Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Tanaka, Takuro*; Fukuoka, Masafumi*; Toda, Kanako*; Nakanishi, Takahiro; Terashima, Motoki; Fujiwara, Kenso; Niwano, Yuma*; Kato, Hiroaki*; Kobayashi, Natsuko*; Tanoi, Keitaro*; et al.
ACS ES&T Water (Internet), 4(8), p.3579 - 3586, 2024/08
Nemoto, Takahiro; Fujiwara, Yusuke; Arakawa, Ryoki; Choyama, Yuya; Nagasumi, Satoru; Hasegawa, Toshinari; Yokoyama, Keisuke; Watanabe, Masashi; Onishi, Takashi; Kawamoto, Taiki; et al.
JAEA-Technology 2024-003, 17 Pages, 2024/06
JAEA-Technology-2024-003.pdf:1.91MB
In order to investigate the cause of the increase in differential pressure in the primary helium circulator filter that occurred during the RS-14 cycle, a clogged filter was investigated. As a result of the investigation, deposits caused by silicone oil were confirmed on the surface of the filter element. These results revealed that the cause of filter clogging was silicone oil mixed into the primary system due to performance deterioration of the charcoal filter in the gas circulator of primary helium purification system. As a measure to prevent the recurrence of this event, in addition to the conventional management based on operating hours for replacing of charcoal filter in the gas circulator of primary helium purification system, we have established a new replacement plan for every three years.
Makiuchi, Takahiko*; Hioki, Tomosato*; Shimizu, Hiroki*; Hoshi, Kojiro*; Elyasi, M.*; Yamamoto, Kei; Yokoi, Naoto*; Serga, A. A.*; Hillebrands, B.*; Bauer, G. E. W.*; et al.
Nature Materials, 23(5), p.627 - 632, 2024/05
Times Cited Count：10 Percentile：94.22(Chemistry, Physical)Elyasi, M.*; Yamamoto, Kei; Hioki, Tomosato*; Makiuchi, Takahiko*; Shimizu, Hiroki*; Saito, Eiji*; Bauer, G. E. W.*
Physical Review B, 109(18), p.L180402_1 - L180402_7, 2024/05
Times Cited Count：1 Percentile：40.97(Materials Science, Multidisciplinary)Amekura, Hiroshi*; Chettah, A.*; Narumi, Kazumasa*; Chiba, Atsuya*; Hirano, Yoshimi*; Yamada, Keisuke*; Yamamoto, Shunya*; Leino, A. A.*; Djurabekova, F.*; Nordlund, K.*; et al.
Nature Communications (Internet), 15, p.1786_1 - 1786_10, 2024/02
Times Cited Count：2 Percentile：62.71(Multidisciplinary Sciences)Injecting high-energy heavy ions in the electronic stopping regime into solids can create cylindrical damage zones called latent ion tracks. Although these tracks form in many materials, none have ever been observed in diamond, even when irradiated with high-energy GeV uranium ions. Here we report the first observation of ion track formation in diamond irradiated with 2-9 MeV C
fullerene ions. Depending on the ion energy, the mean track length (diameter) changed from 17 (3.2) nm to 52 (7.1) nm. High resolution scanning transmission electron microscopy (HR-STEM) indicated the amorphization in the tracks, in which 
-bonding signal from graphite was detected by the electron energy loss spectroscopy (EELS).
Ito, Daisuke*; Odaira, Naoya*; Ito, Kei*; Saito, Yasushi*; Kurita, Keisuke; Iikura, Hiroshi
Journal of Physics; Conference Series, 2605, p.012024_1 - 012024_6, 2023/10
Gas-liquid two-phase flow appears in many heat-exchanging devices. To understand the phenomena in such devices, the two-phase flow dynamics should be clarified. In this study, high-speed neutron imaging is applied to the measurements of two-phase flow dynamics, and the accuracy of the void fraction measurement is investigated.
