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SbO
Piyakulworawat, C.*; Morita, Katsuhiro*; Fukumoto, Yoshiyuki*; Hsieh, W.-Y.*; Chen, W.-T.*; Nakajima, Kenji; Kawamura, Seiko; Zhao, Y.*; Wannapaiboon, S.*; Piyawongwatthana, P.; et al.
Physical Review Research (Internet), 8(1), p.013247_1 - 013247_16, 2026/03
We analyze powder-averaged inelastic neutron scattering and magnetization data for the distorted honeycomb compound CuSbO using a first-order dimer expansion calculation and quantum Monte Carlo simulations. We show that, in contrast to the previously proposed honeycomb lattice model, CuSbO accommodates interacting dimerized spin chains with alternating ferromagnetic-antiferromagnetic couplings along the chain. Moreover, unlike the typical couplings observed in other Cu
-based distorted honeycomb magnets, the spin chains in CuSbO primarily couple through an antiferromagnetic coupling that arises between the honeycomb layers, rather than the expected interchain coupling in the layers. This finding reveals a different magnetic coupling scheme for CuSbO. In addition, utilizing X-ray spectroscopy and transmission electron microscopy, we also refine the crystal structure and stacking-fault model of the compound.
-molybdenum trioxide particles into waterYang, Y.*; Ngo, M. C.*; Kitagawa, Taiga*; Fujita, Yoshitaka; Takahashi, Yukiko*; Suzuki, Tatsuya*; Nakayama, Tadachika*; Do, T. M. D.*; Niihara, Koichi*; Suematsu, Hisayuki*
RSC Advances (Internet), 15(22), p.17222 - 17229, 2025/05
Times Cited Count：0 Percentile：0.00(Chemistry, Multidisciplinary)no abstracts in English
Np, 
Am, and 
Am reaction rates in highly enriched uranium fuel cores at Kyoto University Critical AssemblyPyeon, C. H.*; Oizumi, Akito; Katano, Ryota; Fukushima, Masahiro
Nuclear Science and Engineering, 199(3), p.429 - 444, 2025/03
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Experimental analyses of neptunium-237 (Np), americium-241 (Am), and Am fission and Np capture reaction rates are conducted by the Serpent 2 code together with ENDF/B-VIII.0 and JENDL-5, using experimental data at neutron spectra of thermal and intermediate regions obtained in the solid-moderated and solid-reflected cores with highly-enriched uranium fuel at the Kyoto University Critical Assembly. Also, uncertainty quantification of fission and capture reaction rate ratios of test samples of Np, Am and Am with reference samples of uranium-235 (
U) and gold-197 (
Au) are evaluated by the MARBLE code system. In terms of fission reaction rate ratios of Np/U, Am/U and Am/U, a comparison between experiments and Serpent 2 calculations shows an accuracy about 5, 15 and 10%, respectively, together with ENDF/B-VIII.0 and JENDL-5. For capture reaction rate ratios of Np/Au, Serpent 2 calculations reveal a fairly good accuracy at the thermal neutron spectrum. The total uncertainties of Np/U, Am/U and Am/U fission reaction rate ratios by MARBLE with the covariance data of ENDF/B-VIII.0 and JENDL-5 are found to be about 4% at most in all cores, except for about 8% of Am/U with ENDF/B-VIII.0 at the intermediate neutron spectrum.
Sb
with a honeycomb networkAdachi, Tadashi*; Ogawa, Taiki*; Komiyama, Yota*; Sumura, Takuya*; Saito-Tsuboi, Yuki*; Takeuchi, Takaaki*; Mano, Kohei*; Manabe, Kaoru*; Kawabata, Koki*; Imazu, Tsuyoshi*; et al.
