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Tamai, Hiroshi; Mochiji, Toshiro; Senzaki, Masao*; Iwamoto, Tomonori*; Ishiguro, Yuzuru*; Kitade, Yuta; Sato, Heigo*; Suehiro, Rie*; Taniguchi, Tomihiro*; Fukasawa, Tetsuo*; et al.
Dai-41-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2020/11
In light of recent delay of plutonium use in Japan and the increasing criticism of nuclear non-proliferation and nuclear security in the nuclear fuel cycle, the validity of these criticisms will be examined for the sustainable development of the nuclear fuel cycle policy. Issues on the view point of nuclear non-proliferation and nuclear security are examined.
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.
Mochiji, Toshiro; Senzaki, Masao*; Tamai, Hiroshi; Iwamoto, Tomonori*; Ishiguro, Yuzuru*; Kitade, Yuta; Sato, Heigo*; Suehiro, Rie*; Taniguchi, Tomihiro*; Fukasawa, Tetsuo*; et al.
Enerugi Rebyu, 40(8), p.56 - 57, 2020/07
Strict application of IAEA safeguards and nuclear security should be implemented for Japan's full-scale nuclear fuel cycle. Based on the knowledge and experience of research and development in the nuclear fuel cycle, nuclear material management, the effective and efficient promotion of new technologies should be promoted with scientific and demonstrative measures to strengthen the world's nuclear non-proliferation and nuclear security. Development or sophistication of new technologies, human resource development, and reinforcement of the international framework are future challenge in the international community.
Mochiji, Toshiro; Senzaki, Masao*; Tamai, Hiroshi; Iwamoto, Tomonori*; Ishiguro, Yuzuru*; Kitade, Yuta; Sato, Heigo*; Suehiro, Rie*; Taniguchi, Tomihiro*; Fukasawa, Tetsuo*; et al.
Enerugi Rebyu, 40(7), p.58 - 59, 2020/06
Japan have promoted the peaceful use of plutonium with the nuclear non-proliferation commitment based on IAEA safeguards agreement and Japan-US nuclear cooperation agreement, as well as ensuring transparency of the policy that Japan has no plutonium without purpose of use. In promoting the nuclear fuel cycle, adherence to those measures and maintaining plutonium utilization by means of plutonium-thermal, and a fast reactor cycle to achieve large-scale and long-term energy supply and environmental improvement, therefore, further research and development is essential.
Mochiji, Toshiro; Senzaki, Masao*; Tamai, Hiroshi; Iwamoto, Tomonori*; Ishiguro, Yuzuru*; Kitade, Yuta; Sato, Heigo*; Suehiro, Rie*; Taniguchi, Tomihiro*; Fukasawa, Tetsuo*; et al.
Enerugi Rebyu, 40(6), p.58 - 59, 2020/05
In order to promote the peaceful use of nuclear energy, it is important not only to ensure safety but also to ensure nuclear non-proliferation and nuclear security. Japan has contributed to the international community through strengthening nuclear non-proliferation and nuclear security capabilities with technical and human resource development. However, in the wake of the accident at the Fukushima Daiichi Nuclear Power Plant in 2011, Japan's nuclear power plants have not restarted or plutonium use has not progressed smoothly. Concerns have been shown. Towards appropriate steps of Japan's nuclear fuel cycle policy, such concerns are examined and future efforts are summarized.
Segawa, Tomoomi; Yamamoto, Kazuya; Makino, Takayoshi; Iso, Hidetoshi; Kawaguchi, Koichi; Ishii, Katsunori; Sato, Hisato; Fukasawa, Tomonori*; Fukui, Kunihiro*
Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.738 - 745, 2019/09
In the MOX fuel fabrication process, the dry grinding technology of mixed oxide pellets have been developed for the effective use of nuclear fuel materials. To develop a technology to control the particle size of dry recovered powder, the performance of the buhrstone mill and the collision plate type jet mill were studied using a simulated powder of particle size distribution about 500 
m. We found that the particle size can be controlled at the range of about 250 m or less by both by adjusting the clearance between the grinding wheels of the buhrstone mill, and the clearance and elevation angle of the clarification zone of the collision plate type jet mill. And furthermore, the collision plate type jet mill is considered to be suitable for particle size control because the operating parameters of the classifier can be finely adjusted.
