RESUMOA crescente demanda de estudos voltados para o setor petrolífero vem da preocupação com o NORM (Natural Occurring Radioactive Material) presente nas incrustações e borras, proveniente das atividades de extração de petróleo, que pode prejudicar os trabalhadores, caso esses, sejam expostos a quantidades significativas dessa radiação. Sendo assim, este trabalho tem como objetivo determinar as atividades específicas dos isótopos de Ra, em amostras de incrustações e borras, utilizando um detector semicondutor de germânio de alta pureza -HPGe coaxial, com tempo de aquisição de 86400 s; e avaliar, utilizando um identificador radiológico portátil -IRP com cintilador de NaI(Tl) e tempo de aquisição de 180 s, as taxas de dose associadas a essas amostras e sua eficiência na identificação rápida, "in situ", do NORM presente nas mesmas. A geometria de medição foi padronizada a uma distância de 5 cm amostra-detector. Foram analisadas três amostras de incrustação e uma de borra, retiradas de diferentes pontos da linha de retorno de água produzida do tanque de despejo de um navio plataforma do tipo FPSO. Os resultados mostraram uma variação das atividades específicas de

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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.

The identification of the occurrence of 232Th, by measuring the energies of the children radioisotopes 228Ac, 208Tl, 212 Bi and 212Pb, in their places of origin, using the Mobile Lab for Identification of Radiological and Nuclear Agents - LabMovelRN, by discriminating their environmental concentration normal and NORM [1] is important for the performance of the operational teams of the Brazilian Army Chemical, Biological, Radiological and Nuclear Defense Institute (IDQBRN), optimizing their time of action, and reducing the chain of custody of the sample. Due to the operational difficulty of using HPGe detectors in LabMovelRN, an adaptation is being carried out in the laboratory in order to allow the analysis of 232Th in soil samples by the gamma spectrometry technique using scintillation detectors [2] of NaI (Tl) type well as the characterization of the response of this scintillator detector in energy, resolution and energy efficiency up to 3,000 keV.