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FmOrlandi, R.; Asai, Masato; Makii, Hiroyuki; Nishio, Katsuhisa; Hirose, Kentaro; Tsukada, Kazuaki; Sato, Tetsuya; Ito, Yuta; Suzaki, Fumi; Nagame, Yuichiro*; et al.
Physical Review Letters, 137(8), p.082501_1 - 082501_6, 2026/08
Fukaya, Yuji; Asano, Kazuhito; Sato, Hiroyuki; Ohashi, Hirofumi; Sakaba, Nariaki
JAEA-Review 2026-015, 10 Pages, 2026/06
JAEA-Review-2026-015.pdf:0.96MB
The Japan Atomic Energy Agency (JAEA) is developing SiC matrix fuel as a fuel to improve oxidation resistance. It is a simple manufacturing method called the slurry method, in which raw materials are dissolved in water, molded, and sintered, and are designed to pursue manufacturability in consideration of mass production. On the other hand, there is a patent in the U.S. for SiC matrix fuel, and it was expressed that there is a risk that the JAEA's SiC matrix fuel technology may infringe this patent, and it should be confirmed. In that case of infringement, it could become an obstacle to the social implementation of that technology. Therefore, in order to determine whether the SiC-based fuel for HTGR proposed by the JAEA would constitute a patent infringement against the aforementioned U.S. patent, JAEA requested a formal infringement evaluation from a major U.S. patent law firm. As a result, it was determined that the SiC-based fuel for high-temperature gas reactors proposed by the JAEA does not constitute a patent infringement against the aforementioned U.S. patent. This removed obstacles to the future deployment of the SiC matrix fuel proposed by the JAEA for high temperature gas-cooled reactors.
beam in J-PARCHarada, Hiroyuki; Saha, P. K.; Yoneda, Hitoki*; Michine, Yurina*; Onoda, Genki*; Yamada, Ippei; Shibata, Takanori*; Sato, Atsushi*; Kinsho, Michikazu
JPS Conference Proceedings (Internet), 45, p.011133_1 - 011133_8, 2026/06
In high-intensity proton accelerators, negative hydrogen ions are charge-exchanged to protons by a carbon foil installed at the injection point of a ring accelerator. While this injection method can produce a high-intensity proton beam, it is a destructive method in which beams are passed through the foil, which leads to a short lifetime of the foil itself and to high radiation of the injection devices. Therefore, we proposed a non-destructive laser stripping injection scheme and develop for laser stripping experiment. In this study, a long-distance laser optical path of 70 m was newly constructed for the experiment. In this presentation, an overview of the laser stripping injection will be presented and the construction of the optical path, which is important for the execution of this experiment, will be reported. In addition, future experimental plans and prospects will be discussed.
Fujiwara, Yusuke; Nakajima, Kunihiro; Urabe, Kohei; Nagatsuka, Kentaro; Asano, Kazuhito; Shimizu, Atsushi; Noguchi, Hiroki; Sato, Hiroyuki; Ohashi, Hirofumi; Sumita, Junya; et al.
JAEA-Technology 2026-001, 43 Pages, 2026/05
JAEA-Technology-2026-001.pdf:2.93MB
High Temperature Gas-cooled Reactors (HTGRs) have excellent safety features and can supply high-temperature heat without emitting carbon dioxide, and therefore are expected to stably produce large amounts of hydrogen to contribute carbon neutrality by 2050. The pertinent material for the "Basic Policy for GX Realization" shows the development process for the HTGR demonstrator with the goal of starting operation in the 2030s. Meanwhile, to achieve net-zero, the UK government has started the Advanced Module Reactor (AMR) Research, development and demonstration (RD&D) programme with the aim of starting operations of the HTGR demonstrator in the early 2030s. Against this background, with the aim of early deployment of HTGR technology, Japan Atomic Energy Agency (JAEA), in collaboration with the United Kingdom National Nuclear Laboratory (UKNNL), aims to demonstrate Japanese HTGR technology outside Japan and reflect the development of HTGR demonstrator in the UK to Japan. This document summarizes the results of a market survey of HTGR products and surveys of industrial infrastructure in the UK, the environment and social conditions of Hartlepool, a candidate construction site, with the aim of contributing to the design study of the HTGR demonstrator in the UK (UKJ-HTR).