Karisma, A. D.*; Hamaba, Taishu*; Fukasawa, Tomonori*; Huang, A.-N.*; Segawa, Tomoomi; Fukui, Kunihiro*
Review of Scientific Instruments, 88(2), p.024101_1 - 024101_8, 2017/02
Times Cited Count：4 Percentile：21.22(Instruments & Instrumentation)Microwave heating direct denitration method is used in the nuclear fuel reprocessing process. In order to develop a single-mode-type microwave heating thermogravimetry apparatus which can perform detailed analysis of the characteristics of microwave heating, the temperature dependence of microwave absorption is verified. The temperature distribution, microwave absorption efficiency, and dielectric properties of a CuO pellet that was heated by the microwave irradiation were investigated. The temperature distribution in the CuO pellet due to one-way travel of the microwave in the apparatus was accurately reproduced by a three-dimensional numerical simulation of the electromagnetic field. The numerically determined temperature dependency of the CuO absorption efficiency was found to be in very good agreement with published data.
Segawa, Tomoomi; Fukasawa, Tomonori*; Huang, A.-N.*; Yamada, Yoshikazu; Suzuki, Masahiro; Fukui, Kunihiro*
Chemical Engineering Science, 153, p.108 - 116, 2016/10
Times Cited Count：7 Percentile：26.49(Engineering, Chemical)The influence of the heating method and rate on the morphology of CuO powders synthesized from Cu(NO
)
3HO aqueous solutions by denitration was investigated. The median diameter of the obtained powder was found to decrease as the heating rate increased, independent of the heating method. The microwave heating method remarkably reduced the particle size and enhanced the irregularity and disorder of the shape and surface of the particles, which were found to be more widely distributed. In contrast, the microwave hybrid heating method yielded the most spherical particles with the smoothest surface. It was also found that this heating method sharpened the particle size distribution and had higher energy efficiency than the MW method. Numerical simulations also indicated a difference in the energy efficiency between these two methods. The simulations also revealed that the hybrid method could heat the whole reactor more uniformly with a lower microwave output.
Segawa, Tomoomi; Fukasawa, Tomonori*; Yamada, Yoshikazu; Suzuki, Masahiro; Yoshida, Hideto*; Fukui, Kunihiro*
Proceedings of Asian Pacific Confederation of Chemical Engineering 2015 (APCChE 2015), 8 Pages, 2015/09
A mixed solution of uranyl nitrate and plutonium nitrate is converted to MOX raw powder by the microwave heating de-nitration method in nuclear reprocessing. Copper oxide synthesized by heating de-nitration was used as a model for the de-nitration process. The microwave heating method (MW) and infrared heating method (IR) were used, and how they and their heating rate influence the obtained particle morphology and size were investigated. The particles obtained by the MW and IR were sufficiently similar in the surface morphology and the mass median diameter was decreased by the increased heating rate. The mass median diameters by the MW were the heating rate and smaller than those obtained by IR. The particle size distribution of the particle obtained by the MW was broader than that by the IR. The relationship of the temperature distribution and particle size distribution by the MW was discussed by the numerical simulation.
Hamaba, Taishu*; Segawa, Tomoomi; Fukasawa, Tomonori*; Yoshida, Hideto*; Fukui, Kunihiro*
no journal, ,
no abstracts in English
Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Fukasawa, Tomonori*; Fukui, Kunihiro*
no journal, ,
In the conversion process, a mixed solution of plutonium nitrate and uranyl nitrate recovered from spent fuel is converted into mixed oxide through microwave heating. Both, improvements in heating efficiency and powder characteristics, are important in microwave heating denitration. This study aims to advance microwave heating denitration. Thus, we investigated the effects of heating conditions when using an adiabator and the temperature rising rate of the particle characteristics of a uranium trioxide (UO) powder synthesized from uranyl nitrate solutions through microwave heating. The temperature rising rate significantly increased when the adiabator was used compared to when not used at the same microwave power. The mass median diameters of the UO powders decreased with the increasing temperature rising rate with and without using the adiabator. Heating conditions can control the particle characteristics of UO powders.
Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Suzuki, Masahiro; Fukasawa, Tomonori*; Fukui, Kunihiro*
no journal, ,
In the reprocessing process of spent fuels, a mixed solution of uranyl nitrate and plutonium nitrate is converted into mixed oxide powders by the microwave heating. To evaluate the applicability to the macro-scale based on the knowledge obtained in the laboratory-scale experiments, the microwave heating characteristics and metal oxide powder morphologies using a cerium nitrate, copper nitrate and cobalt nitrate aqueous solution were investigated. It was revealed that the denitration rates and the average particle sizes of the products increased in the order of the cerium nitrate aqueous solution, cobalt nitrate aqueous solution, and copper nitrate aqueous solution, and the denitration rate tends to increase at the periphery position and the average particle size at the center position.
Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Yamamoto, Kazuya; Makino, Takayoshi; Iso, Hidetoshi; Fukasawa, Tomonori*; Fukui, Kunihiro*
no journal, ,
Japan Atomic Energy Agency has been used out of specification mixed oxide (MOX) pellets as a dry recovered powder for the effective use of nuclear fuel material in the MOX fuel fabrication process. The densities of the sintered MOX pellets can be controlled to about 85 %T.D. without adding pore former by adjusting the amount and the particle size of the dry recovered powder into the raw powder. It is required to adjust the particle size of the dry recovered powder to under 250 m, the influence of the operating parameters of the collision plate-type jet mill on the characteristics of pulverization and the influence of pulverized powders on sintering properties were evaluated. The clearance was narrowed, the pulverized powders were confirmed to be adjusted for the particle diameter of under 250 m, and the pellet prepared from the pulverized powder with density of about 85.0 %T.D. was obtained.
Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Suzuki, Masahiro; Fukasawa, Tomonori*; Fukui, Kunihiro*; Kitazawa, Toshihide*
no journal, ,
In the process of the spent fuel reprocessing, a mixture of uranyl nitrate and plutonium nitrate is converted to a mixed oxide powder by the microwave heating direct denitration method. In the case of assuming the heterogeneous cycle in the Na-cooled fast reactor, it is required to denitrate a solution containing mainly MA for which microwave heating denitration characteristics have not been clarified, therefore, it is necessary to obtain microwave heating denitration characteristics data for metal nitrate mixed aqueous solutions. In this study, microwave heating denitration characteristics of copper nitrate and nickel nitrate mixed solution and the complex relative permittivity of the final and intermediate products were evaluated. It was clarified that the mixing ratio and the microwave energy loss of metal oxides as final products remarkably affect the denitration characteristics.
Yamada, Masaaki*; Segawa, Tomoomi; Fukasawa, Tomonori*; Ishigami, Toru*; Fukui, Kunihiro*
no journal, ,
The microwave heating method is used in the reprocessing process of spent fuels. It is possible to improve the quality of raw powder by using microwave heating and an external heating source together. However, the use of external heating in a microwave irradiation field causes a problem of deterioration of equipment. Therefore, the hybrid heating using a carbon nanotube (CNT) -containing alumina composite material with a large relative permittivity as an external heating source has been studied. To clarify the effect of the CNT content on the dielectric properties, the microwave heating characteristics were measured and evaluated, and numerical simulation was carried out. From these results, the microwave heating characteristics can be controlled by adjusting the CNT content in the CNT-containing alumina composite material.
Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Tamaru, Ayaka*; Yamada, Masaaki*; Fukasawa, Tomonori*; Ishigami, Toru*; Fukui, Kunihiro*
no journal, ,
The microwave heating method is used in the reprocessing process of spent fuels. To improve the powder quality in fuel fabrication for the fast reactor, research and development of a microwave hybrid heating method, which combines microwave heating with external heating, is advanced. However, the installation of heating equipment in the cavity may cause damage to the heating equipment due to electrical discharge or induced current under microwave irradiation. To evaluate the effect of the CNT content of the alumina composite on the microwave heating characteristics in detail, the temperature during microwave irradiation and the apparent dielectric loss were measured. As a result of this study, it was found that the microwave heating property can be controlled by adjusting the CNT content, and the prospect that CNT-containing alumina is effective as microwave absorbing heating material was obtained.
