The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
K. Mayer - One of the best experts on this subject based on the ideXlab platform.
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investigation of sulphur isotope variation due to different processes applied during Uranium Ore concentrate production
Journal of Radioanalytical and Nuclear Chemistry, 2016Co-Authors: Judit Krajko, M. Wallenius, K. Mayer, Zsolt Varga, R J M KoningsAbstract:The applicability and limitations of sulphur isotope ratio as a nuclear fOrensic signature have been studied. The typically applied leaching methods in Uranium mining processes were simulated for five Uranium Ore samples and the n(34S)/n(32S) ratios were measured. The sulphur isotope ratio variation during Uranium Ore concentrate (UOC) production was also followed using two real-life sample sets obtained from industrial UOC production facilities. Once the major source of sulphur is revealed, its appropriate application for origin assessment can be established. Our results confirm the previous assumption that process reagents have a significant effect on the n(34S)/n(32S) ratio, thus the sulphur isotope ratio is in most cases a process-related signature.
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measurement of the sulphur isotope ratio 34s 32s in Uranium Ore concentrates yellow cakes for origin assessment
Journal of Analytical Atomic Spectrometry, 2013Co-Authors: Sunho Han, M. Wallenius, Zsolt Varga, Judit Krajko, Kyuseok Song, K. MayerAbstract:A novel method has been developed for the measurement of the 34S/32S isotope ratio in Uranium Ore concentrate (yellow cake) samples for origin assessment in nuclear fOrensics. The leachable sulphate is separated and pre-concentrated by anion exchange separation followed by the 34S/32S ratio measurement by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The effect of sample composition on the accuracy was investigated and optimized. Matching of the sample to the bracketing standard was necessary to obtain accurate results. The method was validated by the measurement of standard reference materials (IAEA-S-2, IAEA-S-3 and IAEA-S-4) and the δ34S value could be determined with an uncertainty between 0.45‰ and 1.9‰ expressed with a coverage factor of 2. The method was then applied for the analysis of Uranium Ore concentrates of world-wide origin. In the studied materials distinct 34S/32S isotope ratios could be observed, which can be a promising signature for the nuclear fOrensic investigations to identify the source of unknown nuclear materials.
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analysis of Uranium Ore concentrates for origin assessment
Proceedings in Radiochemistry A Supplement to Radiochimica Acta, 2011Co-Authors: Zsolt Varga, M. Wallenius, K. Mayer, M MeppenAbstract:Summary. In this study the most important analytical methodologies are presented for the nuclear fOrensic investigation of Uranium Ore concentrates (yellow cakes). These methodologies allow to measure characteristic parameters which may be source material or process inherited. By the combination of the various techniques (e.g. infrared spectrometry, impurity content, rare-earth pattern and U, Sr and Pb isotope ratio analysis by mass spectrometry), the possible provenances of the illicit material can be narrowed down to a few options and its declared origin can be verified. The methodologies serve for nuclear fOrensic investigations as well as for nuclear safeguards, checking the consistency of information.
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origin assessment of Uranium Ore concentrates based on their rare earth elemental impurity pattern
Radiochimica Acta, 2010Co-Authors: Zsolt Varga, M. Wallenius, K. MayerAbstract:The rare-earth element pattern was used as an additional tool for the identification and origin assessment of Uranium Ore concentrates (yellow cakes) for nuclear fOrensic purposes. By this means, the source of an unknown material can be straightforwardly verified by comparing the pattern with that of a known or declared sample. In contrast to other indicators used for nuclear fOrensic studies, the provenance of the material can also be assessed in several cases even if no comparison sample is available due to the characteristic pattern. The milling process was found not to change the pattern and no significant elemental fractionation occurs between the rare-earth elements, thus the pattern in the yellow cakes corresponds to that found in the Uranium Ore.
