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Soma, Shu; Ishigaki, Masahiro*; Shibamoto, Yasuteru
Annals of Nuclear Energy, 219, p.111455_1 - 111455_12, 2025/09
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Aoki, Takeshi; Shimizu, Atsushi; Ishii, Katsunori; Morita, Keisuke; Mizuta, Naoki; Kurahayashi, Kaoru; Yasuda, Takanori; Noguchi, Hiroki; Nomoto, Yasunobu; Iigaki, Kazuhiko; et al.
Annals of Nuclear Energy, 220, p.111503_1 - 111503_7, 2025/09
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Aiming to establish coupling technologies between a high temperature gas cooled reactor and a hydrogen production plant, JAEA has initiated the HTTR Heat Application Test Project and is conducting the safety design and the safety analysis for the licensing of the HTTR Heat Application Test Facility. The present study proposed a relative evaluation methodology for the demarcation of applicable laws and design standards for the nuclear hydrogen production system and applied it to the HTTR Heat Application Test Facility. The evaluation results showed that a candidate applying the High Pressure Gas Safety Act to the Heat Application Test Facility (hydrogen production plant) and design standards established under the High Pressure Gas Safety Act to the steam reformer did not show the lowest category in any of the metrics, and was proposed as the most superior demarcation option for the HTTR Heat Application Test Facility.
Ebihara, Kenichi; Fujihara, Hiro*; Shimizu, Kazuyuki*; Yamaguchi, Masatake; Toda, Hiroyuki*
International Journal of Hydrogen Energy, 136, p.751 - 756, 2025/06
Times Cited Count：0It has been experimentally reported that adding tin (Sn) to high-strength aluminum-zinc-magnesium (Al-Zn-Mg) alloys effectively suppresses hydrogen (H) embrittlement, which may be attributed to H absorption by the second-phase particles of Sn. To verify this fact, a simulation of H entry into the Sn phase in Al was performed using a model based on the reaction-diffusion equation that incorporates the solid solution energy of H evaluated by first-principles calculations. The results showed that the H solid solution site concentration of the second-phase particles must be at least five times higher than that of the Al phase for H absorption by the Sn second-phase particles to suppress H embrittlement. Therefore, the actual H embrittlement suppression effect of Sn second-phase particles is limited, and other factors may influence the suppression of H embrittlement in the experiment.
Machida, Akihiko*; Saito, Hiroyuki*; Aoki, Katsutoshi*; Komatsu, Kazuki*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; Machida, Shinichi*; Sato, Toyoto*; Orimo, Shinichi*
Physical Review B, 111(22), p.224413_1 - 224413_6, 2025/06
Times Cited Count：1The crystal and magnetic structures of antiferromagnetic Mn deuterides formed by hydrogenating Mn metal at high temperature and high pressure, fcc 
-MnDx and hcp 
-MnDx, were investigated by in-situ neutron powder diffraction. Deuterium atoms partially occupied the octahedral interstitial positions of the fcc and hcp metal lattices. The site occupancies increased rapidly with decreasing temperature from 
700 to 450 K and remained down to 300 K. N
el temperature of 543(10) K was determined for -MnD
. For -MnD
, saturation magnetic moment and Nel temperature were determined to be 0.82(1) 
and 347(3) K, respectively. The Nel temperatures determined for -MnD and -MnD are consistent with those predicted by the respective Slater-Pauling curves proposed in previous studies. The updated Nel temperatures provide insights into the development of more accurate Slater-Pauling curves based on electronic band structure calculations.
Sato, Hiroyuki; Yan, X.
