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Fujita, Shunya*; Abe, Yutaka*; Kaneko, Akiko*; Yuasa, Tomohisa*; Segawa, Tomoomi; Yamada, Yoshikazu; Kato, Yoshiyuki; Ishii, Katsunori
Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 8 Pages, 2018/07
Mixed uranium oxide and plutonium oxide powder is produced from uranyl nitrate and plutonium nitrate mixed solution by the microwave heating denitration method in the spent fuel reprocessing process. Since the microwave heating method is accompanied by a boiling phenomenon, it is necessary to fully grasp the operating conditions in order to avoid flashing and spilling in the mass production of denitrification technology for the future. In this research, it was confirmed that a potassium chloride aqueous solution as a simulant of uranyl nitrate aqueous solution with high dielectric loss cause loss of microwave at the solution surface as the dielectric loss increased with the increase of KCl concentration by experimental and electromagnetic field analysis, and revealed that the change in the heating condition affects the generation of flushing.
Yamada, Katsunori; Fujii, Katsutoshi; Kanda, Hiroshi; Higashi, Daisuke; Kobayashi, Toshiaki; Nakagawa, Masahiro; Fukami, Tomoyo; Yoshida, Keisuke; Ueno, Yumi; Nakajima, Junya; et al.
JAEA-Review 2013-033, 51 Pages, 2013/12
JAEA-Review-2013-033.pdf:2.73MB
After the accident at Fukushima Dai-ichi Nuclear Power Plant, various numerical criteria relevant to radiation protection were defined. We surveyed these criteria through internet. As a result of survey, the following 13 items were identified: (1) criteria for taking stable iodine tablets, (2) criteria for the screening of surface contamination, (3) evacuation area, sheltering area, etc., (4) activity concentrations in food, drinking water, etc., (5) dose limit for radiation workers engaged in emergency work, (6) guideline levels of radioactive substances in bathing areas, (7) criteria for use of school buildings and schoolyards, (8) restriction on planting rice, (9) acceptable activity concentrations in feedstuff, (10) acceptable activity concentrations in compost, (11) criteria for export containers and ships, (12) criteria for contaminated waste, (13) standards for radiation workers engaged in decontamination work. In this report, the basis of and issues on these criteria are summarized.
Kobayashi, Toshiaki; Kawamatsu, Yorimitsu; Yamasoto, Kotaro; Yamada, Katsunori; Sekita, Tsutomu; Kabuto, Masayuki
no journal, ,
no abstracts in English
Yoshida, Keisuke; Yamada, Katsunori; Yoda, Tomoyuki; Tsunoda, Junichi; Muto, Yasushi; Kobayashi, Makoto; Kikuchi, Masamitsu
no journal, ,
no abstracts in English
Nakajima, Junya; Yamada, Katsunori; Yokoyama, Hiroya; Shishido, Nobuhito; Muto, Yasushi
no journal, ,
We implement C-14 monitoring of exhaust in such a way as to measure mono-ethanolamine which is a collector of 
CO
with a liquid scintillation counter. Since Aquasol-2, which we have used so far was finished selling, we have done technical examinations on Insta-Gel plus and Ultima Gold for the alternative cocktail of Aquasol-2. In the result, as for the both cocktails, we confirmed that mono-ethanolamine can merge into the cocktails with some chemical additive, and detection limits of C-14 can comply the law limit of C-14 concentration of exhaust. However, chemical luminescence of Ultima Gold was so intense that it might affect the measurement in the case of measuring H-3 at the same time. Because of this, we chose Insta-Gel plus as the alternative cocktail.
Fujita, Shunya*; Abe, Yutaka*; Kaneko, Akiko*; Yuasa, Tomohisa*; Segawa, Tomoomi; Yamada, Yoshikazu; Kato, Yoshiyuki; Ishii, Katsunori
no journal, ,
Mixed uranium oxide and plutonium oxide (MOX) powder is produced from uranyl nitrate and plutonium nitrate mixed solution by the microwave heating denitration method in the spent fuel reprocessing process. Since the MH method is accompanied by a boiling phenomenon, it is necessary to fully grasp the operating conditions in order to avoid flashing and spilling in the mass production of denitrification technology for the future. In this research, for the purpose of clarifying the mechanism of flashing phenomenon during microwave heating, the generation mechanism of bubbles that innumerably occur at the time of flashing is considered. When the contact angle at the heterogeneous nucleation of bubbles was 177 
C, the theoretical value of the heterogeneous nucleation approximately agreed with the experimental value at the time the superheat degree was found to be close to 35 C.
Nakajima, Junya; Yamada, Katsunori; Hasegawa, Rie; Umeda, Masayuki; Seki, Masakazu; Muto, Yasushi; Sawahata, Katsunori
no journal, ,
STACY (Static Experiment Critical Facility) has been under remodeling work. During the demolition work of the previous model of STACY, we conducted radiation management for both internal exposure and external exposure taking the characteristics of the previous model into consideration. As a result, any contamination and internal exposure of the all workers was detected, and external exposure of the all workers were less than the detection limit.
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.
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.