Mizuta, Naoki; Morita, Keisuke; Aoki, Takeshi; Okita, Shoichiro; Ishii, Katsunori; Kurahayashi, Kaoru; Yasuda, Takanori; Tanaka, Masato; Isaka, Kazuyoshi; Noguchi, Hiroki; et al.
Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 6 Pages, 2023/05
Kono, Takahiko; Tanaka, Masato*; Tanaka, Hitomi*; Shimo, Michikuni*; Torii, Hiroyuki*; Uno, Kazuko*
Journal of Radiation Protection and Research, 47(3), p.167 - 179, 2022/09
After the accident at the Fukushima Daiichi Nuclear Power Plant, artificial radionuclides such as radioactive cesium and iodine were released into the environment. It caused great anxiety not only in the vicinity of the Fukushima Daiichi Nuclear Power Plant but also in other regions of the world. Some members of the Japan Health Physics Society (JHPS), a leading academic society in Japan in the field of radiation protection, volunteered to establish a website called "Question and Answer about radiation in Daily Life" shortly after the accident to help reduce the residents anxiety about the health effects of radiation. In August 2011, Committee for "Question and Answer about radiation in Daily Life" was established in JHPS, making the website-related activities a responsibility of JHPS. The Q&A website continued to respond to the questions from the general public with expertise and sincerity until February 2013 when the Committee members decided to end the activities because the number of questions received had gradually decreased with the passage of time. This paper aims to introduce the following: the activities of the Q&A website during the two years (2011-2013), the stance chosen for the activities, the information related to the website activities and the analysis of Twitter data. Building on the experience and the knowledge obtained from the activities, it also discusses issues and experiences that can be utilized in the initial response to emergencies for radiation protection experts as well as other fields.
Kawasaki, Takuro; Fukuda, Tatsuo; Yamanaka, Satoru*; Sakamoto, Tomokazu*; Murayama, Ichiro*; Kato, Takanori*; Baba, Masaaki*; Hashimoto, Hideki*; Harjo, S.; Aizawa, Kazuya; et al.
Journal of Applied Physics, 131(13), p.134103_1 - 134103_7, 2022/04
Watanabe, Masari*; Kurita, Nubuyuki*; Tanaka, Hidekazu*; Ueno, Wataru*; Matsui, Kazuki*; Goto, Takayuki*; Hagihara, Masato
Physical Review B, 105(5), p.054414_1 - 054414_12, 2022/02
Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.
High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02
As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.
Kono, Takahiko; Shimo, Michikuni*; Hayakawa, Hironobu*; Taniguchi, Kazufumi*; Tanaka, Masato*; Tanaka, Hitomi*; Onoue, Yosuke*; Nagaya, Hiroshi*; Torii, Hiroyuki*; Uno, Kazuko*
Hoken Butsuri (Internet), 55(4), p.226 - 238, 2020/12
After the accident at the Fukushima Daiichi Nuclear Power Station, artificial radionuclides such as radioactive cesium and iodine were released into the environment. It caused great anxiety not only in the vicinity of the Fukushima Daiichi Nuclear Power Station but also in other regions of Japan. Some members of the Japan Health Physics Society (JHPS) which is a leading academic society in Japan in the field of radiation protection volunteered to establish the website called "Question and Answer about radiation in Daily Life" just after the accident to reduce the anxiety of the residents about the health effects of radiation. After that, Committee of "Question and Answer about radiation in Daily Life" was established in August 2011 in JHPS, and this activity had been carried out under the responsibility of the society that answered with sincerity against questions from the public as specialists until February 2013. The number of questions on the website had gradually decreased as time passed; therefore, the Committee members decided to end these activities in February 2013. In this paper, following contents were shown; the activities of the Q&A website for about two years, the issues of the stance on our activities, the information related to the website activities and the analysis of Twitter data. Based on the experience and the knowledge obtained from these activities, the issues and experiences that can be utilized in the initial response to emergencies for radiation protection experts as well as other fields are presented.
