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Nakamura, Takemi; Ogasawara, Reira; Ushijima, Hiroki; Okada, Yuji; Yamaguchi, Atsushi; Horiguchi, Hironori; Hirane, Nobuhiko
JAEA-Technology 2026-008, 39 Pages, 2026/07
JAEA-Technology-2026-008.pdf:2.55MB
Irradiation studies targeting thermal neutrons to fast neutrons are being conducted at the JRR-3 research reactor, and to accurately evaluate the irradiation effect, it is necessary to consider the influence of the neutron spectrum. Fuels and cadmium wires used as combustible absorbers are burned by reactions with neutrons because the JRR-3 is a high-power 20MW reactor, and the fuel shuffling and replacement are performed periodically to ensure uniform burnup and long-term operation. Since it is necessary to accurately reproduce the burnup history both temporally and spatially, it is difficult to evaluate the neutron spectrum with high accuracy through computational analysis. Hence, we investigated a method that can easily and accurately evaluate neutron spectra at irradiation facility in equilibrium core of JRR-3 silicide fuel and verified the validity of the evaluation results. This method uses data of initial guess spectrum and response functions for each irradiation field calculated using MCNP code, reaction rate measured from neutron fluence monitors such as Au-Al and Ni wire to perform unfolding using SAND-II. We conducted characteristic measurements from fiscal year 2023 to 2025 and performed unfolding using actual measured values from neutron fluence monitors for seven cycles. As a result, in all cases, the C/E ratio of the reaction rate was 1.000, indicating good convergence, and the difference from the unfolding and measured neutron flux was within 0.3% for hydraulic irradiation facility HR-1, within 0.8% for pneumatic irradiation facility PN-2, and 0% for vertical irradiation facility RG-2. This suggests that the results of the unfolded spectrum are valid. The application of this method can meet a wide range of user needs, and it is expected to greatly contribute to the advancement of irradiation research with improved reliability of the JRR-3 irradiation field.
Hosaka, Atsushi; Kanada-En
o, Yoshiko*; Yamaguchi, Yasuhiro*
European Physical Journal A, 61(5), p.103_1 - 103_17, 2025/05
Times Cited Count：5 Percentile：63.81(Physics, Nuclear)no abstracts in English
Fujishima, Yohei*; Anderson, D.*; Abe, Yu*; Alkebsi, L.*; Oka, Toshitaka; Tani, Atsushi*; Kranrod, C.*; Toyoda, Shin*; Hamasaki, Kanya*; Hirota, Seiko*; et al.
Nihon Hoshasen Jiko, Saigai Igakkai Zasshi, 7(1), p.21 - 26, 2024/12
no abstracts in English
Uno, Koichiro*; Okumura, Masahiko; Nakao, Atsushi*; Yamaguchi, Akiko; Yanai, Junta*
Science of the Total Environment, 949, p.175012_1 - 175012_8, 2024/11
Times Cited Count：5 Percentile：40.64(Environmental Sciences)Frayed edge sites (FES), formed by the partial weathering of mica minerals, selectively adsorb Cs ions. However, the detailed mechanism of this adsorption has not been fully clarified. In this study, cation extraction and Cs adsorption experiments were conducted on mica. It was found that potassium-adsorbed mica adsorbed more Cs than rubidium-adsorbed mica. To elucidate the cause of this, the stability of Cs, rubidium, and potassium adsorbed on FES was evaluated using first-principles calculations. It was determined that the presence of potassium as the cation species prior to Cs adsorption is important for the stability of Cs on the FES.
values calculated from radiocesium interception potentialUno, Koichiro*; Nakao, Atsushi*; Okumura, Masahiko; Yamaguchi, Akiko; Kogure, Toshihiro*; Yanai, Junta*
Nihon Dojo Hiryo Gaku Zasshi, 94(5), p.376 - 384, 2023/10
Radiocesium interception potential (RIP) has been widely used as a quantitative indicator of cesium (Cs) adsorption capacity of soil, but it has been found that RIP does not always correlate with the distribution coefficient () of Cs in the actual environment. In order to clarify the cause of this discrepancy, we measured Kd using more realistic solutions, compared it with RIP, and evaluated the mineral structure. As a result, it was found that the concentration of competing cations, such as potassium and ammonium ions, and the structural change of the mineral itself are important.
