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  • 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.
21

Estudos do tratamento químico da superfície de placas combustíveis nucleares / Chemical treatment studies on nuclear fuel plates surface

Olair dos Santos 11 July 2014 (has links)
O Instituto de Pesquisas Energéticas e Nucleares IPEN-CNEN/SP produz rotineiramente o combustível nuclear necessário para a operação de seu reator de pesquisas IEA-R1. Esse combustível é formado por placas combustíveis contendo núcleos de dispersões U3Si2-Al, obtidas por laminação. As placas combustíveis sofrem um tratamento químico para limpeza de sua superfície, com o objetivo de garantir a remoção de qualquer impureza presente em suas superfícies, incluindo resíduos de urânio. Nos últimos 10 anos foram constatados de forma esporádica aumentos significativos na atividade radioativa da água da piscina do reator IEA-R1. O aumento da atividade no ambiente do reator foi relacionado à entrada na piscina de elementos combustíveis recém-fabricados, entrando em operação. Apesar do processo de tratamento superficial atual estar perfeitamente estável e reprodutível, uma possível causa para o aumento da atividade da água da piscina do reator IEA-R1 é a presença de contaminação residual de urânio na superfície não retirada pelo tratamento químico superficial. Durante anos, esse problema não foi observado devido à baixa potência de operação do reator, no nível de 2 MW. Contudo, com o aumento da potência, acima de 3,5 MW, esse problema começou a ser observado. Esse trabalho verifica a hipótese da contaminação residual de urânio na superfície das placas combustíveis de forma estatística e caracteriza a adequação do processo de tratamento superficial de placas combustíveis. Utilizou-se uma metodologia estatística de avaliação do processo em três níveis: produção presente, contaminação intencional, produção histórica. A contagem de emissões alfa por contador de NaI permitiu a quantificação de urânio residual. Como resultado global, verificou-se que pode ocorrer contaminação abaixo de 1 g de 235U por elemento combustível. Essa contaminação não é significante para causar eventuais acidentes de aumento de atividade no reator IEA-R1. Provou-se no presente trabalho que a metodologia de contagens de emissões alfa é segura, precisa e rápida para se analisarem contaminações superficiais de urânio nas placas combustíveis. / Nuclear and Energy Research Institute - IPEN-CNEN/ SP routinely produces its own nuclear fuel elements, necessary for the operation of its research reactor IEA-R1. This fuel consists of fuel plates containing cores U3Si2-Al dispersions obtained by rolling. Fuel plates undergo a chemical treatment for surface cleaning, aiming to ensure the removal of any impurity present on the surface, including uranium residual dust. Over the past 10 years, it was found sporadically a significant increase of radioactivity emission in water pool of IEA-R1 reactor. The increased activity in the reactor environment was related to the use of newly fabricated fuel elements fed into the core. Although the actual surface treatment process to be perfectly stable and reproducible, a possible cause for the activity increase would be the presence of residual uranium contamination over the surface, which was not removed by chemical surface treatment. For years, this problem was not observed due to the low power of reactor operation, at the level of 2 MW. However, with the increase in power above 3.5 MW, this problem started to be observed. This work verifies the hypothesis of residual uranium contamination on the surface of the fuel plates in a statistical methodology and features the adequacy of the fuel plate surface treatment process. We evaluated, statistically, the process into three levels: present production, intentional contamination, historical production. The NaI alpha emission counter allowed quantification the amount of uranium residual. As an overall result, it was found that contamination may occur below 1 g of 235U per fuel element. The contamination was judged as not significant to cause any activity accidents in the IEA-R1. It has been proven in this paper that the methodology to count alpha emissions is secure, accurate and fast to analyze surface uranium contamination in nuclear fuel plates.
22

Desenvolvimento de uma metodologia de calibração de monitores de contaminação de superfície considerando o mapeamento da uniformidade das fontes extensas de referência / Development of a calibration methodology of surface contamination monitors considering the uniformity mapping of the large area reference sources

