Quantitative radionuclide analysis protocol in a radiological and nuclear mobile laboratory / Protocolo de análise quantitativa de radionuclídeos em um laboratório radiológico e nuclear móvel

Abstract

This study establishes a quantitative analysis protocol of radionuclides in a radiological and nuclear mobile laboratory of the Brazilian Army's Institute of Chemical, Biological, Radiological and Nuclear Defense. The gamma spectrometry technique was used, by a HPGe detector, to identify certified gamma-emitting radioactive sources (Am-241, Cs-137 and Co-60) present in a standard solution diluted in a Marinelli flask of 4L. Energy, resolution and efficiency calibration curves were determined using the LabFit software, for this detector, in the considered geometry. The results show to be satisfactory the linear adjustment (Channel versus Energy) of set points have been obtained experimentally which was confirmed by the determination coefficient achieved (). Besides that, it could be also verified that the exponential function was the mathematical model that best represented the answer of the HPGe detector energy resolution and that the mathematical adjustment options provided by LabFit which allowed to correlate the counting efficiency with the energy of each photopeak, despite the lack of a greater amount of energy. To define specific activities, the measurement errors between theoretical and experimental values were less than 4%, evidencing the reasonable responsiveness of the measurement system.