Progress in Nuclear Science and Technology (Internet), 7, p.293 - 298, 2025/05
Kumada, Takayuki; Iwahara, Daisuke*
Isotope News, (798), p.26 - 27, 2025/04
no abstracts in English
production IS processKubo, Shinji
Shokubai, 67(2), p.71 - 77, 2025/04
no abstracts in English
Kubo, Shinji
Kinzoku, 95(1), p.25 - 33, 2025/01
no abstracts in English
Yamashita, Keishiro*; Komatsu, Kazuki*; Hattori, Takanori; Machida, Shinichi*; Kagi, Hiroyuki*
Acta Crystallographica Section B; Structural Science, Crystal Engineering and Materials (Internet), 80(6), p.695 - 705, 2024/12
Times Cited Count：0 Percentile：0.00(Chemistry, Multidisciplinary)So far, the odd hydration number has been missing in the water-rich magnesium chloride hydrate series (MgCl
HO). In this study, we have identified magnesium chloride heptahydrate, MgCl7HO (or MgCl7DO) which forms at high pressures and high temperatures of above 2 GPa and above 300 K, respectively. Its structure has been determined by a combination of 
single crystal X-ray diffraction at 2.5 GPa and 298 K and powder neutron diffraction at 3.1 GPa and 300 K. The results showed an orientational disorder of water molecules, which was also examined by the density-functional-theory calculations. The disorder involves the reconnection of hydrogen bonds, which differs from those in water ice phases and known disordered salt hydrates. The shrinkage by compression occurs mainly in one direction. In the plane perpendicular to this most compressible direction, oxygen and chlorine atoms are in a hexagonal-like arrangement.
Hattori, Takanori; Komatsu, Kazuki*
Nihon Genshiryoku Gakkai-Shi ATOMO
, 66(12), p.618 - 622, 2024/12
The high-pressure neutron diffractometer PLANET is the first beamline dedicated to high-pressure neutron experiments in Japan. It was constructed at the Materials and Life Science Experimental Facility (MLF) in the Japan Proton Accelerator Research Complex (J-PARC) located at Tokai-mura in Ibaraki Prefecture. Energy-dispersive data measurement using pulsed neutrons, state-of-the-art optical instruments, and a high-pressure device enable us to analyze the structure of crystals, liquids, and glasses over a wide range of pressure and temperature with unprecedented accuracy. In this paper, we will show how this has been achieved and introduce the recently published results on the symmetrization of hydrogen bonds in ice.
Aoki, Takeshi; Hasegawa, Takeshi; Kurahayashi, Kaoru; Nomoto, Yasunobu; Shimizu, Atsushi; Sato, Hiroyuki; Sakaba, Nariaki
Proceedings of 11th International Topical Meeting on High Temperature Reactor Technology (HTR 2024), 6 Pages, 2024/10
Japan Atomic Energy Agency (JAEA) is planning to perform a test named HTTR heat application test coupling HTTR (High temperature engineering test reactor) and a hydrogen production plant. The present study reports results of the safety design and safety analysis for HTTR heat application test facility. As a safety design, safety classification of structures, systems, and components was defined in the test facility based on their safety functions. As a preliminary safety analysis, a thermal-hydraulic analysis was performed with RELAP5 code. The safety analysis revealed that newly identified events for HTTR heat application test facility except for the rupture of heat transfer tube of steam generator was enveloped by the licensing basis events in conventional HTTR. The preliminary analysis proved that the safety criteria is satisfied in the candidate of licensing basis event.
Shinto, Katsuhiro; Okoshi, Kiyonori; Shibata, Takanori*; Nammo, Kesao*; Kawai, Isao*; Ikegami, Kiyoshi*; Ueno, Akira
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.525 - 528, 2024/10
A decade has elapsed since the radio frequency (RF)-driven negative hydrogen (H
) ion source initiated operation at J-PARC. In the 2023/2024 campaign, a single RF-driven H ion source has generated H beams with a beam current of 60 mA, which enabled the J-PARC linac to inject them into the 3 GeV rapid cycling synchrotron (RCS) with a beam current of 50 mA. The continuous operation time of the ion source reached exceeding 4,900 hours in this campaign, which signifies a notable enhancement in operational longevity in comparison to the preceding longest campaign in 2022/2023, which spanned 4,412 hours. This paper provides the operational status of the RF-driven H ion source during this campaign and the current status of the J-PARC-made antenna, which is currently under development.
SO
and HFSasaki, Yuji; Kaneko, Masashi; Matsumiya, Masahiko*
Chemistry Letters, 53(9), p.upae164_1 - upae164_4, 2024/09
Times Cited Count：0 Percentile：0.00(Chemistry, Multidisciplinary)Ion-pair extractions enable to recover the anionic metal ions, such as TcO
and ReO, using cationic extractant. Recently the noble metals in hydrochloric acid are extracted by extractants having secondary and tertiary amino N atoms in their structures. Following this, extractions of Zr, Hf, Nb and Ta, metal anions present in sulfonic and hydrofluoric acids, are examined using this technique. Zr and Hf in HSO, and Zr, Hf, Nb and Ta in HF can be extracted by NTAamide, MIDOA and TOA, and a basic information on their extraction behavior is obtained in this work.
