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Mitsuguchi, Takehiro; Okabe, Nobuaki*; Kokubu, Yoko; Matsuzaki, Hiroyuki*
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 31(2), p.96 - 110, 2024/12
Geological disposal of high-level radioactive waste requires not only selecting sites appropriate for the waste repository, where its isolation ability would not be damaged by natural phenomena for several tens of thousands of years, but also rationally constructing the disposal system depending on site-specific geological environments and their anticipated long-term variability. Recently, elemental/isotopic compositions of underground fluids (deep groundwaters, hot/cold spring waters, brines associated with oil and natural gas reservoirs, and so on) in Japan have been studied for evaluating the long-term stability of the geological environments of this country. Iodine and its radioactive isotope I (half-life = 15.7 million years) are included in the subjects of the study. The current review paper provides overviews of (i) the iodine content and iodine-129/127 ratio (
I/
I ratio) of various materials in Earth's surface layers, (ii) relevant sample pretreatments and measurements, and (iii)
I/
I data of the underground fluids in Japan, then gives (iv) some interpretations of the fluid
I/
I data, along with their problems and uncertainties, and (v) some implications towards evaluating the long-term stability of geological environments.
Nishino, Hiroyuki; Kurisaka, Kenichi; Futagami, Satoshi; Watakabe, Tomoyoshi; Yamano, Hidemasa
Proceedings of Probabilistic Safety Assessment and Management & Asian Symposium on Risk Assessment and Management (PSAM17 & ASRAM2024) (Internet), 10 Pages, 2024/10
The reactor vessel (RV) buckling was a dominant contributor to core damage. However, even if the RV is buckled due to seismic shaking, it is expected that the RV maintains stable state without unstable failure such as rupture, collapse. Realistic consideration of the post-buckling behavior is regarded as a measure for improving the resilience in this study. The purpose of this study is to understand the post-buckling deformation behavior of the RV and to evaluate the RV fragility based on fatigue failure. This study performed structural analysis using a finite element method to quantify time histories of displacement, strain, etc. As the result of the analysis, wrinkles of the buckling appeared at the elevation higher than the liquid level in the RV. The largest strain value was also indicated around this elevation. The cumulative fatigue damage fraction was evaluated in this analysis to evaluate the fragility of fatigue failure in addition to the buckling fragility. The result showed that the seismic intensity for the median fragility of the fatigue failure was about six times larger than the design-basis ground motion. This is 1.2 times larger than the buckling-based result, which suggests that realistic evaluation of the post-buckling behavior could contribute to improving the resilience of the nuclear structure.
Arai, Yoichi; Watanabe, So; Watanabe, Masayuki; Arai, Tsuyoshi*; Katsuki, Kenta*; Agou, Tomohiro*; Fujikawa, Hisaharu*; Takeda, Keisuke*; Fukumoto, Hiroki*; Hoshina, Hiroyuki*; et al.
Nuclear Instruments and Methods in Physics Research B, 554, p.165448_1 - 165448_10, 2024/09
Times Cited Count:0 Percentile:0.00(Instruments & Instrumentation)Endo, Shunsuke; Abe, Ryota*; Fujioka, Hiroyuki*; Ino, Takashi*; Iwamoto, Osamu; Iwamoto, Nobuyuki; Kawamura, Shiori*; Kimura, Atsushi; Kitaguchi, Masaaki*; Kobayashi, Ryuju*; et al.
European Physical Journal A, 60(8), p.166_1 - 166_10, 2024/08
Times Cited Count:0 Percentile:0.00(Physics, Nuclear)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-DF 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.
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
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.
He, Z.*; Kajino, Toshitaka*; Kusakabe, Motohiko*; Zhou, S.-G.*; Koura, Hiroyuki; Chiba, Satoshi*; Li, H.*; Lin, Y.*
Astrophysical Journal Letters, 966(2), p.L37_1 - L37_7, 2024/05
Times Cited Count:0 Percentile:0.00(Astronomy & Astrophysics)Holm-Janas, S.*; Akaki, Mitsuru*; Fogh, E.*; Kihara, Takumi*; Le, M. D.*; Forino, P. C.*; Nikitin, S. E.*; Fennell, T.*; Painganoor, A.*; Vaknin, D.*; et al.
