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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.
Reiser, J. T.*; Neeway, J. J.*; Cooley, S. K.*; Parruzot, B.*; Heredia-Langner, A.*; Gin, S.*; Thomas, M.*; Smith, N. J.*; Icenhower, J. P.*; Stone-Weiss, N.*; et al.
International Journal of Applied Glass Science, 16(4), p.e16707_1 - e16707_16, 2025/10
Times Cited Count：0 Percentile：0.00(Materials Science, Ceramics)Sato, Junya; Takahashi, Yuta; Sunahara, Jun*; Saito, Toshimitsu*; Yoshida, Yukihiko; Sone, Tomoyuki; Osugi, Takeshi
Progress in Nuclear Science and Technology (Internet), 8, p.307 - 312, 2025/09
Kobayashi, Fuminori; Kamiya, Junichiro; Takahashi, Hiroki; Suzuki, Yasuo*; Tasaki, Ryuta*
JAEA-Technology 2024-007, 28 Pages, 2024/07
JAEA-Technology-2024-007.pdf:2.52MB
In J-PARC LINAC, the vacuum system is in place to maintain an ultra-high vacuum in the beam transport line (LINAC to 3GeV RCS beam transportation line: L3BT) between the LINAC to the 3GeV synchrotron. The vacuum system is installed in the LINAC and L3BT buildings and consists of vacuum pumps, vacuum gauges, beam line gate valves (BLGVs), and other vacuum. In existing vacuum systems, vacuum equipment is controlled independently for each area, and vacuum equipment can be operated regardless of the status of adjacent areas. This makes it impossible to eliminate erroneous operation due to human error. In addition, when a vacuum deterioration occurs in the beam transport line, the vacuum deterioration ILK signal is transmitted to the BLGV relay unit via the MPS transmission signal, which causes the BLGVs to be forcibly closed. Because the ILK signal transmission range extends to all BLGVs in the L3BT, however, BLGVs in areas unaffected by vacuum deterioration are also forced to close. This could cause problems such as unnecessary open/close operations leading to more frequent maintenance cycles of the BLGVs. In addition, since the BLGV is operated using the MPS signal path, maintenance of the vacuum control system requires work involving the MPS signal path, making it difficult to maintain the vacuum control system alone and making the work complicated. To solve these problems, it is necessary to improve maintainability by separating the signal paths and automatically controlling BLGV separately. Therefore, the vacuum control system was modified and constructed with the aim of realizing a control system that takes into account the safety and efficient maintenance and operation of the L3BT vacuum system. This report summarizes the development and use of the L3BT vacuum system control system.
Ishikado, Motoyuki*; Takahashi, Ryuta*; Yamauchi, Yasuhiro*; Nakamura, Masatoshi*; Ishimaru, Sora*; Yamauchi, Sara*; Kawamura, Seiko; Kira, Hiroshi*; Sakaguchi, Yoshifumi*; Watanabe, Masao; et al.
JPS Conference Proceedings (Internet), 41, p.011010_1 - 011010_7, 2024/05
Be and 
Al under direct muon-induced spallation in granite quartz and its implications for past high-energy cosmic ray fluxesSakurai, Hirohisa*; Kurebayashi, Yutaka*; Suzuki, Soichiro*; Horiuchi, Kazuho*; Takahashi, Yui*; Doshita, Norihiro*; Kikuchi, Satoshi*; Tokanai, Fuyuki*; Iwata, Naoyoshi*; Tajima, Yasushi*; et al.
Physical Review D, 109(10), p.102005_1 - 102005_18, 2024/05
Times Cited Count：0 Percentile：0.00(Astronomy & Astrophysics)Secular variations of galactic cosmic rays (GCRs) are inseparably associated with the galactic activities and should reflect the environments of the local galactic magnetic field, interstellar clouds, and nearby supernova remnants. The high-energy muons produced in the atmosphere by high-energy GCRs can penetrate deep underground and generate radioisotopes in the rock. As long lived radionuclides such as Be and Al have been accumulating in these rocks, concentrations of Be and Al can be used to estimate the long-term variations in high-energy muon yields, corresponding to those in the high-energy GCRs over a few million years. This study measured the production cross sections for muon induced Be and Al by irradiating positive muons with the momentum of 160 GeV/c on the synthetic silica plates and the granite core at the COMPASS experiment line in CERN SPS. In addition, it the contributions of the direct muon spallation reaction and the nuclear reactions by muon-induced particles on the production of long lived radionuclides in the rocks were clarified.
-odd/
-odd interactions on the 0.75 eV 
-wave resonance in 
+
forward transmission determined using a pulsed neutron beamNakabe, Rintaro*; Auton, C. J.*; Endo, Shunsuke; Fujioka, Hiroyuki*; Gudkov, V.*; Hirota, Katsuya*; Ide, Ikuo*; Ino, Takashi*; Ishikado, Motoyuki*; Kambara, Wataru*; et al.
