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Soma, Yasutaka; Komatsu, Atsushi; Kaji, Yoshiyuki; Yamamoto, Masahiro*; Igarashi, Takahiro
Corrosion Science, 251, p.112897_1 - 112897_15, 2025/07
Times Cited Count：1 Percentile：0.00(Materials Science, Multidisciplinary)Experimental and modeling studies of the oxygen ingression at the crevices of stainless steels were conducted in high-temperature water (288
C). The limiting distance of oxygen ingression, 
, was defined as the point beyond which the primary surface oxide changed (hematite 
magnetite), regardless of crevice gap, oxygen concentration, and time. In situ measurements revealed increased electrical conductivity around the position indicating ion enrichment due to a differential oxygen concentration cell. increased with increasing crevice gap, oxygen concentration, and immersion time. Modeling study suggested that oxide layer growth reduced anodic dissolution and slowed oxygen consumption, allowing oxygen ingression with time.
Ogawa, Tatsuhiko
Annals of Nuclear Energy, 216, p.111256_1 - 111256_12, 2025/06
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)A novel robust method has been developed to simulate the performance of composite neutron sources composed of an alpha-emitting actinide and a light nucleus with low neutron separation energy. This method is based on the JENDL-5 cross-section data library and the Monte-Carlo radiation transport code PHITS. In contrast to previously devised methods, this approach can predict various quantities of the sources, such as actinide grain size dependence, absolute neutron emission intensity, energy spectra of neutrons and parasitic photons, neutron multiplicity, and time structure, with little approximation. The accurate calculation of stopping power of alpha rays in actinide grains and light elements, as well as the use of (
,n) reaction evaluated cross sections, which is one of the unique features of PHITS Ver.3.34 and its later versions, are the essences of the method. This method allows for the calculation of quantities important for practical applications, such as detection signal frequency, coincidence event rate, and the impact of parasitic gamma-rays.
Wakai, Takashi; Ando, Masanori; Okajima, Satoshi; Toyota, Kodai; Onuma, Terumitsu*; Takahashi, Ryoya*; Asayama, Tai
Dai-29-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Yokoshu (Internet), 5 Pages, 2025/06
This paper describes an experimental study for establishing a passive creep-fatigue test technique that mainly utilizes the difference in thermal expansion coefficients of the materials as material surveillance test technique that can be applied to evaluate the structural integrity of the fast reactor components when the components are used beyond the period assumed in the design. Using the test article designed with the aid of a finite element analysis, a long-term creep-fatigue test data has been successfully obtained. In the designing of the test article, it was essential to generate a adequate strain at the gauge portion of the specimen due to the difference of thermal expansion coefficients of the materials, without buckling. After much trial and error, an optimal shape and dimensions of the test article and the cyclic thermal load conditions are established. In the future, miniaturization of the test article for applying the established test technique to the actual nuclear reactors will be required.
-rays emitted from 
S(n,)
S reaction with polarized neutronsEndo, Shunsuke; Fujioka, Hiroyuki*; Ide, Ikuo*; Iinuma, Masataka*; Iwamoto, Nobuyuki; Iwamoto, Osamu; Kameda, Kento*; Kawamura, Shiori*; Kimura, Atsushi; Kitaguchi, Masaaki*; et al.
EPJ Web of Conferences, 329, p.05003_1 - 05003_3, 2025/06
no abstracts in English
Kobayashi, Keita; Nakamura, Hiroki; Okumura, Masahiko; Itakura, Mitsuhiro; Machida, Masahiko
Journal of Chemical Physics, 162(24), p.244508_1 - 244508_11, 2025/06
Times Cited Count：0The specific heat anomaly in (anti-)fluorite structures was analyzed using machine learning molecular dynamics (MLMD) methods. By employing the Farthest Point Sampling method and the Bootstrap method, first-principles training data were efficiently generated, and machine learning potentials were created for thorium dioxide (fluorite structure) and lithium oxide (anti-fluorite structure). As a result, the MLMD method accurately reproduced the reported thermal properties of thorium dioxide and lithium oxide. These materials exhibit a specific heat anomaly at high temperatures due to sublattice disordering. However, the details are complex and not fully understood. In this study, by applying a local order parameter methodology, which has been used in the analysis of liquid-liquid phase transitions, we revealed that the anomalous specific heat in (anti-)fluorite structures can be interpreted as a consequence of local symmetry breaking.
