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Abe, Satoshi; Hamdani, A.; Soma, Shu; Hangai, Ryosuke; Omori, Masashi; Owada, Akihiko; Omiya, Toshihito*; Shibamoto, Yasuteru
Nuclear Engineering and Design, 449, p.114787_1 - 114787_13, 2026/04
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Asamori, Koichi; Sueoka, Shigeru; Komatsu, Tetsuya; Ogata, Manabu; Uchida, Mao; Nishiyama, Nariaki; Tanaka, Kiriha; Kobayashi, Tomoharu; Mitsuguchi, Takehiro; Murakami, Osamu; et al.
JAEA-Review 2025-035, 29 Pages, 2025/10
JAEA-Review-2025-035.pdf:1.12MB
This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency (JAEA), in fiscal year 2025. The objectives and contents of this research are described in detail based on the JAEA 4th Medium- and Long-term Plan (fiscal years 2022-2028). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. The plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.
Iketani, Shotaro; Suzuki, Takeshi; Yokobori, Tomohiko; Sugawara, Satoshi; Yokota, Akira; Kikuchi, Genta; Muraguchi, Yoshinori; Kitahara, Masaru; Seya, Manato; Kurosawa, Tsuyoshi; et al.
JAEA-Technology 2025-001, 169 Pages, 2025/08
JAEA-Technology-2025-001.pdf:14.22MB
The radioactive waste treatment facilities at the Nuclear Science Research Institute includes the Radioactive Waste Treatment Facility No. 3, Waste Size Reduction and Storage Facility, and Waste Volume Reduction Facility. These three facilities come under the purview of the Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors, and are included under Class C of the act based on the seismic requirements specified in the Act. We assessed the seismic capacity of these three radioactive waste treatment facilities based on the current Building Standards Act, to verify whether they comply with the new regulatory requirements enforced by the Nuclear Regulation Authority (NRA) in the aftermath of the 2011 nuclear accident at the Fukushima Daiichi Nuclear Power Station operated by the Tokyo Electric Power Company. We found that the allowable stress of a few structural members used in the construction of the facilities did not meet the regulatory requirements. After studying the approval granted by the NRA for the construction plans, including the design and construction methods (design and construction plans) of the three facilities on March 5, 2021, we made aseismic reinforcement at these facilities between 2021 and 2022. This report presents an overview of the seismic design of these facilities and an outline of the aseismic reinforcement conducted, management system existing, safety measures adopted, and the preoperational inspections conducted at these facilities.
/KNbO nanocomposite particlesYoneda, Yasuhiro; Kobayashi, Toru; Tsuji, Takuya; Shibata, Goro; Takeda, Yukiharu*; Saito, Yuji; Khanal, G. P.*; Fujii, Ichiro*; Ueno, Shintaro*; Sato, Yukio*; et al.
Japanese Journal of Applied Physics, 64(8), p.08SP07_1 - 08SP07_8, 2025/08
Times Cited Count：1 Percentile：41.30(Physics, Applied)It has become possible to synthesize high-quality composite nanoparticles in which a different material is grown on the surface of nanoparticle crystals. To evaluate such nanostructures, it is effective to combine different evaluation methods at various scales. We performed various structural and electronic state evaluations of BaTiO/KNbO nanocomposite particles using synchrotron radiation. From the structural evaluation, it was confirmed that the nanocomposite particles have a core of 100 nm of BaTiO covered with 20 nm of KNbO. The O-K absorption edge spectrum of the outermost surface KNbO was different from that of the bulk and nanoparticles, and it was found that the chemical bonding state changes when KNbO
is made into composite particles.
Iguchi, Satoshi; Yoshida, Masato; Hirano, Hiroshi*; Wada, Masaomi*; Mori, Yoshihito*; Kitamura, Akihiro
Journal of Robotics and Mechatronics, 37(4), p.973 - 983, 2025/08
In nuclear fuel fabrication facilities, gloveboxes are typically dismantled manually. The integration of remotely controlled equipment, comprising a robot arm and a size reduction tool, can enhance work efficiency and mitigate radiation exposure risks in dismantling operations. The hydraulic cutter is regarded as a highly effective tool for reducing the size of steel frame structures, which are commonly composed of gloveboxes. However, when an object is severed by a hydraulic cutter fixed to a robot arm, the resultant reaction force may compromise the integrity of the robot arm or nearby structures. Consequently, in this study, we designed and manufactured a buffer device that can loosely hold the cutter to automatically align the object and absorb the reaction force. Furthermore, a visual support system was developed to assist the operator in performing remote dismantling operations. This system utilized a 3D viewer to project the robot arm, the buffer device, and the working environment. The functionality of the buffer device and 3D viewer was evaluated for the glovebox test bed. The experimental results satisfactorily confirmed the functionality of the buffer device to self-align the object and absorb sudden movements of the hydraulic cutter. Moreover, the 3D viewer provided the robot arm operator with an unobstructed perspective of the work environment, thereby confirming the efficacy of the visual support system in facilitating remote dismantling operations.
