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Made available in DSpace on 2014-10-09T12:55:19Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:56Z (GMT). No. of bitstreams: 0 / O Laboratório de Análise por Ativação com Nêutrons (LAN) do Instituto de Pesquisas Energéticas e Nucleares (IPEN), utiliza esta técnica analítica multielementar, baseada na irradiação de uma amostra por um feixe de nêutrons oriundos de um reator nuclear, que induz a radioatividade; que é medida em um espectrômetro de raios gama, para a obtenção dos espectros de raios gama. Neste trabalho é implementado um software denominado de SAANI (Software Análise por Ativação com Nêutrons Instrumental) para análise de espectros de raios gama, desenvolvido para os usuários do laboratório LAN-IPEN, com a filosofia de software livre, para a substituição do software existente VISPECT/VERSÃO 2, e tem como características principais: tornar a interface mais amigável; facilitar a padronização dos procedimentos realizados pelos pesquisadores, estudantes e técnicos; ser extensível com a utilização da tecnologia de plugins; multiplataforma; código livre. O software foi desenvolvido utilizando a linguagem de programação Python, a biblioteca gráfica Trolltech Qt e algumas de suas extensões científicas. Os resultados preliminares obtidos utilizando o software SAANI foram comparados aos obtidos com o software existente e foram considerados bons. Algumas diferenças encontradas foram verificadas oriundas de erros de precisão na implementação do software. O software SAANI está instalado nos computadores de usuários selecionados para a execução de rotinas de análise para uma maior verificação de sua robustez, precisão e usabilidade. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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The subject of whether fluorine (F) is detrimental to human health has been controversial for many years. Much of the discussion focusses on the known benefits and known detriments to dental care and problems that fluorine causes in bone structure at high doses. It is therefore desirable to have the means to monitor fluorine concentrations in the human body as a means to directly assess exposure. A monitoring tool could be applied in studies of human health and perhaps answer some of the questions regarding levels at which fluorine has protective effects and negative health consequences. This thesis presents work in the further development of a low risk non-invasive method for the monitoring of fluorine in human bone. The work was based on the technique of neutron activation analysis (NAA). Fluorine accumulates in bone as a long term storage site following exposure. In this thesis, the McMaster Tandem accelerator was used to produce neutrons through the 7Li(p,n)7Be reaction, measuring F levels in the human hand bone using IVNAA. The gamma rays emitted through the 19F(n,γ )20F reaction are measured using nine NaI(Tl) detectors with 4π geometry. Four published papers are presented in this thesis. The main outcome of the first publication was the development of a new phantom. This was needed to reduce the aluminum contamination. The main outcome of the second publication was a series of improvements to the method for the in vivo measurement of bone fluorine using NAA of the new phantoms. In the third publication the best hand position and neutron flux map in the irradiation cavity were determined through both Monte Carlo simulation (FLUKA) and experimental methods. Finally, the fourth publication describes the utility of the improved technique in a pilot study of environmentally exposed people. The overall conclusion from this thesis work is that a low risk monitoring tool, based on an NAA technique, has been developed which is capable of monitoring fluorine in urban Canadians. The technique can now be applied in studies of human health. / Thesis / Doctor of Philosophy (PhD)

The radioactivity contributions of several daughter products of the 235,238 U and 232Th isotope decay chains within geological matrices can be assumed to be in equilibrium due to their age if they have remained undisturbed for an extended period of time. Similarly, one can assume that the isotopic mass proportions are equal to natural isotopic abundance. Current methods used to ascertain activity in these decay chains involve alpha particle spectrometry or ICP-MS, both of which can be laborious and time consuming. In this research, thermal and epithermal neutron activation analysis of small samples of various geological materials is used in order to ascertain activities. Through the use of NAA, cumbersome sample preparation and the need for large sample size and extended counting time are obviated. In addition to the decay chains of uranium and thorium, 40K, another large contributor to naturally occurring radioactivity, is determined using epithermal neutron activation analysis to determine total potassium content, and then calculating its isotopic contribution based on its natural isotopic abundance. / text

The ability to quickly and accurately quantify fissile constituents in bulk materials remains essential to many aspects of nuclear forensics and for safeguarding nuclear materials and operations. This often entails the analysis of trace quantities of nuclear debris or effluents, and typically requires bulk sample digestion followed by actinide separation and mass spectrometry. Because destructive methods are time and labor intensive, efforts have been made to develop alternative nondestructive methods for this type of analysis. This work, performed at Oak Ridge National Laboratory at the High Flux Isotope Reactor (HFIR), seeks to utilize delayed neutron activation analysis on samples of interest containing multiple fissile constituents. Based on the variances in the fission product yields of individual fissile nuclides, this work utilizes methods of linear regression to derive a technique that allows for such analysis, forgoing chemical separation and using only a single irradiation and counting step. / text

The need for trace, minor and main element analysis becomes more prevalent each year with an every expanding variety of applications. Neutron Activation Analysis (NAA) is an attractive non-destructive analysis tool that can be utilized on small samples regardless of what physical state the material is in. The analysis process however, typically requires researchers to physically handle a radioactive sample in order to transport the sample to detection systems for data gathering. The purpose of this project was to design a Fully Automated Rapid Irradiated Sample Transit (FARIST) system that could deliver samples into a reactor core and then transfer them to a detector for analysis with zero human interaction. The system would be designed to hold up to 30 samples prior to analysis with the irradiation, decay, and counting times programmed in initially so that once analysis was initiated, no user interaction was required for the next 29 samples. The last requirement of the system was that it supports cyclic NAA. This work discusses the science and history behind NAA as well as the design, construction, installation, and testing of the new FARIST system. / text

Made available in DSpace on 2014-10-09T12:28:42Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:04Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP / FAPESP:08/55680-8

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