Physical Review B, 109(17), p.174413_1 - 174413_11, 2024/05
Times Cited Count:0 Percentile:0.00(Materials Science, Multidisciplinary)Sakurai, 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.
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:0 Percentile:0.00(Physics, Nuclear)Nakabe, 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:0 Percentile:0.00(Physics, Nuclear)Yamauchi, Hiroki; Sari, D. P.*; Yasui, Yukio*; Sakakura, Terutoshi*; Kimura, Hiroyuki*; Nakao, Akiko*; Ohara, Takashi; Honda, Takashi*; Kodama, Katsuaki; Igawa, Naoki; et al.
Physical Review Research (Internet), 6(1), p.013144_1 - 013144_9, 2024/02
Uchibori, Akihiro; Doda, Norihiro; Aoyagi, Mitsuhiro; Sonehara, Masateru; Sogabe, Joji; Okano, Yasushi; Takata, Takashi*; Tanaka, Masaaki; Enuma, Yasuhiro; Wakai, Takashi; et al.
Nuclear Engineering and Design, 413, p.112492_1 - 112492_10, 2023/11
Times Cited Count:2 Percentile:57.39(Nuclear Science & Technology)The ARKAIDA has been developed to realize automatic optimization of plant design from safety evaluation for the advanced reactors represented by a sodium-cooled fast reactor. ARKADIA-Design offers functions to support design optimization both in normal operating conditions and design basis events. The multi-level simulation approach by the coupled analysis such as neutronics, core deformation, core thermal hydraulics was developed as one of the main technologies. On the other hand, ARKAIDA-Safety aims for safety evaluation considering severe accidents. As a key technology, the numerical methods for in- and ex-vessel coupled phenomena during severe accidents in sodium-cooled fast reactors were tested through a hypothetical severe accident event. Improvement of the ex-vessel model and development of the AI technology to find best design solution have been started.
Yoshimoto, Masahiro; Takahashi, Hiroki; Harada, Hiroyuki; Chimura, Motoki; Fuwa, Yasuhiro; Hayashi, Naoki; Kuriyama, Yasutoshi*; Sawabe, Yuki*; Hatakeyama, Shuichiro*
Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.839 - 843, 2023/11
In the J -PARC 3GeV synchrotron accelerator (RCS), a new signal processing system for beam monitors is been developing to replace the existing system for the main beam monitors that monitor the stability of the accelerator: beam loss monitor, beam position monitor and beam current monitor. The new system will consist of a TAG server and an ADC module that can be used commonly for the three main monitors. The main design concepts of the new system are: (1) the TAG server divides various beam J-PARC tag information to each ADC module, (2) the ADC module converts acquisition data from beam monitors to digital signals by ADC and performs high-speed analysis by FPGA with switching analysis methods to suit each monitor, (3) the ADC module periodically outputs the analysis data with tag information by packing the signal processing data of all shots for about 10 seconds, and also outputs any one shot data on-demand, and (4) the raw waveform data, the latest four shots of FFT-related data in the process of analysis and bunch data for each cycle are stored in the internal memory of the ADC module, and the data can be read out as needed. In this presentation, we will report on the progress of the data acquisition test of tag information reading and beam monitor signals using the prototype under development.
