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Reprocessing of spent nuclear fuel in carbonate media: Problems, achievements, and prospects
Stepanov Sergei I.,Boyarintsev Alexander V. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.7
The review discusses various alternative approaches for spent nuclear fuel (SNF) reprocessing in aqueous carbonate media. The main stages, schemes, and methods of the most well-known and well-described processes for reprocessing SNF and some high-level radioactive waste using carbonate systems developed by research groups in Japan, the United States of America, the Republic of Korea, and the Russian Federation described and compared. The main advantages of such methods are outlined compared to the SNF reprocessing in nitric acid media. The levels of development and proximity of the designed processes to the industrial implementation are shown. The main principle achievements, prospects, and routes for the refinement of such methods for the technology of SNF reprocessing and handling of high-level radioactive waste formulated
Чеховская «семиотика»: старение/стирание знака
А.Д. Степанов(Stepanov A.) 한국노어노문학회 2004 노어노문학 Vol.16 No.2
Chekhov's works contain a latent tendency of ageing or erasing of signs. It means that a sign. full of meaning and relevant in the past, frequently turns into an empty shell, a sign of a sign. But while loosing its signified, a sign nevertheless preserves some connotations, inaccessible for heroes, but important for readers and their interpretation of the work. This tendency is demonstrated in the paper both in symbolic and iconic signs: phrases, jokes, quotes, ikons, jestures, pictures, etc.
А.Д. Степанов(A. D. Stepanov) 한국노어노문학회 2004 한국노어노문학회 학술대회 발표집 Vol.2004 No.9
Chekhov's works contain a latent tendency of ageing or erasing of signs. It means that a sign, full of meaning and relevant in the past, frequently turns into an empty shell, a sign of a sign. But while loosing its signified, a sign nevertheless preserves some connotations, inaccessible for heroes, but important for readers and their interpretation of the work. This tendency is demonstrated in the paper both in symbolic and iconic signs: words, phrases, jokes, quotes, ikons, jestures, pictures, etc.
Results of a New Generation of ITER TF Conductor Samples in SULTAN
Bruzzone, P.,Stepanov, B.,Wesche, R.,Salpietro, E.,Vostner, A.,Okuno, K.,Isono, T.,Takahashi, Y.,Hyoung Chan Kim,Keeman Kim,Shikov, A.K.,Sytnikov, V.E. IEEE 2008 IEEE transactions on applied superconductivity Vol.18 No.2
<P>A new generation of ITER TF conductor samples has been assembled and tested in SULTAN in 2007 following a common procedure agreed among the ITER parties. The test results of six SULTAN samples, made of twelve conductor sections manufactured in Europe, Japan, Korea and Russia, are reported here. The conductor layout reflects the ITER TF conductor design, with minor differences for the Nb<SUB>3</SUB>Sn strand characteristics, void fraction and twist pitch. The object of the test is a straight comparison with the ITER requirement of 5.7 K current sharing temperature at 68 kA current and 11.3 T field. A broad range of behavior is observed.</P>
Separation and purification of elements from alkaline and carbonate nuclear waste solutions
Boyarintsev Alexander V.,Stepanov Sergei I.,Kostikova Galina V.,Zhilov Valeriy I.,Safiulina Alfiya M.,Tsivadze Aslan Yu 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.2
This article provides a survey of wet (aqueous) methods for recovery, separation, and purification of uranium from fission products in carbonate solutions during the reprocessing of spent nuclear fuel and methods for removal of radionuclides from alkaline radioactive waste. The main methods such as selective direct precipitation, ion exchange, and solvent extraction are considered. These methods were compared and evaluated for reprocessing of spent nuclear fuel in carbonate media according to novel alternative non-acidic methods and for treatment processes of alkaline radioactive waste.
Milica Veljkovic,Relja Stepanovic,Katarina Banjanac,Marija Ćorović,Ana Milivojevic,Milica Simović,Milan Milivojević,Dejan Bezbradica 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.117 No.-
Within this study, the investigation of potential selective immobilization of fructosyltransferase (FTase) derived from Aspergillus aculeatus (from commercial enzyme preparation Pectinex® Ultra SP-L) onto the polystyrenic macroporous resin Purolite® A109 and its further utilization for the synthesis of a highly valuable group of prebiotic compounds named fructo-oligosaccharides (FOS), was performed. The obtained results suggest that partial purification of fructosyltransferase from complex enzyme mixture with predominant pectinase activity (ratio of activity immobilization yields around 20.0) occurred by performing a simple immobilization protocol, provided that immobilization lasted for 5 h using an enzyme concentration of 50 mg g−1 of support under slightly acidic conditions (pH 6.0). Immobilized preparation was thereafter successfully utilized for FOS synthesis (56–59 % FOS of total sugars) in both a batch and air-lift reactor system. Operational stability study proved the exceptionally high potential of immobilized preparation for reproducible and cost-effective application, since 90 % of initial activity was preserved after ten consecutive reaction cycles. Thereafter, a prospectus for continuous production of FOS in the air-lift reactor was assayed. Achieved yields, 53 % FOS of total sugars for at least 9 h, indicated the great suitability of the obtained immobilized preparation for application in large-scale systems.
Reprocessing of fluorination ash surrogate in the CARBOFLUOREX process
Boyarintsev, Alexander V.,Stepanov, Sergei I.,Chekmarev, Alexander M.,Tsivadze, Aslan Yu. Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.1
This work presents the results of laboratory scale tests of the CARBOFLUOREX (CARBOnate FLUORide EXtraction) process - a novel technology for the recovery of U and Pu from the solid fluorides residue (fluorination ash) of Fluoride Volatility Method (FVM) reprocessing of spent nuclear fuel (SNF). To study the oxidative leaching of U from the fluorination ash (FA) by Na<sub>2</sub>CO<sub>3</sub> or Na<sub>2</sub>CO<sub>3</sub>-H<sub>2</sub>O<sub>2</sub> solutions followed by solvent extraction by methyltrioctylammonium carbonate in toluene and purification of U from the fission products (FPs) impurities we used a surrogate of FA consisting of UF<sub>4</sub> or UO<sub>2</sub>F<sub>2</sub>, and FPs fluorides with stable isotopes of Ce, Zr, Sr, Ba, Cs, Fe, Cr, Ni, La, Nd, Pr, Sm. Purification factors of U from impurities at the solvent extraction refining stage reached the values of 10<sup>4</sup>-10<sup>5</sup>, and up to 10<sup>6</sup> upon the completion of the processing cycle. Obtained results showed a high efficiency of the CARBOFLUOREX process for recovery and separating of U from FPs contained in FA, which allows completing of the FVM cycle with recovery of U and Pu from hardly processed FA.