Katsumura, Kosuke*; Takagi, Junichi*; Miyahara, Naoya*; Uchida, Shunsuke*; Koma, Yoshikazu; Karasawa, Hidetoshi; Miwa, Shuhei; Satou, Yukihiko; Nagai, Haruyasu; Kurata, Masaki; et al.
Nihon Genshiryoku Gakkai-Shi ATOMO
, 67(2), p.128 - 132, 2025/02
no abstracts in English
Okagaki, Yuria; Takeda, Takeshi; Wada, Yuki; Abe, Satoshi; Ichihara, Kyoko*; Shiotani, Hitoshi*
Proceedings of 10th Workshop on Computational Fluid Dynamics for Nuclear Reactor Safety (CFD4NRS-10) (Internet), 12 Pages, 2025/00
Nakanishi, Yohei*; Shibata, Motoki*; Sawada, Satoshi*; Kondo, Hiroaki*; Motokawa, Ryuhei; Kumada, Takayuki; Yamamoto, Katsuhiro*; Mita, Kazuki*; Miyazaki, Tsukasa*; Takenaka, Mikihito*
Polymer, 306, p.127209_1 - 127209_7, 2024/06
Times Cited Count：6 Percentile：53.70(Polymer Science)Okagaki, Yuria; Shibamoto, Yasuteru; Wada, Yuki; Abe, Satoshi; Hibiki, Takashi*
Journal of Nuclear Science and Technology, 60(8), p.955 - 968, 2023/08
Times Cited Count：4 Percentile：53.94(Nuclear Science & Technology)-BaTiO solid solutionsYoneda, Yasuhiro; Kim, S.*; Mori, Shigeo*; Wada, Satoshi*
Japanese Journal of Applied Physics, 61(SN), p.SN1022_1 - SN1022_10, 2022/11
Times Cited Count：5 Percentile：31.47(Physics, Applied)Local structural analysis of the (1-
) BiFeO-BaTiO solid solution was performed by PDF analysis of the data obtained in the synchrotron radiation high-energy X-ray diffraction experiment. First, when XAFS experiments were performed and sample screening was performed, it was found that structural fluctuations were large in the BiFeO-rich composition. Therefore, PDF analysis of a sample with BiFeO-rich composition was performed. As a result, it was found that although the average structure is a cubic structure, the local structure can be reproduced with a rhombohedral crystal structure, and there is a displacement that breaks the symmetry of the rhombohedral structure in a composition with a large fluctuation.
-decay spectroscopy of 
TaMukai, Momo*; Hirayama, Yoshikazu*; Watanabe, Yutaka*; Watanabe, Hiroshi*; Koura, Hiroyuki; Jeong, S. C.*; Miyatake, Hiroari*; Brunet, M.*; Ishizawa, Satoshi*; Kondev, F. G.*; et al.
Physical Review C, 105(3), p.034331_1 - 034331_6, 2022/03
Times Cited Count：8 Percentile：66.85(Physics, Nuclear)Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.
Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03
Times Cited Count：64 Percentile：95.06(Astronomy & Astrophysics)Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 
C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.
Kumada, Takayuki; Oba, Yojiro; Motokawa, Ryuhei; Morooka, Satoshi; Tominaga, Aki; Tanida, Hajime; Shobu, Takahisa; Konno, Azusa; Owada, Kenji*; Ono, Naoko*; et al.
Journal of Nuclear Materials, 528, p.151890_1 - 151890_7, 2020/01
Times Cited Count：1 Percentile：7.24(Materials Science, Multidisciplinary)We have developed an anomalous small-angle X-ray scattering (ASAXS) diffractometer in SPring-8 to investigate irradiation-induced nanostructural change in ion-beam irradiated stainless steel. A thermally-aged MA956 stainless steel sample displays power-law scattering that follows the Porod law at the magnitude of scattering vector, Q, below 0.5 nm
and an overlapped shoulder around 0.7 nm. After the ion-beam irradiation, the intensity of the shoulder remained unchanged, whereas that of the power-law scattering nearly doubled. This result indicates that none of the structural parameters of the Cr-rich nanoprecipitates, such as the number density, size, and interface roughness, were changed by the irradiation.
nanocrystalsYoneda, Yasuhiro; Kunisada, Ryoichi*; Chikada, Tsukasa*; Ueno, Shintaro*; Fujii, Ichiro*; Nagata, Hajime*; Ohara, Koji*; Wada, Satoshi*
Japanese Journal of Applied Physics, 58(SL), p.SLLA03_1 - SLLA03_7, 2019/11
Times Cited Count：5 Percentile：20.10(Physics, Applied)Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.
