling processes or to loss of criticality in the case of a reactor. While methods such as zone freezing and ion exchange have been proven for the separation of these fission products in LiCl-KCl salts, they require extra equipment and processing steps. Addition of a liquid metal electrode to molten salt media, such as the electrorefiner of a pyroprocessing scheme or the salt cleaning stage of a molten salt fast reactor, offers the possibility to selectively extract group I/II fission products with minimal extra equipment. This work has studied the fundamental electrochemical behaviors of Cs, Sr, Ba, and Ce in LiCl-KCl at a liquid Bi cathode and produced values for their mass transport and kinetics properties. These have allowed for an assessment of a Bi cathode for electrochemical separations in a pyrochemical processing scheme.

Thesis: M.S., Massachusetts Institute of Technology, Department of Chemical Engineering, 1979 / Includes bibliographical references (leaves 207-212). / by Saeed Tajik. / M.S. / M.S. Massachusetts Institute of Technology, Department of Chemical Engineering