RAFAEL COELHO MARIN
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Resumo IPEN-doc 24596 The use of SEM-EDX for the identification of uranium compounds in swipe samples for nuclear safeguards2017 - SARKIS, J.E.S.; PESTANA, R.C.B.; MARIN, R.C.; CARVALHO, E.F.U.Environmental swipe sampling for safeguards purposes has been used by International Atomic Energy Agency since 1996 and is a powerful tool to detect undeclared materials and activities in States under safeguards agreements. The Secondary Electron Microscope with Energy-Dispersive X-Ray analyzing system (SEM-EDX) can be particularly useful in the initial identification of uranium in swipe samples and might be appropriate to identify and characterize uranium particles This work describes the use of SEM-EDX, as an initial screening technique, in real-life swipe samples for identifying and characterizing uranium particles. The swipe samples were collected in a conversion plant at the Nuclear and Energy Research Institute – IPEN/CNEN, São Paulo, BrazilResumo IPEN-doc 24595 The use of ICP-MS and LA-ICP-MS techniques for uranium analysis in real-life swipe samples for safeguards purposes2017 - SARKIS, J.E.S.; PESTANA, R.C.B.; MARIN, R.C.; ABREU-JUNIOR, C.H.; CARVALHO, E.F.U.Environmental swipe sampling is a powerful tool to detect undeclared materials and activities in States under safeguards agreements and has been used by the International Atomic Energy Agency since 1996. This work describes the utilization of the inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for determining uranium isotopic ratios in a real-life swipe samples collected in a conversion plant at IPEN/CNEN, Brazil. Uncertainties were estimated by following the International Organization for Standardization –Guide to the Expression of Uncertainties in Measurement (ISO GUM), with a confidence level of 95%.Resumo IPEN-doc 24594 Uranium isotope ratio measurements by LA-HR-ICP-MS2017 - SARKIS, J.E.S.; MARIN, R.C.This work describes the utilization of LA-HR-ICP-MS (laser ablation high resolution inductively mass spectrometry) for characterize the uranium isotope ratio of a UO2 pellet supplied and certified by New Brunswick Laboratory (NBL). This method is useful measurements of 233U, 234U, 235U, 236U and 238U, reaching relative standard deviations (RSD) from 1.55% to 2.45%. The Laser ablation ICP-MS technique shows a high level of instability, compromising the precision of the measurements, although could be made some adjustments to improve its stability. To reach the better stability were made the adjustments of laser ablation and ICP-MS parameters, such as RF power, laser beam diameter, defocusing of laser beam, auxiliary gas and sample gas. The parameters which caused the greatest impact in order to improve the stability signal were RF power, defocusing and laser beam diameter. To carry out the adjustments of the parameters was used a glass standard NIST 610, supplied and certified by National Institute of Standards and Technology (NIST). The measurements were carried out on a single spot ablation with low energy density and defocusing, which demonstrated to be the improved way to reach good signal stability. The results presented by the measurements revealed that the Laser ablation ICP-MS technique offers a rapid and accurate way to perform uranium isotope ratios without any sample preparation, since it allows carrying out the measurements straight on the sample, besides to preserve the sample that is very important to safeguards and nuclear forensics.Resumo IPEN-doc 24589 The use of laser ablation sector field inductively coupled plasma mass spectrometry for swipe samples analysis2017 - SARKIS, J.E.S.; MARIN, R.C.; PESTANA, R.C.B.This work describes the utilization of laser ablation sector field inductively coupled plasma mass spectrometry (LA-SF-ICP-MS) for determining uranium isotopic composition in a simulated swipe sample by deposition of U3O8 powder with natural enrichment level. This method is useful to measure 234U/238U and 235U/238U isotopic ratios. The measurements were performed on a continuous ablation with low energy density and defocusing, which improved the signal stability, in a cluster