Ono, Shinya*; Tanaka, Kazuma*; Kodama, Hiraku*; Tanaka, Masatoshi*; Yoshigoe, Akitaka; Teraoka, Yuden*
Surface Science, 697, p.121600_1 - 121600_6, 2020/07
The initial oxidation on silicon surfaces with (113) orientation has been investigated by high-resolution photoelectron spectroscopy with synchrotron radiation. In the present study, we investigated both the Si2p state and O1s state to evaluate the oxide thickness, composition, and to assess the strain at the SiO/Si interface. In the Si2p state, the oxidized components (Si, Si, Si, Si) were analyzed. In the O1s state, a low-binding-energy component (LBC) and a high-binding-energy component (HBC) were analyzed. To investigate the non-thermal oxidation process, we utilized the supersonic seeded molecular beam (SSMB) to enhance the translational kinetic energies () of oxygen molecules. We demonstrate that the oxide quality and oxidation kinetics are largely altered by changing .
Kuroda, Kenta*; Arai, Yosuke*; Rezaei, N.*; Kunisada, So*; Sakuragi, Shunsuke*; Alaei, M.*; Kinoshita, Yuto*; Bareille, C.*; Noguchi, Ryo*; Nakayama, Mitsuhiro*; et al.
Nature Communications (Internet), 11, p.2888_1 - 2888_9, 2020/06
Cappia, F.*; Tanaka, Kosuke; Kato, Masato; McClellan, K.*; Harp, J.*
Journal of Nuclear Materials, 533, p.152076_1 - 152076_14, 2020/05
Kim, J.*; Yamanaka, Satoru*; Murayama, Ichiro*; Kato, Takanori*; Sakamoto, Tomokazu*; Kawasaki, Takuro; Fukuda, Tatsuo; Sekino, Toru*; Nakayama, Tadachika*; Takeda, Masatoshi*; et al.
Sustainable Energy & Fuels (Internet), 4(3), p.1143 - 1149, 2020/03
Naoe, Takashi; Kogawa, Hiroyuki; Tanaka, Nobuatsu*; Futakawa, Masatoshi
Advanced Experimental Mechanics, 4, p.17 - 21, 2019/08
We have introduced the following two techniques to mitigate the pressure wave-induced cavitation damage in the mercury target. One is the gas microbubble injection into the flowing mercury, and the other is the double-walled structure with a narrow gap channel at the proton beam entrance portion of the mercury vessel. The latter is expected to mitigate the cavitation damage due to the high-speed liquid flow ( 4 m/s) and the narrow gap boundary (2 mm). To quantitatively investigate the effect of double-walled structure on cavitation damage, cavitation damage tests were conducted by parametrically changing mercury flow velocity and gap width of the channel wall. The results showed that the damage evaluated as a surface roughness was reduced by increasing the flow velocity. By contrast, the effect of gap width on cavitation damage was hardly observed under flowing conditions.
Kawamura, Shunsuke; Naoe, Takashi; Ikeda, Tsubasa*; Tanaka, Nobuatsu*; Futakawa, Masatoshi
Advanced Experimental Mechanics, 4, p.33 - 37, 2019/08
A mercury enclosure vessel made of stainless steel is used as a spallation target in the pulsed spallation neutron source at J-PARC. It is severely damaged by the cavitation induced with pressure waves in association with the pulsed proton beam injection. A double-walled structure with a narrow mercury channel was adopted in the front end of the target vessel to reduce the cavitation damage. It has been experimentally demonstrated that the cavitation damage could be mitigated in the narrow channel but its mechanism has been unclarified yet. In this study, we investigated the cavitation from growing to collapsing through visualizing the spark-induced cavitation bubbles under flow field using a high-speed video camera. Furthermore, we measured the wall vibration due to the cavitation bubble collapse with changing flow velocity parametrically. It was found that the microjet collided perpendicular to the wall in the stagnant flow condition while it collided with an inclined angle from the perpendicular direction, suggesting that the collision pressure on the wall was reduced by flowing.
Myagmarjav, O.; Iwatsuki, Jin; Tanaka, Nobuyuki; Noguchi, Hiroki; Kamiji, Yu; Ioka, Ikuo; Kubo, Shinji; Nomura, Mikihiro*; Yamaki, Tetsuya*; Sawada, Shinichi*; et al.