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Anion analysis in Uranium Ore concentrates by ion chromatography
Journal of Radioanalytical and Nuclear Chemistry, 2009Co-Authors: V. Badaut, M. Wallenius, K. MayerAbstract:In the present exploratory study, the applicability of anionic impurities for attributing nuclear material to a certain chemical process or origin has been investigated. Anions (e.g., nitrate, sulphate, fluoride, chloride) originate from acids or salt solutions that are used for processing of solutions containing Uranium or plutonium. The study focuses on Uranium Ore concentrates (“yellow cakes”) originating from different mines. Uranium is mined from different types of Ore body and depending on the type of rock, different chemical processes for leaching, dissolving and precipitating the Uranium need to be applied. Consequently, the anionic patterns observed in the products of these processes (the “Ore concentrates”) are different. The concentrations of different anionic species were measured by ion chromatography using conductivity detection. The results show clear differences of anion concentrations and patterns between samples from different Uranium mines. Besides this, differences between sampling campaigns in a same mine were also observed indicating that the Uranium Ore is not homogeneous in a mine. These within-mine variations, however, were smaller than the between-mine variations.
M. Wallenius - One of the best experts on this subject based on the ideXlab platform.
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investigation of sulphur isotope variation due to different processes applied during Uranium Ore concentrate production
Journal of Radioanalytical and Nuclear Chemistry, 2016Co-Authors: Judit Krajko, M. Wallenius, K. Mayer, Zsolt Varga, R J M KoningsAbstract:The applicability and limitations of sulphur isotope ratio as a nuclear fOrensic signature have been studied. The typically applied leaching methods in Uranium mining processes were simulated for five Uranium Ore samples and the n(34S)/n(32S) ratios were measured. The sulphur isotope ratio variation during Uranium Ore concentrate (UOC) production was also followed using two real-life sample sets obtained from industrial UOC production facilities. Once the major source of sulphur is revealed, its appropriate application for origin assessment can be established. Our results confirm the previous assumption that process reagents have a significant effect on the n(34S)/n(32S) ratio, thus the sulphur isotope ratio is in most cases a process-related signature.
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measurement of the sulphur isotope ratio 34s 32s in Uranium Ore concentrates yellow cakes for origin assessment
Journal of Analytical Atomic Spectrometry, 2013Co-Authors: Sunho Han, M. Wallenius, Zsolt Varga, Judit Krajko, Kyuseok Song, K. MayerAbstract:A novel method has been developed for the measurement of the 34S/32S isotope ratio in Uranium Ore concentrate (yellow cake) samples for origin assessment in nuclear fOrensics. The leachable sulphate is separated and pre-concentrated by anion exchange separation followed by the 34S/32S ratio measurement by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The effect of sample composition on the accuracy was investigated and optimized. Matching of the sample to the bracketing standard was necessary to obtain accurate results. The method was validated by the measurement of standard reference materials (IAEA-S-2, IAEA-S-3 and IAEA-S-4) and the δ34S value could be determined with an uncertainty between 0.45‰ and 1.9‰ expressed with a coverage factor of 2. The method was then applied for the analysis of Uranium Ore concentrates of world-wide origin. In the studied materials distinct 34S/32S isotope ratios could be observed, which can be a promising signature for the nuclear fOrensic investigations to identify the source of unknown nuclear materials.
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analysis of Uranium Ore concentrates for origin assessment
Proceedings in Radiochemistry A Supplement to Radiochimica Acta, 2011Co-Authors: Zsolt Varga, M. Wallenius, K. Mayer, M MeppenAbstract:Summary. In this study the most important analytical methodologies are presented for the nuclear fOrensic investigation of Uranium Ore concentrates (yellow cakes). These methodologies allow to measure characteristic parameters which may be source material or process inherited. By the combination of the various techniques (e.g. infrared spectrometry, impurity content, rare-earth pattern and U, Sr and Pb isotope ratio analysis by mass spectrometry), the possible provenances of the illicit material can be narrowed down to a few options and its declared origin can be verified. The methodologies serve for nuclear fOrensic investigations as well as for nuclear safeguards, checking the consistency of information.