He, X.*; Kagi, Hiroyuki*; Komatsu, Kazuki*; Iizuka, Riko*; Okajima, Hajime*; Hattori, Takanori; Sano, Asami; Machida, Shinichi*; Abe, Jun*; Goto, Hirotada*; et al.
Journal of Molecular Structure, 1310, p.138271_1 - 138271_8, 2024/08
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)High-pressure responses of the O-D
F hydrogen bonds in deuterated magnesium hydroxyfluoride were investigated using neutron powder diffraction and Raman spectroscopy. The Rietveld analysis at ambient conditions revealed a chemical formula of Mg(OD)
F
and hydroxyl group/fluorine disorder (OD/F disorder) in the crystal structure, which gave rise to two hydrogen-bonding configurations. The Rietveld analysis showed the hydrogen-bonding geometries remains up to 9.8 GPa, indicating no pressure-induced strengthening of hydrogen bonds. The Raman spectra at ambient conditions showed three hydroxyl stretching bands at 2613, 2694, and 2718 cm
. The high frequencies of the O-D stretching modes indicated that the hydroxyls should be involved in weak or none hydrogen-bonding interactions. Up to 20.2 GPa, the mode initially centered at 2694 cm displayed a pressure-induced blue shift, revealing no strengthening of hydrogen bonds under compression. We discuss the existence of hydrogen bonds and the causes of the blue-shifting hydroxyls at ambient and at high pressures.
ion sourceShibata, Takanori*; Okoshi, Kiyonori; Ueno, Akira; Ikegami, Kiyoshi*; Shinto, Katsuhiro; Nammo, Kesao*; Kawai, Isao*; Oguri, Hidetomo
Kasokuki, 21(2), p.94 - 100, 2024/07
In the recent J-PARC user operation from Nov. 10th, 2022 to Jun. 22nd, 2023, continuous operation of 4,412 hours with hydrogen negative ion (H ion) beam current up to 60 mA was achieved by J-PARC radio frequency (RF) H ion source. This was also the first time to supply H ion beam to the linac in the yearly J-PARC user operation term by a single ion source (w/o ion source exchange). To satisfy the requirements of the further upgrade in J-PARC, a soundness evaluation of the present ion source components has been performed. Furthermore, the RF ion source with a newly manufactured RF antenna coil has been under development.
Kumada, Takayuki
Shiki, 63, p.2 - 5, 2024/07
We introduce recent studies of spin-contrast-variation neutron scatterings, which utilizes the property that scattering power of neutron against proton remarkably depends on their relative spin directions, to reveal nanostructure of composite materials.
O ice observed by neutron diffractionKomatsu, Kazuki*; Hattori, Takanori; Klotz, S.*; Machida, Shinichi*; Yamashita, Keishiro*; Ito, Hayate*; Kobayashi, Hiroki*; Irifune, Tetsuo*; Shimmei, Toru*; Sano, Asami; et al.
Nature Communications (Internet), 15, p.5100_1 - 5100_7, 2024/06
Times Cited Count：5 Percentile：67.98(Multidisciplinary Sciences)Hydrogen bond symmetrisation is the phenomenon where a hydrogen atom is located at the centre of a hydrogen bond. Theoretical studies predict that hydrogen bonds in ice VII eventually undergo symmetrisation upon increasing pressure, involving nuclear quantum effect with significant isotope effect and drastic changes in the elastic properties through several intermediate states with varying hydrogen distribution. Despite numerous experimental studies conducted, the location of hydrogen and hence the transition pressures reported up to date remain inconsistent. Here we report the atomic distribution of deuterium in DO ice using neutron diffraction above 100 GPa and observe for the first time the transition from a bimodal to a unimodal distribution of deuterium at around 80 GPa. At the transition pressure, a significant narrowing of the peak widths of 110 was also observed, attributed to the structural relaxation by the change of elastic properties.