Physical Review B, 111(10), p.L100508_1 - L100508_6, 2025/03
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)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
Zheng, X.-G.*; Yamauchi, Ichihiro*; Hagihara, Masato; Nishibori, Eiji*; Kawae, Tatsuya*; Watanabe, Isao*; Uchiyama, Tomoki*; Chen, Y.*; Xu, C.-N.*
Nature Communications (Internet), 15, p.9989_1 - 9989_12, 2024/11
Times Cited Count：1 Percentile：11.55(Multidisciplinary Sciences)
Mo/
Tc radioisotope separation by modified extraction methodPratama, C.*; Fujita, Yoshitaka; Saptiama, I.*; Marlina, M.*; Triyatna, F.*; Ilhami, A.*; Maria, C. P.*; Tsuchiya, Kunihiko; Teguh, A.*; Prasetyo, I.*
Journal of Physics; Conference Series, 2828, p.012025_1 - 012025_12, 2024/10
no abstracts in English
Meleshenkovskii, I.*; Van den Brandt, K.*; Ogawa, Tatsuhiko; Datema, C.*; Mauerhofer, E.*
European Physical Journal Plus (Internet), 139, p.565_1 - 565_9, 2024/07
Times Cited Count：1 Percentile：24.78(Physics, Multidisciplinary)Fast neutron inelastic scattering is a promising non-destructive assay technique for various analytical applications. As an active neutron interrogation technique, its performance is a function of various different factors and parameters that require optimization. Monte Carlo simulation codes are indispensable for such tasks. However, the internal simulation routines implemented in such codes can rely on different physical models that can yield discrepancies in the simulation results. In this work we conduct an intercomparison of PHITS and Geant4 codes performance in application to fast neutron inelastic scattering simulations. The goal of this paper is twofold. First, we explain the differences in code configuration with respect to gamma and neutron transport, as well as internal simulation routines. Second, we conduct a performance assessment of the two codes using two different measurement configurations. One configuration consisted of a source of gamma-rays in a broad energy range (100 keV - 9000 keV) and a CeBr
detector. The other configuration consisted of a monoenergetic 2.5 MeV fast neutron source, Fe, Nd, Dy, B targets and a CeBr detector. Selected simulation configurations were chosen with a goal to compare the performance differences in neutron energy distribution, produced prompt gamma-rays and energy deposition in CeBr detector between the two codes. Results of our study reveal a good coherence of both codes performance in the application of fast neutron inelastic scattering simulations. The simulation geometries and observed differences are described in detail.
Zeng, Z.*; Zhou, C.*; Zhou, H.*; Han, L.*; Chi, R.*; Li, K.*; Kofu, Maiko; Nakajima, Kenji; Wei, Y.*; Zhang, W.*; et al.
Nature Physics, 20(7), p.1097 - 1102, 2024/07
Times Cited Count：21 Percentile：95.80(Physics, Multidisciplinary)Johnson, M.*; Emura, Yuki; Clavier, R.*; Matsuba, Kenichi; Kamiyama, Kenji; Brayer, C.*; Journeau, C.*
Nuclear Engineering and Design, 423, p.113165_1 - 113165_14, 2024/07
Times Cited Count：4 Percentile：65.33(Nuclear Science & Technology)Experimental investigation of two interactions between molten jets and sodium, pertaining to severe accidents in a sodium-cooled fast reactor, have been undertaken at the JAEA's MELT facility. X-ray imaging and debris analysis reveal rapid formation of a crust at the melt coolant-interface, instigating thermal fragmentation events. Heat transfer calculations at the jet-coolant interface, supported by particle tracking velocimetry characterisation of the jet velocity, imply the formation of a solid crust within milliseconds of contact with the coolant. A mechanism for enhanced thermal fragmentation is proposed, inspired by observations from the X-ray imaging of coolant entrainment into the jet.
