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(La
K)
RuO
; Muon spin relaxation and neutron diffraction studiesKawasaki, Ikuto; Oyama, Kenji*; Iwasa, Kazuaki*; Higemoto, Wataru; Nakamura, Jumpei*; Yokoyama, Makoto*; 5 of others*
Physical Review B, 114(21), p.214404_1 - 214404_11, 2026/10
Yamamoto, Hajime*; Ochi, Keigo*; Aoyama, Takuya*; Ishii, Kenji*; Matsumura, Daiju; Tsuji, Takuya; Ogushi, Kenya*; Abukawa, Tadashi*
ACS Omega (Internet), 11(14), p.22093 - 22098, 2026/04
Times Cited Count：2 Percentile：70.31(Chemistry, Multidisciplinary)Kuwagaki, Kazuki; Hamase, Erina; Yokoyama, Kenji; Doda, Norihiro; Tanaka, Masaaki
Proceedings of International Conference on the Physics of Reactors (PHYSOR 2026) (Internet), 8 Pages, 2026/04
Hayashida, Shohei*; Wada, Takeshi*; Ishikado, Motoyuki*; Munakata, Koji*; Iida, Kazuki*; Kamazawa, Kazuya*; Kajimoto, Ryoichi; Inamura, Yasuhiro; Nakamura, Mitsutaka; Iwasa, Kazuaki*; et al.
High Pressure Research; An International Journal, 14 Pages, 2026/00
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)Kato, Shinya; Doda, Norihiro; Yokoyama, Kenji; Tanaka, Masaaki; Endo, Tomohiro*
Proceedings of 2025 International Congress on Advances in Nuclear Power Plants (ICAPP 2025) (Internet), 11 Pages, 2025/09
During a reactor power increase in ULOF and UTOP events in sodium-cooled fast reactors, core deformation due to thermal expansion of core elements is expected to cause a negative feed-back effect to suppress this power increase. An analytical evaluation method of core deformation reactivity for design is being developed in JAEA. However, the neutronics calculation module uses several approximations. This study aims to develop the detailed evaluation method as a reference neutron transport calculation code for confirmation of the validity of the calculated core deformation reactivity. Here, the two-dimensional finite volume method (FVM) code based on simplified P3 (SP3) approximation with unstructured mesh have been developed as the first step of the development. This paper describes the calculation theory of the FVM code, the procedure of introducing SP3 approximation into the code and the verification results of the functions developed.
Vu, TheDang*; Shishido, Hiroaki*; Aizawa, Kazuya; Oku, Takayuki; Oikawa, Kenichi; Harada, Masahide; Kojima, Kenji M*; Miyajima, Shigeyuki*; Soyama, Kazuhiko; Koyama, Tomio*; et al.
Nuclear Instruments and Methods in Physics Research A, 1075, p.170425_1 - 170425_9, 2025/06
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)Noguchi, Yuji*; Aso, Seiyu*; Oyama, Kenji*; Ishigaki, Toru*; Yoneda, Yasuhiro; Matsuo, Hiroki*
Physical Review B, 111(21), p.214113_1 - 214113_13, 2025/06
Times Cited Count：5 Percentile：71.87(Materials Science, Multidisciplinary)We explore the electronic structure of high-quality bismuth sodium titanate (Bi
NaTiO) powders through a comprehensive approach combining the maximum entropy method (MEM)/Rietveld analysis of synchrotron radiation X-ray diffraction data collected at 200 K with density functional theory (DFT) calculations. We conclude that the covalent Bi-O bond and the resultant ferroelectricity stem primarily from the Bi-6p-O3-2p orbital interaction mediated through Ti-3d.
phases in undoped and Ca-modified sodium niobatesAso, Seiyu*; Matsuo, Hiroki*; Yoneda, Yasuhiro; Morikawa, Daisuke*; Tsuda, Kenji*; Oyama, Kenji*; Ishigaki, Toru*; Noguchi, Yuji*
Physical Review B, 111(17), p.174114_1 - 174114_12, 2025/05
Times Cited Count：2 Percentile：40.34(Materials Science, Multidisciplinary)We investigate the crystal structures, phase transitions, and phase stability of undoped and Ca-modified NaNbO through a combined analysis of high-resolution synchrotron radiation X-ray and neutron diffraction, convergent-beam electron diffraction, and density functional theory (DFT) calculations. It is demonstrated that the antiferroelectric (AFE)- phase is stabilized over a wide temperature range of 200 to 800 K by Ca modification, and that the NaNbO is stabilized by temperature-driven isostatic pressure accompanied by lattice expansion, whereas the Ca-modified NaNbO is induced by composition-induced chemical pressure along with lattice shrinkage.
Katsumura, Kosuke*; Takagi, Junichi*; Miyahara, Naoya*; Uchida, Shunsuke*; Koma, Yoshikazu; Karasawa, Hidetoshi; Miwa, Shuhei; Satou, Yukihiko; Nagai, Haruyasu; Kurata, Masaki; et al.
Nihon Genshiryoku Gakkai-Shi ATOMO
, 67(2), p.128 - 132, 2025/02
no abstracts in English
Kuwagaki, Kazuki; Hamase, Erina; Yokoyama, Kenji; Doda, Norihiro; Tanaka, Masaaki
Annals of Nuclear Energy, 225, p.111754_1 - 111754_10, 2025/01
Times Cited Count：1 Percentile：37.36(Nuclear Science & Technology)Fukada, Yukimasa; Aoyagi, Yumito*; Yokoyama, Misaki*; Horibe, Yoichi*; Kano, Jun*; Kaneda, Miyu*; Fujii, Tatsuo*; Yoshigoe, Akitaka; Kobata, Masaaki; Fukuda, Tatsuo; et al.