ion sourceShinto, Katsuhiro; Shibata, Takanori*; Okoshi, Kiyonori; Nammo, Kesao*; Kawai, Isao*; Ikegami, Kiyoshi*
Journal of Physics; Conference Series, 2743, p.012023_1 - 012023_5, 2024/05
Times Cited Count：0 Percentile：0.00(Physics, Particles & Fields)We have been conducting the test of a new J-PARC-made internal antenna for the J-PARC RF-driven cesiated H ion source. After the development of the first J-PARC-made antenna, the composition of the porcelain enamel coating of the antenna was changed because we were afraid of the outgassing of the impurities from the previous antenna coating. During the test of high-density plasma production by the new antenna, we monitored the outgassing characteristics of the new antenna by measuring mass spectrometry and optical spectrum analysis. It is confirmed that no remarkable impurities were emitted from the new antenna. We also carried out the H beam extraction and measured the H beam characteristics by using the new antenna. It is found that the emittances of the H beam extracted from the J-PARC RF-driven cesiated H ion source by using the new antenna were similar to those in the case by using the SNS-made antenna. To accelerate the endurance test of the new antenna, we applied the antenna for the high-density plasma production to the 5% duty factor (1 ms pulse width with 50 Hz repetition rate) with the 2 MHz RF input power of approximately 60 kW, whose values were much higher than those in the J-PARC nominal operation; 0.8 ms pulse width with 25 Hz repetition rate (the duty factor of 2%) with the RF input power of approximately 30 kW. This presentation shows the results of the characteristics of the new J-PARC-made antenna and discusses the feasibility of the new antenna for use in the J-PARC accelerator operation.
ion sourceUeno, Akira
Journal of Physics; Conference Series, 2743(1), p.012001_1 - 012001_8, 2024/05
Times Cited Count：1 Percentile：87.02(Physics, Particles & Fields)On 2020, the 8 hours operation of the J-PARC cesiated RF-driven H ion source (IS) with a 69.9 keV 120 mA beam was reported. Many times and large amount of Cs and HO injections were required. The very high plasma etectrode temperature (T
) of 245
C suggests a novel cesiation surviving against high T and plasma bombardments. A procedure based upon a hypothesis of the HO (chemically bound with Mo) mediated cesiation was examined. The innovative cesiation derived a 76.5 keV 145 mA beam stably with the small beam fluctuation and transverse emittances suitable for RFQs of high energy LINACs. Furthermore, the beam intensity for the J-PARC IS operation energy of 52.5 keV was increased from 72 mA to 83 mA which should contribute for the stable J-PARC LINAC 60 mA operation in near future.
ion beam extracted from an RF wave excited ion source plasmaWada, Motoi*; Shibata, Takanori*; Shinto, Katsuhiro
Journal of Physics; Conference Series, 2743, p.012031_1 - 012031_5, 2024/05
Times Cited Count：0 Percentile：0.00(Physics, Particles & Fields)An internal antenna type RF driven negative hydrogen (H) ion source supplies beams to the J-PARC accelerator facility. The H ion beam current exhibits high stability, while it fluctuates with less than 5% amplitude of the DC current when a Faraday cup measures the current extracted from the source mounted on a test stand. Two frequencies are identified as the main oscillation components, 2 MHz and 4 MHz which are the driving RF frequency and the second harmonics, respectively. The amplitude levels of these components appear larger as parts of the beam directing specific angles passing through a slit are detected. A possible reason for observing a small amplitude oscillation in the total beam intensity is the averaged phase-shift of the local beam depending upon the position of the H ion production and the succeeding trajectory reaching the Faraday cup. To confirm if the phase-shift is the main reason for diminishing the oscillation amplitude for the total beam, the phase-shift between the 2 MHz and 4 MHz components were measured for beams passing through a 0.1 mm slit coupled to a Faraday cup having a 0.1 mm entrance slit. The result indicated the phase-shift changed substantially depending upon the position, but no simple model can explain the measured spatial distribution of the phase-shift. Further attempts will be made to clarify the beam dynamics relevant to the H ion beam transport including the measurements of the beam current phase-shift with respect to the RF antenna current, and the time evolution of Balmer-
light emission.
