• Nuclear Engineering and Technology
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• v.56 no.5
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• pp.1880-1886
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• 2024

To elucidate the mechanism of damage caused by hyphae and organic acids produced by Aspergillus Niger on the surface and internal structure of uranium ore, direct uranium leaching, indirect uranium leaching and semidirect uranium leaching were conducted, and the surface morphology, strength, mineral crystallinity, porosity, and permeability of the ore were analyzed. The results demonstrated that the combination of biomechanical forces exerted by hyphae and the complexation effects of organic acids led to the dissolution of SiO₂ and other substances on the surface of ore, resulting in exfoliation from the exterior to the interior, thereby promoting uranium recovery. Furthermore, the proton exchange involving H⁺ and the complexation of organic acids resulted in the dissolution of cations within the ore, causing destruction to the crystal lattice structure of minerals and increasing the porosity and permeability inside the ore. The dominant factor contributing to ore damage during recovery was organic acids.

• Economic and Environmental Geology
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• v.27 no.6
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• pp.601-609
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• 1994

Uranium resources of Mongolia are generally confined to sediments deposited during Jurassic to Cretaceous volcanism. Territory of Mongolian uranium deposits is divided into four districts as follows; Mongol-Priargun, Gobi-Tamtsag, Hentii-Dauer, North-Mongolian. Potential uranium deposits were discovered by Airborne Gamma ray Spectrometric Survey(AGSM). One of them, Haraat deposit, which was interested to us, has been under detailed survey for exploitation by one of American companies, Concord company. The Erdes uranium mine is partly operated by about hundred Russian staffs at the open pit, while underground mining facilities such as the main hoist are almost closed. Ore minerals of the Erdes Mine are coffinite and pitchblende. Uranium content in ore ranges from 0.06% to 1%, averaging 0.2%. Ore reserves of uranium ore in the Dornod deposit including the Erdes Mine accounts 29,000 ton. It is reported that Uranium resources of Mongolia are 1,471,000 ton.

• KSBB Journal
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• v.11 no.3
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• pp.353-359
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• 1996

The experiments were conducted in the leaching of aqueous uranium from low-grade uranium ore by Thiobacillus ferrooxidans. The optimal concentration of ferrous iron in 9K medium was 16.2g/L when the uranium ore concentration in slurry was 40g/L. The leaching rates were increased by decreasing the particle size of uranium ore and by increasing uranium ore concentration. In the leaching experiments in an agitated vessel reactor, only 39.3% of uranium was leached out within 12 days, which was comparable as that in the shaking incubator, without any notable improvement. Hence, it was observed that an agitated vessel reactor was not effective in the leaching of uranium from uranium ore by T. ferrooxidans. In the leaching experiments in a draught-tube reactor, the maximum concentration of uranium leached and cell number were a 12.8mg/L and $2.47{\times}1010cells/mL$ respectively. The uranium yield reached up to 91.4% within 11 days culture due to enhanced aeration and mixing characteristics of draught-tube reactor as compared to agitated vessel reactor.

• Resources Recycling
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• v.22 no.1
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• pp.3-10
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• 2013

This general paper covers three parts of the uranium research and development. Part one covers scope of research and development of uranium ore and future prospect, supply and demand of uranium in the world market, deposit, grade and properties of Korean uranium ore and the second part covers status of previous study and supply target for yellow cake, technology of leaching, separation and preparation, procedure of the recovery of U / V from Korean black shale ore. Final part concludes the summary of the present discussion.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.547-555
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• 2023

Due to enhanced precision in uranium isotope measurements with MC-ICP-MS, there has been a surge in studies concerning the naturally occurring uranium isotope ratio (²³⁸U/²³⁵U) and its associated fractionation processes. Several researchers have highlighted that the ²³⁸U/²³⁵U ratio, previously assumed to be constant, can vary by several per mil depending on different natural fractionation processes. This review paper outlines the uranium isotope values (δ²³⁸U) for major terrestrial reservoirs and their variations. It discusses the range of δ238U values and uranium isotope fractionation seen in uranium ore deposits, based on deposit type and ore-forming conditions. In conclusion, this paper emphasizes the importance of studies on uranium ore deposits. Such deposits serve as natural simulation models vital for designing high-level radioactive waste repository sites.

