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Takahashi, Yoshio*; Miura, Hikaru*; Yamada, Shinya*; Sekizawa, Oki*; Nitta, Kiyofumi*; Hashimoto, Tadashi*; Yomogida, Takumi; Yamaguchi, Akiko; Okada, Shinji*; Itai, Takaaki*; et al.
Journal of Hazardous Materials, 495, p.139031_1 - 139031_19, 2025/09
Times Cited Count：1 Percentile：0.00(Engineering, Environmental)In this presentation, we analyzed the chemical state of cesium in radiocesium-bearing microparticles (CsMPs) released during the 2011 Fukushima Daiichi Nuclear Power Plant accident using high-resolution X-ray absorption spectroscopy (XANES) and micro X-ray fluorescence (
-XRF). The results identified two forms of cesium: one dissolved in glass and the other enriched on the surfaces of internal voids. The latter is considered to have originally existed as a gas and became concentrated during the cooling and solidification of the molten glass. These findings are crucial for understanding the formation process of CsMPs during the accident, as well as for future decommissioning and safety assessments.
Soma, Yasutaka; Komatsu, Atsushi; Kaji, Yoshiyuki; Yamamoto, Masahiro*; Igarashi, Takahiro
Corrosion Science, 251, p.112897_1 - 112897_15, 2025/07
Times Cited Count：2 Percentile：66.69(Materials Science, Multidisciplinary)Experimental and modeling studies of the oxygen ingression at the crevices of stainless steels were conducted in high-temperature water (288
C). The limiting distance of oxygen ingression, 
, was defined as the point beyond which the primary surface oxide changed (hematite 
magnetite), regardless of crevice gap, oxygen concentration, and time. In situ measurements revealed increased electrical conductivity around the position indicating ion enrichment due to a differential oxygen concentration cell. increased with increasing crevice gap, oxygen concentration, and immersion time. Modeling study suggested that oxide layer growth reduced anodic dissolution and slowed oxygen consumption, allowing oxygen ingression with time.
Mori, Takashi*; Shimada, Takahiro*; Motegi, Haruki*; Kai, Satoru*; Otani, Akihito*; Yamamoto, Tomohiko; Yan, X.
Proceedings of the ASME 2025 Pressure Vessels & Piping Conference (PVP2025) (Internet), 9 Pages, 2025/07
crystalsTakatori, Sayuri*; Pimon, M.*; Pollitt, S.*; Bartokos, M.*; Beeks, K.*; Gr
neis, A.*; Hiraki, Takahiro*; Homma, Tetsuo*; Hosseini, N.*; Leitner, A.*; et al.
New Journal of Physics (Internet), 27(4), p.043024_1 - 043024_10, 2025/04
Times Cited Count：2 Percentile：53.65(Physics, Multidisciplinary)Recent reports on laser excitation of the low-energy thorium-229 (
Th) nuclear isomeric state in calcium fluoride single crystals render this system a promising candidate for a solid-state nuclear clock. However, experimental characterization of the microscopic ion arrangement around the doped Th and its electronic charge state, crucial for the precise control of the clock transition and assessing the solid-state clock's performance, remains an unresolved task. This study uses X-ray absorption fine structure spectroscopy of Th:CaF to investigate the charge state and coordination environment of doped Th. The results indicate that Th is doped with a 4+ valence at the substitutional site of the Ca
ion, with charge compensated provided by two F
ions located at interstitial sites adjacent to Th.
-FeOOH; The Spin-reorientation transition and hydrogen-bond symmetrizationIkeda, Osamu*; Yamamoto, Hajime*; Sano, Asami; Sakamaki, Tatsuya*; Kuribayashi, Takahiro*; Noda, Yukio*; Suzuki, Akio*
Journal of the American Chemical Society, 147(5), p.4005 - 4016, 2025/02
Times Cited Count：3 Percentile：74.77(Chemistry, Multidisciplinary)The compression behavior of iron oxyhydroxide -FeOOH is complex, with variations in its magnetic property and bonding character. In this study, in situ powder neutron diffraction experiments were conducted on -FeOOH and -FeOOD up to pressures exceeding 20 GPa to investigate a spin-reorientation transition, hydrogen-bond symmetrization, and their correlation. The magnetic transition was observed at 8 GPa in both -FeOOH and -FeOOD. The crystal symmetry and H-bonds of -FeOOH transitioned from P21nm with asymmetric H-bonds to Pnnm with disordered H-bonds at 17.90 GPa, while -FeOOD remained asymmetric. The pressure evolution of the interatomic angles and distances indicates that the coordinate geometry of Fe transitioned toward H-bond symmetrization and would have affected the magnetic anisotropy.
