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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.
Co in the digestive glands of the common octopus, 
, in the East China SeaMorita, Takami*; Otosaka, Shigeyoshi; Fujimoto, Ken*; Nishiuchi, Ko*; Kimoto, Katsunori*; Yamada, Haruya*; Kasai, Hiromi*; Minakawa, Masayuki*; Yoshida, Katsuhiko*
Marine Pollution Bulletin, 60(8), p.1193 - 1199, 2010/08
Times Cited Count：3 Percentile：10.23(Environmental Sciences)Significant concentrations of Co, 
Cs and 
Ag were detected in common octopus specimens collected in the East China Sea during two periods, 1986-1989 and 1996-2005. The radionuclides detected in the former period were thought to originate from the global fallout. On the other hand, the source of Co in the latter period has remained unclear because the Co concentration decreased continuously with shorter half-lives than the physical half-lives. This tendency suggests that the source of Co in 1996-2005 was identical and was temporary supplied to the East China Sea. Investigations of common octopus in the other area indicated that the origin of the pollutant source of Co in 1996-2005 occurred locally in the restricted area in the East China Sea rather than in the coastal area of Japan.
Tanaka, Kenji*; Takenaga, Hidenobu; Muraoka, Katsunori*; Michael, C.*; Vyacheslavov, L. N.*; Yokoyama, Masayuki*; Yamada, Hiroshi*; Oyama, Naoyuki; Urano, Hajime; Kamada, Yutaka; et al.
Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 8 Pages, 2008/10
Comparative studies were carried out in LHD heliotron and JT-60U tokamak plasmas to elucidate the most essential parameter(s) for control of density profiles in toroidal systems. A difference in the collisionality dependence was found between the two devices. In LHD, the density peaking factor decreased with decrease of the collisionality at the magnetic axis position (R
) 3.6 m, while the density peaking factor gradually increased with a decreased of collisionality at R = 3.5 m. On the other hand, in JT-60U, the density peaking factor clearly increased with a decrease of the collisionality. The difference in the collisionality dependence between R = 3.5 and R = 3.6 m is likely due to the contribution of the anomalous transport. At R = 3.5 m, larger anomalous transport caused a similar collisionality dependence. Change of the fluctuation property was observed with different density profiles in the plasma core region on both devices. In JT-60U, the increase of the radial coherence was observed with higher density peaking profile suggesting enhanced diffusion and inward directed pinch. For a magnetic axis positions (R) at 3.6 m in LHD, the increase of the fluctuation power with an increase in P
was observed for a hollow density profile suggesting an increase on diffusion due to anomalous processes. Change of density profiles from peaked to hollow indicates change in the convection direction. This is due to increase in neoclassical processes. The reduction of the density peaking factor with increase of P in LHD is partly due to the neoclassical effect and partly due to the anomalous effect.
Tanaka, Kenji*; Michael, C.*; Vyacheslavov, L. N.*; Yokoyama, Masayuki*; Murakami, Sadayoshi*; Wakasa, Arimitsu*; Takenaga, Hidenobu; Muraoka, Katsunori*; Kawahata, Kazuo*; Tokuzawa, Tokihiko*; et al.
Plasma and Fusion Research (Internet), 3, p.S1069_1 - S1069_7, 2008/08
Density profiles in LHD were measured and particle transport coefficients were estimated from density modulation experiments in LHD. The dataset of different magnetic axis, toroidal magnetic filed and heating power provided data set of widely scanned neoclassical transport. At minimized neoclassical transport configuration (
= 3.5 m, 
= 2.8 T) showed peaked density profile. Its peaking factor increased gradually with decrease of collisional frequency. This is a similar result observed in JT-60U. At other configuration, peaking factor reduced with decrease of collsional frequency. Data set showed that larger contribution of neoclassical transport produced hollowed density profile. Comparison between neoclassical and estimated particle diffusivity showed different minimum condition. Clear difference of spatial profile of turbulence was observed between hollowed and peaked density profiles. Major part of fluctuation existed in the unstable region of ion temperature gradient mode.