Tamaru, Ayaka*; Segawa, Tomoomi; Yamada, Masaaki*; Fukasawa, Tomonori*; Ishigami, Toru*; Fukui, Kunihiro*
no journal, ,
The microwave heating method is used in the reprocessing process of spent fuels. It is possible to improve powder quality by microwave and external heating together. However, the use of external heating in a microwave irradiation field causes a problem of deterioration of equipment. Hybrid heating using CNT-containing alumina with a large relative permittivity as an external heating source has been studied. The characteristics of the hybrid heating in a cavity-type reactor and the relationship between the relative dielectric losses of the materials were evaluated. The relative dielectric losses of the CNT-containing alumina and sample powders were measured by the cavity resonator method and the MW-TG method, respectively. The relative dielectric loss measured by the MW-TG was consistent with the selectivity of heating and was confirmed to be an appropriate index for evaluating the microwave heating characteristics.
Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Nagakawa, Genta*; Tamaru, Ayaka*; Fukasawa, Tomonori*; Ishigami, Toru*; Fukui, Kunihiro*
no journal, ,
Microwave heating in combination with an external heating source has been used to improve powder properties by compensating for heat transfer losses. However, the external heating source in the microwave irradiation field may degrade the heating elements. A hybrid heating method has been developed to use composite ceramic jacket prepared by adding carbon nanotube (CNT) to alumina. To evaluate the effect of CNT-containing alumina composite ceramic jacket (CNT jacket), experiments were implemented. In both copper nitrate solution and nickel nitrate solution, the time to reach the maximum temperature was earlier when the CNT jacket was used than when the alumina jacket was used. The temperature of the nickel nitrate solution was kept at the maximum temperature when the CNT jacket was used, while the temperature tended to decrease after reaching to 280
C when the alumina jacket was used. The hybrid heating method using the CNT jacket can obtain metal oxides.
Tamaru, Ayaka*; Nagakawa, Genta*; Segawa, Tomoomi; Fukasawa, Tomonori*; Ishigami, Toru*; Fukui, Kunihiro*
no journal, ,
This study aims to investigate the effect of hybrid heating on the denitration reaction of a nickel nitrate aqueous solution to evaluate the feasibility of hybrid heating method with an alumina jacket containing carbon nanotube (CNT) as a microwave heating medium. When an alumina jacket without CNT was used, the temperature decreased and the denitration reaction stopped due to the formation of an intermediate product Ni(NO)
(OH)
with low dielectric loss. Whereas, when an alumina jacket containing 0.2 mass% CNT was used, the denitration reaction was completed and nickel oxide particles were obtained. It is presumed that the denitration reaction proceeds by heat conduction from the CNT-containing alumina jacket because the jacket is selectively heated by microwaves more than the Ni(NO)(OH). It is clarified that hybrid heating can be realized by a CNT-containing alumina jacket.
Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Yamada, Masaaki*; Tamaru, Ayaka*; Nagakawa, Genta*; Fukasawa, Tomonori*; Ishigami, Toru*; Fukui, Kunihiro*; Murakami, Hiroyuki*
no journal, ,
To compensate for heat dissipation through the vessel and reduced microwave absorption due to intermediate in the fabrication process of the metallic oxide powder by the microwave heating denitration method, alumina composite ceramic material containing CNT which has a high relative dielectric loss as the external heating source with self-heating by microwave heating. The CNT was observed by SEM of the CNT-containing alumina composite ceramic material to observe the CNT presence in the base material of alumina. The surface resistivities decreased significantly when the CNT content increased from 0.2 to 0.5 mass%, and there was not much of a significant difference when the CNT content increased from 0.5 to 1.0 mass%. These results are consistent with the results of the previous studies of the apparent dielectric loss that showed a trend toward an increase in the apparent dielectric loss as the CNT content increased from 0.2 to 0.5 mass% in the CNT-containing alumina composites.