Iremar Alves da Silva Junior 06 December 2017 (has links)
Uma das exigências na calibração de monitores de radiação de contaminação de superfície consiste no uso de fontes extensas de referência com um valor de uniformidade superior a 90%. Entretanto, foi verificado em alguns laboratórios de calibração que suas fontes não atendiam essa exigência, o que obrigaria esses laboratórios a não utilizarem tais fontes em suas calibrações. Foi neste contexto que foi desenvolvido um estudo para propor o uso dessas fontes, desde que sejam utilizados fatores de correção, que são propostos neste trabalho, que foram avaliados e desenvolvidos usando o código de transporte MCNP como ferramenta de análise e avaliação, a partir dos dados de mapeamento da uniformidade. Também foi desenvolvido um software para calcular esses fatores de correção, utilizando o mapeamento da uniformidade das fontes como dados de entrada e um sistema automatizado para calibração de monitores de radiação de contaminação de superfície. O grande ganho com esse trabalho foi poder utilizar fontes extensas de referência, mesmo quando essas estão em desacordo com as exigências de uniformidade da norma ABNT ISO 8769:2016. / One of the requirements in the calibration of surface contamination radiation monitors is the use of wide area reference sources with a uniformity value greater than 90%. However, it has been found, in some calibration laboratories, that their sources were not meeting this requirement, which would not allow these laboratories to use such sources in their calibration procedures. It was in this context that a study was developed to propose the use of these sources, provided that correction factors are used, which are proposed in this work, which were evaluated and developed using the MCNP radiation transport code as an evaluation tool, from the uniformity mapping data. A software was also developed to calculate these correction factors using the source uniformity mapping as an input data along with an automated system for calibration of surface contamination radiation monitors. The great gain in this work was to be able to use wide area reference sources, even when they are in disagreement with the uniformity requirements of ISO 8769:2016.
23

Sampling for Beryllium Surface Contamination using Wet, Dry and Alcohol Wipe Sampling

Kerr, Kent January 2004 (has links)
Thesis (M.S.); Submitted to Central Missouri State University, Warrensburg, MO (US); 17 Dec 2004. / Published through the Information Bridge: DOE Scientific and Technical Information. Kerr, Kent. NNSA Kansas City Site Office (US) NNSA Kansas City Site Office. 12/17/2004. Report is also available in paper and microfiche from NTIS.
24

Níveis de contaminação de superfície com gencitabina utilizando dispositivos de segurança em sistema fechado versus a técnica de preparo padrão