Watakabe, Tomoyoshi; Yamamoto, Tomohiko; Okamura, Shigeki; Miyazaki, Masashi; Miyagawa, Takayuki; Uchita, Masato*; Hirayama, Tomoyuki*; Somaki, Takahiro*; Yukawa, Masaki*; Fukasawa, Tsuyoshi*; et al.
Proceedings of the ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 10 Pages, 2024/07
To secure the seismic safety of the thin-walled mechanical components and piping under a severe design earthquake level, employing a three-dimensional (3D) seismic isolation system has been planned in a sodium-cooled fast reactor. The development results of the 3D isolation system have been reported in previous papers so far. Its update is reported in Part 7 to Part 9. Part 7 describes the overview of the development, the test plan of the isolation system in the assembled state of each element, and the performance of individual isolation elements. In part 8, the performance of the isolation device that each element was assembled into was investigated through loading tests. Part 9 reports analytical studies by an analysis model validated based on the insight of the test results.
Somaki, Takahiro*; Yukawa, Masaki*; Fukasawa, Tsuyoshi*; Hirayama, Tomoyuki*; Uchita, Masato*; Miyagawa, Takayuki; Okamura, Shigeki; Yamamoto, Tomohiko; Watakabe, Tomoyoshi; Miyazaki, Masashi; et al.
Proceedings of the ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 9 Pages, 2024/07
Fukasawa, Tsuyoshi*; Somaki, Takahiro*; Yukawa, Masaki*; Hirayama, Tomoyuki*; Watakabe, Tomoyoshi; Yamamoto, Tomohiko; Okamura, Shigeki; Miyazaki, Masashi; Uchita, Masato*; Miyagawa, Takayuki; et al.
Proceedings of the ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 10 Pages, 2024/07
Yamamoto, Masahiro*; Igarashi, Takahiro
Corrosion Modelling with Cellular Automata; European Federation of Corrosion Publications, Number 71, p.131 - 153, 2024/03
In order to elucidate corrosion phenomena in spent fuel reprocessing plant, experimental corrosion tests and computer simulations were carried out. From experimental results, variation of intergranular corrosion rate were caused by following; (i) surface corrosion, (ii) increase of corrosion rate due to a part of grains dropping out, (iii) high corrosion rate due to continuous of dropping out of grains. Intergranular corrosion rates obtained from the simulation using the developed intergranular corrosion model were relatively good agreement with those from the experimental data.
Yamamoto, Yusuke*; Watanabe, Takahiro; Niwa, Masakazu; Shimada, Koji
JAEA-Testing 2023-003, 67 Pages, 2024/02
JAEA-Testing-2023-003.pdf:4.63MB
A long-term geosphere stability for geological disposal is evaluated by the past geological environmental changes and modern conditions. Stable hydrogen and oxygen isotope ratios (
D, 
O) of geological samples are useful information to estimate the past environmental changes and modern conditions. Recently, the thermal conversion elemental analyzer and isotope ratio mass spectrometer (TC-EA/IRMS) were installed in the Tono Geoscience Center for D and O measurements of geological samples. In this study, we reported analytical methods of D and O using international standard reference materials. In addition, evaluation tests of uncertainty by repeated analyses of the standards were performed using the TC-EA/IRMS. Furthermore, the D and O analyses by the TC- EA/IRMS were also applied to fault rock samples.
Yamamoto, Tomohiko; Okamura, Shigeki; Hirayama, Tomoyuki*; Somaki, Takahiro*
Haikan Gijutsu, 65(13), p.1 - 4, 2023/11
The authors are conducting research and development on three-dimensional seismic isolation devices to improve the earthquake resistance of future sodium-cooled fast reactors. This paper introduces an overview of the device and how to use it.