-
origin assessment of Uranium Ore concentrates based on their rare earth elemental impurity pattern
Radiochimica Acta, 2010Co-Authors: Zsolt Varga, M. Wallenius, K. MayerAbstract:The rare-earth element pattern was used as an additional tool for the identification and origin assessment of Uranium Ore concentrates (yellow cakes) for nuclear fOrensic purposes. By this means, the source of an unknown material can be straightforwardly verified by comparing the pattern with that of a known or declared sample. In contrast to other indicators used for nuclear fOrensic studies, the provenance of the material can also be assessed in several cases even if no comparison sample is available due to the characteristic pattern. The milling process was found not to change the pattern and no significant elemental fractionation occurs between the rare-earth elements, thus the pattern in the yellow cakes corresponds to that found in the Uranium Ore.
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Anion analysis in Uranium Ore concentrates by ion chromatography
Journal of Radioanalytical and Nuclear Chemistry, 2009Co-Authors: V. Badaut, M. Wallenius, K. MayerAbstract:In the present exploratory study, the applicability of anionic impurities for attributing nuclear material to a certain chemical process or origin has been investigated. Anions (e.g., nitrate, sulphate, fluoride, chloride) originate from acids or salt solutions that are used for processing of solutions containing Uranium or plutonium. The study focuses on Uranium Ore concentrates (“yellow cakes”) originating from different mines. Uranium is mined from different types of Ore body and depending on the type of rock, different chemical processes for leaching, dissolving and precipitating the Uranium need to be applied. Consequently, the anionic patterns observed in the products of these processes (the “Ore concentrates”) are different. The concentrations of different anionic species were measured by ion chromatography using conductivity detection. The results show clear differences of anion concentrations and patterns between samples from different Uranium mines. Besides this, differences between sampling campaigns in a same mine were also observed indicating that the Uranium Ore is not homogeneous in a mine. These within-mine variations, however, were smaller than the between-mine variations.
L E Borg - One of the best experts on this subject based on the ideXlab platform.
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nuclear fOrensic analysis of an unknown Uranium Ore concentrate sample seized in a criminal investigation in australia
Forensic Science International, 2014Co-Authors: Elizabeth Keegan, L E Borg, Rachel E. Lindvall, Michael J Kristo, Michael Colella, Martin Robel, Ross W Williams, Gary R Eppich, Sarah K Roberts, Amy M GaffneyAbstract:Early in 2009, a state policing agency raided a clandestine drug laboratory in a suburb of a major city in Australia. During the search of the laboratory, a small glass jar labelled “Gamma Source” and containing a green powder was discovered. The powder was radioactive. This paper documents the detailed nuclear fOrensic analysis undertaken to characterise and identify the material and determine its provenance. Isotopic and impurity content, phase composition, microstructure and other characteristics were measured on the seized sample, and the results were compared with similar material obtained from the suspected source (Ore and Ore concentrate material). While an extensive range of parameters were measured, the key ‘nuclear fOrensic signatures’ used to identify the material were the U isotopic composition, Pb and Sr isotope ratios, and the rare earth element pattern. These measurements, in combination with statistical analysis of the elemental and isotopic content of the material against a database of Uranium Ore concentrates sourced from mines located worldwide, led to the conclusion that the seized material (a Uranium Ore concentrate of natural isotopic abundance) most likely originated from Mary Kathleen, a former Australian Uranium mine.
