PAULO ROBERTO RELA
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Artigo IPEN-doc 26739 Gamma radiation of quartz from Entre Rios (SC) and Quaraí (RS)2019 - ENOKIHARA, C.T.; SCHULTZ-GUTTLER, R.A.; RELA, P.R.The availability of gamma ray irradiators in Brazil increased the possibilities of the treatment of gemstones for color enhancement. One of the minerals with very high potential for these treatments is the quartz, a very widespread mineral with many colored commercial varieties. There is a specific variety of quartz in nature, showing a green color that may be produced artificially, by gamma radiation (60Co). In Brazil, the widely scattered geode occurrence from Quaraí, at Brazil southernmost location up to Uberlandia, in Minas Gerais, is one of these events. Quartz from these occurrences have been formed by strong hydrothermal activities. Hence, many quartz crystals showed a very fast growth occurrence, facilitating the formation of consequent defects and the uptake of water under the form of micro inclusions, molecular water, silanol (Si-OH) and OH. In the present work, the material analyzed is from hydrothermal regimes located near the towns Entre Rios and Quaraí. To characterize these materials, analyses have been made by ICP, NAA, electron microscopy, water loss techniques plus UV-VIS and NIR-FTIR spectroscopic measurements. Silanol complexes have been found by radiation, due to gamma rays forming the color center NBOHC (Non-Bonding Oxygen Hole Center), showing absorption between 590 to 620 nm and leaving a transmission window at about 550nm, responsible for the green color. The spectroscopic water determination showed less molecular water (up to 2300 ppm, per weight), probably due to remaining silanol complexes. The water content, with up to 3200 ppm by weight, exceeds the amount of charge balancing cations (Fe, Al, Li).Artigo IPEN-doc 26270 Comparative analysis of quartz treated with gamma radiation originated from the hydrothermal geodes of the Paraná Basin (Artigas-Uruguay region), with quartz generated in the hydrothermal veins of Serra do Espinhaço (Curvelo-MG and Brejinho-BA regions)2019 - ENOKIHARA, CYRO T.; SCHULTZ-GUTTLER, RAINER A.; RELA, PAULO R.In Brazil, hydrothermal quartz may be found in the geodes of the basaltic rocks of the Paraná Basin and in the vein systems of quartzites of the Serra do Espinhaço. The quartz of hydrothermal origin of the Paraná Basin contains a great amount of structurally bound water in the form of molecular water, silanol, hydroxyl and abundant growth defects that are responsible for the green color formed by irradiation. To register the influence of water in the formation of the green color in the quartz of the Paraná Basin, quartz samples from the following regions were analyzed: Artigas, located in the Paraná Basin, Curvelo and Brejinho located in Serra do Espinhaço. The quartz from Artigas, formed at low temperature, has high concentration of molecular water and silanol and a greater amount of Fe than Al. The quartz from Curvelo with Al, but, without water molecular and silanol was formed by intermediate temperature and the quartz from Brejinho has very little Al, Fe and a small silanol and molecular water content. To characterize these samples, ICP and NIR-FTIR spectroscopic measurements have been taken, together with water loss techniques and color stability, by UV treatment and heating. The analysis by FTIR spectrometry of Artigas quartz samples shows strong absorptions of H2O and Si-OH, respectively, near the regions of 5300 cm-1 and 4500 cm-1. This content of molecular water and silanol in hydrothermal quartz of Artigas is responsible for the formation of NBOHC defects that produce, by gamma radiation, the green color.Artigo IPEN-doc 24183 Gamma radiation of quartz from Entre Rios (SC) and Quaraí (RS)2017 - ENOKIHARA, CYRO T.; SCHULTZ-GUTTLER, RAINER A.; RELA, PAULO R.The availability of gamma ray irradiators in Brazil increased the possibilities of treatments of gemstones for color enhancements. One of the minerals with a very high potential of these treatments is quartz, a very widespread mineral with many colored commercial varieties. A specific variety of quartz showing a green color in nature or induced artificially by radiation gamma (60Co) is quite rare. In Brazil the widely scattered geode occurrences along a 600 km stretch from Quaraí at Brazil southernmost tip to Uberlandia in Minas Gerais is one of these. Quartz from these occurrences have been formed by strong hydrothermal activities. That way much quartz crystals showed a very fast growth history facilitating the formation of growth defects and the uptake of water in form of micro inclusions, molecular water, silanol (Si-OH) and OH. In the present work the material analyzed is from hydrothermal regimes located near the towns Entre Rios (SC) and Quaraí (RS). To characterize these materials analyses have been made by ICP, NAA, electron microscopy, water loss techniques and UV-VIS and NIR-FTIR spectroscopic measurements. Silanol complexes are found, which by radiation due to gamma rays form the color center NBOHC (Non-Bonding Oxygen Hole Center), showing absorption between 590 to 620 nm and leaving a transmission window at about 550nm, responsible for the green color. The spectroscopic water determination showed less molecular water (up to 2300 ppm by weight), probably due to remaining silanol complexes.The water content with up to 3200 ppm by weight exceeds the amount of charge balancing cations (Fe, Al, Li).Resumo IPEN-doc 23058 Multipurpose gamma-irradiator and mobile unit with an electron beam accelerator developed in Brazil2017 - CALVO, W.A.P.; DUARTE, C.L.; SOMESSARI, S.L.; SPRENGER, F.E.; COSTA, F.E.; FEHER, A.; SALVADOR, P.A.V.; OMI, N.M.; SILVA, L.G.A.; LAINETTI, F.F.; RELA, P.R.; SAMPA, M.H.O.Radiation