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Aosai, Daisuke*; Yamamoto, Yuhei*; Mizuno, Takashi; Ishigami, Toru*; Matsuyama, Hideto*
Colloids and Surfaces A; Physicochemical and Engineering Aspects, 461, p.279 - 286, 2014/11
Times Cited Count：10 Percentile：25(Chemistry, Physical)In studies of colloids in deep groundwater, a serious problem exists because the properties of the colloids are influenced by changes in the chemistry of groundwater upon exposure to the atmosphere and pressure release during sampling. Then, ultrafiltration technique, while maintaining in situ hydrochemical conditions was developed. As the result of the investigation using the method at the Mizunami underground Research Laboratory (MIU), different types of colloids consisting of inorganic and organic substances were observed and complex formation between the colloids and REEs was suggested. Furthermore, characteristic partitioning of REEs depending on colloids size was observed in complex natural environments without chemical disturbance. The current findings are useful for understanding migration of radionuclides.
Ishigami, Tsutomu; Sakamoto, Toru*; Kobayashi, Kensuke; *
JAERI-M 88-093, 89 Pages, 1988/05
no abstracts in English
Kobayashi, Kensuke; Ishigami, Tsutomu; Sakamoto, Toru*; Fujiki, Kazuo
Severe accidents in Nuclear Power Plants,Vol. 1, p.323 - 329, 1988/00
no abstracts in English
Abe, Kiyoharu; Watanabe, Norio; Ida, Mitsuo; Sakamoto, Toru; Ishigami, Tsutomu; Harami, Taikan
Proc.on Probabilistic Safety Assessment and Risk Management PSA87, Vol.3, p.945 - 950, 1987/00
no abstracts in English
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.