Katano, Ryota; Oizumi, Akito; Fukushima, Masahiro; Pyeon, C. H.*; Yamamoto, Akio*; Endo, Tomohiro*
Nuclear Science and Engineering, 198(6), p.1215 - 1234, 2024/06
Times Cited Count：1 Percentile：15.37(Nuclear Science & Technology)In this study, we have demonstrated that data assimilation using lead and bismuth sample reactivities measured in the Kyoto University Critical Assembly A-core can successfully reduce the uncertainty of the coolant void reactivity in accelerator-driven systems derived from inelastic-scattering cross-sections of lead and bismuth. We re-evaluated and highlighted the experimental uncertainties and correlations of the sample reactivities for the data assimilation formula. We used the MCNP6.2 code to evaluate the sample reactivities and their uncertainties, and performed data assimilation using the reactor analysis code system MARBLE. The high-sensitivity coefficients of the sample reactivities to lead and bismuth allowed us to reduce the cross-section-induced uncertainty of the void reactivity of the accelerator-driven system from 6.3% to 4.8%, achieving a provisional target accuracy of 5% in this study. Furthermore, we demonstrated that the uncertainties arising from other dominant factors, such as minor actinides and steel, can be effectively reduced by using integral experimental data sets for the unified cross-section dataset ADJ2017.
Xu, Z.*; Litzinger, A.*; Sakuma, Kazuyuki; Arora, B.*; Hazenberg, P.*; Wang, L.*; Gonzalez Raymat, H.*; Fabricatore, E.*; Wainwright, Haruko*; Eddy-Dilek, C.*
Proceedings of Waste Management Symposia 2024 (WM2024) (Internet), 14 Pages, 2024/03
Pyeon, C. H.*; Katano, Ryota; Oizumi, Akito; Fukushima, Masahiro
Nuclear Science and Engineering, 197(11), p.2902 - 2919, 2023/11
Times Cited Count：3 Percentile：45.53(Nuclear Science & Technology)Sample reactivity and void reactivity experiments are carried out in the solid-moderated and solid-reflected cores at the Kyoto University Critical Assembly (KUCA) with the combined use of aluminum (Al), lead (Pb) and bismuth (Bi) samples, and Al spacers simulating the void. MCNP6.2 eigenvalue calculations together with JENDL-4.0 provide good accuracy of sample reactivity with the comparison of experimental results; also experimental void reactivity is attained by using MCNP6.2 together with JENDL-4.0 and ENDF/B-VII.1 with a marked accuracy of relative difference between experiments and calculations. Uncertainty quantification of sample reactivity and void reactivity is acquired by using the sensitivity coefficients based on MCNP6.2/ksen and covariance library data of SCALE6.2 together with ENDF/B-VII.1, arising from the impact of uncertainty induced by Al, Pb and Bi cross sections. A series of reactivity analyses with the Al spacer simulating the void demonstrates the means of analyzing the void in the solid-moderated and solid-reflected cores at KUCA
Meng, Q.*; Hiyama, Emiko*; Oka, Makoto*; Hosaka, Atsushi; Xu, C.*
Physics Letters B, 846, p.138221_1 - 138221_6, 2023/11
Times Cited Count：16 Percentile：93.05(Astronomy & Astrophysics)no abstracts in English
Mo hot atoms made by a neutron capture method from 
-MoO to waterQuach, N. M.*; Ngo, M. C.*; Yang, Y.*; Nguyen, T. B.*; Nguyen, V. T.*; Fujita, Yoshitaka; Do, T. M. D.*; Nakayama, Tadachika*; Suzuki, Tatsuya*; Suematsu, Hisayuki*
Journal of Radioanalytical and Nuclear Chemistry, 332(10), p.4057 - 4064, 2023/10
Times Cited Count：5 Percentile：66.06(Chemistry, Analytical)Technetium-99m (Tc) is the most widely used medical radioisotope in the world and is produced from molybdenum-99 (Mo). Production of Mo via the neutron capture method draws attention as an alternative to fission-derived Mo due to non-proliferation issues, but the specific radioactivity of Mo is extremely low. In this work, a porous -MoO wire was prepared as an irradiation target in order to improve the specific activity by extracting Mo. Porous -MoO wire is synthesized from Mo metal wire by a two-step heating procedure. The hot atom effect of Mo was confirmed by activity and isotope measurements of the porous -MoO wire after neutron irradiation and the water used for extraction. In term of the extraction effectiveness, the effectiveness of Mo extraction in the porous -MoO wire was comparable to that of commercial -MoO powder.
