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Electron microsscopy of mixed uranium oxidePienkowski, Marian Czeslaw January 1989 (has links)
No description available.
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Uranium Isotope Variations in Nature: Mechanisms, Applications, and ImplicationsJanuary 2011 (has links)
abstract: Historically, uranium has received intense study of its chemical and isotopic properties for use in the nuclear industry, but has been largely ignored by geoscientists despite properties that make it an intriguing target for geochemists and cosmochemists alike. Uranium was long thought to have an invariant 238U/235U ratio in natural samples, making it uninteresting for isotopic work. However, recent advances in mass spectrometry have made it possible to detect slight differences in the 238U/235U ratio, creating many exciting new opportunities for U isotopic research. Using uranium ore samples from diverse depositional settings from around the world, it is shown that the low-temperature redox transition of uranium (U6+ to U4+) causes measurable fractionation of the 238U/235U ratio. Moreover, it is shown experimentally that a coordination change of U can also cause measurable fractionation in the 238U/235U ratio. This improved understanding of the fractionation mechanisms of U allows for the use of the 238U/235U ratio as a paleoredox proxy. The 238U/235U ratios of carbonates deposited spanning the end-Permian extinction horizon provide evidence of pronounced and persistent widespread ocean anoxia at, or immediately preceding, the extinction boundary. Variable 238U/235U ratios correlated with proxies for initial Cm/U in the Solar System's earliest objects demonstrates the existence of 247Cm in the early Solar System. Proof of variable 238U/235U ratios in meteoritic material forces a substantive change in the previously established procedures of Pb-Pb dating, which assumed an invariant 238U/235U ratio. This advancement improves the accuracy of not only the Pb-Pb chronometer that directly utilizes the 238U/235U ratio, but also for short-lived radiometric dating techniques that indirectly use the 238U/235U ratio to calculate ages of Solar System material. / Dissertation/Thesis / Ph.D. Geological Sciences 2011
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Geological factors affecting the grade and tonnage of sandstone uranium depositsHolliman, K A 19 March 2013 (has links)
The largest known reserves of uranium are found in sandstone deposits, in the form of roll-front, peneconcordant and stacked types. Drilling on spacings of between 50 m and 5 m centres is the current method of attempting to delineate such ore bodies but because of the apparent random distribution of the mineralization there is a large degree of uncertainty in these predictions. Even on drilling grids of 3,5 m centres the uncertainty in predicting the distribution of stringer ore in roll front mineralization is still 100 per cent. (Sandefur & Grant 1980). Because of escalating costs it is becoming increasingly less economically feasible to delineate bodies of this nature in this manner and much more reliance will have to be placed on the geologist's interpretation of ore distribution when calculating ore reserves. The grade and tonnage of a sandstone uranium deposit can only be calculated with some degree of confidence if the processes forming the ore body are fully understood. The aim of this review is to examine the factors governing the formation and geometry of a sandstone body, the mobility and fixation of uranium and to establish criteria which will enable a more confident prediction to be made of the distribution of sand bodies and the distribution of the mineralization within them
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Phase transformations and deformation metallography in dilute uranium alloysJenkins, Brent Allan January 1988 (has links)
No description available.
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Medidas de percentagem atomica de fissao do U-235 por espectrometria de massa termoionicaTADDEI, J.F.A.C. 09 October 2014 (has links)
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01278.pdf: 867974 bytes, checksum: e6a2da417abddf96bd95df76d467b39a (MD5) / Dissertacao (Mestrado) / IEA/D / Escola Politecnica, Universidade de Sao Paulo - POLI/USP
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Untersuchungen zur herstellung von sphaerischen carbidhaltigen urandioxidteilchen nach dem hydrolyseverfahrenPUSCHEL, CLAUDIO R. 09 October 2014 (has links)
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Operacao de uma unidade semi-industrial de producao de UO-3BABA, SHIGUEAKI 09 October 2014 (has links)
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Separacao e concentracao de microconstituintes em uranio por extracao com aminas de alto peso molecular em meio HC1-KI .Determinacao por espectofotometria atomica na fase organicaMORAES, SERGIO de 09 October 2014 (has links)
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01015.pdf: 998775 bytes, checksum: 24043b75e9a372f6fca29bba4af963d3 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Química - Universidade de São Paulo - IQ/USP
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Determinacao de uranio e tritio em urina de trabalhadoresPASSARELLI, MIRIAM M. 09 October 2014 (has links)
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Microestruturas de solidificacao de ligas aluminio-uranioAMBROZIO FILHO, FRANCISCO 09 October 2014 (has links)
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