• Nuclear Engineering and Technology
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• v.30 no.6
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• pp.518-530
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• 1998

A natural analogue study has been performed for the Koongarra uranium ore deposit in Australia as an international agreement of the Analogue Studies in the Alligator Rivers Region (ASARR). Rocks obtained from the Koongarra deposit, Northern Territory of Australia, were examined in order to understand uranium migration processes of primary and secondary ore-body in both weathered and unweathered zones. Total alpha activities of rock samples were measured to compare the relative amount of uranium in the sample. Uranium distributions have been investigated by means of both the alpha-autoradiography and the fission track registration technique after irradiation in a flux of thermal neutrons (~10$\times$$10^{13}$nㆍ$cm^{-2}$ㆍs$^{-1}$) for 2 minutes. The mineral phases corresponding to the registered alpha-tracks and fission tracks were identified by petrological observation with optical microscope as well as X-ray diffraction and electron microprobe analysis (EPMA). Uranium was found mostly inside of the fracture of the quartzite and its mineral phase was identified as sklodowskite. The mineral phase associated with high uranium concentration was found as illeminite by petrological observation with optical microscope as well as EPMA.

• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.4033-4041
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• 2021

To better understand the permeability of uranium sandstone, improve the leaching rate of uranium, and explore the change law of pore structure characteristics and blocking mechanism during leaching, we systematically analyzed the microstructure of acid-leaching uranium sandstone. We investigated the variable rules of pore structure characteristics based on nuclear magnetic resonance (NMR). The results showed the following: (1) The uranium concentration change followed the exponential law during uranium deposits acid leaching. After 24 h, the uranium leaching rate reached 50%. The uranium leaching slowed gradually over the next 4 days. (2) Combined with the regularity of porosity variation, Stages I and II included chemical plugging controlled by surface reaction. Stage I was the major completion phase of uranium displacement with saturation precipitation of calcium sulfate. Stage II mainly precipitated iron (III) oxide-hydroxide and aluminum hydroxide. Stage III involved physical clogging controlled by diffusion. (3) In the three stages of leaching, the permeability of the leaching solution changed with the pore structure, which first decreased, then increased, and then decreased.

• The Korean Journal of Ecology
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• v.5 no.4
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• pp.137-142
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• 1982

From 1975 to 1981, the survey was carried out to find out radioecological effects of uranium ore deposits on natural vegetation in Koisan, Korea. The symptoms of spotty and mosaic chlorosis, and necrosis were observed in flowering plants in the areas of uranium ore deposits at Deok-Peung-Ri A, B, and C in Koisan. Although 13 species were found to be chlorosis and necrosis, foliages observed are small and very rare. The features of these symptoms closely resemble those occured by the effects of heavy meetals. The amount of transparent radiation throughout the depth of soils from uranium radiation sources decreases exponentially. The mean contents in leaves of spotty and mosaik chlorotic plants, and soils were 1.36~1.53 and 5.3~7.4 ppm, respectively.

• Nuclear Engineering and Technology
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• v.7 no.4
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• pp.295-310
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• 1975

A system of model price data for the fuel cost estimation of the Go-ri plant is developed. With the application of MITCOST-II computer code the levelized unit fuel costs over the entire lifetime of the plant are evaluated. It is found that the overall levelized unit fuel cost is 7.332 mills/Kwhe and that the uranium ore and enrichment service represent more than 85% of the unit cost, assuming a simple once-through fuel cycle process with no reprocessing of the spent fuel. The effects of the cost fluctuations in these fuel cycle elements and the capacity factor changes are also evaluated. The results indicate that the fuel costs are most sensitive to the variation of uranium ore price. Efforts must, therefore, be employed for the arrangement of cheap and timely supply of uranium ore in order to achieve the economic generation of nuclear power.

• Nuclear Engineering and Technology
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• v.29 no.4
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• pp.327-335
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• 1997

The correlation of isotope composition of uranium, plutonium and neodymium with the burnup in M uranium dioxide fuel has been investigated experimentally. The total and fractional($^{235}$ U) burnup were determined by Nd-148 and, U and Pu mass spectrometric method respectively. The isotope compositions of these elements, after their separation from the fuel samples were measured by mass spectrometric. The content of the elements in the irradiated fuel ore determined by isotope dilution mass spectrometric method using $^{233}$ U, $^{242}$ Pu and $^{150}$ Nd as spikes. The content of plutonium in the irradiated fuel was expressed by the correlation with uranium isotopes. The correlations between isotope compositions themselves and the total and fractional burnup ore compared with those calculated from ORIGEN2 code.