Physical Review C, 109(4), p.L041602_1 - L041602_4, 2024/04
Times Cited Count：1 Percentile：9.15(Physics, Nuclear)-wave resonance of 
+
Okudaira, Takuya*; Nakabe, Rintaro*; Auton, C. J.*; Endo, Shunsuke; Fujioka, Hiroyuki*; Gudkov, V.*; Ide, Ikuo*; Ino, Takashi*; Ishikado, Motoyuki*; Kambara, Wataru*; et al.
Physical Review C, 109(4), p.044606_1 - 044606_9, 2024/04
Times Cited Count：2 Percentile：54.52(Physics, Nuclear)Hasemi, Hiroyuki; Takahashi, Ryuta*; Yamauchi, Yasuhiro*; Ishikado, Motoyuki*; Kawamura, Seiko; Komine, Ryota
JPS Conference Proceedings (Internet), 41, p.011003_1 - 011003_5, 2024/03
-ray discrimination based on the property and thickness controls of scintillators using Li glass and LiCAF(Ce) in a -ray fieldKaburagi, Masaaki; Shimazoe, Kenji*; Terasaka, Yuta; Tomita, Hideki*; Yoshihashi, Sachiko*; Yamazaki, Atsushi*; Uritani, Akira*; Takahashi, Hiroyuki*
Nuclear Instruments and Methods in Physics Research A, 1046, p.167636_1 - 167636_8, 2023/01
Times Cited Count：7 Percentile：80.85(Instruments & Instrumentation)We focus on the thickness and property controls of inorganic scintillators used for thermal neutron detection in intense -ray fields without considering pulse shape discrimination techniques. GS20
(a lithium glass) and LiCaAlF
:Ce(LiCAF:Ce) cintillators with thicknesses of 0.5 and 1.0 mm, respectively, have been employed. Pulse signals generated by photomultiplier tubes, to which the scintillators were coupled, were inserted into a digital pulse processing unit with 1 Gsps, and the areas of waveforms were integrated for 360 ns. In a 
Co -ray field, the neutron detection for GS20 with a 0.5-mm thickness was possible at dose rates of up to 0.919 Gy/h; however, for LiCAF:Ce, neutron detection was possible at 0.473 Gy/h, and it failed at 0.709 Gy/h. Threfore, in a Co -ray field, the neutron/-ray discrimination of GS20 was better than that of LiCAF:Ce due to its better energy resolution and higher detection efficiency.
-edge to assess the U(V) electronic structure in FeUO
Yomogida, Takumi; Akiyama, Daisuke*; Ouchi, Kazuki; Kumagai, Yuta; Higashi, Kotaro*; Kitatsuji, Yoshihiro; Kirishima, Akira*; Kawamura, Naomi*; Takahashi, Yoshio*
Inorganic Chemistry, 61(50), p.20206 - 20210, 2022/12
Times Cited Count：7 Percentile：61.12(Chemistry, Inorganic & Nuclear)FeUO was studied to clarify the electronic structure of U(V) in a metal monouranate compound. We obtained the peak splitting of HERFD-XANES spectra utilizing high-energy-resolution fluorescence detection-X-ray absorption near edge structure (HERFD-XANES) spectroscopy at the U L-edge, which is a novel technique in the U(V) compounds. Theoretical calculations revealed that the peak splitting was caused by splitting the 6d orbital of U(V). Such distinctive electronic states are of major interest to researchers and engineers working in various fields, from fundamental physics to the nuclear industry and environmental sciences for actinide elements.
Mochimaru, Takanori*; Koizumi, Mitsuo; Takahashi, Tone; Hironaka, Kota; Kimura, Yoshiki; Sato, Yuki; Terasaka, Yuta; Yamanishi, Hirokuni*; Wakabayashi, Genichiro*
Dai-42-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2021/11
no abstracts in English
Suzuki, Masaaki*; Ito, Mari*; Hashidate, Ryuta; Takahashi, Keita; Yada, Hiroki; Takaya, Shigeru
2020 9th International Congress on Advanced Applied Informatics (IIAI-AAI 2020), p.797 - 801, 2021/07
Toyota, Kodai; Hashidate, Ryuta; Takahashi, Keita; Yada, Hiroki; Takaya, Shigeru
Hozengaku, 20(2), p.95 - 103, 2021/07
Hashidate, Ryuta; Toyota, Kodai; Takahashi, Keita; Yada, Hiroki; Takaya, Shigeru
Hozengaku, 19(4), p.115 - 122, 2021/01
In order to improve both safety and economic efficiency of a nuclear power plant, it is necessary to realize rational maintenance based on characteristics of the plant. The prototype fast-breeder reactor in Japan, Monju, spent most of the year for the maintenance. Thus, it is important to identify causes of the prolonged maintenance of Monju and to investigate countermeasures for implementation of rational maintenance of next-generation fast reactors. In this study, the authors investigated the causes of the prolonged maintenance of Monju during reactor cold shutdown based on the plant schedule of Monju. In addition, we proposed the maintenance optimization idea for next-generation fast reactors to solve the revealed issues.
