• 방사성폐기물학회지
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• 제18권1호
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• pp.1-18
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• 2020

Molten salt solutions consisting of eutectic LiCl-KCl and concentrations of samarium chloride (0.5 to 3.0 wt%) at 500℃ were analyzed using both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The CV technique gave the average diffusion coefficient for Sm³⁺ over the concentration range. Equipped with Sm³⁺ diffusion coefficient, the Randles-Sevcik equation predicted Sm³⁺ concentration values that agree with the given experimental values. From CV measurements; the anodic, cathodic, and half-peak potentials were identified and subsequently used as a parameter to acquire EIS spectra. A six-element Voigt model was used to model the EIS data in terms of resistance-time constant pairs. The lowest resistances were observed at the half-peak potential with the associated resistance-time constant pairs characterizing the reversible reaction between Sm³⁺ and Sm²⁺. By extrapolation, the Voigt model estimated the polarization resistance and established a polarization resistance-concentration relationship.

• 전기화학회지
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• 제16권3호
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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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• 제53권5호
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• pp.1534-1539
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• 2021

This study reports on the dissolution behavior of SrO in LiCl at varying SrO concentrations from low concentrations to excess. The amount of SrO dissolved in the molten salt and the species present upon cooling were determined. The thermal behavior of LiCl containing various concentrations of SrO was investigated. The experimental results were compared with results from the simulated results using the HSC Chemistry software package. Although the reaction of SrO with LiCl in the standard state at 650 ℃ has a slightly positive Gibbs free energy, SrO was found to be highly soluble in LiCl. Experimentally determined SrO concentrations were found to be considerably higher than those present in used nuclear fuel (<2 g/kg). As Sr-90 is one of the most important heat-generating nuclides in used nuclear fuel, this finding will be impactful in the development of fast, simple, and proliferation-resistant heat reduction processes for used nuclear fuel without the need for separating nuclear materials. Heat reduction is important as it decreases both the volume necessary for final disposal and the worker handling risk.

• Journal of Ceramic Processing Research
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• 제13권spc2호
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• pp.308-311
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• 2012

A wide range of possible hazards existing in thermal batteries are mainly caused by thermal runaway, which results in overheating or explosion in extreme case. Battery separators ensure the separation between two electrodes and the retention of ion-conductive electrolytes. Thermal runaways in thermal batteries can be significantly reduced by the adoption of these separators. The high operating temperature and the violent reactivity in thermal batteries, however, have limited the introduction of conventional separators. As a substitute for separators, MgO powders have been mostly used as a binder to hold molten salt electrolyte. During recent decades the fabrication technology of ceramic fiber, which has excellent mechanical strength and chemical stability, has undergone significant improvement. In this study we adopted wet-laid nonwoven paper making method instead of the electrospinning method which is costly and troublesome to produce in volume. Polymeric precursor can readily be coated on the surface of wet-laid ceramic paper, and be formed into ceramic film after heat treatment. The mechanical strength and the thermo-chemical stability as well as the wetting behaviors of ceramic separators with various molten salts were investigated to be applicable to thermal batteries. Due to their excellent chemical, mechanical, and electrical properties, wet-laid nonwoven separators made from ceramic fibers have revealed positive possibility as new separators for thermal batteries which operate at high temperature with no conspicuous sign of a short circuit and corrosion.

• Nuclear Engineering and Technology
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• 제43권6호
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• pp.547-556
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• 2011

Two computational methods for determining equilibrium states for the Mark-IV electrorefiner (ER) have been assessed to improve the current computational electrorefiner model developed at University of Idaho. Both methods were validated against measured data to better understand their effects on the calculation of the equilibrium compositions in the ER. In addition, a sensitivity study was performed on the effect of specific unknown activity coefficients-including sodium in molten cadmium, zirconium in molten cadmium, and sodium chloride in molten LiCl-KCl. Both computational methods produced identical results, which stayed within the 95% confidence interval of the experimental data. Furthermore, sensitivity to unavailable activity coefficients was found to be low (a change in concentration of less than 3 ppm).

• 한국세라믹학회지
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• 제25권4호
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• pp.349-356
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• 1988

The PTCR characteristics of (Ba0.8Pb0.2)TiO3 ceramics prepared by the molten salt sysnthesis (MSS) method have been investigated as a function of the amount of Nb2O5 dopant and KCl flux. When the weight ratio of KCl to raw material is 0.8, the resistivity at room temperature decreases with increasing amount of Nb dopant up to 0.6 atom%. It can be explained by compensation for electrons due to Nb+5 ion and holes due to K+ ion. The resistivity of (Ba0.8Pb0.2)(Ti0.994Nb0.006)O3 ceramics at room temperature decreases with increasing the ratio of KCl to raw material up to 0.6, and then increases. These results can be explained by the effect of K+ ion.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2002년도 추계 학술발표회 논문집
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• pp.81-87
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• 2002

원자로계통 전체가 원자로 용기안에 일체형으로 내장되었으며 열ㆍ에너지 수송회로와 물질ㆍ방사선 수송회로가 각각 분리, 혼합된 복합 원자력에너지시스템인 250MW$_{th}$ 실증로급 AMBIDEXTER (Advanced Molten-salt Break-even Inherently-safe Dual-missioning Experimental and TEst Reactor)는 부의 핵연료 반응도로 인한 고유안전성과 핵확산 방지, 폐기물 감축, 핵연료 경제성 및 자원 이용의 효율성을 갖춘 원자로로서 현재 아주대학교에 서 개념 설계중이다.(중략)

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.161-164
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• 2008

For the development of solar thermal power tower plant from the early 80' to today, various kinds of receiver have been tested and evaluated. Most of 1st generation receiver used water/steam as a working fluid to operate steam turbine and now the first commercial solar power tower PS-10 also makes saturated steam. However, to increase thermal efficiency of storage system and to obtain practical use of solar energy, molten salt system have been used from THEMIS project in France at 1984. The Solar Tres plant of 17 MWe power generation will be constructed in Spain and have plan to operate 24 hours in summer. The air volumetric receiver system can be integrated with combined cycle of gas turbine and HRSG and also with steam turbine easily. Therefore, related researches to develop higher efficient solar power tower plant and to operate with stable are widely performed in the world.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.721-723
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• 1992

The electrical resistivity and piezoelectric properties have been studied for Lead Zirconate-Titanate(PZT) with $Nb_2O_5$ dopant, fabricated from conventional mixed-oxide powders and molten salt synthesis. The resistivity and electromechanical coupling factor(Kp) were increased with increasing Nb contents. The reason for increasing of the electrical resistivity below the Curie Temperature(Tc), It is believed that the p-type electrical conduction in PZT is caused by the lead vacancies. The electromechanical coupling factor(Kr) and piezoelectric constant $d_{33}$ were improved by Nb additives. This behavior can be explained as a compensation effect and $Nb^{5+}$ can serve as a donar and contribute electrons to the conduction process. As a result, the optimized $Nb_2O_5$ dopants on the PZT specimens were 0.75 wt%.

• 한국세라믹학회지
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• 제25권3호
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• pp.293-299
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• 1988

The effects of flux KCl and dopants, La2O3 and Ta2O5, on the PTCR characteristics in molten salt synthesized BaTiO3 have been studied. The resistivity of BaTiO3 at room temperature decreases with increasing amount of dopant La2O3 up to 0.2 atom%, and then increases with La2O3 content. In case of dopant Ta2O5, it increases with increasing amount ofthe dopant. These results could be explained by observation of the microstructure and defect equation. From the results of complex impedance-frequency characteristics, the grain resistances are almost same but the resistances at the grain boundary are quite different.