Science, 364(6437), p.272 - 275, 2019/04
Times Cited Count：319 Percentile：99.60(Multidisciplinary Sciences)The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.
-site randomness on the antiferroelectric/relaxor nature of the ground state; Diffuse and inelastic X-ray scattering study of Pb(In
Nb)OOwada, Kenji*; Tsukada, Shinya*; Fukuda, Tatsuo; Tsutsui, Satoshi*; Baron, A. Q. R.*; Mizuki, Junichiro*; Owa, Hidehiro*; Yasuda, Naohiko*; Terauchi, Hikaru*
Physical Review B, 98(5), p.054106_1 - 054106_10, 2018/08
Times Cited Count：5 Percentile：20.60(Materials Science, Multidisciplinary)
= 100 with a multireflection time-of-flight mass spectrographIto, Yuta*; Schury, P.*; Wada, Michiharu*; Arai, Fumiya*; Haba, Hiromitsu*; Hirayama, Yoshikazu*; Ishizawa, Satoshi*; Kaji, Daiya*; Kimura, Sota*; Koura, Hiroyuki; et al.
Physical Review Letters, 120(15), p.152501_1 - 152501_6, 2018/04
Times Cited Count：69 Percentile：92.07(Physics, Multidisciplinary)Masses of 
Es, 
Fm and the transfermium nuclei 
Md, and 
No, produced by hot- and cold-fusion reactions, in the vicinity of the deformed 
neutron shell closure, have been directly measured using a multi-reflection time-of-flight mass spectrograph. The masses of Es and 
Md were measured for the first time. Using the masses of 
Md as anchor points for 
decay chains, the masses of heavier nuclei, up to 
Bh and 
Mt, were determined. These new masses were compared with theoretical global mass models and demonstrated to be in good agreement with macroscopic-microscopic models in this region. The empirical shell gap parameter 
derived from three isotopic masses was updated with the new masses and corroborate the existence of the deformed neutron shell closure for Md and Lr.
nanocrystals with cubic shapeYoneda, Yasuhiro; Kunisada, Ryoichi*; Chikada, Tsukasa*; Ueno, Shintaro*; Ohara, Koji*; Wada, Satoshi*
Transactions of the Materials Research Society of Japan, 43(2), p.93 - 96, 2018/04
KNbO nanocrystals were grown by solvothermal technique assisted by a microwave treatment. We performed high-energy X-ray diffraction to extract average and local structural parameters. The particle size can be evaluated by the Scherrer's equation. The unit cell size was reduced as the particle size increased. The local structure was found to be a rhombohedral structure, which was similar to that of the bulk KNbO.
Ebisuzaki, Toshikazu*; Wada, Satoshi*; Saito, Norihito*; Fujii, Takashi*; Nishimura, Akihiko
Reza Kenkyu, 45(10), p.664 - 665, 2017/10
no abstracts in English
Ouchi, Satoshi; Kurumada, Osamu; Kamiishi, Eigo; Sato, Masayuki; Ikekame, Yoshinori; Wada, Shigeru
JAEA-Technology 2016-015, 42 Pages, 2016/06
JAEA-Technology-2016-015.pdf:3.53MB
The purpose of the control rod drive mechanism seating position detector for JRR-3 is one of a method for confirming the shutdown condition of the reactor. The detector has been utilizing more than 25 years with maintenance regularly. However, it is occurred some trouble recently. Moreover, the detector has already been end of manufacture, and even in the successor detector, it unsuitable for the control rod drive mechanism of JRR-3 was confirmed. Therefore, it was necessary to select the adequate detector to the control rod drive mechanism of JRR-3. Accordingly, we built a test device with the aim of verify several detectors for integrity and function. At the time of the test for performance confirmation, it was occurred unexpected problems. Nevertheless, we devise improvement of the problems and took measures. Thus we were able to collect adequate detector for JRR-3 and replace to enhanced detector. This paper reports the Enhanced of Control rod drive mechanism seat position detector.
