ROBERTO VICENTE

ROBERTO VICENTE

(Fonte: Lattes)

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Degree in Physics from Universidade de São Paulo (1977); master degree in Nuclear Technology from Universidade de São Paulo (1980) and doctorate in Nuclear Technology from Universidade de São Paulo (2002). Has experience in radioactive waste management, acting on the following subjects: radioactive waste characterization, treatment and disposal; disposal of disused sealed radioactive sources. (Text obtained from the Currículo Lattes on November 25th 2021)

É bacharel em Física pela Universidade de São Paulo (1977), tem mestrado em Tecnologia Nuclear pela Universidade de São Paulo (1980) e doutorado em Tecnologia Nuclear pela Universidade de São Paulo (2002). Atualmente é tecnologista da Comissão Nacional de Energia Nuclear. Tem experiência na área de Engenharia Nuclear, com especialização em Gestão de Rejeitos Radioativos, atuando principalmente nos seguintes temas: gerenciamento, tratamento e deposição de rejeitos radioativos. (Texto extraído do Currículo Lattes em 25 nov. 2021)

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Precautionary and preventive measures in Brazilian law applied to radioactive waste management
2022 - ANDRADE, M.V.; VICENTE, R.
Nuclear technologies and radiation have offered technological and scientific growth nowadays, but there is a frequent paradox in this. While these technologies substantially increase the quality of human life, they also produce radioactive waste, which, when not properly managed, can generate risks that threaten to harm the environment and health. As a result, in risk management of radioactive waste, decision-making processes need to be guided by a framework of principles, including the precautionary and preventive principles. For this reason, the present work proposes to develop a legal analysis on radioactive waste risk management using the principles of precaution and prevention. These principles have similarities, but it is the differences in their structure that deserve to be highlighted, which is discussed and exemplified throughout this work. Furthermore, national and international experience in environmental damage has taught us that an identification and assessment of risk is necessary, because if preventive measures are not taken radioactive waste can be dispersed and harm the environment. When it comes to assessing the risk of radioactive waste, one of the precautionary measures is the application of a conservative stance in modelling scenarios, as there are still uncertain risks. Therefore, comprehending the different circumstances surrounding precautionary and preventive measures and having effective information about risk is essential for successful risk management.
Dose estimation in abdominal CT scans using CT-EXPO software
2022 - SOUZA, D.C.B.; VICENTE, R.; SA, L.V.; SILVA, E.H.; OLIVEIRA, M.V.L.; CIDRAL, M.E.V.; FARIA, C.R.; CAMILO, N.F.
The application of ionizing radiation in diagnostic medicine has increased worldwide in the last decades. Computed Tomography (CT) is the main radiological procedure that contributes to the increase of the collective dose in the population. The aim of this study was to estimate the doses received by patients undergoing CT scans in a public hospital in Santa Catarina - Brazil, employing data from the DICOM header and utilizing the CT-Expo V. 2.7 software. The data were selected from 45 abdominal CT scans consisting of two series: pre-contrast and one post-contrast intravenous, of adult patients performed in December 2020. The spreadsheets with the data extracted from the DICOM headers were provided by the Santa Catarina Telemedicine System (STT). The effective dose and organ doses were calculated by CTDIvol and DLP values using the software. Overall, the organs that showed the higher equivalent doses were the kidneys (19.5 mSv), spleen (18.5 mSv), stomach (18.9 mSv), and liver (18.1 mSv). The estimated effective doses were 7.31 and 8.41 mSv, for non-contrast and contrast-enhanced examinations. The use of software such as CT-Expo can support the estimation of effective doses received by patients through the information extracted from the DICOM header. The presented methodology can be a useful tool to retrospectively estimate the doses in CT services in Brazil.
Evaluation of recovery yields of 60Co and 137Cs in extraction procedures
2022 - ALMEIDA, M.A.; AYLLON, R.M.; ANGELINI, M.; VICENTE, R.; SILVA, P.S.C.
