• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.697-702
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• 2011

Ion exchange resins have been synthesized from chloromethylated styrene-1,4-divinylbenzene (DVB) with 1%, 2%, 5% and 15%-crosslinkage and macrocyclic ligand of $OenNdien-H_4$ by copolymerization. The adsorption characteristics of uranium (${UO_2}^{2+}$), potassium ($K^+$) and neodymium ($Nd^{3+}$) metallic ions have been investigated. The synthesis of these resins was confirmed by content of chlorine, element analysis, and IR-spectrum. The effects of pH, time, and crosslinkage on adsorption of metallic ions were also studied. The uranium ion showed the fast adsorption on the resins above pH 3. The optimum equilibrium time for the adsorption of metallic ions was about two hours. The adsorption selectivity determined in methanol solution was in increasing order uranium (${UO_2}^{2+}$) > potassium ($K^+$) > neodymium ($Nd^{3+}$) ion. Moreover, the adsorption was increased with the crosslinkage concentration in order of 1%, 2%, 5% and 15%-crosslinkage resin.

• Advances in environmental research
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• v.4 no.2
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• pp.135-142
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• 2015

In this study, we evaluated the adsorption/desorption of uranium (U) in pure soil environment using continuous column reactor. We additionally investigated the adsorption/desorption mechanism of U on vivianite surface in molecular scale using quantum calculation. We observed that below $0.1{\mu}M$ of U was detected after 20 d from U injection ($1{\mu}M$) in adsorption test. However, all of absorbed U was detached from vivianite surface in 24 h by injection of CARB solution ($1.44{\times}10^{-2}M\;NaHCO_3$ and $2.8{\times}10^{-3}M\;Na_2CO_3$). Based on exchange energy calculation, we found that $UO_2(CO_3)_2{^{2-}}$ and $UO_2(CO_3)_3{^{4-}}$ species have higher repulsive energy than $UO_2(OH)_2$ species. The results obtained from this study could be applied to predict the behavior of uranium in contaminated and remediation sites.

• Journal of the Korean Electrochemical Society
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• v.16 no.3
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• pp.138-144
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• 2013

Electrochemical reductions of $UO_2$ at various anode-to-cathode distances (1.3, 2.3, 3.2, 3.7 and 5.8 cm) were carried out to investigate the effect of the anode-to-cathode distance on the electrochemical reduction rate. The geometry of the electrolysis cell in this study, apart from the anode-to-cathode distance, was identical for all of the electrolysis runs. Porous $UO_2$ pellets were electrolyzed by controlling a constant cell voltage in molten $Li_2O-LiCl$ at $650^{\circ}C$. A steel basket containing the porous $UO_2$ pellets and a platinum plate were used as the cathode and anode, respectively. The metallic products were characterized by means of a thermogravimetric analyzer, an X-ray diffractometer and a scanning electron microscope. The electrolysis runs conducted during this study revealed that a short anode-to-cathode distance is advantageous to achieve a high current density and accelerate the electrochemical reduction process.

• Nuclear Engineering and Technology
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• v.29 no.3
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• pp.196-200
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• 1997

The variation of sintered density and fain size in ex-AUC, ex-ADU and granulated ex-ADU UO$_2$ pellets in which 0.1~1.0wt% Nb$_2$O$_{5}$ were doped were examined. Pellets were sintered in an atmosphere of H$_2$ at 1$700^{\circ}C$ for 4h. All the specimens tested shooed more than 94% T.D.(Theoretical Density). Sintered density decreased with increasing the amount of Nb$_2$O$_{5}$. Powder types had little influence on the sintered density. Pore size distribution was shifted to the larger ones as Nb$_2$O$_{5}$ was added. The increase of total pore volume and grain growth due to the addition of Nb$_2$O$_{5}$ were thought to be the cause of the sintered density decrease. The largest grain size was seen in the 1. 0wt% Nb$_2$O$_{5}$ doped ex-AUC UO$_2$ pellets. Their average size was 13.9 ${\mu}{\textrm}{m}$.m}$.