Sasa, Kimikazu*; Honda, Maki; Hosoya, Seiji*; Takahashi, Tsutomu*; Takano, Kenta*; Ochiai, Yuta*; Sakaguchi, Aya*; Kurita, Saori*; Satou, Yukihiko; Sueki, Keisuke*
Journal of Nuclear Science and Technology, 58(1), p.72 - 79, 2021/01
Times Cited Count：13 Percentile：73.86(Nuclear Science & Technology) gamma-ray spectrometer suitable for the decommissioning of the Fukushima Daiichi Nuclear Power StationKaburagi, Masaaki; Shimazoe, Kenji*; Otaka, Yutaka*; Uenomachi, Mizuki*; Kamada, Kei*; Kim, K. J.*; Yoshino, Masao*; Shoji, Yasuhiro*; Yoshikawa, Akira*; Takahashi, Hiroyuki*; et al.
Nuclear Instruments and Methods in Physics Research A, 971, p.164118_1 - 164118_8, 2020/08
Times Cited Count：8 Percentile：56.59(Instruments & Instrumentation)Kondo, Yasuhiro; Hirano, Koichiro; Ito, Takashi; Kikuzawa, Nobuhiro; Kitamura, Ryo; Morishita, Takatoshi; Oguri, Hidetomo; Okoshi, Kiyonori; Shinozaki, Shinichi; Shinto, Katsuhiro; et al.
Journal of Physics; Conference Series, 1350, p.012077_1 - 012077_7, 2019/12
Times Cited Count：2 Percentile：68.36(Physics, Particles & Fields)We have upgraded a 3-MeV linac at J-PARC. The ion source is same as the J-PARC linac's, and the old 30-mA RFQ is replaced by a spare 50-mA RFQ, therefore, the beam energy is 3 MeV and the nominal beam current is 50 mA. The main purpose of this system is to test the spare RFQ, but also used for testing of various components required in order to keep the stable operation of the J-PARC accelerator. The accelerator has been already commissioned, and measurement programs have been started. In this paper, present status of this 3-MeV linac is presented.
Kawamura, Seiko; Takahashi, Ryuta*; Ishikado, Motoyuki*; Yamauchi, Yasuhiro*; Nakamura, Masatoshi*; Ouchi, Keiichi*; Kira, Hiroshi*; Kambara, Wataru*; Aoyama, Kazuhiro*; Sakaguchi, Yoshifumi*; et al.
Journal of Neutron Research, 21(1-2), p.17 - 22, 2019/05
The Cryogenics and Magnets group in the Sample Environment team is responsible for operation of cryostats and magnets for user's experiments at the MLF in J-PARC. We have introduced a top-loading 
He cryostat, a bottom-loading 
He cryostat, a dilution refrigerator insert and a superconducting magnet. The frequency of use of them dramatically becomes higher in these two years, as the beam power and the number of proposal increase. To respond such situation, we have made efforts to enhance performance of these equipment as follows. The He cryostat originally involves an operation software for automatic initial cooling down to the base temperature and automatic re-charge of He. Recently we made an additional program for automatic temperature control with only the sorb heater. Last year, a new outer vacuum chamber of the magnet with an oscillating radial collimator (ORC) was fabricated. The data quality was drastically improved by introducing this ORC so that the magnet can be used even for the inelastic neutron scattering experiments.
Watanabe, Masao; Nojiri, Hiroyuki*; Ito, Shinichi*; Kawamura, Seiko; Kihara, Takumi*; Masuda, Takatsugu*; Sahara, Takuro*; Soda, Minoru*; Takahashi, Ryuta
JPS Conference Proceedings (Internet), 25, p.011024_1 - 011024_5, 2019/03
Recently, neutron scattering experiments have been rapidly progressed under high magnetic field. In the J-PARC, proto-type compact pulse magnet system with the power supply, the coil and the sample stick has been developed. Basic specifications of the power supply are as follows; maximum charged voltage with capacitor is 2 kV, maximum current is 8 kA, repetition rate is a pulse per several minutes and pulse duration is several msec. Maximum magnetic field in the coil is more than 30 Tesla. The sample stick is designed for Orange-Cryostat. In this presentation, We report the details of the pulsed magnet system and the performance of it on neutron scattering experiments at MLF beam line (HRC).
