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Identificação por ultra-som das regiões de tensões trativas e compressivas numa barra fletida
No full textErgonomia na concepção de interfaces gráficas de salas de controle avançadas de reatores nucleares.
No full text
Cost-Based Optimization Of A Nuclear Reactor Core Design: a preliminary mode
Get PDFA new formulation of a nuclear core design optimization problem is introduced in this article. Originally, the
optimization problem consisted in adjusting several reactor cell parameters, such as dimensions, enrichment and materials, in order to minimize the radial power peaking factor in a three-enrichment zone reactor, considering restrictions on the average thermal flux, criticality and sub-moderation. Here, we address the same problem using the minimization of the fuel and cladding materials costs as the objective function, and the radial power peaking factor as an operational constraint. This cost-based optimization problem is attacked by two metaheuristics, the standard genetic algorithm (SGA), and a recently introduced Metropolis algorithm called the Particle Collision Algorithm (PCA). The two algorithms are submitted to the same computational effort and their results are compared. As the formulation presented is preliminary, more elaborate models are also discussed
Estudo da influência da concentração de PVP K-30/90 na morfologia do filme de PES
Get PDFO objetivo deste trabalho foi avaliar morfologicamente as membranas de PES preparadas a partir do uso de misturas de polivinilpirrolidona (PVP K-30 e K-90), visando ajustar as condições de síntese para a obtenção de uma membrana isenta de macroporos
Development of an image reconstruction algorithm for a few number of projection data
No full textAn image reconstruction algorithm was developed for specific cases of radiotracer applications in industry (rotating cillindrical mixers), involving a very few number of projection data. The algorithm was planned for imaging radioactive isotope distributions around the center of circular planes. The method consists of adapting the original expectation maximization algorithm (EM) to solve the ill-posed emission tomography inverse problem in order to reconstruct transversal 2D images of an object with only four projections. To achieve this aim, counts of photons emitted by selected radioactive sources in the plane, after they had been simulated using the commercial software MICROSHIELD 5.05, constitutes the projections and a computational code (SPECTEM) was developed to generate activity vectors or images related to those sources. SPECTEM is flexible to support simultaneous changes of the detectors’s geometry, the medium under investigation and the properties of the gamma radiation. As a consequence of the code had been followed correctly the proposed method, good results were obtained and they encoraged us to continue the next step of the research: the validation of SPECTEM utilizing experimental data to check its real performance. We aim this code will improve considerably radiotracer methodology, making easier the diagnosis of fails in industrial processes
The numerical solution of the two-dimensional radiative transfer equation for a medium with properties of absorption and isotropic scattering
No full textThe two-dimensional radiative transfer equation will be formulated considering the axial projections and this
equation will be approached angularly for the discrete ordinate method. The variational formulation for the
system of differential equations of 1st order with boundary conditions in the incident flow is approached by a
mesh of pixels that are generated using a natural basis. The system of partial differential equations generated of this approach is numerically solved by the discontinuous finite element method. This work investigates the
sensibility of the emergent flow knowing the properties of absorption and isotropic scattering of the medium and
presents the numerical results of the influence of these properties in the mapping of incident-emergent flow for
the nonhomogeneous case
Core Reactor Calculation Using the Adaptive Remeshing with a Current Error Estimator
Get PDFWith the objective to improve the reactor physics calculation on a 2D and 3D nuclear reactor via the Diffusion
Equation, an adaptive automatic finite element remeshing method, based on the elementary area (2D) or volume (3D) constraints, has been developed. The adaptive remeshing technique, guided by a posteriori error estimator, makes use of two external mesh generator programs: Triangle and TetGen. The use of these free external finite element mesh generators and an adaptive remeshing technique based on the current field continuity show that they are powerful tools to improve the neutron flux distribution calculation and by consequence the power solution of the reactor core even though they have a minor influence on the critical coefficient of the calculated reactor core examples. Two numerical examples are presented: the 2D IAEA reactor core numerical benchmark and the 3D model of the Argonauta research reactor, built in Brasil
Monitoramento de radionuclídeos gerados na produção de I-123 por espectometria gama associada à cromatografia de partição
No full textO Instituto de Engenharia Nuclear (IEN) instalou o sistema denominado Karlsruhe Iodine Production System (KIPROS), para a produção do radioisótopo I-123 de alta pureza (maior de 99,4 % de pureza radionuclídica). O I-123 é um dos mais importante radioisótopos em medicina nuclear , usado em moléculas com especificidade para muitos órgãos e funções do corpo humano, principalmente nos diagnósticos de distúrbios da tireóide. Tendo em vista a presença de outros radionuclídeos, gerados no processo, tais como: Te-121, Te-121m, Te-123m, Te-125m, Tc-95, Tc-95m, realizou-se um monitoramento sistemático da produção de I-123. Além disso, visando desenvolver um método analítico rápido para controle de qualidade, realizou-se um estudo para a separação de espécies químicas de iodo e telúrio, utilizando diversas reações redox seguidas de separação cromatográfica dos ânions, em papel cromatográfico Whatman n°1. A identificação e quantificação dos radionuclídeos foi realizada por espectrometria de raios gama, utilizando-se um detector de germânio acoplado a um analisador de altura de pulso 8192 canais