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Journal Articles

Verification of a simple procedure to simulate solvent extraction by pulsed columns

Kobayashi, Tsuguyuki

Nuclear Technology, 177(2), p.231 - 244, 2012/02

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

A simple procedure to simulate the important kinetic features of counter current processes in pulsed columns has been developed. The validity of these simplifications was confirmed by comparing the calculation results with a wide range of measured data. An example of its application in a flow sheet calculation was demonstrated.

Journal Articles

Development of short stroke shearing technology for FBR fuel pin

Higuchi, Hidetoshi; Koizumi, Kenji; Hirano, Hiroyasu; Tasaka, Masayuki*; Washiya, Tadahiro; Kobayashi, Tsuguyuki*

Journal of Power and Energy Systems (Internet), 4(1), p.244 - 251, 2010/04

no abstracts in English

Journal Articles

Design and fabrication of the FBR fuel disassembly system

Kitagaki, Toru; Tasaka, Masayuki; Higuchi, Hidetoshi; Koizumi, Kenji; Hirano, Hiroyasu; Washiya, Tadahiro; Kobayashi, Tsuguyuki*

Proceedings of 17th International Conference on Nuclear Engineering (ICONE-17) (CD-ROM), 5 Pages, 2009/06

JAEA has been developing a reliable disassembly system for FBR fuel reprocessing as a part of Fast Reactor Cycle Technology Development (FaCT). We fabricated the disassembly system testing machine. In this paper, we described design of it.

Journal Articles

Evaluation of the decay heat limits in electrorefiners for reprocessing spent metallic fuels

Kobayashi, Tsuguyuki

Nuclear Technology, 166(2), p.134 - 145, 2009/05

 Times Cited Count:1 Percentile:10.23(Nuclear Science & Technology)

Design limits on the accumulated decay heat in the molten salt of an electrorefiner (ER) are proposed based on two dimensional steady state calculations. It was found that forced convection cooling of the outer surface of ER allows at maximum about 30 to 40% larger decay heat than that for natural circulation cooling. The validity of a steady state calculation is confirmed by comparison with a one dimensional non-steady state calculation. Estimated decay heat limits are compared with that of NaCl resulting from the bonding Na in the spent metallic fuel and the lanthanides concentration in the salt. These comparisons suggest that consideration of the decay heat is very important for the continuous usage of the salt in the ER.

Journal Articles

Development of disassembly & pin chopping technology for FBR spent fuels

Kobayashi, Tsuguyuki*; Namba, Takashi*; Kawabe, Yukinari*; Washiya, Tadahiro

Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM), 6 Pages, 2008/10

Japan Atomic Power Company (JAPC) and Japan Atomic Energy Agency (JAEA) have been developing fuel disassembly and fuel pin chopping systems for a future Japanese commercial FBR. At first, the wrapper tube is cut by the slit-cut to pull it out, then the fuel pins are cut by the crop-cut at their end-plugs to separate them from the entrance nozzle. The pins are transferred to the magazine of the chopping machine. A series of tests were performed to develop this procedure. As the result of mechanical cutting tests, the CBN wheel was selected. The slit-cut tests were carried out to evaluated the cutting performance of the wheel. Fuel pin handling tests were performed to transfer them from the disassembly machine to the chopping machine. The Saucer tray was selected to receive the disassembled pins. All the pins were transferred and loaded into a magazine of the chopping machine.

Journal Articles

An Assessment of multistage counter current extraction of TRU from spent molten salt into liquid metal, 2; Effect of stage efficiency, scrub stage, and TRU concentration

Kobayashi, Tsuguyuki

Journal of Nuclear Science and Technology, 45(1), p.79 - 83, 2008/01

 Times Cited Count:6 Percentile:40.16(Nuclear Science & Technology)

Calculation procedures were developed to evaluate the performance of the multi-stage counter current extraction of TRU from spent molten salt into liquid metal. This procedure considers the stage efficiency and the scrub stage. The following was found using procedures, which supplements previous papers. When Cd is used as the liquid metal, at least 4 stages are necessary to recover 99% of TRU from the salt with decontamination factor ($$DF$$) higher than 5. Stage efficiency of the extraction should be better than 80% for a practical application. The scrub stage is not very effective in improving the $$DF$$ when the total number of extractions is limited. The $$DF$$ slightly increases with higher TRU concentration in the salt due to the effect of the accompanying lanthanide FP as reductant. It was found to be very difficult to separate Np, Am or Cm from Pu, so that the extraction process has inherent proliferation resistance.

