LEANDRO GOULART DE ARAUJO
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Artigo IPEN-doc 28679 Enhanced removal of radium from radioactive oil sludge using microwave irradiation and non-ionic surfactant2022 - LINHARES, VANESSA do N.; ARAUJO, LEANDRO G. de; VICENTE, ROBERTO; MARUMO, JULIO T.Surfactant-based technologies have been studied for the treatment of radioactive waste containing isotopes of radium. Nevertheless, the use of combined processes to remove radium from radioactive oil sludge is scarce in the literature. The objective of this work was to investigate the potential of a non-ionic surfactant to remove radium from raw oil sludge (ROS) and pre-treated, microwave-irradiated oil sludge (POS). Characterization of ROS and POS was made using the following methods: Thermal Gravimetric Analysis, X-ray diffraction, Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy, and gamma spectrometry. The effects of surfactant concentration (0.5–7.5%), temperature (25-60 °C), and contact time (30 and 60 min) were investigated. For ROS, little or no influence on the decontamination process was found for variations in the selected process parameters. For POS, the lowest surfactant concentration (2.5%) was the most efficient, removing about 94% of 226Ra and 228Ra. Neither contact time nor temperature affected removal. For ROS, removal percentages were 50–60% for 226Ra and 35–45% for 228Ra. The results indicated that the surfactant acted more efficiently in the decontamination of POS.Artigo IPEN-doc 28406 Experimental study on treatment of simulated radioactive waste by thermal plasma2021 - PRADO, E.S.P.; MIRANDA, F.S.; ARAUJO, L.G.; PETRACONI, G.; BALDAN, M.R.; ESSIPTCHOUK, A.; POTIENS JUNIOR, A.J.Thermal plasma technology is a process that demonstrates high performance for the processing of different types of waste. This technology can also be applied in the treatment of radioactive wastes, which requires special care. Beyond that, volumetric reduction, inertization, as well as a cheap and efficient process are necessary. In this context, the purpose of this paper is to demonstrate the application of thermal plasma technology for the treatment of solid radioactive waste. For this, stable Co and Cs were used to simulate compactable and non-compactable radioactive waste; about 0.8 g Co and 0.6 g Cs were added in each experimental test. The experimental tests were conducted using plasma of transferred arc electric discharge generated by the graphite electrode inside the process reactor. The behavior and distribution of the radionuclides present in the waste were assessed during the plasma process. The results show that the significant amounts of Co and Cs leave the melt by volatilization and are transferred to the gas phase with a small portion retained in the molten slag. The retention rate of Co in the slag phase is about 0.03% and 0.30% for compactable and non-compactable waste, respectively. On the other hand, Cs is completely transferred to the gas phase when added to the compactable waste. Conversely, when in the non-compactable waste, only 1.4% Cs is retained.Artigo IPEN-doc 27180 The use of rice and coffee husks for biosorption of U (total), 241Am, and 137Cs in radioactive liquid organic waste2020 - FERREIRA, RAFAEL V. de P.; ARAUJO, LEANDRO G. de; CANEVESI, RAFAEL L.S.; SILVA, EDSON A. da; FERREIRA, EDUARDO G.A.; PALMIERI, MAURICIO C.; MARUMO, JULIO T.Rice and coffee husks (raw and chemically activated) are examined as potential biosorption materials regarding their capacity to remove U (total), 241Am, and 137Cs. The physical parameters evaluated were the morphological characteristics of the biomass, real and apparent density, and surface area. Contact times for the batch experiments were 0.5, 1, 2, and 4 h, and the concentrations tested ranged between 10% of the total concentration and the radioactive waste itself without any dilution. The results were evaluated by experimental sorption capacity, ternary isotherm, and kinetics models. The kinetics results showed that equilibrium was reached after 2 h for all biomass. Raw coffee husk showed the best adsorption results in terms of maximum capacity (qmax) for all three radionuclides, which were 1.96, 39.4 × 10−6, and 46.6 × 10−9 mg g−1 for U, Am, and Cs, respectively. The biosorption process for the raw and activated rice husks was best represented by the Langmuir ternary isotherm model with two sites. For the coffee husk, in the raw and activated states, the biosorption process was best described by the modified Jain and Snoeyink ternary model. These results suggest that biosorption with these biomaterials can be applied in the treatment of liquid organic radioactive waste containing mainly uranium and americium.Artigo IPEN-doc 26878 Inventorying the radionuclides in spent cartridge filters from the primary circuit of a nuclear research reactor by the dose-to-activity method2020 - TESSARO, ANA P.G.; ARAUJO, LEANDRO G. de; VICENTE, ROBERTOThe high activity of spent cartridge filters from the cooling water polishing system of a nuclear research reactor precludes, in routine work of a waste characterization program, the usual method of radiochemical analysis of filter samples. For this waste, the dose-to-activity method, using a gamma spectrometer and a dose rate meter, is an alternative for the determination of the activities of the gamma emitters with acceptable accuracy. The ratio of photon peak-areas from different radionuclides, corrected by the detector energy-dependent efficiency, allowed estimating the proportions between the activities of the different radionuclides present. Finally, the simulation of the counting geometry, using the point-kernel method to estimate the air dose rate resulting from an arbitrary concentration of those radionuclides and the comparison of the calculated with the measured air dose rate have yielded the needed estimates of the activity concentrations. The aim of this paper is to report the development of the method applied for the determination of the concentration of the gamma-emitters present in cartridge filters from the IEA-R1 Nuclear Research Reactor.