Nuclear technology has been implemented in several sectors of society, among them, it is possible to highlight medicine, industry, research, among others. The high demand of these nuclear applications has caused problems with regard to the generation of radioactive waste. The laser ablation method has been pointed out in the last years for the decontamination of surfaces and the contamination removed is completely retained in paper filters. This requires a safe and inexpensive method to perform the characterization of the radioisotopic inventory present in the laser filter samples. In this study, the extraction and quantification of the radionuclides present in the filter was evaluated using 60Co and 137Cs radionuclides. Two forms of extraction were tested: with Soxhlet equipment and by digesting the filter samples in a beaker, both using 3M HNO3 as extractant. The chemical yield was calculated using gamma ray countings obtained before and after extraction. It was observed that the extraction method by digesting the filter directly in a beaker presented the highest yield recovery results.
Brazilian clays for environmental solutions applied to radioactive waste management
2021 - MACHADO, G.G.; KRUPSKAYA, V.V.; ZAKUSIN, S.V.; HARADA, J.; VICENTE, R.; SOUZA, R.P.; ARAUJO, L.G.; MONTALVAN, E.T.; ESPINOSA, D.C.R.; KAHN, H.; GUILHEN, S.N.
Clayey materials have been adopted in most nuclear waste producing countries as a key constituent in engineered barrier systems for final disposal facilities at all levels of radioactive wastes (LILW-SL, LILW-LL, and HLW). The following study presents a thorough characterization upon five Brazilian clay-rich deposits, mostly smectite bearing clays, aiming to evaluate their expected performance as barrier under the conditions associated to a Low and Intermediate Level Waste Repository; being the former a matter of national strategic interest. Samples coming from the Brazilian states of Paraná, Bahia, Paraíba, and Maranhão were treated and analyzed by means of X-Ray diffraction as main technique. Other techniques such as FTIR, LALLS, XRF, and SEM-EDS, were performed in order to establish the mineralogical composition, particle size distribution, and chemical composition. Moreover, several standard clay treatments over the <1 μm size fraction were carried out to reveal information regarding layer charge, major interlayer cations, unit formula and other crystal features of smectite species present in a mineralogical assembly, aiming to provide information for the construction of a molecular model over which would be realistic to simulate the diffusion of radionuclides. Results obtained on 133Cs adsorption experiments indicate that mineralogical composition would probably be the single most influential factor controlling transport capacity of positively charged radionuclides in the current setup. The composition is especially expressed in terms of smectite contents, favoring montmorillonite rich materials containing majorly Na+ as compensating cation in interlayer position. All tested samples can be considered as suitable candidates to be used in the design of final destination storage for nuclear waste. Thus, efficiency on 133Cs adsorption trials also indicate that these materials could have potential uses as sorptive matrices (Sorbents) for water treatment of radionuclide polluted waters such as TENORM waste waters. However, these trends are yet to be contrasted against hydraulic conductivity measurements and swelling pressure in order to have a more comprehensive perspective of this clayey prospects as barrier enhanced layer; aligned to the multilayer barrier system approach for nuclear waste management.
Preliminary studies on electron beam irradiation as a treatment method of radioactive oil sludge
2021 - TESSARO, A.P.G.; VICENTE, R.; MARUMO, J.T.; TEIXEIRA, A.C.S.C.; ARAUJO, L.G.
Radiation-induced advanced oxidation processes have been proposed for the treatment of various types of wastes. However, electron beam technologies for the removal of recalcitrant compounds in petroleum wastes are still poorly understood. This work aims at evaluating the effects on the degradation of organic matter from oil sludge by electron beam irradiation. Characterization methods were employed to identify the chemical elements present in the waste. Radiometric analysis was performed to identify radionuclides and measure dose rates. Preliminary immobilization of the untreated waste with cement indicated resistance values very close to the minimum established in national regulation. To treat the waste, an electron beam accelerator, model Dynamitron II, with variable current up to 25 mA was employed and the irradiation doses ranged from 20 to 200 kGy. Solutions were prepared with an initial H2O2 concentration of 1.34 mol·L-1. The effects on the removal of total organic carbon are discussed.
Plutonium-238
2021 - SMITH, R.B.; ROMERO, F.; VICENTE, R.