International Journal of Hydrogen Energy, 44(35), p.19141 - 19152, 2019/07
Naoe, Takashi; Teshigawara, Makoto; Futakawa, Masatoshi; Mizutani, Haruki; Muramatsu, Toshiharu; Yamada, Tomonori; Ushitsuka, Yuji*; Tanaka, Nobuatsu*; Yamasaki, Kazuhiko*
Proceedings of 8th International Congress on Laser Advanced Materials Processing (LAMP 2019) (Internet), 5 Pages, 2019/05
Laser cutting is one of the options in the disposal of radio-active waste, such as spallation neutron target vessel in J-PARC, etc. Due to unique characteristic of laser, such as non-contact system, it is more easily to provide remote-controlled system in comparison with conventional one, such as mechanical cutting machine, etc. However, a demerit of laser cutting is the sputter and fume caused by laser cutting, resulting in contamination with radio-active materials its surroundings. Recently it was developed that the spatter suppression technique by controlling laser beam profile in laser welding process. In order to apply this suppression technique to laser cutting, first of all, we attempted to observe the phenomenon at melting area during laser cutting using a high-speed video camera in order to make the physical model. The result showed that the appearance of fume and sputter were independently confirmed in the time evolution.
Strasser, P.*; Abe, Mitsushi*; Aoki, Masaharu*; Choi, S.*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; et al.
EPJ Web of Conferences, 198, p.00003_1 - 00003_8, 2019/01
Kono, Takahiko; Tanaka, Masato*; Sakoda, Akihiro; Tanaka, Hitomi*; Takeuchi, Masato*; Kataoka, Noriaki*
Proceedings of World Engineers Convention Australia 2019 (WEC 2019) (Internet), p.486 - 496, 2019/00
Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Takeda, Masatoshi*; et al.
Advanced Sustainable Systems (Internet), 2(11), p.1800067_1 - 1800067_8, 2018/11
Moro, Takuya*; Kim, J.*; Yamanaka, Satoru*; Murayama, Ichiro*; Kato, Takanori*; Nakayama, Tadachika*; Takeda, Masatoshi*; Yamada, Noboru*; Nishihata, Yasuo; Fukuda, Tatsuo; et al.
Journal of Alloys and Compounds, 768, p.22 - 27, 2018/11
Tanaka, Taiki*; Narikiyo, Yoshihiro*; Morita, Kosuke*; Fujita, Kunihiro*; Kaji, Daiya*; Morimoto, Koji*; Yamaki, Sayaka*; Wakabayashi, Yasuo*; Tanaka, Kengo*; Takeyama, Mirei*; et al.
Journal of the Physical Society of Japan, 87(1), p.014201_1 - 014201_9, 2018/01
Excitation functions of quasielastic scattering cross sections for the Ca + Pb, Ti + Pb, and Ca + Cm reactions were successfully measured by using the gas-filled recoil-ion separator GARIS. Fusion barrier distributions were extracted from these data, and compared with the coupled-channels calculations. It was found that the peak energies of the barrier distributions for the Ca + Pb and Ti + Pb systems coincide with those of the 2n evaporation channel cross sections for the systems, while that of the Ca + Cm is located slightly below the 4n evaporation ones. This results provide us helpful information to predict the optimum beam energy to synthesize superheavy nuclei.
Yamaguchi, Akiko*; Honda, Tasuku*; Tanaka, Masato*; Tanaka, Kazuya; Takahashi, Yoshio*
Geochemical Journal, 52(5), p.415 - 425, 2018/00
Ion-adsorption type REE deposits in weathered granite are main sources of REE essential for high-technology industries. However, these type deposits have not been searched in Japan. In this study, Bulk REE abundances (= REE), ion-exchangeable REE (= REE) by ammonium chloride solution, and percentage of REE relative to REE (= REE) in fresh and weathered granite samples in Southwest Japan (i.e., Hiroshima and Shimane Prefectures) were determined. The REE and REE were comparable to those of ion-adsorption type REE deposits in China. Extended X-ray adsorption fine structure (EXAFS) spectra of REE in original samples and samples after the extraction of ion-exchangeable REE showed that (i) REE in samples with high REE mainly forms outer-sphere complexes and (ii) the remaining REE in the rocks after the extraction forms inter-sphere complexes.