[297012] Artigo – CBMRI – Congresso Brasileiro de Metrologia das Radiações Ionizantes

Resumo: The use of ionizing radiation sources in the oil prospecting industry poses a challenge to workers and to radiological safety. During oil well logging procedures, workers are exposed to radiation emitted by radioactive sources used to obtain information on rock types, reservoir layer thicknesses, porosity, permeability, and others. Among several sources of ionizing radiation, 241Am-Be is one of the most commonly used. The objective of this research is to develop computational exposure scenarios involving workers during the logging of oil wells with nuclear probes and to determine the radioactive doses that these individuals are exposed to. A set of conversion factors for equivalent and effective dose was calculated for the tube operator and the driver of the vehicle transporting the tube. The absorbed doses in the workers organs and tissues, and the fluence of particles around the oil well were determined using the radiation transport code MCNPX2.7.0. The exposed individuals were represented by computational anthropomorphic phantoms from ICRP 110 reference. Particle fluence maps were determined to characterize the radiation field, around the well, generated by the 241Am-Be source. Considering an exposure time of 10 minutes and a typical activity of 333 GBq, an effective dose of 73 mSv for the operator was obtained, which is higher than the dose limit recommended by the ICRP of 20 mSv per year. Particle fluence maps showed that the most critical points for the workers were when the source is operated at the well entrance. Therefore, the results showed that neutron source handling must follow operational procedures, training, handling, regular verification of devices, and regulatory control.