Saito, Yasushi*; Ito, Daisuke*; Odaira, Naoya*; Kurita, Keisuke; Iikura, Hiroshi
Journal of Physics; Conference Series, 2605, p.012028_1 - 012028_6, 2023/10
To observe flow velocity distributions by Neutron Imaging, suitable tracer is necessary. The requirements are its density, its visibility, and its wettability (if applied to liquid metal). Gold cadmium tracers have been developed for the Pb-Bi two-phase flow, however, the visibility have not been verified depending on the particle size and the measurement system. As the candidates of tracer particles, Ag, Cd, Au-Cd, and Ag-Cd have been tested by varying its compositions and its diameters. Results show enough visibility if the particles size is larger than 1mm. In addition, Cd tracer particles were applied to the fluidized bed, where the bed materials are metallic particle made of stainless steel, with 1mm diameter. The diameter of Cd trace is about 1.5 mm. From the neutron imaging, the visibility of the tracers is enough to measure the velocity distributions in the fluidized bed.
Kurita, Keisuke; Iikura, Hiroshi; Tsuchikawa, Yusuke; Kai, Tetsuya; Shinohara, Takenao; Odaira, Naoya*; Ito, Daisuke*; Saito, Yasushi*; Matsubayashi, Masahito
Journal of Physics; Conference Series, 2605, p.012005_1 - 012005_6, 2023/10
The Japan Research Ractor-3 (JRR-3) is operation resumed on February 26, 2021, and the shared use was also restarted in July, 2021. With the resumption of JRR-3 operation, two imaging facilities called TNRF and CNRF have also resumed their utilization. In this presentation, we report the details of these two neutron facilities.
OKondo, Yosuke*; Achouri, N. L.*; Al Falou, H.*; Atar, L.*; Aumann, T.*; Baba, Hidetada*; Boretzky, K.*; Caesar, C.*; Calvet, D.*; Chae, H.*; et al.
Nature, 620(7976), p.965 - 970, 2023/08
Times Cited Count：27 Percentile：94.86(Multidisciplinary Sciences)no abstracts in English
Ne at the transition into the island of inversion; Detailed structure study of NeWang, H.*; Yasuda, Masahiro*; Kondo, Yosuke*; Nakamura, Takashi*; Tostevin, J. A.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Poves, A.*; Shimizu, Noritaka*; Yoshida, Kazuki; et al.
Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08
Times Cited Count：4 Percentile：69.46(Astronomy & Astrophysics)Detailed 
-ray spectroscopy of the exotic neon isotope Ne has been performed using the one-neutron removal reaction from Ne. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N = 20 and N = 28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.
Saito, Kei*; Hirade, Tetsuya; Takai, Kenichi*
Key Engineering Materials, 967, p.11 - 16, 2023/07
Hydrogen-enhanced strain-induced vacancy, one of the defects associated with promising hydrogen embrittlement mechanisms, was validated for tempered martensitic steel showing quasi-cleavage fracture with a tensile strength of 1500 MPa level by slow strain rate tensile test in-situ electrochemical hydrogen charging. The effect of newly formed vacancy-type defects on mechanical properties of tempered martensitic steel was also studied. Combined use of low-temperature thermal desorption spectroscopy (L-TDS) and the tensile test revealed the following three things: (i) hydrogen enhanced the accumulation of vacancy-type defects with plastic straining, (ii) accumulated vacancy-type defects deteriorated the ductility of the tempered martensitic steel after hydrogen release, and (iii) aging in the range from 50
C to 150C after applying given plastic strain with hydrogen charging decreased the amount of newly formed vacancy-type defects, and then resulted in the recovery of the ductility.
Kozawa, Takayuki; Suganuma, Takuro; Homma, Fumitaka; Higashimura, Keisuke*; Ukai, Takayuki*; Saito, Kenji
JAEA-Technology 2023-007, 24 Pages, 2023/06
JAEA-Technology-2023-007.pdf:2.24MB
To improve the reliability of the HTTR wide range monitor in a high-temperature environment, structural changes of the wide range monitor were investigated. It was clear that the structure for directly joins of the MI cable core wire and metal tube instead of the joins with lead wire is the most reliable method with shortest way. From a result of the thermal cycle tests and high temperature endurance tests for a mock-up connecting this connection parts, it was clear that the soundness of the connection part was maintained under the usage conditions of the HTTR.