Ness, Sandro Luis Ribeiro January 2014 (has links)
Introdução: A manipulação de medicamentos antineoplásicos em Serviços de Saúde expõem os profissionais aos riscos químicos desses agentes, assim é fundamental monitorar e prevenir a exposição ocupacional. A utilização de dispositivos de Segurança no preparo de medicamentos tem sido recomendada por diversos órgãos internacionais de boas práticas no manuseio de medicamentos citotóxicos. Objetivo: Comparar, através da técnica de Cromatografia Líquida de Alta Eficiência com detector Ultravioleta (CLAE-UV), as taxas de contaminação de superfícies de trabalho, com a Gencitabina, utilizando Dispositivos de Segurança em Sistema Fechado em relação à técnica de preparo padrão com agulha. Métodos: A coleta de amostras foi realizada na farmácia de manipulação pela técnica de wipe test e posterior extração. As amostras foram analisadas com CLAE-UV, com leitura de detecção de 268 nm. Resultados: De um total de 303 amostras coletadas para análise da Gencitabina, 272 compararam a técnica com dispositivo de sistema fechado com a técnica padrão, apresentando percentuais de contaminação em quase 50% dos frascos coletados em cada técnica. Os resultados encontrados nos frascos, campo de preparo e seringas apresentaram média de quantidade de resíduos inferiores na técnica com dispositivos de segurança. Nos frascos intactos retirados da caixa original de Gencitabina, foram encontrados resíduos em 16,1%. Conclusões: A técnica utilizada foi adequada para identificar a presença de Gencitabina em materiais e Equipamentos de Proteção Individual – EPI na manipulação de medicamentos, demonstrando dessa forma o risco de exposição aos profissionais e a importância da utilização da do sistema fechado para diminuir os aerossóis e quantidades de resíduos eliminados durante a manipulação. / Introduction: Health professionals who handle antineoplastic agents are exposed to several chemical hazards. Therefore, their occupational exposure must be carefully monitored and prevented. The use of closed-system devices in drug preparation has been recommended by several international guidelines for the handling of cytotoxic drugs. Objective: To compare the contamination of work surfaces with gemcitabine following closed-system preparation versus standard needle techniques, using high-performance liquid chromatography-ultraviolet (HPLC-UV). Method: Wipe test samples were collected from a drug handling facility, then extracted and analyzed by HPLC-UV. Readings were taken at 268 nm. Resultados: Of the 303 samples collected, 31 were obtained from intact vials, while 272 were used to compare gemcitabine contamination levels following conventional versus closed-system preparation. Approximately 50% of samples obtained following each procedure tested positive for the contaminant. The amount of contamination on vials, sterile fields and syringes was lower when closed-system devices were used for drug manipulation. A total of 16.1% of the intact vials removed from their original packaging were also contaminated. Conclusion: The method used in the present study was effective in detecting gemcitabine in the devices and individual protective equipment involved in drug manipulation. These findings demonstrate the exposure risk of health professionals who handle these substances, and the importance of closed-system devices in reducing aerosol formation and contamination during handling.
25

Níveis de contaminação de superfície com gencitabina utilizando dispositivos de segurança em sistema fechado versus a técnica de preparo padrão

Ness, Sandro Luis Ribeiro January 2014 (has links)
Introdução: A manipulação de medicamentos antineoplásicos em Serviços de Saúde expõem os profissionais aos riscos químicos desses agentes, assim é fundamental monitorar e prevenir a exposição ocupacional. A utilização de dispositivos de Segurança no preparo de medicamentos tem sido recomendada por diversos órgãos internacionais de boas práticas no manuseio de medicamentos citotóxicos. Objetivo: Comparar, através da técnica de Cromatografia Líquida de Alta Eficiência com detector Ultravioleta (CLAE-UV), as taxas de contaminação de superfícies de trabalho, com a Gencitabina, utilizando Dispositivos de Segurança em Sistema Fechado em relação à técnica de preparo padrão com agulha. Métodos: A coleta de amostras foi realizada na farmácia de manipulação pela técnica de wipe test e posterior extração. As amostras foram analisadas com CLAE-UV, com leitura de detecção de 268 nm. Resultados: De um total de 303 amostras coletadas para análise da Gencitabina, 272 compararam a técnica com dispositivo de sistema fechado com a técnica padrão, apresentando percentuais de contaminação em quase 50% dos frascos coletados em cada técnica. Os resultados encontrados nos frascos, campo de preparo e seringas apresentaram média de quantidade de resíduos inferiores na técnica com dispositivos de segurança. Nos frascos intactos retirados da caixa original de Gencitabina, foram encontrados resíduos em 16,1%. Conclusões: A técnica utilizada foi adequada para identificar a presença de Gencitabina em materiais e Equipamentos de Proteção Individual – EPI na manipulação de medicamentos, demonstrando dessa forma o risco de exposição aos profissionais e a importância da utilização da do sistema fechado para diminuir os aerossóis e quantidades de resíduos eliminados durante a manipulação. / Introduction: Health professionals who handle antineoplastic agents are exposed to several chemical hazards. Therefore, their occupational exposure must be carefully monitored and prevented. The use of closed-system devices in drug preparation has been recommended by several international guidelines for the handling of cytotoxic drugs. Objective: To compare the contamination of work surfaces with gemcitabine following closed-system preparation versus standard needle techniques, using high-performance liquid chromatography-ultraviolet (HPLC-UV). Method: Wipe test samples were collected from a drug handling facility, then extracted and analyzed by HPLC-UV. Readings were taken at 268 nm. Resultados: Of the 303 samples collected, 31 were obtained from intact vials, while 272 were used to compare gemcitabine contamination levels following conventional versus closed-system preparation. Approximately 50% of samples obtained following each procedure tested positive for the contaminant. The amount of contamination on vials, sterile fields and syringes was lower when closed-system devices were used for drug manipulation. A total of 16.1% of the intact vials removed from their original packaging were also contaminated. Conclusion: The method used in the present study was effective in detecting gemcitabine in the devices and individual protective equipment involved in drug manipulation. These findings demonstrate the exposure risk of health professionals who handle these substances, and the importance of closed-system devices in reducing aerosol formation and contamination during handling.
26