Plutonium-238 is currently still the best fuel to power satellites to be sent to deep space in regions where the solar panels can no longer efficiently receive the sunlight. For 50 years, the National Aeronautics and Space Administration (NASA) has used this radioisotope as a fuel in radioisotope thermoelectric generators (RTGs) installed on satellites such as Pioneer 10 and 11, Voyager 1 and 2, Cassini-Huygens and New Horizons, as well as the various rovers sent to the Moon and to Mars, among others. Plutonium-238 is not a naturally occurring isotope on the planet, it was produced in greater quantity during the Cold War period as a by-product of the production of Plutonium-239 used for nuclear bombs. However, after the shutting down of the Savannah River reactors in 1988 and the ending of the Soviet Union in 1991, the United States stock of Plutonium-238 has been increasingly reduced, which threatens NASA's future space projects. This paper presents a brief bibliographic review about the subject, as well as commentaries on the options available to the United States, from restarting the production of this fuel, to possible alternatives for a new type of fuel or equipment that may supply the spacecrafts.
Immobilization of liquid radioactive waste in cement
2021 - FRANCA, A.A.S.; VICENTE, R.
Immobilization of radioactive waste is required to comply with nuclear regulations and waste acceptance criteria in a repository, which require the waste to be solid or immobilized in solid form within a durable and resistant matrix [1-4]. Cement is the most frequently used material for the immobilization of liquid, low-level waste, since it has many advantages, such as the ease of preparation at room temperature and the low cost [5, 6]. In this paper, we describe the characteristics of cement-water mixtures, homogenized in a drum using a vibration table as the mixing device. Common Portland cement was used as the immobilization matrix. The homogeneity of the mixtures is evaluated using cement dye in appropriate amounts. Initially, the distribution of the mineral dye was made by visual inspection. The batches were carried out with three different ways of feeding the components. Different results were obtained depending on the feeding methods employed.
Advanced heavy water reactor
2020 - SMITH, RICARDO B.; SACHDEVA, MAHIMA; BISURI, INDRANIL; VICENTE, ROBERTO
One of the great advances in the current evolution of nuclear power reactors is occurring in India, with the Advanced Heavy Water Reactor (AHWR). It is a reactor that uses thorium as part of its fuel, which in its two fueling cycle options, in conjunction with plutonium or low enriched uranium, produces energy at the commercial level, generating less actinides of long half-life and inert thorium oxide, which leads to an optimization in the proportion of energy produced versus the production of burnt fuels of the order of up to 50%. The objective of this work is to present the most recent research and projects in progress in India, and how the expected results should be in compliance with the current sustainability models and programs, especially the "Green Chemistry", a program developed since the 1990s in the United States and England, which defines sustainable choices in its twelve principles and that can also be mostly related to the nuclear field. Nevertheless, in Brazil, for more than 40 years there has been the discontinuation of research for a thorium-fueled reactor, and so far there has been no prospect of future projects. The AHWR is an important example as an alternative way of producing energy in Brazil, as the country has the second largest reserve of thorium on the planet.
Knowledge management in the decommissioning of nuclear facilities in Brazil
2020 - SMITH, R.B.; SALVETTI, T.C.; TESSARO, A.P.G.; MARUMO, J.T.; VICENTE, R.V.
In the second half of the twentieth century in Brazil, several nuclear facilities were built for the most varied objectives. The largest number of such facilities is at the Nuclear and Energy Research Institute in São Paulo (IPEN-CNEN/SP). For different reasons, some of these facilities had their projects finalized and were deactivated. Some of the equipment was then dismantled, but the respective nuclear and radioactive material remained isolated in the original sites waiting for the proper decommissioning procedures. The Celeste Project is an example of a facility where the nuclear material has been kept, and is subject to Argentine-Brazilian Agency for Accounting and Control of Nuclear Materials (ABACC) periodic inspections. Because of a number of interests, including financial and/or budgeting situations at the institutions, decades have passed without any further action; the people who originally worked there, and possessed information and knowledge about these facilities, have already moved away from the area, or are in the process of. Therefore, because of the absence of knowledge management techniques in force at the time of establishing and operating these installations, this work proposes an analysis about the possible consequences in case of loss of perhaps the only one remaining knowledge, the one from the people who designed those departments and worked there.