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Kawaguchi, Koichi; Segawa, Tomoomi; Ishii, Katsunori
Funtai Kogakkai-Shi, 59(6), p.283 - 290, 2022/06
In the Japan Atomic Energy Agency, in order to effectively use the out-of-standard pellets in the fuel manufacturing process for high-speed furnaces, we are developing techniques for crushing and reusing them with raw material powder. By analyzing in detail the particle size distribution before and after grinding, it was shown that the grinding powder is composed of three different component particles having different characteristics of the particle size distribution. In addition, we examined the method of predicting pulverized powder particle size distribution from the supply powder particle size distribution.
Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Suzuki, Masahiro; Fukasawa, Tomonori*; Fukui, Kunihiro*
Funtai Kogakkai-Shi, 57(9), p.485 - 494, 2020/09
In the spent fuel reprocessing process, a mixed solution of uranyl nitrate and plutonium nitrate is converted into mixed oxide powder by the microwave heating. To evaluate the applicability to the industrial-scale and acquire the characteristics data of the microwave heating denitration of various metal nitrate aqueous solutions based on the knowledge studied in the development of laboratory-scale basic experiments, the microwave heating characteristics and metal oxide powder properties were investigated using cerium nitrate, cobalt nitrate and copper nitrate aqueous solutions. The progress rate of the denitration reaction was depended on the position, and the denitration reaction proceeded faster at the periphery than at the center. The morphologies of the synthesized products were porous and hard dry solid with cerium nitrate aqueous solution, foamed dry solid with cobalt nitrate aqueous solution, and powdery particles with copper nitrate aqueous solution. The denitration ratio and average particle size of the synthesized products increased in the order of the cerium nitrate aqueous solution, the cobalt nitrate aqueous solution, and the copper nitrate aqueous solution. The numerical simulations revealed that the periphery of the bottom surface of the metal nitrate aqueous solution was heated by microwaves. This results consistent with the experimental results in which the denitration reaction started from the periphery of the metal nitrate aqueous solution.
Kawaguchi, Koichi; Segawa, Tomoomi; Yamamoto, Kazuya; Makino, Takayoshi; Iso, Hidetoshi; Ishii, Katsunori
Funtai Kogakkai-Shi, 57(9), p.478 - 484, 2020/09
A collision plate type jet mill is assumed to be a pulverizer that can control the particle size for nuclear fuel fabrication. The collision plate type jet mill consists of two modules, a classifier and a mill chamber. Coarse component of powder is cycled in the equipment and finally pulverized into objective particle size. In this report, simulated crushed powders were classified and pulverized step by step, and particle size distribution were compared. The collision plate type jet mil can produce objective size particles with low overgrinding.
Segawa, Tomoomi
Funtai Kogakkai-Shi, 55(10), P. 547, 2018/10
no abstracts in English
Suzuki, Michitaka*; Yoshikawa, Mao*; Iimura, Kenji*; Satone, Hiroshi*; Ishii, Katsunori
Funtai Kogakkai-Shi, 50(6), p.405 - 409, 2013/06
The glass substrate is coated by the silica nanoparticle suspension using dipping or spin coat method and dried in an electric oven. The glass substrate surface is covered with nanoparticle thin layer and the transparent and tiny rugged surface can be produced on a substrate. It was experimentally confirmed to prevent dust adhesion by covering the surface of the glass substrate with nanoparticle. The adhesion force between particle and substrate is measured by the centrifugal method and the relation between the adhesion force and the surface roughness is discussed from experimental and theoretical point of view. The measured and calculated results by Van der Waals force show that adhesion force decreased with the increment of the surface roughness. From the results, nanoparticle coating is very effective to prevent the dust adhesion on the substrate and the various application of nanoparticle coating can be expected.
Ishii, Katsunori; Suzuki, Masahiro; Yamamoto, Takuma; Kihara, Yoshiyuki; Yasuda, Masatoshi*; Matsusaka, Shuji*
Funtai Kogakkai-Shi, 45(5), p.290 - 296, 2008/05
Particle flowability test using a vibrating tube with a tapered end was carried out to evaluate the applicability of this method to the analysis of MOX particles for nuclear fuel pellet fabrication. In this experiment, zirconia particles were used as model particles, which are less than several hundred micrometers in diameter. The sample particles were prepared by mixing the particles with different sizes, whose shape and surface state were changed by a mechanical treatment. The experimental results showed that the removal of smaller particles is more effective than the mechanical surface treatment to improve the flowability. Furthermore, it was found that the vibrating tube method can identify the difference of the particle flowability more easily and clearly than the method based on Carr's flowability index.
Ishii, Katsunori; Suzuki, Masahiro; Kihara, Yoshiyuki; Fujii, Kanichi*
Funtai Kogakkai-Shi, 42(7), p.472 - 477, 2005/00
To optimize sphere-pac fuel pin fabrication process, internal structure of fuel pin under small particles infiltration process was observed by micro focus X-ray CT system. Some small particles block the space among large particles. Small particles arrive at the bottom of fuel column, and fill the space among large particles, and form completed packing layer. Sphere-pac process progresses with growth of the layer from bottom to top of the column. A unique layer is formed around the top of fuel column shot time after starting vibration. Small particles completely intrude between large particles and pin wall in the layer. The structure never changes after completion of small particles infiltration process. The formation of the unique layer can be qualitatively explained by simulation.