Níveis de contaminação de superfície com gencitabina utilizando dispositivos de segurança em sistema fechado versus a técnica de preparo padrão

Ness, Sandro Luis Ribeiro January 2014 (has links)
Introdução: A manipulação de medicamentos antineoplásicos em Serviços de Saúde expõem os profissionais aos riscos químicos desses agentes, assim é fundamental monitorar e prevenir a exposição ocupacional. A utilização de dispositivos de Segurança no preparo de medicamentos tem sido recomendada por diversos órgãos internacionais de boas práticas no manuseio de medicamentos citotóxicos. Objetivo: Comparar, através da técnica de Cromatografia Líquida de Alta Eficiência com detector Ultravioleta (CLAE-UV), as taxas de contaminação de superfícies de trabalho, com a Gencitabina, utilizando Dispositivos de Segurança em Sistema Fechado em relação à técnica de preparo padrão com agulha. Métodos: A coleta de amostras foi realizada na farmácia de manipulação pela técnica de wipe test e posterior extração. As amostras foram analisadas com CLAE-UV, com leitura de detecção de 268 nm. Resultados: De um total de 303 amostras coletadas para análise da Gencitabina, 272 compararam a técnica com dispositivo de sistema fechado com a técnica padrão, apresentando percentuais de contaminação em quase 50% dos frascos coletados em cada técnica. Os resultados encontrados nos frascos, campo de preparo e seringas apresentaram média de quantidade de resíduos inferiores na técnica com dispositivos de segurança. Nos frascos intactos retirados da caixa original de Gencitabina, foram encontrados resíduos em 16,1%. Conclusões: A técnica utilizada foi adequada para identificar a presença de Gencitabina em materiais e Equipamentos de Proteção Individual – EPI na manipulação de medicamentos, demonstrando dessa forma o risco de exposição aos profissionais e a importância da utilização da do sistema fechado para diminuir os aerossóis e quantidades de resíduos eliminados durante a manipulação. / Introduction: Health professionals who handle antineoplastic agents are exposed to several chemical hazards. Therefore, their occupational exposure must be carefully monitored and prevented. The use of closed-system devices in drug preparation has been recommended by several international guidelines for the handling of cytotoxic drugs. Objective: To compare the contamination of work surfaces with gemcitabine following closed-system preparation versus standard needle techniques, using high-performance liquid chromatography-ultraviolet (HPLC-UV). Method: Wipe test samples were collected from a drug handling facility, then extracted and analyzed by HPLC-UV. Readings were taken at 268 nm. Resultados: Of the 303 samples collected, 31 were obtained from intact vials, while 272 were used to compare gemcitabine contamination levels following conventional versus closed-system preparation. Approximately 50% of samples obtained following each procedure tested positive for the contaminant. The amount of contamination on vials, sterile fields and syringes was lower when closed-system devices were used for drug manipulation. A total of 16.1% of the intact vials removed from their original packaging were also contaminated. Conclusion: The method used in the present study was effective in detecting gemcitabine in the devices and individual protective equipment involved in drug manipulation. These findings demonstrate the exposure risk of health professionals who handle these substances, and the importance of closed-system devices in reducing aerosol formation and contamination during handling.
27

