• Nuclear Engineering and Technology
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• v.47 no.5
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• pp.559-566
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• 2015

The thermalehydraulic characteristics for the CANadian Deuterium Uranium Flexible (CANFLEX)-burnable poison (BP) fuel channel, which is loaded with a BP at the center ring based on the CANFLEX-RU (recycled uranium) fuel channel, are evaluated and compared with that of standard 37-element and CANFLEX-NU (natural uranium) fuel channels. The distributions of fuel temperature and critical channel power for the CANFLEX-BP fuel channel are calculated using the NUclear Heat Transport CIRcuit Thermohydraulics Analysis Code (NUCIRC) code for various creep rate and burnup. CANFLEX-BP fuel channel has been revealed to have a lower fuel temperature compared with that of a standard 37-element fuel channel, especially for high power channels. The critical channel power of CANFLEX-BP fuel channel has increased by about 10%, relative to that of a standard 37-element fuel channel for 380 channels in a core, and has higher value relative to that of the CANFLEX-NU fuel channel except the channels in the outer core. This study has shown that the use of a BP is feasible to enhance the thermal performance by the axial heat flux distribution, as well as the improvement of the reactor physical safety characteristics, and thus the reactor safety can be improved by the use of BP in a CANDU reactor.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.2
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• pp.101-116
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• 2017

The interaction of U(VI) (hexavalent uranium) species with natural organic matter (NOM) in KURT (KAERI Underground Research Tunnel) groundwater is investigated using a laser spectroscopic technique. The luminescence spectra of the NOM are observed in the ultraviolet and blue wavelength regions by irradiating a laser beam at 266 nm in groundwater. The luminescence spectra of U(VI) species in groundwater containing uranium concentrations of $0.034-0.788mg{\cdot}L^{-1}$ are measured in the green-colored wavelength region. The luminescence characteristics (peak wavelengths and lifetime) of U(VI) in the groundwater agree well with those of $Ca_2UO_2(CO_3)_3(aq)$ in a standard solution prepared in a laboratory. The luminescence intensities of U(VI) in the groundwater are weaker than those of $Ca_2UO_2(CO_3)_3(aq)$ in the standard solution at the same uranium concentrations. The luminescence intensities of $Ca_2UO_2(CO_3)_3(aq)$ in the standard solution mixed with the groundwater are also weaker than those of $Ca_2UO_2(CO_3)_3(aq)$ in the standard solution at the same uranium concentrations. These results can be ascribed to calcium-U(VI)-carbonate species interacting with NOM and forming non-radiative U(VI) complexes in groundwater.

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.277.1-277
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• 2002

• Proceedings of the Korean Nuclear Society Conference
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• 2003.10a
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• pp.501-501
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• 2003

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.10a
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• pp.151-152
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• 2017

• Economic and Environmental Geology
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• v.51 no.2
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• pp.77-85
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• 2018

There would be a possibility of uranium contamination around the nuclear power plants and the underground waste disposal sites, where the uranium could further migrate and diffuse to some distant places by groundwater. It is necessary to understand the biogeochemical behaviors of uranium in underground environments to effectively control the migration and diffusion of uranium. In general, various kinds of microbes are living in soils and geological media where the activity of microbes may be closely connected with the redox reaction of nuclides resulting in the changes of their solubility. We investigated the adsorption and precipitation behaviors of dissolved uranium on some solid materials using hydrogen gas as an electron donor instead of organic matters. Although the effect of hydrogen gas did not appear in a batch experiment that used granite as a solid material, there occurred a reduction of uranium concentration by 5~8% due to hydrogen in an experiment using bentonite. This result indicates that some indigenous bacteria in the bentonite that have utilized hydrogen as the electron donor affected the behavior (reduction) of uranium. In addition, the bentonite bacteria have showed their strong tolerance against a given high temperature and radioactivity of a specific waste environment, suggesting that the nuclear-biogeochemical reaction may be one of main mechanisms if the natural bentonite is used as a buffer material for the disposal site in the future.

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.4
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• pp.210-214
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• 1998

In general the concentration of uranium in natural water such as fresh water and sea water is in the range of 0.01∼5 ppb, therefore trace analytical technique is required. The aim of present work is to compare a direct and preconcentration methods by evaporation and to investigate rapid and accurate trace analysis of uranium in groundwater using Instrumental Neutron Activation Analysis (INAA) which are sensitive and nondestructive method. Identification of analytical procedure was carried out using uranium standard solution of the range of 0.5∼100 ppb. In the given concentration, the deviation of calibration curve was less than 2%, and the standard deviation of measured values at each concentration was the range of 2∼12%. The difference of U content with sampling time for the same sample site was about 10.3%. Using this established method, the concentrations of uranium in samples collected at the 17 spring of Choongchung areas were found to be in the range of 1∼80 ppb.