Takenaga, Hidenobu; Tanaka, Kenji*; Muraoka, Katsunori*; Urano, Hajime; Oyama, Naoyuki; Kamada, Yutaka; Yokoyama, Masayuki*; Yamada, Hiroshi*; Tokuzawa, Tokihiko*; Yamada, Ichihiro*
Nuclear Fusion, 48(7), p.075004_1 - 075004_11, 2008/07
Times Cited Count：32 Percentile：75.35(Physics, Fluids & Plasmas)In order to understand particle transport systematically in toroidal plasmas, electron density profiles were compared in JT-60U tokamak and LHD helical plasmas with low collisionality. Peakedness of density profiles increased with decreasing collisionality in ELMy H-mode plasmas of JT-60U, when the collisionality at half the minor radius was in the collisionless regime. Collisionality dependence of density profiles in LHD plasmas was similar to that in JT-60U plasmas in the same collisionality regime, when neoclassical transport was suppressed by geometrical optimization. On the other hand, in the LHD plasmas having relatively larger neoclassical transport than that in the above case, peakedness of density profiles decreased with decreasing collisionality. Neoclassical transport enhanced by the non-axisymmetric effect significantly affected density profiles with low collisionality in LHD plasmas. Density profiles in LHD plasmas tended to approach those in JT-60U, which are dominated by anomalous transport, as the contribution of neoclassical transport was reduced.
Motojima, Osamu*; Yamada, Hiroshi*; Komori, Akio*; Oyabu, Nobuyoshi*; Muto, Takashi*; Kaneko, Osamu*; Kawahata, Kazuo*; Mito, Toshiyuki*; Ida, Katsumi*; Imagawa, Shinsaku*; et al.
Nuclear Fusion, 47(10), p.S668 - S676, 2007/10
Times Cited Count：34 Percentile：73.71(Physics, Fluids & Plasmas)The performance of net-current free heliotron plasmas has been developed by findings of innovative operational scenarios in conjunction with an upgrade of the heating power and the pumping/fuelling capability in the Large Helical Device (LHD). Consequently, the operational regime has been extended, in particular, with regard to high density, long pulse length and high beta. Diversified studies in LHD have elucidated the advantages of net-current free heliotron plasmas. In particular, an internal diffusion barrier (IDB) by a combination of efficient pumping of the local island divertor function and core fuelling by pellet injection has realized a super dense core as high as 5
10
m
, which stimulates an attractive super dense core reactor. Achievements of a volume averaged beta of 4.5% and a discharge duration of 54 min with a total input energy of 1.6 GJ (490 kW on average) are also highlighted. The progress of LHD experiments in these two years is overviewed by highlighting IDB, high-beta and long pulse.
Motojima, Osamu*; Yamada, Hiroshi*; Komori, Akio*; Oyabu, Nobuyoshi*; Kaneko, Osamu*; Kawahata, Kazuo*; Mito, Toshiyuki*; Muto, Takashi*; Ida, Katsumi*; Imagawa, Shinsaku*; et al.
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 12 Pages, 2007/03
The performance of net-current free Heliotron plasmas has been developed by findings of innovative operational scenarios in conjunction with an upgrade of the heating power and the pumping/fueling capability in the Large Helical Device (LHD). Consequently, the operational regime has been extended, in particular, with regard to high density, long pulse length and high beta. Diversified studies in LHD have elucidated the advantages of net-current free heliotron plasmas. In particular, an Internal Diffusion Barrier (IDB) by combination of efficient pumping of the local island divertor function and core fueling by pellet injection has realized a super dense core as high as 510m, which stimulates an attractive super dense core reactor. Achievements of a volume averaged beta of 4.5 % and a discharge duration of 54-min. with a total input energy of 1.6 GJ (490 kW in average) are also highlighted. The progress of LHD experiments in these two years is overviewed with highlighting IDB, high 
and long pulse.
Matsunaga, Takeshi; Tsuzuki, Katsunori; Yanase, Nobuyuki; Hanzawa, Yukiko; Naganawa, Hirochika; Inoue, Takanobu*; Yamada, Toshiro*; Miyata, Akifumi*
Proceedings of International Symposium on Environmental Modeling and Radioecology, p.243 - 246, 2007/03
The aim of this work is to obtain a fundamental scheme of stream discharge of inorganic toxic materials derived from Characteristics of the stream discharge of metallic elements were investigated in two forested catchments in the Oda River and the Ijira River watersheds. Precipitations, stream water and soil water samples were collected in raining events and were analyzed for inorganic elements, dissolved organic carbon and isotopic abundance of deuterium. Results revealed an accelerated discharge of specific metals of Cu, Sb and Cr and all the studied REE in dissolved form. This feature was commonly found in the two catchments. The specific metals are strongly suspected to be of anthropogenic origin. An analysis of hydrological discharge, using chemical and isotopic tracers, suggested that the increased discharge of the metals originate from their deposits on the ground surface and/or instantaneous resuspension of stream sediment. Contrary, REE discharge was tightly coupled with that of dissolved humic substances.
ELMy H-mode discharges in JT-60UIsayama, Akihiko; Kamada, Yutaka; Hayashi, Nobuhiko; Suzuki, Takahiro; Oikawa, Toshihiro; Fujita, Takaaki; Fukuda, Takeshi; Ide, Shunsuke; Takenaga, Hidenobu; Ushigusa, Kenkichi; et al.