Nemoto, Takahiro; Arakawa, Ryoki; Kawakami, Satoru; Nagasumi, Satoru; Yokoyama, Keisuke; Watanabe, Masashi; Onishi, Takashi; Kawamoto, Taiki; Furusawa, Takayuki; Inoi, Hiroyuki; et al.
JAEA-Technology 2023-005, 33 Pages, 2023/05
JAEA-Technology-2023-005.pdf:5.25MB
During shut down of the HTTR (High Temperature engineering Test Reactor) RS-14 cycle, an increasing trend of filter differential pressure for the helium gas circulator was observed. In order to investigate this phenomenon, the blower of the primary helium purification system was disassembled and inspected. As a result, it is clear that the silicon oil mist entered into the primary coolant due to the deterioration of the charcoal filter performance. The replacement and further investigation of the filter are planning to prevent the reoccurrence of the same phenomenon in the future.
Song, K.*; Ito, Kei*; Ito, Daisuke*; Odaira, Naoya*; Saito, Yasushi*; Matsushita, Kentaro; Ezure, Toshiki; Tanaka, Masaaki
Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 10 Pages, 2023/05
Gas entrainment (GE) phenomena caused by a free surface vortex may cause the disturbance in core power of sodium-cooled fast reactor (SFR). For this reason, the entrained gas flow rate by the GE should be evaluated accurately for the practical safety design of SFRs. In this study, for the purpose of examining the applicability of CFD for the accurate evaluation of GE phenomena, a CFD is applied to the simulation of the free surface vortex and accompanied GE phenomena in a cylindrical vessel with a suction pipe, and the CFD results and the experimental data of the GE are compared. As a result, the CFD and experiments show similar two-phase flow pattern inside the suction pipe, and the shape of the gas core at the free surface is also very similar. Therefore, it is confirmed that the CFD can predict the GE phenomena triggered by a free surface vortex properly and accurately within the acceptable error range.
Yamamoto, Seishiro*; Odaira, Naoya*; Ito, Daisuke*; Ito, Kei*; Saito, Yasushi*; Imaizumi, Yuya; Matsuba, Kenichi; Kamiyama, Kenji
Konsoryu, 37(1), p.79 - 85, 2023/03
Ito, Daisuke*; Odaira, Naoya*; Ito, Kei*; Saito, Yasushi*; Kurita, Keisuke; Iikura, Hiroshi
Konsoryu, 37(1), p.73 - 78, 2023/03
Gas-liquid two-phase flow is a very complicated flow phenomenon that involves the interaction between gas and liquid phases. Recently, an accurate simulation technique of two-phase flow has been developed. However, the validation of the simulated results is insufficient due to less experimental data. It is especially difficult to measure interfacial behavior with significant spatiotemporal fluctuation. To understand such phenomena, measurement methods with high spatial and temporal resolutions are required. Neutron imaging is a powerful tool for two-phase flow visualization. In this study, two-phase flow in the narrow rectangular channel was visualized by high-speed neutron imaging.
Lee, O.*; Yamamoto, Kei; Umeda, Maki; Zollitsch, C. W.*; Elyasi, M.*; Kikkawa, Takashi*; Saito, Eiji; Bauer, G. E. W.*; Kurebayashi, Hidekazu*
Physical Review Letters, 130(4), p.046703_1 - 046703_6, 2023/01
Times Cited Count：16 Percentile：91.47(Physics, Multidisciplinary)
TaS
with perpendicular magnetic anisotropy; Comparison with FeTiSShibata, Goro; Won, C.*; Kim, J.*; Nonaka, Yosuke*; Ikeda, Keisuke*; Wan, Y.*; Suzuki, Masahiro*; Koide, Tsuneharu*; Tanaka, Arata*; Cheong, S.-W.*; et al.
Photon Factory Activity Report 2022 (Internet), 2 Pages, 2023/00
no abstracts in English
Yamamoto, Seishiro*; Odaira, Naoya*; Ito, Daisuke*; Ito, Kei*; Saito, Yasushi*; Imaizumi, Yuya; Matsuba, Kenichi; Kamiyama, Kenji
Proceedings of 12th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS12) (Internet), 4 Pages, 2022/10
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.