Giachino, A.*; Hosaka, Atsushi; Santopinto, E.*; Takeuchi, Sachiko*; Takizawa, Makoto*; Yamaguchi, Yasuhiro*
Physical Review D, 108(7), p.074012_1 - 074012_6, 2023/10
Times Cited Count：22 Percentile：84.22(Astronomy & Astrophysics)no abstracts in English
Toyoda, Shin*; Inoue, Kazuhiko*; Yamaguchi, Ichiro*; Hoshi, Masaharu*; Hirota, Seiko*; Oka, Toshitaka; Shimazaki, Tatsuya*; Mizuno, Hideyuki*; Tani, Atsushi*; Yasuda, Hiroshi*; et al.
Radiation Protection Dosimetry, 199(14), p.1557 - 1564, 2023/09
Times Cited Count：2 Percentile：25.59(Environmental Sciences)Interlaboratory comparison studies are important for radiation dosimetry in order to demonstrate how the technique is universally available. The set of standard samples are examined in each participating laboratory in the present study. After a set of standard samples together with the samples with unknown doses, which were prepared in the same laboratory as the standard samples, are measured at a participating laboratory, those samples are sent to another participating laboratory for next measurement. There is some small difference observed in the sensitivity (the slope of the dose response line) of the standard samples while the differences in the obtained doses for the samples with unknown doses are rather systematic, implying that the difference is mostly due to the samples but not to measurements.
Wakamatsu, Katsuhiro*; Sekihara, Akihori*; Yamaguchi, Yoshihiko*; Matsushima, Ryo*; Matsumura, Daiju; Kuila, T.*; Yoshikawa, Hirofumi*
Batteries & Supercaps (Internet), 6(1), p.e202200385_1 - e202200385_8, 2023/01
Times Cited Count：10 Percentile：44.13(Electrochemistry)
la the nuclear forceYamaguchi, Yasuhiro; Yasui, Shigehiro*; Hosaka, Atsushi
Physical Review D, 106(9), p.094001_1 - 094001_16, 2022/11
Times Cited Count：7 Percentile：38.68(Astronomy & Astrophysics)
(3872) revisited; The Roles of OPEP and the quark degrees of freedomTakeuchi, Sachiko*; Yamaguchi, Yasuhiro; Hosaka, Atsushi; Takizawa, Makoto*
Few-Body Systems, 62(4), p.77_1 - 77_4, 2021/12
Times Cited Count：3 Percentile：25.47(Physics, Multidisciplinary)
and 
as interfering 
and 
threshold cuspsNakamura, Satoshi*; Hosaka, Atsushi; Yamaguchi, Yasuhiro
Physical Review D, 104(9), p.L091503_1 - L091503_8, 2021/11
Times Cited Count：33 Percentile：82.95(Astronomy & Astrophysics)Yamaguchi, Yasuhiro; Garc
a-Tecocoatzi, H.*; Giachino, A.*; Hosaka, Atsushi; Santopinto, E.*; Takeuchi, Sachiko*; Takizawa, Makoto*
Few-Body Systems, 62(3), p.33_1 - 33_7, 2021/09
Times Cited Count：1 Percentile：9.27(Physics, Multidisciplinary)We investigate the hidden-charm pentaquarks as hadronic molecules of 
and 
coupled to a 
compact core by employing an interaction satisfying the heavy quark and chiral symmetries. Our model can consistently explain the masses and decay widths of 
, 
and 
with spin parity assignments 
, 
and 
, respectively. We find that the mass ordering is dominantly determined by the short-range interaction given by coupling to the compact core, while the decay widths by the tensor force of the one-pion exchange.
