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Watanabe, Kaho; Nishiyama, Yutaka; Imahashi, Masaki; Taguchi, Yuji; Iitsuka, Yoshinobu; Ouchi, Takuya; Inoue, Shuichi; Kozawa, Takayuki; Nemoto, Takahiro; Sugaya, Takashi; et al.
JAEA-Testing 2025-001, 56 Pages, 2025/11
JAEA-Testing-2025-001.pdf:2.61MB
There is an emergency response team against 7 nuclear facilities (JRR-3 in Nuclear Science Research Institute, Tokai Reprocessing Plant (TRP) in Nuclear Fuel Cycle Engineering Laboratories, JMTR, HTTR and Joyo in Oarai Research and Development Institute, Prototype Fast Breeder Reactor Monju, Fugen Decommissioning Engineering Center) accidents of Japan Atomic Energy Agency (JAEA). The team is in Naraha Center for Remote Control Technology Development (NARREC). On site surveys which are about the situations and the access entering route of the 7 site emergencies were conducted by the team in 2021. And the results of the surveys made the team get two Spot (quadrupedal robots) in 2022. This is because the team thought using Spot gave operators the less exposure than using crawler robots which had been belonged to the team. After that it was confirmed that the Spot have the ability to respond to the emergency on the route of each facility in 2023. This report shows the results of the Spot's run function (= shooting videos, running oversteps, running up and down stairs, and so on) confirmation about 6 facilities (JRR-3, JMTR, HTTR, Joyo, Monju and Fugen).
Ouchi, Takuya; Nagata, Hiroshi; Shinoda, Yuya; Yoshida, Hayato; Inoue, Shuichi; Chinone, Marina; Abe, Kazuyuki; Ide, Hiroshi; Watahiki, Shunsuke
JAEA-Technology 2025-006, 25 Pages, 2025/10
JAEA-Technology-2025-006.pdf:1.59MB
In the future, radioactive waste which generated from nuclear research facilities in Japan Atomic Energy Agency are planning to be buried for the near surface disposal. It is necessary to establish the method to evaluate the radioactivity concentrations of the radioactive wastes. Therefore, at the Oarai Nuclear Engineering Institute, in order to contribute to the study of methods for evaluating radioactivity concentrations of the radioactive wastes from nuclear research facilities, samples were taken from radioactive waste that are expected to be buried in the future and radiochemical analysis is used to obtain data on the radioactivity concentration of each nuclide contained in the radioactive waste. This report presents the concept of selecting sample collection targets and summarizes the sampling of radioactive materials conducted at the JMTR reactor facility in fiscal years 2023 and 2024 to obtain data on radioactivity concentrations.
Inoue, Yuhei*; Nonoyamz, Tomonobu*; Kang, Z.; Yabunaka, Shunsuke; Tsugawa, Satoru
Journal of the Physical Society of Japan, 94(9), p.094001_1 - 094001_6, 2025/09
Times Cited Count：0 Percentile：0.00Alam, M. M.*; Yamakita, Eri*; Inoue, Yuzuru*; Koarashi, Jun; Atarashi-Andoh, Mariko; Abe, Yukiko; Nakayama, Hiromasa; Mori, Yuki*; Hiradate, Shuntaro*
Soil Science and Plant Nutrition, 12 Pages, 2025/03
Iyota, Muneyoshi*; Matsuda, Tomoki*; Sano, Tomokazu*; Shigeta, Masaya*; Shobu, Takahisa; Yumoto, Hirokatsu*; Koyama, Takahisa*; Yamazaki, Hiroshi*; Semba, Yasunori*; Ohashi, Haruhiko*; et al.