Sato, Yuki; Kakuto, Takeshi*; Tanaka, Takayuki*; Shimano, Hiroyuki*
European Physical Journal; Special Topics, 235(4), p.949 - 958, 2026/04
Times Cited Count：1 Percentile：37.78(Physics, Multidisciplinary)Yamane, Towa*; Inatsu, Masaru*; Kawano, Jun*; Sato, Takuto; Kusaka, Hiroyuki*
Agricultural and Forest Meteorology, 379, p.111052_1 - 111052_9, 2026/03
Times Cited Count：0 Percentile：0.00(Agronomy)This study aims to obtain fundamental information on birch pollen deposition data by field observation for the high-resolution, accurate pollen modeling. On the peak dispersal day in 2024, simple pollen collectors were installed just below and at three downwind points of an isolated birch tree line in Ebetsu, Hokkaido, Japan. Meteorological observation were also conducted at the site during the days. The birch pollen captured on slide glasses was imaged by a microscope. We first developed the automatic pollen counting technique by applying a machine learning algorithm YOLO to the images. This technique was validated by comparison with subjective counting, and we successfully achieved the automatic counting that has never been done before. The results suggested that the pollen count was highest in the point 200 m downstream from the tree line and diurnal variations were observed at all distances. A simple linear regression analysis of pollen count and meteorological factors revealed a significant positive correlation with temperature. Additionally, a positive correlation with wind speed was also found only at the point just below the tree line. The large-eddy simulation with the pollen advection supported the observation results, though the pollen deposition position was more concentrated near the tree in the simulation.
Umeda, Maki; Chudo, Hiroyuki; Imai, Masaki; Matsuo, Mamoru; Sato, Nana; Mori, Michiyasu; Maekawa, Sadamichi*; Saito, Eiji
Applied Physics Letters, 128(12), p.122402_1 - 122402_6, 2026/03
Times Cited Count：0 Percentile：0.00(Physics, Applied)Harada, Hiroyuki; Saha, P. K.; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Sato, Atsushi*; Kinsho, Michikazu
Progress of Theoretical and Experimental Physics (Internet), 2026(2), p.023G01_1 - 023G01_17, 2026/02
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)no abstracts in English
meson mass modification in cold nuclear matter in p+A collisions at J-PARCSako, Hiroyuki; Ichikawa, Masaya; Naruki, Megumi; Sakaguchi, Takao; Sato, Susumu; 12 of others*
Proceedings of Science (Internet), 500, p.260_1 - 260_5, 2026/01
N(
,
)
O reaction rates via the 
F(,
)
F reactionKim, S. H.*; Chae, K. Y.*; Asai, Masato; Hirose, Kentaro; Sato, Tetsuya; Makii, Hiroyuki; Nishio, Katsuhisa; Orlandi, R.; Smallcombe, J.; Suzaki, Fumi; et al.
Journal of the Korean Physical Society, 6 Pages, 2026/00
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)no abstracts in English
Terada, Atsuhiko; Thwe Thwe, A.; Hino, Ryutaro*; Harai, Yasutaka*; Sasaki, Gaku*; Shingeya, Hideshi*; Yamashita, Toshiyuki*; Yoneda, Jiro*; Okabayashi, Kazuki*; Sakamoto, Hiroyuki*; et al.
JAEA-Data/Code 2025-012, 151 Pages, 2025/12
JAEA-Data-Code-2025-012.pdf:9.69MB
Based on the lessons learned from the Fukushima Daiichi Nuclear Power Station accident, we have highly paid attention to the advancement of the fundamental technologies which are indispensable in timely response to hydrogen safety measures and assessments especially in both nuclear reactors and decommissioning. Focusing on this attention, we developed an analysis system that predicts the behavior of hydrogen from generation to diffusion, combustion and explosion. The system utilizes the commercial computational fluid dynamics software (FLUENT, AUTODYN), and incorporates new modules and pre/post-processors in order to withstand the general practical use. We also developed a system by utilizing open-source code (OpenFOAM) that can be used in hydrogen disaster prevention plans for nuclear facilities. So far, we have expanded the system to deal with the phenomena that should be considered from the practical point of view for PWR (Pressurized Water Reactor) in nuclear power plants. This report summarizes the overview of the integrated analysis system for hydrogen behavior, the handling method, and real scale analysis examples.
