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Nuclear Energy
Published in Efstathios E. Michaelides, Energy, the Environment, and Sustainability, 2018
Uranium metal, which is the most common nuclear fuel, naturally exists with other chemicals in several minerals. Rich uranium ores contain up to 2% uranium metal and medium-grade ores 0.5–1% of the metal. At these compositions, the mined uranium needs to be refined to be used as a fuel. Most of the uranium mines are surface mines, where the ore is extracted with giant earth excavation systems. The uranium ore is then crushed and ground to a coarse powder. Sulfuric acid (H2SO4) is used to form sulfate salts with the metals in the ore and to separate the metals from the rest of the chemicals of the ore. The uranium is then separated from the other metal sulfides and by conversion to uranium oxide U3O8, which precipitates in the acid solution. This solid oxide is often commonly called yellowcake and is shipped to the processing or enrichment facilities.
Minerals of radioactive metals
Published in Francis P. Gudyanga, Minerals in Africa, 2020
Uraninite is commonly mined by open-pit, underground, in-situ leaching, and borehole mining to extract uranium. It is crushed and ground to powder then leached with either an acid or alkali. The solution is then put through several sequential stages of precipitation, solvent extraction and ion exchange. The resultant yellowcake product contains uranium oxide U3O8 which is calcined to remove impurities before refining and conversion [768].
Nuclear Waste Management
Published in William J. Nuttall, Nuclear Renaissance, 2022
With the exception of mill, tailings LLW is the category applied to all US wastes that are neither HLW nor TRU [134]. US LLW generally has shorter half-lives than either HLW or TRU. Uranium milling consists of the mechanical and chemical processes by which raw uranium ore from the mine is processed into dry yellowcake ready for transport to enrichment facilities or, increasingly less commonly, directly to fuel fabricators. Chemically yellowcake is a uranium oxide (U308) powder that unsurprisingly is a rich yellow in colour.
Extraction of Uranium from Synthetic Nuclear Conversion Plant Waste
Published in Solvent Extraction and Ion Exchange, 2019
M. Potgieter, J. C. Barry, D. J. van der Westhuizen, H. M. Krieg
The U Extraction (UREX) process is an adaptation to the PUREX process used to recover and purify U and Tc. It has been used to extract 99.9 % U (also using 30% TBP) from a waste fuel stream without extraction of the transuranium elements also present.[14] In a research study, Sato[15] investigated uranyl nitrate extraction using 19% TBP from an optimum nitric acid concentration of 6 M, achieving extraction values of 97% for uranyl nitrate feed concentrations below 10 g/L. An optimised U extraction and purification of 98% was achieved by Stas et al.[16] from yellowcake with Fe (1 g/L) as the major impurity from 5.75 M nitric acid using 0.363–0.726 M (10–20%) TBP. Due to the successful separation of impurities and recovery from various starting matrices, it is clear from these studies that TBP is a suitable extractant choice to recover U from waste materials such as those discussed above. Other studies included U extraction in the presence of various impurities also present in the conversion plant waste, and found that U could be extracted with minimal influence from these impurities.[17,18] Mention was also made of an influence of F on U extraction at certain concentrations.[18] However, these studies investigated neither varying amounts of impurities in relation to each other or U, nor the possible interactions of these impurities with each other.
Current Status of Decommissioning and Waste Management at the Ningyo-Toge Environmental Engineering Center
Published in Nuclear Technology, 2023
Yusuke Ohashi, Masamitsu Shimaike, Takashi Matsumoto, Nobuo Takahashi, Kaoru Yokoyama, Yasuyuki Morimoto
An engineering test of the hydrometallurgical process, which produces uranium tetrafluoride using ores without going through yellowcake, was conducted. The operation of the facility ended in 1982. The facility and building were dismantled by 2002. Figure 1 shows the state of the dismantling.