Watanabe, Takahiro; Yamamoto, Yusuke; Kitamura, Akihisa*
Chigaku Zasshi, 132(5), p.417 - 437, 2023/10
To improve a geochemical discrimination method of paleotsunami deposit, quantitative analysis of major and trace elements in boring cores from the Shizuoka plain on the Pacific coast of middle Japan was performed using a portable energy dispersive X-ray fluorescence spectrometry system (portable XRF). Geochemical approaches by the portable XRF contribute to study of the simple and rapid methods for detecting paleotsunami deposits. Most of our quantitative data by portable XRF were good agreement with reported values measured by stationary-type energy dispersive XRF in previous studies. Therefore, the portable XRF can be applied to geochemical study in the samples from Shizuoka plain in our case.
Hirano, Tatsumi*; Maeda, Takehiro*; Murata, Tetsuyuki*; Yamamoto, Takahiro*; Matsubara, Eiichiro*; Shobu, Takahisa; Shiro, Ayumi*; Yasuda, Ryo*; Takamatsu, Daiko*
SPring-8/SACLA Riyo Kenkyu Seikashu (Internet), 11(5), p.345 - 353, 2023/10
no abstracts in English
Takayama, Yusuke; Yamamoto, Yoichi*; Goto, Takahiro*
Jiban Kogaku Janaru (Internet), 18(3), p.317 - 330, 2023/09
It has been reported that the deformation greatly increased in the secondary consolidation process in the past long-term consolidation test of 1.8 years on Na-type bentonite/sand mixed soil. Therefore, we analyzed potential contributing factors in this behavior. A long-term consolidation test for about 10 years on bentonite and kaolinite was started using the test equipment with countermeasures against these factors. In this paper, the secondary consolidation behavior of bentonite was investigated based on the long-term consolidation test data for 2.7, 3.7 and 4 years. The results were generally consistent with the conventional findings on soil mechanics that the deformation due to secondary consolidation progresses linearly with respect to logarithm of time. This test will be continued for about 10 years and longer-term secondary consolidation behavior will be investigated.
Fukasawa, Tsuyoshi*; Hirayama, Tomoyuki*; Yokoi, Shinobu*; Hirota, Akihiko*; Somaki, Takahiro*; Yukawa, Masaki*; Miyagawa, Takayuki; Uchita, Masato*; Yamamoto, Tomohiko; Miyazaki, Masashi; et al.
Nihon Kikai Gakkai Rombunshu (Internet), 89(924), p.23-00023_1 - 23-00023_17, 2023/08
no abstracts in English
Mori, Takashi*; Shimada, Takahiro*; Kai, Satoru*; Otani, Akihito*; Yamamoto, Tomohiko; Yan, X.
Proceedings of the ASME 2023 Pressure Vessels and Piping Conference (PVP 2023) (Internet), 8 Pages, 2023/07
Mori, Takashi*; Shimada, Takahiro*; Kai, Satoru*; Otani, Akihito*; Yamamoto, Tomohiko; Yan, X.
Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 8 Pages, 2023/05
Fujita, Natsuko; Miyake, Masayasu; Matsubara, Akihiro*; Ishii, Masahiro*; Watanabe, Takahiro; Jinno, Satoshi; Nishio, Tomohiro*; Ogawa, Yumi; Yamamoto, Yusuke; Kimura, Kenji; et al.
Dai-23-Kai AMS Shimpojiumu Hokokushu, p.1 - 4, 2022/12
The JAEA-AMS-TONO facility at the Tono Geoscience Center, JAEA has three accelerator mass spectrometers. We report the present status of the JAEA-AMS-TONO.
Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
Times Cited Count：10 Percentile：72.91(Nuclear Science & Technology)In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
Fukasawa, Tsuyoshi*; Somaki, Takahiro*; Miyagawa, Takayuki*; Uchita, Masato*; Yamamoto, Tomohiko; Ishizuka, Futoshi*; Suzuno, Tetsuji*; Okamura, Shigeki*; Fujita, Satoshi*
Kozo Kogaku Rombunshu, B, 68B, p.462 - 475, 2022/04