Hodnocení radiační zátěže pacientů a možnost vzniku a řešení radiačních mimořádných událostí na oddělení nukleární medicíny Nemocnice České Budějovice, a.s. / The evaluation of radiation burden of patients and the possibility of radiation emergence and management of emergencies at the nuclear medicine department of the Hospital České Budějovice, PLC

DAŇOVÁ, Kristína January 2019 (has links)
The aim of my thesis was to evaluate radiation consequences in patients, and to evaluate unusual occurrences stemming from radiation at the department of nuclear medicine in hospital Ceske Budejovice. In the theory part, I worked with professional literature, applicable laws and internal documentation provided by the department of nuclear medicine in hospital Ceske Budejovice Plc The thesis reacted to the need of the department of nuclear medicine (dept. NM) in hospital Ceske Budejovice to evaluate the optimisation of doses for the patients and set local diagnostic levels. Different organisations worldwide deal with the question of optimising radiation protection, and their recommendations and standards are used in the Czech Republic. For this purpose, it is necessary to know the real activity of radiopharmaceuticals applied in each examination and to conduct a forecast resulting in effective doses also based on CT scans. The thesis also evaluates the occurrence of special radiation events really experienced at the department of NM (nuclear medicine) in the hospital mentioned above, the reasons for these events happening and precautions preventing them from happening in future. The owner of the permission for this activity, meaning the use of the source of ionizing radiation, has the duty to keep all documentation and paperwork in accordance with the law regulating nuclear power, abide by the rules of good practices and the real state of allowed practice. The occurrence of unusual events is closely connected with the documentation - internal emergency plan and monitoring program. (Law 263/2016) Therefore, it was recommended to compare these to the actual state and to review them based on the facts found. The values of applied activities and effective doses found were compared to the values published in the last report from UNSCEAR in 2016 and national referential values published in the bill about radiation protection no 422/ 2016. All results were inputted into tables and graphs. It was found that the applied activities at the department of NM in hospital Ceske Budejovice are in agreement with the values presented in UNSCEAR report and that they are lower than the national referential levels, which shows that there is optimised state of radiation protection for patients. The occurrence of concrete unusual radiation events at the department of NM in hospital Ceske Budejovice and their analysis revealed certain shortcomings in the process and the absence of security elements needed while holding radioactive liquid waste in storage at the hospital. It was necessary to find and implement such precautions, which will prevent similar type of events in future. The thesis will be handed in to the person tending to the radiation protection for the use of evaluation and providing the protection at the department of NM at the hospital Ceske Budejovice and to enable the documentation to be completed for the allowed activity.
28

Mesure et discrimination de rayonnements bêta et gamma dans une ambiance gamma élevée et fluctuante : conception, développement et caractérisation d'un contaminamètre haute sensibilité / Measurement and discrimination of beta and gamma radiations in a high and fluctuating gamma environment : design, development and characterization of a high sensitivity contamination meter

Karst, Maxime 13 December 2016 (has links)
Dans le cadre des activités de maintenance des centrales nucléaires, les personnes intervenant sur des chantiers en zone contrôlée doivent effectuer des mesures de contamination surfacique sur leurs outils, gants, sur tenue de travail et sur les parties de leur corps susceptible d’être contaminées (cou et tête par exemple). Or, les mesures de contamination surfacique bêta ne peuvent pas toujours être réalisées au plus près des chantiers. Le bruit de fond gamma présent à ces endroits étant élevé et fluctuant, ce dernier perturbe les appareils utilisés habituellement pour la mesure de contamination surfacique. L’objectif principal de ce travail était de concevoir un appareil de mesure adapté à la détection de contamination surfacique bêta de quelques Bq/cm2 (typiquement < 4 Bq/cm2), dans une ambiance gamma de quelques dizaines de µSv/h (typiquement < 100 µSv/h) et fluctuante (typiquement de l’ordre de 30% en 1 seconde). / In the framework of the nuclear power plants maintenance, the onsite workers incontrolled areas must performed some surface contamination controls of their tools, gloves, workingsuits and over their body parts which may be contaminated (neck and head for instance). However,surface beta contamination measurements can’t always been done as close as possible of the working location. The onsite ambient gamma background, being high and fluctuating, may disturb the radiation protection devices commonly used for surface contamination measurements.The main goal of this work was to conceive a radiation protection device adapted to the betasurface contamination of about a few Bq/cm2 (< 4Bq/cm2 typicaly) in a fluctuating (typicaly 30%variation per second) ambient gamma background of a few μSv/h (typicaly <100 μSv/h).
29

