Authors:Choon-ho Cho, Yun-sang Lee, Eung-soo Kim, Jeong-guk Kim, and Han-soo Lee
The uranium ingot casting process is one of the steps which consolidate uranium deposits produced by electrorefiner in an
ingot form in a pryprocessing technique. Since molten uranium metal reacts with a graphite crucible when the uranium is being
dissolved, a graphite crucible cannot be used. Accordingly, a ceramic material must be selected which does not react with
the dissolving uranium and this must be used as a coating material on the graphite crucible surface. As to this research,
a reactivity experiments were performed between the coating layer and uranium by applying a thermal spray coating to the graphite
material with alumina and YSZ ceramic material. As shown in the experimental result, the YSZ coating layer showed a stronger
adhesive property on the side where there is no Ni–Al binding material. Moreover, no reaction was apparent between the YSZ
coating layer and the uranium. Accordingly, the YSZ material and the process of thermal spray coating are considered to solve
the reactive problem between uranium and a graphite crucible.
Authors:Tack-Jin Kim, Yong-Kwang Jeong, Jun-Gill Kang, Yongju Jung, Do-Hee Ahn, and Han-Soo Lee
The spontaneous reduction of Eu3+ to Eu2+ was examined when EuCl3 was added into a pyroprocessing media of LiCl molten salt at 923 K. The amount of Eu2+ was calculated by measuring the total charge consumed to oxidize Eu2+ ions to Eu3+ ions. The concentration ratio of Eu2+ to Eu3+ was estimated to be about 0.40 in the media. In addition, it is confirmed that the reduction of Eu3+ to Eu2+ is caused by the oxidation power of Cl− to Cl2. The coexistence of Eu3+ and Eu2+ in the LiCl molten salt system was examined by UV–Visible and luminescence spectroscopy. The molar absorptivities of Eu3+ and Eu2+, calculated from UV–Visible absorption spectra, were 423 and 1954 M−1 cm−1, respectively.
Authors:Lina Han, Soo-Jin Choi, Moon-Seok Park, Seon-Myong Lee, Yu-Jin Kim, Moon-Il Kim, Binyuan Liu, and Dae-Won Park
In this study, a series of imidazolium-based ionic liquids (ILs) having carboxylic acid moieties were synthesized and used as new homogeneous catalysts to synthesize cyclic carbonates from CO2 and epoxides. Even in the absence of any co-catalyst and organic solvent, carboxylic-acid-functionalized ILs showed better catalytic activity in the coupling reaction of CO2 and styrene oxide for the production of styrene carbonate than did hydroxyl-functionalized ILs and conventional ILs without any functional moieties. A detailed investigation was carried out on a variety of factors that affected the reactivity, such as the alkyl chain length and the molecular composition of IL molecules including the halide ions. The effect of various reaction parameters such as reaction time, temperature, CO2 pressure and catalyst amount was also investigated in detail. The mechanism underlying the enhanced rate of the cycloaddition reaction in the presence of carboxylic-acid-functionalized ILs was proposed.