Analysis of the in vivo monitoring program at IPEN in the last 14 years

Abstract

This paper presents the results of the in vivo monitoring analysis for Occupationally Exposed Individuals that handle unsealed sources at Nuclear and Energy Research Institute (IPEN). The facilities are: the Radiopharmacy Center, the Cyclotron, the IEA-R1 Reactor and Research Laboratories. The in vivo monitoring program is carried out in a whole-body counter for radionuclides emitting gamma rays with energy above 100 keV. This system is equipped with 8x4 and 3x3 inch NaI(Tl) detector, for whole body and thyroid measurements, respectively. The objective of this work is to analyze the results of the internal monitoring program according to the dose received by the Occupationally Exposed Individuals from 2005 to 2018. During this period about 6,000 measurements were accomplished. The radionuclides that presented measured values above the detection limit of the system were: 131I, 99Mo, 99mTc, 153Sm, 177Lu, 111In, 192Ir, 125I, 123I, 181Hf, 203Hg, 67Ga, 18F, 51Cr, 201Tl. These measurements have amounted less than 6.9% of the total whole-body monitoring’s performed in this period. Among these radionuclides, 131I, 99mTc, 125I and 18F have contributed with 69% of all measurements above the limit of detection, but most dose results were below the recording level under installations normal operating conditions. Regarding to the radionuclides that have presented doses above the recording level we can mention the 131I, 67Ga, 111In that occurred in small unexpected situations. The results shown by this analysis give a good support to the internal individual monitoring program implemented by the radioprotection service in these facilities.