of uranium particles. Optimization of measurements was achieved by adjusting the following parameters: RF power, laser beam diameter, defocusing of laser beam, laser energy, laser energy-density, auxiliary gas and sample gas. The 235U/238U isotope ratio was 0.00719 0.00020 and its precision was 1.2 % RSD (relative standard deviation). Uncertainties were estimated following the International Organization for Standardization – Guide to the Expression of Uncertainty in Measurement (ISO – GUM), with a confidence level of 95.45% (k = 2.00). The results indicate that the Laser Ablation ICP-MS technique offers a rapid and accurate alternative for the measurement of uranium isotope ratios in uranium particle. The technique has the added advantage of allowing measurements straight on the sample (without further preparation), preserving the testimony which is very important for safeguards and nuclear forensics purposes.Resumo IPEN-doc 24587 Nuclear forensics2017 - SARKIS, J.E.S.; MARIN, R.C.; PESTANA, R.C.B.The use of environmental monitoring as a technique to identify activities related to the nuclear fuel cycle has been proposed, by international organizations, as an additional measure to the safeguards agreements in force. The elements specific for each kind of nuclear activity, or "nuclear signatures", inserted in the ecosystem by several transfer paths, can be intercepted with better or worse ability by different live organisms. Depending on the kind of signature of interest, the anthropogenic material identification and quantification require the choice of adequate biologic indicators and, mainly, the use of sophisticated techniques associated with elaborate sample treatments. This work demonstrates the technical viability of using pine needles as bioindicators of nuclear signatures associated with uranium enrichment activities. Additionally, it proposes the use of a technique widely diffused nowadays in the scientific community, the High Resolution Inductively Coupled Plasma Mass Spectrometer (HR-ICP-MS), to identify the signature corresponding to that kind of activities in the ecosystem. It can be also found a description of a methodology recently being applied in analytical chemistry, based on uncertainties estimates metrological concepts, used to calculate the uncertainties associated with the obtained measurement results. Nitric acid solutions with a concentration of 0.3 mol kg1, used to wash pine needles sampled near facilities that manipulate enriched uranium and containing only 0.1 g kg1 of uranium, exhibit a 235U:238U isotopic abundance ratio of 0.0092 ? 0.0002, while solutions originated from samples collected at places located more than 200 km far from activities related to the nuclear fuel cycle exhibit a value of 0.0074 ? 0.0002 for this abundance ratio. Similar results were obtained for sample solutions prepared by microwave assisted acid digestion and dry ashing process. The different values of 235U:238U isotopic abundance ratio obtained for samples collected in different places permit to confirm the presence of anthropogenic uranium and demonstrate the viability of using this technique and the methodology proposed in this work.Artigo IPEN-doc 20317 Brazil's participation in the galaxy serpent exercise2014 - SARKIS, JORGE E.S.; BORDON, ISABELLA C.A.C.; PESTANA, RAFAEL C.B.; MARIN, RAFAEL C.Artigo IPEN-doc 19330 The use of laser ablation sector field inductively coupled plasma mass spectrometry for swipe samples analysis: a viewpoint from safeguard and nuclear forensic2013 - MARIN, RAFAEL C.; SARKIS, JORGE E.S.; PESTANA, RAFAEL C.B.Artigo IPEN-doc 19315 Nuclear forensics: strategies and analytical techniques2013 - MARIN, RAFAEL C.; SARKIS, JORGE E.S.; PESTANA, RAFAEL C.B.Artigo IPEN-doc 19249 The use of SEM-EDX for the identification of uranium compounds in swipe samples for nuclear safeguards2013 - PESTANA, RAFAEL C.B.; SARKIS, JORGE E.S.; MARIN, RAFAEL C.; CARVALHO, ELITA F.U.Artigo IPEN-doc 19248 The use of ICP-MS and LA-ICP-MS techniques for uranium analysis in real-life swipe samples for safeguards purposes2013 - PESTANA, RAFAEL C.B.; SARKIS, JORGE E.S.; MARIN, RAFAEL C.; ABREU JUNIOR, CASSIO H.; CARVALHO, ELITA F.U.