• Journal of Soil and Groundwater Environment
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• v.16 no.6
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• pp.133-142
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• 2011

A total of 247 samples were collected from groundwater being used for drinking-water supply, and hydrogeochemistry and radionuclide analysis were performed. In-situ analysis of groundwaters resulted in ranges of $13.7{\sim}25.1^{\circ}C$ for temperature, 5.9~8.5 for pH, 33~591 mV for Eh, $66{\sim}820{\mu}S/cm$ for EC, and 0.2~9.4 mg/L for DO. Major cation and anion concentrations of groundwaters were in ranges of 0.5~227.6 for Na, 1.0~279.3 for Ca, 0.0~9.3 for K, 0.1~100.1 for Mg, 0.0~3.3 for F, 0.9~779.1 for Cl, 0.3~120.4 for $SO_4$, 0.0~27.4 for $NO_3$-N, and 6~372 mg/L for $HCO_3$. Uranium-238 and radon-222 concentrations were detected in ranges of N.D-$131.1{\mu}g/L$ and 18-15,953 pCi/L, respectively. In case of some groundwaters exceeding USEPA MCL level ($30{\mu}g/L$) for uranium concentration, their pH ranged from 6.8 to 8.0 and Eh showed a relatively low value(86~199 mV) compared to other areas. Most groundwaters belonged to Ca-(Na)-$HCO_3$ type, and groundwaters of metamorphic rock exhibited the highest concentration of Na, Mg, Ca, Cl, $NO_3$-N, U, and those of plutonic rock showed the highest concentration of $HCO_3$, and Rn. Uranium and fluoride from granite areas did not show any correlation. However, uranium and bicarbonate displayed a positive relation of some areas in plutonic rocks($R^2$=0.3896).

• Journal of the Korean Chemical Society
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• v.27 no.5
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• pp.361-367
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• 1983

The selective separation and the quantitative recovery of uranium from Korean monazite sand have been studied by anion-exchange chromatography. It has been shown that method of anion-exchange chromatography under controlled conditions of elution can be applied to the production of relatively high purity of Uranium Oxide from monazite sand. Under the optimum separation conditions, the recoveries from standard sample were up to 99.3% as $U_3O_8$ on sulfate form anion resin bed and 99.2% as $U_2O_3{\cdot}P_2O_7$ on phosphate form anion resin bed. The possibility of recovering uranium from the monazite sulfate solution using a strong base anion exchange resin-Amberlite IRA-900. Uranium was successfully recovered about 92 percent. Phosphate ion did not seem to interfere with the process.

• Journal of Soil and Groundwater Environment
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• v.18 no.1
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• pp.36-45
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• 2013

We analyzed natural radionuclides in 80 wells in volcanic rock areas and investigated environmental characteristics. Uranium and radon concentrations ranged from ND to $9.70{\mu}g/L$ (median value: 0.21) ${\mu}g/L$, 38~29,222 pCi/L (median value: 579), respectively. In case of gross-${\alpha}$, 26 samples exceeded MDA (minimum detectable activity, < 0.9 pCi/L) value and the activity values ranged from 1.05 to 8.06 pCi/L. The radionuclides concentrations did not exceed USEPA MCL (maximum contaminant level) value of Uranium ($30{\mu}g/L$) and gross-${\alpha}$ (15 pCi/L). But Rn concentrations in 4 samples exceeded USEPA AMCL (Alternative maximum contaminant level, 4,000 pci/L) and one of them showed a significantly higher value (29,222 pCi/L) than the others. The levels of uranium concentrations in volcanic rock aquifer regions were detected in order of andesite, miscellaneous volcanic rocks, rhyolite, basalt aquifer regions. Radon, however, was detected in order of miscellaneous volcanic rocks, rhyolite, andesite, basalt aquifer regions. The correlation coefficient between uranium and radon was r = 0.45, but we found that correlations of radionuclides with in-situ data or major ions were weak or no significant. The correlation coefficient between the depth of wells and uranium concentrations was a slightly higher than that of depth of wells and radons. Radionuclide concentrations in volcanic rock aquifers showed lower levels than those of other rock aquifers such as granite, metamorphic rock aquifers, etc. This result may imply difference of host rock's bearing-radioactive-mineral contents among rock types of aquifers.