processing technology for industrial and environmental applications has been developed and used worldwide in the fields of water treatment, advanced materials, nanotechnology, medicine, tissue engineering, disinfestations and disinfection of books and documents, processes and industrial production and natural resources, among others. The Radiation Technology Centre (RTC) of the Nuclear Energy Research Institute (IPEN), of CNEN, Brazil, developed a small size continuous run and multipurpose industrial - irradiator with a revolutionary design and national technology to be used as a demonstration facility for manufacturers and contract service companies that need economical and logistical in-house irradiation system alternatives. It will be useful for supporting the local scientific community for product and process development using -radiation, assisting the traditional and potential users on process validation, and for training and qualification of operators and radioprotection officers. The technology developed for this facility consists of a continuous tote box transport system comprising a single concrete vault, where the automated transport system of products in and out of the irradiator utilizes a revolving door integrated with the shielding, avoiding the traditional maze configuration. Covering 76 m2 of floor area, the irradiator design is product overlap sources with a maximum 60Co capacity of 37 PBq (tote boxes, Category IV, wet storage). The performed qualification programme of this multipurpose irradiator was based on AAMI/ISO 11137 standard. The irradiator currently holds 7:4 PBq (200 kCi) of 60Co. For irradiator dose optimization, the source distribution was done using the Cadgamma software. The poly-methylmetacrylate (PMMA) dosimeter system was used for irradiator dose mapping. The economic analysis and performance, concerning to the dose uniformity and 60Co utilization efficiency were calculated and compared with other commercial irradiators available in the market. The RTC is involved in establishing a mobile electron beam accelerator unit to treat industrial effluents for reuse purposes. The mobile unit will be equipped with an electron beam accelerator (0:7 MeV, 20 kW) with safety requirements (BSS, IAEA and CNEN Safety Standards), and can be used for effluent treatment from petroleum production, for petroleum desulfurization, and, in addition, for degradation of toxic organic compounds in wastewater for reuse. This project is supported by the IAEA (TC Project BRA1035, 2016–2018) and by the Brazilian Financial of Studies and Project (FINEP). To enlarge the national capacity to treat industrial effluents using electron beam accelerators, the mobile unit treating effluents on site from 1 m3/h up to 1000 m3/day, will provide an effective facility between a laboratory-scale plant to a large-scale plant, with the objective to demonstrate its efficacy and to transfer the technology. Studies have taken place in various productive sectors in the country and in other foreign laboratories to prove that radiation treatment offers technological and economic benefits over conventional techniques for treating recalcitrant pollutants.Capítulo IPEN-doc 22483 Overview of radiation technology for environmental remediation in Brazil2016 - DUARTE, C.L.; BORRELY, S.I.; OIKAWA, H.; MORI, M.N.; RELA, P.R.; COSTA, F.E.; SAMPA, M.H.O.Artigo IPEN-doc 20962 Characterization of hydrothermal green quartz produced by gamma radiation2015 - ENOKIHARA, CYRO T.; SCHULTZ-GUTTLER, RAINER A.; RELA, PAULO R.Resumo IPEN-doc 17800 Gamma and neutron maze efficiency enhancement2011 - OMI, N.M.; RODRIGUES JUNIOR, O.; CALVO, W.A.P.; RELA, P.R.The design of radiation bunkers is based on the existence of thick walls and mazes, ducts with bends, in penetration points. These mazes tend to have traditional designs with three or more bends with plain finished walls, penetrating the bunker walls with low radiation transmission rate. The traditional designs require wide installation footprints and long transport systems, following the respective maze. Reducing the radiation transmission of each bend, it's possible to reduce the amount of curves and the length of their ducts, or legs, to reach the desired maze radiation transmission rate. Minimizing the maze legs can reduce significantly the costs of the installation construction and maintenance. The proposed maze modifications, effective for gamma and neutron fluxes, have the radiation transmission many times lower than a traditional maze with the same duct number and lengths. The main purpose of this work is to show that it is possible to enhance the maze efficiency to reduce the radiation transmission adopting radiation "traps". Each "trap" have to be optimized for the radiation source and maze section. As example, the efficiency enhancement of one of these modifications for gamma radiation is determined by comparative simulations. The results of Monte Carlo simulations are presented in this work.Artigo IPEN-doc 19358 Study on the formation of ozone gas in industrial irradiation process2013 - UZUELI, DANIEL H.; RELA, PAULO R.; VASQUEZ, PABLO A.S.; HAMADA, MARGARIDA M.; COSTA, FABIO E. daArtigo IPEN-doc 17032 Development of an encapsulation method using plasma arc welding to produce iodine-125 seeds for brachytherapy2011 - FEHER, ANSELMO; CALVO, WILSON A.P.; ROSTELATO, MARIA E.C.M.; ZEITUNI, CARLOS A.; SOMESSARI, SAMIR L.; COSTA, OSVALDO L.; MOURA, JOAO A.; MOURA, EDUARDO S.; SOUZA, CARLA D.; RELA, PAULO R.Artigo IPEN-doc 16879 Montezuma prasiolite: gamma radiation effects2011 - GUTTLER, RAINER A.S.; ENOKIHARA, CYRO T.; HELFENBERGER, ANDRE F.M.; RELA, PAULO R.