Journal of Manufacturing Processes, 94, p.424 - 434, 2023/05
Times Cited Count：8 Percentile：58.35(Engineering, Manufacturing)Sato, Tomonori; Hata, Kuniki; Kaji, Yoshiyuki; Taguchi, Mitsumasa*; Seito, Hajime*; Inoue, Hiroyuki*; Tada, Eiji*; Abe, Hiroshi*; Akiyama, Eiji*; Suzuki, Shunichi*
Isotope News, (782), p.40 - 44, 2022/08
The stagnant water in the reactor building at Fukushima Daiichi Nuclear Power Station (1F) is exposed to the radiation from fuel debris and radioactive species. This water contains much amounts of impurities from the seawater which was injected in the emergency cooling. The impurities will affect the radiolysis and corrosive conditions in the water under irradiation. So, the water radiolysis data, corrosion data of steels under irradiations, and the evaluated potential impacts of corrosion in the decommissioning process of 1F are arranged as the database for corrosion under irradiation. This paper introduces the outline of this database.
Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.
Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07
This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.
Sato, Tomonori; Hata, Kuniki; Kaji, Yoshiyuki; Ueno, Fumiyoshi; Inoue, Hiroyuki*; Taguchi, Mitsumasa*; Seito, Hajime*; Tada, Eiji*; Abe, Hiroshi*; Akiyama, Eiji*; et al.
JAEA-Review 2021-001, 123 Pages, 2021/06
JAEA-Review-2021-001.pdf:10.33MB
In the implement of the decommissioning of Fukushima Daiichi Nuclear Power Station (1F), there are many problems to be solved. Specially, the mitigation of the aging degradation by the corrosion of the structural materials is important to implement the decommissioning safely and continuously. However, there are limited data for the environmental factors of corrosion in 1F, and the condition of 1F is continuously changing. So, the literature data for the water radiolysis and the corrosion under irradiation are listed as the database of corrosion under irradiation in this report. And the new obtained radiolysis and corrosion data, which have not been reported in the literature and will be required in the decommissioning of 1F, are reported.
Tokita, Shun*; Kadoi, Kota*; Aoki, So; Inoue, Hiroshige*
Corrosion Science, 175, p.108867_1 - 108867_8, 2020/10
Times Cited Count：28 Percentile：77.49(Materials Science, Multidisciplinary)The purpose of this study is to evaluate the corrosion resistance of weld metal by electrochemical methods and discuss the relationship between microstructure and corrosion resistance. Intergranular and pitting corrosion resistances were measured using electrochemical potentiokinetic reactivation (EPR) test and pitting potential measurement respectively. The reactivation ratio and pitting potential corresponded to its chemical composition. The specimens containing more Cr and Mo showed higher resistance. In the EPR test, the dendrite core with a relatively low Cr content was corroded. In the pitting corrosion test, Nb carbide became the initiation site of pitting corrosion which propagated along the cell structure.
Wijesinghe, J. N.*; Koarashi, Jun; Atarashi-Andoh, Mariko; Kokubu, Yoko; Yamaguchi, Noriko*; Sase, Takashi*; Hosono, Mamoru*; Inoue, Yuzuru*; Mori, Yuki*; Hiradate, Shuntaro*
Geoderma, 374, p.114417_1 - 114417_10, 2020/09
Times Cited Count：12 Percentile：41.72(Soil Science)Omori, Atsushi*; Akiyama, Eiji*; Abe, Hiroshi*; Hata, Kuniki; Sato, Tomonori; Kaji, Yoshiyuki; Inoue, Hiroyuki*; Taguchi, Mitsumasa*; Seito, Hajime*; Tada, Eiji*; et al.
Zairyo To Kankyo, 69(4), p.107 - 111, 2020/04
To evaluate the effect of oxidants, which are formed by radiolysis of water under gamma ray irradiation, on the corrosion of a carbon steel in humid environment, ozone was introduced as a model oxidant in to humidity-controlled air at 50
C in a thermo-hygrostat chamber. Corrosion monitoring was performed by using an Atmospheric Corrosion Monitor-type (ACM) sensor consisting of a carbon steel anode and an Ag cathode. The output current of the ACM sensor was increased with the increase in relative humidity and it was obviously increased with the increase in the introduced ozone concentration at each relative humidity. The results indicate that ozone accelerates the corrosion of the carbon steel. The effect of ozone on the corrosion acceleration is attributed to the fast reduction reaction and fast dissolution reaction in to water compared to that of oxygen.
laser stripping at J-PARC 3-GeV RCSSaha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Miura, Akihiko; Yoshimoto, Masahiro; Okabe, Kota; Suganuma, Kazuaki; Yamane, Isao*; Irie, Yoshiro*; Liu, Y.*; et al.
Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.806 - 810, 2018/08
Harada, Hiroyuki; Saha, P. K.; Yoneda, Hitoki*; Michine, Yurina*; Inoue, Shunsuke*; Sato, Atsushi*; Suganuma, Kazuaki; Yamane, Isao*; Kinsho, Michikazu; Irie, Yoshiro*
Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.811 - 815, 2018/08
The high-intensity proton accelerator adopts a charge exchange injection scheme, which injects with exchanging from negative Hydrogen ion to proton by using carbon foil. This scheme can realize high intensity proton beam but the uncontrolled beam losses occur by scattering at the foil. Additionally, the beam collision at the foil may cause the break itself. Therefore, a new injection scheme for higher intensity is needed as an alternative to the foil. We newly propose and develop a laser stripping injection scheme. At the first step, we propose a proof-of-principle (POP) experiment of the scheme in J-PARC and develop a laser system. In this presentation, we will introduce the laser stripping injection scheme and describe an overview of a POP experiment. We will report a current status of the laser system.
Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Inoue, Takashi; Kashiwagi, Mieko; Grisham, L. R.*; Akino, Noboru; Endo, Yasuei; Komata, Masao; Mogaki, Kazuhiko; et al.
Plasma and Fusion Research (Internet), 8(Sp.1), p.2405146_1 - 2405146_4, 2013/11
Distributions of H
and H
in the source plasmas produced at the end-plugs of JT-60 negative ions source were measured by Langmuir probes and emission spectroscopy in order to experimentally investigate the cause of lower density of the negative ions extracted from end-plugs in the source. Densities of H and H in end-plugs of the plasma grid in the source were compared with those in the center regions. As a result, lower density of the negative ion at the edge was caused by lower beam optics due to lower and higher density of the H and H.
Ueno, Fumiyoshi; Shiraishi, Hironori; Inoue, Shun; Motooka, Takafumi; Kato, Chiaki; Yamamoto, Masahiro; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*
Proceedings of 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference (ICONE-20 & POWER 2012) (DVD-ROM), 8 Pages, 2012/07
In PUREX process for spent fuel reprocessing plants, heating portions in the components are severely corroded in the boiling solution under heat transfer (HT) conditions. In this paper, authors have focused on the effects of surface temperature and heat flux on corrosion rates (CRs) of stainless steels in boiling nitric acid under HT conditions. Two types of cells for HT and immersion conditions were applied for corrosion tests. Test solution used was 33 mol/m
vanadium added to 3 kmol/m nitric acid solution, and was heated at boiling temperature under atmospheric pressure. Additionally, a boiling curve which was indicated the relation between heat flux and degree of superheating was investigated experimentally. Surface temperatures during corrosion tests were estimated from a boiling curve. The results showed that CR did not depend on heat flux, but depended on surface temperature. Arrhenius plots on CRs indicated that CR was accelerated by solution boiling against non-boiling.
Hanada, Masaya; Kojima, Atsushi; Tanaka, Yutaka; Inoue, Takashi; Watanabe, Kazuhiro; Taniguchi, Masaki; Kashiwagi, Mieko; Tobari, Hiroyuki; Umeda, Naotaka; Akino, Noboru; et al.
Fusion Engineering and Design, 86(6-8), p.835 - 838, 2011/10
Times Cited Count：17 Percentile：75.07(Nuclear Science & Technology)Neutral beam (NB) injectors for JT-60 Super Advanced (JT-60SA) have been designed and developed. Twelve positive-ion-based and one negative-ion-based NB injectors are allocated to inject 30 MW D beams in total for 100 s. Each of the positive-ion-based NB injector is designed to inject 1.7 MW for 100s at 85 keV. A part of the power supplies and magnetic shield utilized on JT-60U are upgraded and reused on JT-60SA. To realize the negative-ion-based NB injector for JT-60SA where the injection of 500 keV, 10 MW D beams for 100s is required, R&Ds of the negative ion source have been carried out. High-energy negative ion beams of 490-500 keV have been successfully produced at a beam current of 1-2.8 A through 20% of the total ion extraction area, by improving voltage holding capability of the ion source. This is the first demonstration of a high-current negative ion acceleration of 
1 A to 500 keV. The design of the power supplies and the beamline is also in progress. The procurement of the acceleration power supply starts in 2010.