Calculating Minimum Detectable Activity for a moving scintillator detector using real-time speed measurement : Implementing a monitoring system to improve accuracy of surface contamination measurement systems / Beräkning av minsta detekterbara aktivitet för en mobil scintillatordetektor med hastighetsmätning i realtid : Implementation av ett övervakande system som förbättrar mätsäkerheten vid detektion av radioaktiv ytkontamination

Amcoff, Artur, Persson, Oscar January 2021 (has links)
Surface contamination occurs in nuclear facilities, something that is important to detect easily and efficiently. Using today’s methods to detect nuclear surface contamination may cause certain inconsistencies as the human operator is solely trusted to keep the detector at the correct distance and move it at the correct speed. This thesis project aims to address the problem of inconsistent measurements with respect to the current measurement methods. A system is designed to monitor the measurement process with regards to detector velocity and height. The system will trigger a warning when the minimum detectable activity is too high, as it would lead to inconsistent results. This system consists of a cart-detector setup with a scintillation detector and velocity measurement device(s). Software will utilize the measurement data to implement the aforementioned monitoring. The system aims to be compliant with international standards, such as the ISO 11929 and the ISO 7503 standards, and will thus make use of these standards. The result of the part-analysis for each component of the system showed a large inaccuracy regarding the Intertial Measurement Units (IMUs); hence, the robotic wheels were chosen as the main method of measuring speed for this project. The robotic wheels and the detector were shown to be sufficiently accurate for the desired measurements. The Raspberry Pi 4 model B, the on- board computer, was also shown to be performance-wise and property-wise well suited for the project. This project showed that there is a theoretical way to implement the speed of a moving detector-rig into the Minimum Detectable Activity (MDA) formula. However, the implementation investigated in this project suggests that full compatibility with ISO 7503 was not achievable. / Radioaktiv ytkontaminering förekommer i kärnkraftverk, vilket är viktigt att upptäcka snabbt och effektivt. Dagens metoder för att upptäcka radioaktiv ytkontaminering kan lida av viss osäkerhet eftersom man förlitar sig helt på att operatören kan manövrera detektorn på rätt höjd och hastighet. Detta examensarbete behandlar en lösning till det ovan nämnda problemet. Ett ”proof-of-concept”-system som kan övervaka mätprocessen designas. Genom att mäta hastighet och känna till höjden över marken kan en varning meddelas användaren när den minsta detekterbara aktiviteten (MDA) når ett tröskelvärde. Det färdiga systemet är en plattform på hjul med en scintillator- detektor monterad tillsammans med en eller flesta hastighetsmätningsenheter. Systemet bör vara kompatibelt med internationella standarder, till exempel ISO 11929 och ISO 7503. Resultaten från den utvärdering av varje individuell komponent som gjorts visade på en stor mätosäkerhet i de två utvärderade IMUerna. Detta medförde att robothjulen valdes som enda källa för hastighetsmätning. Robothjulen, samt detektorn påvisade god mätsäkerhet, väl lämpad för detta projekt. Även mikrodatorn, Raspberry Pi 4 model B, visade sig vara lämplig sett till prestanda och egenskaper. Projektet resulterade i att det är trott att det finns en lämpligt sätt att i teorin implementera hastighet som en parameter i formeln för MDA. Det är dock värt att nämna att resultaten tyder på att det i denna implementation inte var möjligt att uppnå fullständig kompabilitet ISO 7503.

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