Journal of Electronic Materials, 54, p.686 - 692, 2025/01
Times Cited Count：2 Percentile：19.51(Engineering, Electrical & Electronic)no abstracts in English
Vu, TheDang*; Shishido, Hiroaki*; Aizawa, Kazuya; Oku, Takayuki; Oikawa, Kenichi; Harada, Masahide; Kojima, Kenji M*; Miyajima, Shigeyuki*; Soyama, Kazuhiko; Koyama, Tomio*; et al.
IEEJ Transactions on Electrical and Electronic Engineering, 19(11), p.1888 - 1894, 2024/11
Times Cited Count：0 Percentile：0.00(Engineering, Electrical & Electronic)
Gd
Mn
O
Ishii, Yuta*; Sakakura, Terutoshi*; Ishikawa, Yoshihisa*; Kiyanagi, Ryoji; Lustikova, J.*; Aoyama, Takuya*; Ogushi, Kenya*; Wakabayashi, Yusuke*; Kimura, Hiroyuki*; Noda, Yukio*
Physical Review B, 110(18), p.184404_1 - 184404_7, 2024/11
Times Cited Count：1 Percentile：1.27(Materials Science, Multidisciplinary)Wen, J.*; Kamada, Yuto*; Yokoyama, Kosei*; Matsumoto, Tatsuya*; Liu, W.*; Morita, Koji*; Imaizumi, Yuya; Tagami, Hirotaka; Matsuba, Kenichi; Kamiyama, Kenji
Proceedings of 13th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS13) (Internet), 8 Pages, 2024/11
Seki, Akiyuki; Kondo, Yuki; Hashidate, Ryuta; Yoshikawa, Masanori; Yokoyama, Kenji; Takaya, Shigeru; Enuma, Yasuhiro; Hazama, Taira; Wakai, Takashi; Asayama, Tai
Proceedings of 31st International Conference on Nuclear Engineering (ICONE31) (Internet), 7 Pages, 2024/11
Wen, J.*; Kamada, Yuto*; Yokoyama, Kosei*; Matsumoto, Tatsuya*; Liu, W.*; Morita, Koji*; Imaizumi, Yuya; Tagami, Hirotaka; Matsuba, Kenichi; Kamiyama, Kenji
Proceedings of 31st International Conference on Nuclear Engineering (ICONE31) (Internet), 8 Pages, 2024/11
Soyama, Kazuhiko; Hayashida, Hirotoshi*; Maruyama, Ryuji; Yamazaki, Dai; Goto, Yoshiki*; Kobayashi, Yuki*; Arakawa, Shohei*; Yamamoto, Yugo*; Suba, Kenta*; Yamamura, Kazuya*
JAEA-Research 2024-006, 15 Pages, 2024/10
JAEA-Research-2024-006.pdf:1.51MB
A neutron optics design has been conducted for a neutron magnetic microscope that utilize a Wolter type I multilayer supermirror for the purpose of magnetic fields imaging in magnetic materials. Ray trace simulation was performed for a magnifying imaging optical system with a magnification rate of 12.5 times. Based on classical model of Lamor precession, depolarization due to magnetic domains was simulated, and the effect of slope errors on the Wolter mirror created by the replica method on the spatial resolution of the microscope was investigated. As a result, reference data about the shape error required to obtain spatial resolution on the order of micrometers was obtained.
Yokoyama, Kenji; Hazama, Taira; Taninaka, Hiroshi; Oki, Shigeo
JAEA-Data/Code 2024-007, 41 Pages, 2024/10
JAEA-Data-Code-2024-007.pdf:1.1MB
The third version of the versatile reactor analysis code system, MARBLE3, has been developed. In the development of the former version of MARBLE, object-oriented scripting language Python (Python2) had been used and then the latest version of Python (Python3) was released. However, due to its backward incompatibility, MARBLE no longer worked with Python3. For this reason, MARBLE3 has been fully modified and maintained to work with Python3. In MARBLE3, newly developed analysis codes and newly proposed calculation methods were incorporated, and the user interface was extended and solvers were reimplemented for maintainability, extensibility, and flexibility. In MARBLE3, the three-dimensional hexagonal/triangular transport code MINISTRI Ver.7 (MINISTRI7) and the three-dimensional hexagonal/triangular diffusion code D-MINISTRI are available as the new analysis codes. These codes can be used in the neutronics analysis system SCHEME and the fast reactor burnup analysis system OPRHEUS, which are the subsystems of MARBLE. In addition, the user interface of CBG, a core analysis system embedded in MARBLE, was extended so that the diffusion and transport calculation solvers for the 2-dimensional RZ system of CBG can be used on SCHEME. On the other hand, MARBLE3 has extended the functionality of the burnup calculation solver so that it can use the numerical methods proposed in the papers on the improvement of the Chebyshev rational function approximation method and the minimax polynomial approximation method. From the viewpoint of maintainability, the point reactor kinetics solver POINTKINETICS, which was introduced in MARBLE2, has been newly reworked as the KINETICS solver in MARBLE3.
by multiple-wavelength neutron holographyYamakawa, Kota*; Nakada, Hajime*; Kimura, Koji*; Oikawa, Kenichi; Harada, Masahide; Inamura, Yasuhiro; Oyama, Kenji*; Hayashi, Koichi*
Journal of the Physical Society of Japan, 93(10), p.104601_1 - 104601_5, 2024/10
Times Cited Count：2 Percentile：31.93(Physics, Multidisciplinary)Nakamura, Takeshi*; Sato, Kenichiro*; Toyama, Takeshi*; Okada, Masashi*; Kobayashi, Aine*; Yamada, Ippei; Shobuda, Yoshihiro
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.881 - 886, 2024/10
no abstracts in English