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natural variations in Uranium isotope ratios of Uranium Ore concentrates understanding the 238u 235u fractionation mechanism
Earth and Planetary Science Letters, 2010Co-Authors: Gregory A Brennecka, I D Hutcheon, L E Borg, Michael A Sharp, Ariel D. AnbarAbstract:Abstract Precise measurement of the 238 U/ 235 U ratio in geologic samples is now possible with modern techniques and mass spectrometers. Natural variations in this ratio have been shown in previous studies. In this study, data obtained from Uranium Ore concentrates of mining facilities around the world show clear evidence that the depositional redox environment in which Uranium is precipitated is the primary factor affecting 238 U/ 235 U fractionation. Low-temperature Uranium deposits are, on average, isotopically ∼ 0.4‰ heavier than Uranium deposited at high temperatures or by non-redox processes. 238 U/ 235 U ratios coupled with 235 U/ 234 U ratios in the same sample provide evidence that the redox transition (U VI → U IV ) at low temperatures is the primary mechanism of 238 U/ 235 U fractionation and that aqueous alteration plays a very limited, if any, role in fractionation of the 238 U/ 235 U ratio. The isotopic variation of U is therefOre a potential signature that can be used to trace the origin of Uranium Ore concentrate.
Motohide Takahama - One of the best experts on this subject based on the ideXlab platform.
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Effects of Uranium Ore dust on cultured human lung cells
Environmental toxicology and pharmacology, 1998Co-Authors: Susumu Ohshima, Motohide TakahamaAbstract:Effects of Uranium Ore dust on cell proliferation, lipid peroxidation and micronuclei formation were compared with silica (DQ12) and titanium oxide in normal human distal airway epithelial cells (NHDE), human lung cancer cells (A549) and human lung fibroblast cells. Cell proliferation was significantly inhibited with Uranium Ore dust and silica but not with titanium oxide. Lipid peroxidation was significantly enhanced only with Uranium Ore dust. Micronuclei formation was significantly stimulated with Uranium Ore dust in A549 and NHDE cells, but not in fibroblast cells. Silica stimulated micronuclei formation only in A549 cells. The results showed the outstanding effect of Uranium Ore dust on lipid peroxidation and micronuclei formation in human lung cells compared to silica and titanium dioxide.
Judit Krajko - One of the best experts on this subject based on the ideXlab platform.
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investigation of sulphur isotope variation due to different processes applied during Uranium Ore concentrate production
Journal of Radioanalytical and Nuclear Chemistry, 2016Co-Authors: Judit Krajko, M. Wallenius, K. Mayer, Zsolt Varga, R J M KoningsAbstract:The applicability and limitations of sulphur isotope ratio as a nuclear fOrensic signature have been studied. The typically applied leaching methods in Uranium mining processes were simulated for five Uranium Ore samples and the n(34S)/n(32S) ratios were measured. The sulphur isotope ratio variation during Uranium Ore concentrate (UOC) production was also followed using two real-life sample sets obtained from industrial UOC production facilities. Once the major source of sulphur is revealed, its appropriate application for origin assessment can be established. Our results confirm the previous assumption that process reagents have a significant effect on the n(34S)/n(32S) ratio, thus the sulphur isotope ratio is in most cases a process-related signature.
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measurement of the sulphur isotope ratio 34s 32s in Uranium Ore concentrates yellow cakes for origin assessment
Journal of Analytical Atomic Spectrometry, 2013Co-Authors: Sunho Han, M. Wallenius, Zsolt Varga, Judit Krajko, Kyuseok Song, K. MayerAbstract:A novel method has been developed for the measurement of the 34S/32S isotope ratio in Uranium Ore concentrate (yellow cake) samples for origin assessment in nuclear fOrensics. The leachable sulphate is separated and pre-concentrated by anion exchange separation followed by the 34S/32S ratio measurement by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The effect of sample composition on the accuracy was investigated and optimized. Matching of the sample to the bracketing standard was necessary to obtain accurate results. The method was validated by the measurement of standard reference materials (IAEA-S-2, IAEA-S-3 and IAEA-S-4) and the δ34S value could be determined with an uncertainty between 0.45‰ and 1.9‰ expressed with a coverage factor of 2. The method was then applied for the analysis of Uranium Ore concentrates of world-wide origin. In the studied materials distinct 34S/32S isotope ratios could be observed, which can be a promising signature for the nuclear fOrensic investigations to identify the source of unknown nuclear materials.