• Nuclear Engineering and Technology
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• v.43 no.2
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• pp.141-148
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• 2011

This paper presents the quantitative analysis results of research on the burnup effect on the nuclear fuel cycle cost of BeO-$UO_2$ fuel. As a result of this analysis, if the burnup is 60 MWD/kg, which is the limit under South Korean regulations, the nuclear fuel cycle cost is 4.47 mills/kWh at 4.8wt% of Be content for the BeO-$UO_2$ fuel. It is, however, reduced to 3.70 mills/kWh at 5.4wt% of Be content if the burnup is 75MWD/kg. Therefore, it seems very advantageous, in terms of the economic aspect, to develop BeO-$UO_2$ fuel, which does not have any technical problem with its safety and is a high burnup & long life cycle nuclear fuel.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.11-18
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• 2022

In this research, curium oxide (CmO₂) is studied as fuel for VVER-1200 reactor to get an attention to its energy value and possibilities. For this purpose, CmO₂ is used in fuel rods or integrated burnable absorber (IBA) rods with and without UO₂ and then compared with the conventional fuel assembly of VVER-1200 reactor. It is burned to 60 GWd/t by using SRAC-2006 code and JENDL-4.0 data library. From these studies, it is found that CmO₂ is competent like UO₂ as a fuel due to higher fission cross-section of ²⁴³Cm and ²⁴⁵Cm isotopes and neutron capture cross-section of ²⁴⁴Cm and ²⁴⁶Cm isotopes. As a result, when some or all of the UO₂ of fuel rods or IBA rods are replaced by CmO₂, we get a similar k-inf like the reference even with lower enrichment UO₂ fuels. These studies show that the use of CmO₂ as IBA rods is more effective than the fuel rods considering the initially loaded amount, power peaking factor (PPF), fuel temperature and void coefficient, and the quality of spent fuel. From a detailed study, 3% CmO₂ with inert material ZrO₂ in IBA rods are recommended for the VVER-1200 reactor assembly from the once through concept.

• Applied Chemistry for Engineering
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• v.3 no.2
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• pp.312-317
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• 1992

The interaction of dioxouranium(VI) (uranyl) ion with nitrate ion has been studied by $^{17}O$ NMR spectroscopy. The $^{17}O$ resonance of uranyl oxygen atoms(uranyl oxygens hereafter) of $UO_2NO_3{^+}$ was at lower field than that of uranyl ion. The stability constants of $UO_2NO_3{^+}$ were obtained from the variation of $^{17}O$ chemical shifts with nitrate-ion concentration at 5, 15, 25, $35^{\circ}C$ and depend on the ionic strength. Thermodynamic parameters calculated from temperature dependence of the stability constants were as follows : ${\Delta}H=-(27.2{\pm}1.7)kJ\;mol^{-1}$ and ${\Delta}S=-(110{\pm}7)JK^{-1}mol^{-1}$. There was a linear relationship between the enthalpy and entropy for 1:1 complex formation of the uranyl ion with a variety of anionic ligands.

• Applied Chemistry for Engineering
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• v.19 no.3
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• pp.304-309
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• 2008

Cryptand series ion exchange resins were synthesized with 1-aza-12-crown-4 macrocyclic ligand attached to styrene (4 series dangerous matter) divinylbenzene (DVB) copolymer with crosslink of 1％, 2％, 4％ and 8％ by a substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, electron micrograph, and IR-spectrum. The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of uranium (${UO_2}^{2+}$) ion were investigated. The uranium ion showed a fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium (${UO_2}^{2+}$) > nickel ($Ni^{2+}$) > gadolinium ($Gd^{3+}$) ion. The adsorption was in order of 1％, 2％, 4％, and 8％ crosslinked resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.

• Analytical Science and Technology
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• v.17 no.2
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• pp.91-97
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• 2004

Cryptand ion exchange resins were synthesized with 1-aza-15-crown-5 macrocyclic ligand attached to styrene divinylbenzene (DVB) copolymer with crosslink of 1%, 2%, 5% and 10% by substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, and IR-spectrum. The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of uranium ($UO{_2}^{2+}$) ion were investigated. The uranium ion was showed fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium ($UO{_2}^{2+}$), magnesium ($Mg^{2+}$), neodymium ($Nd^{3+}$) ion. The adsorption was in order of 1%, 2%, 5%, and 10% crosslink resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.

• Nuclear Engineering and Technology
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• v.23 no.1
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• pp.49-55
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• 1991

The microstructure and pore characteristics have been studied on the sintered UO$_2$pellet which was made of the UO$_2$powder manufactured via AUC process. The open porosity decrease with the density and is nearly annihilated above the density of 10.45 g/㎤. The round pore smaller than 3 $\mu$m exist In all densities. The large and elongated pore appears additionally In low density The pore in low density is more elongated than the pore in high density The distribution of the pore area versus the pore size is monomodal and shows its peak on the pore size of 2 to 3 $\mu$m. As the density decreases, the related area of large pore Increases.