Nagayama, Shota; Kinsho, Michikazu; Harada, Hiroyuki; Yamada, Ippei; Chimura, Motoki; Kojima, Kunihiro; Yamamoto, Kazami; Shimogawa, Tetsushi*; Sato, Atsushi*
Proceedings of 16th International Particle Accelerator Conference (IPAC25) (Internet), p.1025 - 1028, 2025/11
Slow extraction method of synchrotrons is used in nuclear and particle physics experiments, radiation therapy, and many other applications. In the slow extraction process, beam loss at the septum electrode, which separates the extracted beam from the circumferential side, induces activation and damage to the device. To solve this problem, we have devised an electric field measurement device named "Beam separation test device" to evaluate the two-dimensional electric field distribution of the nondestructive electrostatic septum that we are developing. The device consists of a prototype septum, horizontal and vertical wire scanners, and an electron gun installed on a movable stage fixed to a drive unit. This device measures the electric field by injecting an electron beam into the electric field and measuring the bending angle of the beam orbit. In developing this device, an additional optics system was designed to make a narrow electron beam to improve the measurement accuracy of the electric field distribution. In addition, we designed a beam dump that reduces secondary electron emission by utilizing energy loss when particles collide with materials. According to calculations of secondary electron emission, this beam dump can reduce secondary-emission into the chamber by up to 98%.
Sakaba, Nariaki; Ohashi, Hirofumi; Sato, Hiroyuki
Nihon Genshiryoku Gakkai-Shi ATOMO
, 67(10), p.593 - 597, 2025/10
no abstracts in English
Ishii, Katsunori; Ono, Masato; Noguchi, Hiroki; Shimizu, Atsushi; Nomoto, Yasunobu; Sato, Hiroyuki; Sakaba, Nariaki
Proceedings of World Hydrogen Technologies Convention 2025 (WHTC 2025) (Internet), p.26 - 28, 2025/10
demand and HTGR development potential in the industrial complex in JapanNoguchi, Hiroki; Ishii, Katsunori; Ono, Masato; Kasahara, Seiji; Sato, Hiroyuki; Sakaba, Nariaki
Proceedings of World Hydrogen Technologies Convention 2025 (WHTC 2025) (Internet), p.50 - 52, 2025/10
Achieving carbon neutrality in Japan in 2050, hydrogen is expected to be used as an alternative to fossil fuels in the hard-to-abate sectors. In steelmaking, hydrogen-based reduction process has been developed as a substitute for the conventional blast furnace steelmaking process, which involves the reduction of iron ore by coke. In chemical industry, a novel olefin production process has been developed using hydrogen and CO, through methanol as an intermediate chemical. A large amount of hydrogen is required for these novel processes. Nuclear energy is well-suited to large-scale low-carbon hydrogen production. High temperature gas cooled reactor (HTGR) is a type of nuclear reactor featuring extraction of high temperature heat. The heat can be applicable to hydrogen production. This study predicts hydrogen demand in five industrial complexes in Japan in 2050 and estimates the potential for introducing HTGR to meet the demand. The introduction of HTGR could be a promising solution for decarbonizing industrial complexes due to their large-scale hydrogen supply capacity.
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：2 Percentile：70.03(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.
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：1 Percentile：28.15(Materials Science, Multidisciplinary)The 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.
Abe, Takato*; Sato, Takuto; Boku, Taisuke*; Fujita, Norihisa*; Kusaka, Hiroyuki*
Joho Shori Gakkai Kenkyu Hokoku, p.1 - 11, 2025/05
no abstracts in English
Abe, Noriaki; Hoshi, Hiroyuki*; Haji, Toshiki*; Sato, Katsushi*; Niki, Sota*; Hirata, Takafumi*; Iwano, Hideki*; Danhara, Toru*
Chishitsugaku Zasshi (Internet), 131(1), p.59 - 70, 2025/04
To constrain the upper limit of the depositional age of the Tanabe Group, Early-Middle Miocene forearc basin deposit, this study obtained the detrital zircon U-Pb ages separated from eight sedimentary rock samples. We obtained 221 concordant ages from 330 zircon grains. The youngest grain age was 19.4 Ma, suggesting the upper limit of the depositional age is younger than 19.4 Ma, and no grain showed the depositional age indicated by foraminifera (16.3-15.1 Ma). Large-scale volcanic activities occurred in the Middle Miocene around Kii Peninsula, mainly after 15 Ma. The lack of grain younger than 15 Ma suggests that the Tanabe Group was deposited before 15 Ma. Sluggish volcanic activities in the provenance areas before 15 Ma may have caused the lack of zircons having ages close to the depositional period inferred from foraminifera.
Md produced in the 
He + 
Es reactionNishio, Katsuhisa; Hirose, Kentaro; Makii, Hiroyuki; Orlandi, R.; Kean, K. R.*; Tsukada, Kazuaki; Toyoshima, Atsushi*; Asai, Masato; Sato, Tetsuya; Chiera, N. M.*; et al.
Physical Review C, 111(4), p.044609_1 - 044609_12, 2025/04
Times Cited Count：1 Percentile：47.92(Physics, Nuclear)