Taguchi, Shigeo; Taguchi, Katsuya; Makino, Risa; Yamanaka, Atsushi; Suzuki, Kazuyuki; Takano, Masato; Koshino, Katsuhiko; Ishida, Michihiko; Nakano, Takafumi; Yamaguchi, Toshiya
Nihon Hozen Gakkai Dai-17-Kai Gakujutsu Koenkai Yoshishu, p.499 - 502, 2021/07
In 2018, Tokai Reprocessing Plan (TRP) shifted to the decommissioning stage. In order to proceed with steady decommissioning work, TRP effort to enhance project management function. This paper describes the establishment and role of the Decommissioning Project Management Office, effectiveness of applying the project management tool and its utilization concept, and the method of materialize the equipment dismantling plan.
Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.
Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03
Times Cited Count：66 Percentile：94.76(Astronomy & Astrophysics)Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 
C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.
Yamaguchi, Akiko; Asano, Ikumi*; Kitagawa, Yuri*; Meng, C.*; Nakao, Atsushi*; Okumura, Masahiko
Proceedings of Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo 2020 (SNA + MC 2020), p.127 - 130, 2020/10
no abstracts in English
-ray measurements of the 
Th isomerMuramatsu, Haruka*; Hayashi, Tasuku*; Yuasa, Naoki*; Konno, Ryohei*; Yamaguchi, Atsushi*; Mitsuda, Kazuhisa*; Yamasaki, Noriko*; Maehata, Keisuke*; Kikunaga, Hidetoshi*; Takimoto, Misaki; et al.
Journal of Low Temperature Physics, 200(5-6), p.452 - 460, 2020/09
Times Cited Count：2 Percentile：7.72(Physics, Applied)Yamaguchi, Yasuhiro*; Hosaka, Atsushi; Takeuchi, Sachiko*; Takizawa, Makoto*
Journal of Physics G; Nuclear and Particle Physics, 47(5), p.053001_1 - 053001_67, 2020/05
Times Cited Count：88 Percentile：88.76(Physics, Nuclear)
pentaquarks with chiral tensor and quark dynamicsYamaguchi, Yasuhiro; Garca-Tecocoatzi, H.*; Giachino, A.*; Hosaka, Atsushi; Santopinto, E.*; Takeuchi, Sachiko*; Takizawa, Makoto*
Physical Review D, 101(9), p.091502_1 - 091502_7, 2020/05
Times Cited Count：77 Percentile：94.57(Astronomy & Astrophysics)We investigate the hidden-charm pentaquarks as hadronic molecules of and coupled to a compact core by employing an interaction satisfying the heavy quark and chiral symmetries. Our model can consistently explain the masses and decay widths of , and with spin parity assignments , and , respectively. We find that the mass ordering is dominantly determined by the short-range interaction given by coupling to the compact core, while the decay widths by the tensor force of the one-pion exchange.
Giachino, A.*; Hosaka, Atsushi; Santopinto, E.*; Takeuchi, Sachiko*; Takizawa, Makoto*; Yamaguchi, Yasuhiro*
Recent Progress in Few-Body Physics; Springer Proceedings in Physics, Vol.238, p.621 - 627, 2020/01
Times Cited Count：3 Percentile：87.59(Quantum Science & Technology)Th nuclear clock isomer determined by absolute -ray energy differenceYamaguchi, Atsushi*; Muramatsu, Haruka*; Hayashi, Tasuku*; Yuasa, Naoki*; Nakamura, Keisuke; Takimoto, Misaki; Haba, Hiromitsu*; Konashi, Kenji*; Watanabe, Makoto*; Kikunaga, Hidetoshi*; et al.
Physical Review Letters, 123(22), p.222501_1 - 222501_6, 2019/11
Times Cited Count：62 Percentile：91.08(Physics, Multidisciplinary)