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Uranium
Published in Earle A. Ripley, E. Robert Redmann, Adèle A. Crowder, Tara C. Ariano, Catherine A. Corrigan, Robert J. Farmer, L. Moira Jackson, Environmental Effects of Mining, 2018
A. Ripley Earle, Robert E. Redmann, Adèle A. Crowder, Tara C. Ariano, Catherine A. Corrigan, Robert J. Farmer, Earle A. Ripley, E. Robert Redmann, Adèle A. Crowder, Tara C. Ariano, Catherine A. Corrigan, Robert J. Farmer, L. Moira Jackson
Underground extraction has been used at most of the Ontario mines, while the Saskatchewan deposits have been mined mainly by surface methods. Some of the latter currently use a combination of surface and underground methods in order to maximize efficiency. All of Canada’s uranium mills use acid-leaching processes to concentrate the mined ores to a magnesium or ammonium diuranate product, called “yellowcake” (Sirois and MacDonald 1983). Uranium in yellowcake is mostly 238U, with a small proportion of readily fissile 235U. These concentrates are then either exported or shipped to Canada’s only refining and conversion facilities. Refining is done at Blind River and conversion at Port Hope, both in Ontario. The refining process changes the yellowcake into uranium trioxide (UO3). This compound is subsequently converted either to uranium dioxide (UO2) for use in CANDU reactors or to uranium hexafluoride (UF6) for use in foreign light-water reactors (Whillans 1994).
Direct Dissolution of Used Nuclear Fuel in PUREX Solvent: Review and Flowsheet Development
Published in Nuclear Technology, 2022
Relevant to this study, no significant difference in the acid-dissolution rates of nonvoloxidized UNF and that treated by standard voloxidation has been observed, with both requiring between 2 and 3 h to completely dissolve, which is typical for acid dissolution of UNF (Ref. 28). This could be considered a surprising result given the voloxidized UNF existed as a powder rather than pellets for the nonvoloxidized material. However, the result is likely due to ramping the temperature increase and nitric acid addition in both cases to avoid excessive emission of off-gas for the voloxidized UNF. Triuranium octoxide (the product of standard voloxidation) has been observed to dissolve somewhat faster than uranium dioxide powder followed by uranium trioxide powder.29 As reviewed earlier, durations of UNF dissolution in the TBP solvent can be substantially less and certainly less than 1 h. Therefore, while there are uncertainties in how voloxidized actual (i.e., irradiated) UNF will dissolve, the foregoing results overall indicate the dissolution time could be substantially reduced while also reducing the temperature to a value close to ambient. The magnitude of this reduction could mean a continuous dissolution process may be practical without extensive additional mechanical processes at a temperature close to ambient.
Fabrication of UN-Mo CERMET Nuclear Fuel Using Advanced Manufacturing Techniques
Published in Nuclear Technology, 2021
Alicia M. Raftery, Rachel L. Seibert, Daniel R. Brown, Michael P. Trammell, Andrew T. Nelson, Kurt A. Terrani
Uranium nitride microspheres were fabricated at Oak Ridge National Laboratory using a processing methodology previously described in the literature. First, microspheres of carbon-containing hydrated uranium trioxide (UO3·H20 + 2.65 C) were produced using a chemistry-based internal solution-gelation (sol-gel) method.19 The sol-gel microspheres were then converted to UN using a carbothermic reduction-nitridation process20,21 and further densified using a hot isostatic pressing (HIP) technique.22 The resulting microspheres had an average diameter of 810 µm and a density of 13.60 g/cm3 (94.89% TD). What is referred to hereafter as UN is in fact a solid solution of uranium carbide–nitride, U(C,N). The carbon content of the UN microspheres after conversion was determined to be 9800 ppm using Vegard’s law on X-ray diffraction data. The carbon content corresponds to a stoichiometry of UC0.2N0.8, which is generally considered high for bulk-pellet UN fuel,23 but is considered inconsequential for particle fuel application. Figures 1a, 1b, and 1c show a series of scanning electron microscope (SEM) images of the UN microspheres. Energy dispersive spectroscopy (EDS) was used to analyze the material for impurities. Sulfur impurities were detected (Fig. 1c), the presence of which is likely due to a dispersing agent that is used in the sol-gel process.
Uranium exposed at Expo 58: the colonial agenda behind the peaceful atom
Published in History and Technology, 2021
The UMHK was a crucial agent in this constellation, considering the political impact this company had on science and nuclear power in the twentieth century. First, the company had access to the virtually unlimited funds of the Banque de la Société Générale de Belgique. Founded in 1906 under the rule of Leopold II, and granted a territory of almost twenty square kilometers in the Katanga region of Congo, the mining company was in charge of the extraction of uranium and other minerals. By the early 1920s, the company held a quasi-monopoly over the uranium market.71 Twenty years later, the UMHK became the main supplier of uranium for the Manhattan project and therefore provided the source material for the atomic bombs dropped on Hiroshima and Nagasaki.72 This uranium was mostly refined at Oolen (Société Générale Metallurgique de Hoboken – also present in the Atomium exhibition) in Belgium, and from there sold on further, as uranium trioxide (UO3) in uranium deals between Belgium, Canada, Great Britain, and the United States.73