Journal Articles

An Assessment of the multi-stage counter current extraction of TRUs from spent molten salt, into liquid metal (Errata)

Kobayashi, Tsuguyuki

Journal of Nuclear Science and Technology, 44(4), p.673 - 674, 2007/04

 Times Cited Count:1 Percentile:60.71(Nuclear Science & Technology)

The errors in the calculation formula for the multi-stage counter current extraction in the previous paper (J. Nucl. Sci. Technol. 43(7), p.819-823, (2006)) were corrected. The figures and tables calclulated by the corected formula were also provided.

Journal Articles

An Assessment of the multi-stage counter current extraction of TRUs from spent molten salt, into liquid metal

Kobayashi, Tsuguyuki

Journal of Nuclear Science and Technology, 43(7), p.819 - 823, 2006/07

 Times Cited Count:9 Percentile:53.51(Nuclear Science & Technology)

A new calculation procedure for the multi-stage counter current reductive extraction was described and its characteristics were investigated. It was confirmed that the Nd extracted at the 1st stage worked as a mild reducing agent to extract Americium in the 2nd stage. This makes the Cd-Li extraction superior to that of Cd-U in terms of its DF. Higher separation performance of Bi-Li extraction was also evaluated quantitatively. Difference of separation behavior among the lanthanides is also evaluated quantitatively.

Journal Articles

Study of Low Current Efficiency in MOX Co-Deposition Tests

Fukushima, Mineo; Kobayashi, Tsuguyuki; Myochin, Munetaka; Keiiji, Fujii,*

Journal of Nuclear Science and Technology, 42(10), p.861 - 868, 2005/10

 Times Cited Count:5 Percentile:35.83(Nuclear Science & Technology)

Focusing on the cover layer materials (as the Radon Barrier Materials), which could have the effect to restrain the radon from scattering into the air and the effect of the radiation shielding, we produced the radon barrier materials with crude bentonite on an experimental basis, using the rotary type comprehensive unit for grinding and mixing, through which we carried out the evaluation of the characteristics thereof.

Journal Articles

Investigation of plutonium precipitation in the MOX co-deposition tests for the oxide electrowinning process

Kobayashi, Tsuguyuki; Vavilov, S.; Sato, Fuminori; Myochin, Munetaka; Namba, Takashi*; Namba, T.*

Journal of Nuclear Science and Technology, 42(3), p.295 - 300, 2005/00

 Times Cited Count:10 Percentile:56.75(Nuclear Science & Technology)

The concept of air transport of A Type package containing nuclear fuel materials according to the nuclear disaster countermeasures law, and the experience of a transportation of plutonium solution from France are shown.

Journal Articles

Principle and Test Experience of the RIAR's Oxide Pyro-Process

Vavilov, S.; Kobayashi, Tsuguyuki; Myochin, Munetaka

Journal of Nuclear Science and Technology, 41(10), p.1018 - 1025, 2004/00

 Times Cited Count:43 Percentile:76.79(Nuclear Science & Technology)

Principles and operation experience of the Oxide Pyrp-Process being developed at RIAR Russia are described. Needed basic data are also evaluated based on open literature data.

Journal Articles

Evaluation of Thermodynamic Properties for Pyro-Process and their Significance to the Process

Kobayashi, Tsuguyuki; Vavilov, S.; Myochin, Munetaka

Proceedings of 11th Symposium on Thermodynamics of Nuclear Materials (STNM-11), P. 91, 2004/00

The thermodunamic properties such as the Redox potential, diffusion coefficient, and oxidation rate constant of Pu are evaluated. These properties are used for the fieasibility study of the pyro-process.

JAEA Reports

Principles of the Oxide Electrowinning Process

Vavilov, S.; Kobayashi, Tsuguyuki; Myochin, Munetaka

JNC TN8400 2003-030, 121 Pages, 2003/12

JNC-TN8400-2003-030.pdf:1.27MB

The principles and basic data such as potential, diffusion coefficient and equilibrium constants for the Oxide Pyro-Process are summerlized. The basic data are independently evaluated based on open liturature.