Hanada, Masaya; Kojima, Atsushi; Inoue, Takashi; Watanabe, Kazuhiro; Taniguchi, Masaki; Kashiwagi, Mieko; Tobari, Hiroyuki; Umeda, Naotaka; Akino, Noboru; Kazawa, Minoru; et al.
AIP Conference Proceedings 1390, p.536 - 544, 2011/09
Times Cited Count：8 Percentile：86.55(Physics, Atomic, Molecular & Chemical)no abstracts in English
Kojima, Atsushi; Hanada, Masaya; Tanaka, Yutaka*; Kawai, Mikito*; Akino, Noboru; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Usui, Katsutomi; Sasaki, Shunichi; et al.
Nuclear Fusion, 51(8), p.083049_1 - 083049_8, 2011/08
Times Cited Count：54 Percentile：87.59(Physics, Fluids & Plasmas)Hydrogen negative ion beams of 490 keV, 3 A and 510 keV, 1 A have been successfully produced in the JT-60 negative ion source with three acceleration stages. These successful productions of the high-energy beams at high current have been achieved by overcoming the most critical issue, i.e., a poor voltage holding of the large negative ion sources with the grids of 2 m
for JT-60SA and ITER. To improve voltage holding capability, the breakdown voltages for the large grids was examined for the first time. It was found that a vacuum insulation distance for the large grids was 6-7 times longer than that for the small-area grid (0.02 m). From this result, the gap lengths between the grids were tuned in the JT-60 negative ion source. The modification of the ion source also realized a significant stabilization of voltage holding and a short conditioning time. These results suggest a practical use of the large negative ion sources in JT-60SA and ITER.
layersUmenyi, A. V.*; Hommi, Masashi*; Kawashiri, Shinya*; Shinagawa, Teruyoshi*; Miura, Kenta*; Hanaizumi, Osamu*; Yamamoto, Shunya; Inoue, Aichi; Yoshikawa, Masahito
Key Engineering Materials, 459, p.168 - 172, 2011/04
A new type of two-dimensional photonic crystal (2-D PhC) waveguide was designed using finite difference time domain method to operate at a wavelength of 1.55 
m applicable to optical fiber-communication systems. We estimated that a triangular-lattice 2-D PhC structure formed by air holes with a diameter of 465 nm and a period of 664 nm suit our purpose. To form a core of the waveguide, Si ions were implanted into a SiO layer by using a 400-kV ion implanter. The implantation energy was 80 keV and the implantation amount was 1
10
ions/cm. The electron beam resist was spin-coated on a substrate and the designed pattern was written lithographically in the resist using Electron Beam. Atomic force microscope measurements revealed that the diameter and the period of air holes of the waveguide were 466 and 666 nm. These values were nearly equal to the designed ones. We thus succeeded in fabricating 2-D PhC waveguides in a Si-ion-implanted SiO layer.
Kojima, Atsushi; Hanada, Masaya; Tanaka, Yutaka*; Kawai, Mikito*; Akino, Noboru; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Usui, Katsutomi; Sasaki, Shunichi; et al.
Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03
Hydrogen negative ion beams of 490keV, 3A and 510 keV, 1A have been successfully produced in the JT-60 negative ion source with three acceleration stages. These successful productions of the high-energy beams at high current have been achieved by overcoming the most critical issue, i.e., a poor voltage holding of the large negative ion sources with the grids of 
2 m for JT-60SA and ITER. To improve voltage holding capability, the breakdown voltages for the large grids was examined for the first time. It was found that a vacuum insulation distance for the large grids was 6-7 times longer than that for the small-area grid (0.02 m). From this result, the gap lengths between the grids were tuned in the JT-60 negative ion source. The modification of the ion source also realized a significant stabilization of voltage holding and a short conditioning time. These results suggest a practical use of the large negative ion sources in JT-60 SA and ITER.
