• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.3
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• pp.177-181
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• 2005

Yellowish uranium compounds were enriched at the interface between a Ca-bentonite block and a waste glass, containing about $20\%$ uranium oxide, in contact with the block due to the dissolution of uranium by a synthetic granitic groundwater in Ar atmosphere. The uranium compound formed for 6 years leach time was identified as a beta-uranophane $[Ca(UO_2)_2(SiO_{3}OH)_{2}5H_{2}O]$ using XRD, IR and mass spectrometer. The solubility of the beta-uranophane was measured to be about $10^{-6}\;mole/L$ in de-mineralized water at $80^{\circ}C$.

• Economic and Environmental Geology
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• v.17 no.4
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• pp.289-298
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• 1984

Uraniferous black slates of the Okchon sequence occur in Koesan (northeast) through Miwon-Boun (middle) to the southwest off Taejon (southwest) within the Okchon fold belt. The Uraniferous balck slates in the southwest off Taejon are particularly well developed in Chubu (northeast) and Moksso-ri (middle) areas whereas they are less developed in Jinsan (southwest) area. The uraniferous beds range from less than a meter to 40 meters in thickness and range from less than 0.02% $U_3O_8$ (cut-off-grade) to 0.05% $U_3O_8$ in the southwestern district off Taejon. Electron microprobe analysis of uranium-minerals found in graphitic slate samples enables to estimate their major compositions semi-quantitatively so that uraninite, ferro-uranophane and chlopinite are tentatively identified. Uranium-minerals are closely associated with carbon and metal sulfides. Correlation analysis of trace element concentrations revealed that U and F.C., and U and Mo are lineary correlative respectively and their correlation coefficients are positively high whereas those of U and V, U and Mn, and U and Zr are negatively low, implying that uranium mineralization has been closely related with concentrations of carbon and molybdenum. Stable isotope analyses of pyrite sulfur range widely from +11.5% to -23.3% in ${\delta}^{34}S$ values whereas those of graphite carbon fall within a narrow range between -23.3% and -28.9% in ${\delta}^{13}C$ values. The wide range of ${\delta}^{34}S$ values suggests that the sulfur could be of meteoric origin rather than of igneous source. The narrow range of ${\delta}^{13}C$ values, which are close to those of coal, indicates that the graphite is organic carbon in origin. Therefore, it is concluded that the uranium mineralization in the Okchon sequence took place primarily in sedimentary environment rich in organic matter and sulfide ion, both of which served as the reducing agents to convert soluble uranyl complex to insoluble uranium dioxide.

• Nuclear Engineering and Technology
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• v.56 no.10
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• pp.4141-4148
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• 2024

The study focused on syenogranite and its altered variety, and specifically monitored the activities of ²²⁶Ra, ²³²Th, and ⁴⁰K using NaI(Tl) gamma-ray spectroscopy. Syenogranites in the study area in Egypt were investigated to determine their potential use in industries such as ornamental stones and ceramics. The main outcrops in the study area consist of metasediments, metavolcanics, metagabbro, syn-to late-orogenic granites, and post-orogenic granites (syenogranites). There are also numerous dikes and veins of various shapes and compositions that have intruded and penetrated all the older rocks in the area. The mean activity (± standard deviation, SD) of these radioelements in the granites is ²²⁶Ra (63 ± 71 Bq kg^-1), ²³²Th (76 ± 170 Bq kg^-1), and ⁴⁰K (1248 ± 532 Bq kg^-1) were found to be greater than the world average. The radiological hazards are mostly attributed to the γ-rays emitted by granitic rocks. The granites studied in this study deviate from international standards mainly due to the presence of minerals containing radioelements such as zircon, allanite, monazite, sphene titanite, apatite, thorite, samarskite, fergusonite, xenotime, columbite, apatite and fluorite. As a result, granitic rocks are unsuitable for home building.

• Nuclear Engineering and Technology
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• v.56 no.11
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• pp.4921-4928
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• 2024

The present study employed statistical methods to evaluate the possible radiological hazards linked to granitic rocks-bearing mineralization in the ELgarra region of Egypt. The geological structures influence the occurrence of uranium mineralization in this area and are primarily associated with altered granites. Gamma-ray spectrometry was utilized to examine the quantities of ²³⁸U, ²³²Th, and ⁴⁰K in granitic rock samples. The recorded levels of radioisotope activity concentrations in the analyzed regions ranged from 374 to 1740 Bq.kg^{-1 238}U, with an average of 1018 Bq.kg^-1. For ²³²Th, the range was between 71 and 163 Bq.kg^-1, with an average of 119 Bq.kg^-1. Lastly, for ⁴⁰K, the range was 756-1789 Bq.kg^-1, with an average of 1212 Bq.kg^-1. The detected levels of ²³⁸U, ²³²Th, and ⁴⁰K in the examined rock samples were observed to exceed the permissible limits of 35, 45, and 412 Bq.kg^-1, respectively. The primary radiological risks linked to these granitic rocks were attributed to the gamma rays released by the radioactive elements. Estimations of the radiological hazards in the granitic rocks were made, and statistical approaches were utilized to demonstrate the associations among radionuclides and radiological factors. The assessment confirmed that uranium, potassium, and their respective minerals in the granitic rocks were the key factors contributing to the radiological risks. As a result, the study determined that the granite rocks found in the study area needed precautions to be taken due to their high levels of radioactivity.

• The Journal of Engineering Geology
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• v.23 no.4
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• pp.399-407
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• 2013

Some groundwater in Korea contains high U concentrations, especially where two-mica granite occurs in the Daejeon area. The elemental U in the two-mica granite is lower than that in normal granites elsewhere in the world, and U-minerals have yet to be reported in the two-mica granite in the Daejeon area. This study focuses on investigating the occurrence of U-minerals serving as the U source in groundwater. In situ gamma ray spectrometry and mineralogical analyses using EPMA were performed. U-count anomalies were identified in a granitic dyke and in hydrothermally altered granite. Uraniferous granitic dykes occur along the contact zone between the two-mica granite and mica-schist. The uraniferous parts within the two-mica granite are developed in the hydrothermally altered zone, which contains numerous quartz veinlets within a fracture zone. Hydrothermal alteration is dominated by potassic and prophylitic alteration. Uraninite is a common U-mineral in granitic dykes and hydrothermally altered granite. Coffinite and uranophane occur in the hydrothermally altered granite. All of these U-minerals are commonly accompanied by hydrothermal alteration minerals such as muscovite, chlorite, epidote, and calcite. It is concluded that granitic dyke and hydrothermally altered granite are the main source rocks of U in groundwater.