Measurement of integral parameters at IPEN/MB-01 reactor

This experimental aim to obtain Integral Parameters at the core of the Nuclear Reactor IPEN/MB-01, taken from the irradiation of fuel rods and uranium foils both bare and covered with cadmium. The obtained parameters were the spectral ratio 28 ρ, 25 δ, modified conversion ratio (C*) C8/F and (C8/F)epithermal, all of them obtained with high precision at the asymptotic core region. The epithermal reaction ratios were obtained from the gamma spectrometry of irradiated fuel elements, with cadmium sleeves, as well as from enriched and depleted uranium foils, both covered with cadmium. Correcting factors were obtained in order to correct the disturbances caused by cadmium. The corrections were obtained experimentally from the understanding of the physical phenomenology concerned, which allowed us to obtain the undisturbed extrapolated value from the physical understanding, resulting from the calculation of these same factors. Such calculations, carried out by the Monte Carlo method, show the behavior of these factors as related to the variation of the length of the cadmium sleeves. The correction factors were obtained from the MCNP-4B program which calculated the factors according to the cadmium sleeves, as well as for for the uranium foils and catcher foils, of cadmium and aluminium introduced and irradiated inside special fuel elements. The calculation showed the dependency of the obtained values according to the types of nuclear data that were used in the evaluation of the correction factors, which in this case are the ENDF/B V and VI library. The experimental results corrected by the calculated correction factors through code MCNP-4B, using ENDF/B-VI library were closer to the corrected experimental values with the experimental correction factors obtained in this work. (author)