Made available in DSpace on 2014-10-09T12:42:24Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:10Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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Made available in DSpace on 2014-10-09T12:42:24Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:10Z (GMT). No. of bitstreams: 0 / Um dos componentes mais importantes de um Reator Nuclear é o Combustível Nuclear. Atualmente, o mais avançado combustível comercial, cuja aplicabilidade nos reatores brasileiros vem sendo desenvolvida pelo IPEN desde 1985, é o siliceto de urânio U3Si2. Este é formado por placas combustíveis com núcleos de dispersão (onde o material físsil (U3Si2) é disperso homogeneamente em uma matriz de alumínio) revestidos por alumínio. Tal combustível é produzido no Brasil com tecnologia totalmente nacional, resultado do esforço realizado pelo grupo de fabricação de combustíveis nucleares (CCN Centro do Combustível Nuclear) do IPEN. Diante da necessidade do aumento da potência do reator IEA-R1 e da construção do Reator Multipropósito Brasileiro (RMB), para a produção de radioisótopos principalmente para fins na área da medicina , haverá significativo aumento na produção deste combustível nuclear no IPEN. Em face desta conjuntura, faz-se necessário o desenvolvimento de técnicas de qualificação mais modernas e automatizadas. Visando a este objetivo, neste trabalho foi desenvolvido um novo método computacional de medição de espessuras de núcleos e revestimentos de placas combustíveis, o qual é capaz de realizar tais medidas em tempo menor e com dados estatísticos mais significativos, quando comparado com o método atual de medição. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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Room temperature photomodulated reflectance (PR), Photoluminescence (PL) and double crystal x-ray diffraction (DCXRD) measurements have been performed on a series of tensilely strained InxGa1-xAs (0.316 ≤ x ≤ 0.533) multiple quantum well (QW) structures, with In0.80Ga0.20As0.43P0.57 barriers. The DCXRD measurements provided accurate information on composition, strain and layer thickness, while PR was used to determine the energies of the full manifold of allowed and forbidden critical point interband QW transitions. A three-band effective mass formalism was used to model the QW transitions to derive structural information on each sample. The energies of the ground-state QW transitions, H11 and L11, were found to increase with tensile strain, becoming degenerate near 0.36% tensile strain. Room temperature PR and conventional reflectance (R) measurement have been performed on two I.R. emitting InGaAs/GaAs/A1As vertical cavity surface emitting laser (VCSEL) structures. The R measurements were modelled using a transfer matrix formalism to determine errors in the growth fluxes. A new PR lineshape model has been developed based on energy dependent Seraphin coefficients, to describe the cavity mode interaction with a confined-state QW transition. The model is demonstrated on a set of PR spectra, and used in a novel way to derive the Deltaepsilon2 spectrum of the QW layers directly. The results are compared with those taken of the QW layers directly after removing the top Bragg stack reflector. Whilst the QW layers in one sample were found to be close to nominal, the in composition of QW in the other sample was found to depart significantly from the nominal 23%, and was found to be 28%. Room temperature and ~ 80K PR measurements were performed on three InAs/GaAs self-assembled quantum dot (QD) structures: a sample with a single layer of QDs, and two with two layers. The PR revealed five equally spaced confined-state QD transitions, at both 80K and room temperature, with ~ 54 meV separation. The behaviour of the QD1 transition as a function of temperature was investigated and an anomalous increase in linewidth was observed on cooling. Annealing of one of the samples produced a strong blue shift (~ 250 meV) and narrowing of the QD transitions.

The objective of my thesis is description of contactless measuring methods, their principle and distribution. There are compiled basic facts about the measurement of laser and ultrasound. In this work is also described non-contact temperature measurement. Part of thesis is non-contact flow measurement on the model.