Nuclear Fusion, 43(10), p.1272 - 1278, 2003/10
Times Cited Count：130 Percentile：95.67(Physics, Fluids & Plasmas)no abstracts in English
Tsuzuki, Katsunori; Matsunaga, Takeshi; Inoue, Takanobu*; Miyata, Akifumi*; Yamada, Toshiro*
no journal, ,
no abstracts in English
Tsuzuki, Katsunori; Matsunaga, Takeshi; Inoue, Takanobu*; Yamada, Toshiro*
no journal, ,
no abstracts in English
Tanaka, Kenji*; Takenaga, Hidenobu; Muraoka, Katsunori*; Michael, C.*; Vyacheslavov, L. N.*; Yokoyama, Masayuki*; Yamada, Hiroshi*; Murakami, Sadayoshi*; Wakasa, Arimitsu*; Kawahata, Kazuo*; et al.
no journal, ,
In order to understand mechanisms for determining density profiles in toroidal plasmas, density profiles were compared in JT-60U tokamak and LHD helical plasmas. Transport theory indicates that neoclassical transport is enhanced in helical plasmas with low collisionality due to helical ripple. In JT-60U plasmas, density peaking increased with decreasing the collisionality. In LHD plasmas for magnetic axis (Rax) of 3.5m with small effective helical ripple, density peaking slightly increased with decreasing the collisionality as similar to that in tokamak plasmas. On the other hand, in LHD plasmas for Rax
3.6m with relatively large effective helical ripple, density profile became hollow as the collisionality decreased. Different turbulence structures are observed for Rax=3.5m and Rax=3.6m in LHD plasmas. Turbulence propagated towards electron diamagnetic direction for Rax=3.5m and towards ion diamagnetic direction for Rax=3.6m. This difference could be related to the difference of density profiles, as well as difference of neoclassical transport. Furthermore, when density decreased in the core region due to increase of electron temperature, it was found that turbulence was first modified in the edge region and then in the core region.
Tanaka, Kenji*; Takenaga, Hidenobu; Muraoka, Katsunori*; Michael, C.*; Vyacheslavov, L. N.*; Mishchenko, A.*; Yokoyama, Masayuki*; Yamada, Hiroshi*; Oyama, Naoyuki; Urano, Hajime; et al.
no journal, ,
Comparative studies were carried out in LHD heliotron and JT-60U tokamak plasmas to elucidate effects of turbulence transport on density profiles in toroidal systems. A difference in the collisionality dependence was found between the two devices. In LHD, the density peaking factor decreased with decrease of the collisionality at the magnetic axis position (R
) of 3.6 m. On the other hand, in JT-60U, the density peaking factor clearly increased with a decrease of the collisionality. For R=3.6 m in LHD, the increase of the fluctuation power with an increase in P
was observed for a hollow density profile suggesting an increase on diffusion due to anomalous processes. In JT-60U, the increase of the radial coherence was observed with higher density peaking profile suggesting enhanced diffusion and inward directed pinch. The effects of curvature pinch on density profiles were also investigated in both devices. The curvature pinch produces a peaked density profile in JT-60U and a hollow density profile in LHD depending on their magnetic shear. However, these effects were too small to explain the density profiles observed in both devices.
Kobayashi, Toshiaki; Kawamatsu, Yorimitsu; Yamasoto, Kotaro; Yamada, Katsunori; Sekita, Tsutomu; Kabuto, Masayuki
no journal, ,
no abstracts in English
Tanaka, Kenji*; Takenaga, Hidenobu; Muraoka, Katsunori*; Yoshida, Maiko; Michael, C.*; Vyacheslavov, L. N.*; Mikkelsen, D. R.*; Yokoyama, Masayuki*; Oyama, Naoyuki; Urano, Hajime; et al.
no journal, ,
Density profile and turbulence was compared in JT-60U tokamak and LHD heliotron. Density peaking increases with decrease of collisionality in JT-60U. Density gradient predicted from zero flux condition agrees within factor 2 for Te/Ti=1, but large discrepancies are found for Te/Ti 
=0.5. In LHD, peaked profile and increase of density peaking with decrease of collisionality are found in strong magnetic hill configuration (Rax = 3.5 m). Hollowed-peaked density profile and increase of density peaking with increase of collisionality are found in weak magnetic hill configuration (Rax = 3.6 m). Fluctuation is localized in core gradient region and edge gradient region. Density gradient predicted from zero flux condition are compared. Then both cases agrees the sign and absolute values within factor 2.
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.