JAEA Reports

Flow analysis of electrode reaction in pyrochamical reprocessing -Estimation of the a diffusion layer thickness in oxide electrowinning method-

*; Sakai, Takaaki; Kobayashi, Tsuguyuki

JNC TN9400 2003-020, 65 Pages, 2003/03

JNC-TN9400-2003-020.pdf:1.57MB

A pyrochemical reprocessing system using a molten salt electrolysis has been studied as one of the feasible concepts for the FBR fuel reprocessing system. In order to calculate the amount of deposits of the salvaged material in molten salt electrolysis process in high accuracy, it is necessary to evaluate appropriately the concentration diffusion layer thickness of a deposit ingredient near the electrode surface. However, measurement of diffusion layer thickness is extremely difficult. Therefore, it has been a subject to develop the evaluation methods of the diffusion layer thickness. In this report, we have developed the two-dimensional analysis code, in order for numerical analysis to estimate the diffusion layer thickness near the electrode surface. This code can solve simultaneously a deposit by electrode reaction of Nernst's equation, concentration distribution of reactant near the electrode surface, and the natural convection resulting from the density change by concentration change. By using the code, we carried out analysis of the oxide electrolysis experiment in Russia, and evaluated the characteristic of diffusion layer thickness and the polarization curve. As a result, although indeterminacy remained in the physica1-properties value, the polarization curve in analysis agreed with the experiment result in general. By the analysis of a molten salt electrolysis, it was clarified that the diffusion layer is formed with hundreds micrometers thickness along the natural convection on the cathode surface, and the diffusion layer thickness changes corresponding to the velocity boundary layer of the natural convection flow which is driven by mass transfer at the electrode surface. In addition, Ito's mass transfer correlation for aqueous solutions shows good agreement with the molten salt calculation within a reasonable accuracy. Therefore, it is prospected that the diffusion layer thickness in the molten salt can be evaluated from Ito's correlation.

JAEA Reports

Development of JURA -A Simulation Code for Electrochemical Processes in Molten Salt-

Kobayashi, Tsuguyuki

JNC TN8400 2003-001, 46 Pages, 2003/03

JNC-TN8400-2003-001.pdf:0.55MB

A simulation code for electrochemical processes in molten salt named JURA has been developed. This code can simulate the time history of the processes such as the metal pyro-process and the oxide pyro-process by the diffusion layer theory at various temperature and melts. This report describes the specific formulations of the theory for various electrodes such as the solid cathode, the Cd cathode, and the Cd pool anode. Explanation of the input data and sample calculations of the solid cathode, the Cd cathode as well as the MOX co deposition experiments are also given.

Journal Articles

The Coordinated Research Program on "Inter-cemparison of LMFBR Seismic Analysis Codes" Organized by IAEA

Morishita, Masaki; Ito, Kunihiro*; Kobayashi, Tsuguyuki*; Horiuchi, Toshihiko*

Nihon Genshiryoku Gakkai-Shi, 38(3), p.205 - 210, 1996/00

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

None

Oral presentation

Study of the decay heat limitation accumulated in the molten salt of an electrorefiner

Kobayashi, Tsuguyuki; Sato, Fuminori

no journal, , 

no abstracts in English

Oral presentation

Study of the multi stage counter current extraction of TRUs with liquid metal

Kobayashi, Tsuguyuki

no journal, , 

A new theoretical study on the separation of TRUs by the multi stage counter current extraction from the spent molten salt of the metal puro-process was performed. The effects of the scrub stage was studied. It was found that up to 4 stages of extraction, the decontamination coefficient(DF) became higher for those without the scrub stage. It was also found that DF becomes higher when the concentration of TRU in the spent salt is higher and it is difficult to separate Np, Am, and Cm from Pu with 4 stages of extraction.

Oral presentation

Development of FBR fuel disassembly and pin bundle chopping technology, 1; Development plan and summary of 2006JFY results

Kobayashi, Tsuguyuki*; Washiya, Tadahiro

no journal, , 

no abstracts in English

Oral presentation

Development of FBR fuel disassembly and pin bundle chopping technology, 3; Results of basic laser cutting test during 2006JFY

Minehara, Eisuke; Kobayashi, Tsuguyuki*; Washiya, Tadahiro; Tasaka, Masayuki

no journal, , 

In order to develop future FBR nuclear fuel disassembling technology, and in order to acquire the fundamental laser cutting knowledge, various laser cutting experiments have been done. In comparison with the present technology, it has been concluded that the laser cutting could be applied to chop the nuclear fuel assembly components finely.

34 (Records 1-20 displayed on this page)