Measurement of the neutron flux in the core of the IPEN/MB-01 reactor by irradiation of activation foils

Abstract

The knowledge of the neutron flux in the core of a reactor is of fundamental importance for determining the power it generated, the burning of nuclear fuel and the consequent estimate of the lifetime of a particular configuration of a core, in addition to the validation of the methodology of calculation used in the design of the reactor’s core. Through the technique of activation analysis it was determined the neutron flux in three separated bands of energy, thermal, intermediate and fast. For this purpose it was used activation foils, in special infinitely diluted gold foils to determine the thermal and intermediate flux and indium foils to determine the fast flux. For the analysis it was used the gamma spectrometry that has been made using a detection system of hyper-pure germanium detector (HPGe) and MAESTRO software for the gamma spectra data analysis. The knowledge of the net count of the element formed for each position of the irradiation, which is obtained by the induced activity and consequently the neutron flux in the point in question. The measured values of thermal, intermediate and fast neutron flux in the core of the reactor in its default configuration rectangular 28x26 fuel rods were compared with those obtained by the reactor physics codes MCNP and the result shows a good agreement.