-MoO whiskers in Mo/
Tc radioisotope production and Mo/Tc extraction using hot atomsNgo, M. C.*; Fujita, Yoshitaka; Suzuki, Tatsuya*; Do, T. M. D.*; Seki, Misaki; Nakayama, Tadachika*; Niihara, Koichi*; Suematsu, Hisayuki*
Inorganic Chemistry, 62(32), p.13140 - 13147, 2023/08
Times Cited Count：6 Percentile：54.59(Chemistry, Inorganic & Nuclear)Technetium-99m (Tc) is one of the most important radioisotopes for diagnostic radio-imaging applications. Tc is a daughter product of the Mo isotope. There are two methods used to produce Mo/Tc: the nuclear fission (n,f) and the neutron capture (n,
) methods. Between them, the (n,f) method is the main route, used for approximately 90% of the world's production. However, the (n,f) method faces numerous problems, including the use of highly enriched uranium, the release of highly radioactive waste, and nonproliferation problems. Therefore, the (n,) method is being developed as a future replacement for the (n,f) method. In this work, -MoO whiskers prepared by the thermal evaporation method and -MoO particles were irradiated in a nuclear reactor to produce Mo/Tc via neutron capture. The irradiated targets were dispersed into water to extract the Mo/Tc. As a result, -MoO whisker yielded higher Mo extraction rate than that from -MoO. In addition, by comparing the dissolved 
Mo concentrations in water, we clarified a prominent hot-atom of -MoO whiskers. This research is the first demonstration of -MoO being used as an irradiation target in the neutron capture method. On the basis of the results, -MoO is considered a promising irradiation target for producing Mo/Tc by neutron capture and using water for the radioisotope extraction process in the future.
Takano, Kazuya; Oki, Shigeo; Ozawa, Takayuki; Yamano, Hidemasa; Kubo, Shigenobu; Ogura, Masashi*; Yamada, Yumi*; Koyama, Kazuya*; Kurita, Koichi*; Costes, L.*; et al.
EPJ Nuclear Sciences & Technologies (Internet), 8, p.35_1 - 35_9, 2022/12
The France and Japan teams have carried out collaborative works to have common technical views regarding a sodium-cooled fast reactor concept. Japan has studied the feasibility of an enhanced high burnup low-void effect (CFV) core and fuel using oxide dispersion-strengthened steel cladding in ASTRID 600. Regarding passive shutdown capabilities, Japan team has performed a preliminary numerical analysis for ASTRID 600 using a complementary safety device, called a self-actuated shutdown system (SASS), one of the safety approaches of Japan. The mitigation measures of ASTRID 600 against a severe accident, such as a core catcher, molten corium discharge assembly, and the sodium void reactivity features of the CFV core, are promising to achieve in-vessel retention for both countries. The common design concept based on ASTRID 600 is feasible to demonstrate the SFR core and safety technologies for both countries.
Kuwata, Haruka*; Tazoe, Hirofumi*; Kranrod, C.*; Fujiwara, Kenso; Terashima, Motoki; Matsueda, Makoto; Hirao, Shigekazu*; Akata, Naofumi*
Radiation Protection Dosimetry, 198(13-15), p.1014 - 1018, 2022/09
Times Cited Count：0 Percentile：0.00(Environmental Sciences)
= 
quasikagome-lattice compound CeRhPdSn investigated using muon spin relaxation and neutron scatteringTripathi, R.*; Adroja, D. T.*; Ritter, C.*; Sharma, S.*; Yang, C.*; Hillier, A. D.*; Koza, M. M.*; Demmel, F.*; Sundaresan, A.*; Langridge, S.*; et al.
Physical Review B, 106(6), p.064436_1 - 064436_17, 2022/08
Times Cited Count：10 Percentile：58.35(Materials Science, Multidisciplinary)Arai, Yosuke*; Kuroda, Kenta*; Nomoto, Takuya*; Tin, Z. H.*; Sakuragi, Shunsuke*; Bareille, C.*; Akebi, Shuntaro*; Kurokawa, Kifu*; Kinoshita, Yuto*; Zhang, W.-L.*; et al.
Nature Materials, 21(4), p.410 - 415, 2022/04
Times Cited Count：18 Percentile：75.78(Chemistry, Physical)