Oikawa, Kenichi; Sato, Hirotaka*; Watanabe, Kenichi*; Su, Y. H.; Shinohara, Takenao; Kai, Tetsuya; Kiyanagi, Yoshiaki*; Hasemi, Hiroyuki
Journal of Physics; Conference Series, 2605, p.012013_1 - 012013_6, 2023/10
Horiguchi, Naoki; Yoshida, Hiroyuki; Kaneko, Akiko*; Abe, Yutaka*
Nihon Kikai Gakkai Kanto Shibu Dai-29-Ki Sokai, Koenkai Koen Rombunshu (Internet), 5 Pages, 2023/10
To elucidate the behavior of molten fuels as a liquid jet in a shallow pool, which is assumed in a core meltdown accident of an LWR, and develop the evaluation method, we investigated the behavior of the vortical liquid film of the simulated wall-impinging liquid jet using 3-dimensional interface shape data obtained by the experiment in a liquid-liquid system.
Saha, P. K.; Harada, Hiroyuki; Okabe, Kota; Okita, Hidefumi; Shobuda, Yoshihiro; Tamura, Fumihiko; Yamamoto, Kazami; Yoshimoto, Masahiro; Hotchi, Hideaki*
Proceedings of 68th ICFA Advanced Beam Dynamics Workshop on High Intensity and High Brightness Hadron Beams (HB2023) (Internet), p.147 - 152, 2023/10
Shobuda, Yoshihiro; Harada, Hiroyuki; Saha, P. K.; Takayanagi, Tomohiro; Tamura, Fumihiko; Togashi, Tomohito; Watanabe, Yasuhiro; Yamamoto, Kazami; Yamamoto, Masanobu
Proceedings of 68th ICFA Advanced Beam Dynamics Workshop on High Intensity and High Brightness Hadron Beams (HB2023) (Internet), p.162 - 169, 2023/10
At the 3-GeV Rapid Cycling Synchrotron (RCS) within the Japan Proton Accelerator Research Complex (J-PARC), kicker impedance causes beam instability. A 1-MW beam with a large emittance can be delivered to the Material and Life Science Experimental Facility (MLF) by suppressing beam instabilities without the need for a transverse feedback system - simply by turning off the sextuple magnets. However, we require other high-intensity and high-quality beams with smaller emittances for the Main Ring (MR). To address this, we proposed a scheme for suppressing the kicker impedance using a diode stack and resistors, which effectively reduces beam instability. Importantly, these devices have a negligible effect on the extracted beam from the RCS.
Watanabe, Nao; Yamashita, Susumu; Uesawa, Shinichiro; Nishihara, Kenji; Yoshida, Hiroyuki
Proceedings of 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20) (Internet), p.3522 - 3534, 2023/08
Accelerator-driven system (ADS), the coolant of which is lead-bismuth eutectic (LBE), has been designed by Japan Atomic Energy Agency. Estimating corrosion rate at the wall surface of LBE channel is an important issue in considering safety and the life of the entire structure. The corrosion rate depends on state of oxygen layers forming at the material surface. Therefore, this study aims to develop a method to evaluate the corrosion rate in ADS for the design study by estimation of the oxide layer growth and dissolution (OLGD) rates by means of numerical analysis. The OLGD rates, mass transfer rates of oxygen and iron between the material and LBE and advection-diffusion rates of them in LBE depend on each other. Therefore, in order to estimate OLGD rates, the three numerical analysis models should be coupled. For the advection-diffusion calculation, to use CFD code should be reasonable approach to analyze complex flow in ADS, while for the OLGD and the mass transfer calculation, to use some correlation equations should be reasonable because their scales are much smaller than the advection-diffusion. The present work has developed the analysis method of OLGD rates by using JUPITER code, which is CFD code developed in JAEA. In terms of the correlation equations of OLGD and mass transfer rates, existing models used in a previous study were used with modified.
Kazama, Hiroyuki; Konashi, Kenji*; Suzuki, Tatsuya*; Koyama, Shinichi; Maeda, Koji; Sekio, Yoshihiro; Onishi, Takashi; Abe, Chikage*; Shikamori, Yasuyuki*; Nagai, Yasuyoshi*
Journal of Analytical Atomic Spectrometry, 38(8), p.1676 - 1681, 2023/07
Times Cited Count:3 Percentile:62.40(Chemistry, Analytical)