-Ps) in fluorinated polymers and silica glassKobayashi, Yoshinori*; Sato, Kiminori*; Yamawaki, Masato*; Michishio, Koji*; Oka, Toshitaka; Washio, Masakazu*
Journal of Physics; Conference Series, 3029, p.012001_1 - 012001_7, 2025/06
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
He neutron spin filter at J-PARCTakahashi, Shingo; Kiyanagi, Ryoji; Okudaira, Takuya*; Takada, Shusuke*; Kobayashi, Ryuju; Okuizumi, Mao; Ino, Takashi*; Asai, Kanta*; Tsuchikawa, Yusuke; Oikawa, Kenichi; et al.
Nuclear Instruments and Methods in Physics Research A, 1075, p.170410_1 - 170410_8, 2025/06
Machida, Akihiko*; Saito, Hiroyuki*; Aoki, Katsutoshi*; Komatsu, Kazuki*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; Machida, Shinichi*; Sato, Toyoto*; Orimo, Shinichi*
Physical Review B, 111(22), p.224413_1 - 224413_6, 2025/06
Times Cited Count：1The crystal and magnetic structures of antiferromagnetic Mn deuterides formed by hydrogenating Mn metal at high temperature and high pressure, fcc -MnDx and hcp 
-MnDx, were investigated by in-situ neutron powder diffraction. Deuterium atoms partially occupied the octahedral interstitial positions of the fcc and hcp metal lattices. The site occupancies increased rapidly with decreasing temperature from 
700 to 450 K and remained down to 300 K. N
el temperature of 543(10) K was determined for -MnD
. For -MnD
, saturation magnetic moment and Nel temperature were determined to be 0.82(1) 
and 347(3) K, respectively. The Nel temperatures determined for -MnD and -MnD are consistent with those predicted by the respective Slater-Pauling curves proposed in previous studies. The updated Nel temperatures provide insights into the development of more accurate Slater-Pauling curves based on electronic band structure calculations.
Matsushita, Taiki*; Ozawa, Akihiro*; Araki, Yasufumi; Fujimoto, Junji*; Sato, Masatoshi*
Physical Review B, 111(24), p.245131_1 - 245131_11, 2025/06
Times Cited Count：0
Co
)Sn studied by 
SRCai, Y.*; Yoon, S.*; Sheng, Q.*; Zhao, G.*; Seewald, E. F.*; Ghosh, S.*; Ingham, J.*; Pasupathy, A. N.*; Queiroz, R.*; Lei, H.*; et al.
Physical Review B, 111(21), p.214412_1 - 214412_17, 2025/06
Times Cited Count：0Meguro, Tomonari*; Ozawa, Akihiro*; Kobayashi, Koji*; Araki, Yasufumi; Nomura, Kentaro*
Physical Review Research (Internet), 7(2), p.L022065_1 - L022065_8, 2025/06
Auh, Y. H.*; Neal, N. N.*; Arole, K.*; Regis, N. A.*; Nguyen, T.*; Ogawa, Shuichi*; Tsuda, Yasutaka; Yoshigoe, Akitaka; Radovic, M.*; Green, M. J.*; et al.
ACS Applied Materials & Interfaces, 17(21), p.31392 - 31402, 2025/05
Times Cited Count：0 Percentile：0.00(Nanoscience & Nanotechnology)Uesawa, Shinichiro; Ono, Ayako; Nagatake, Taku; Yamashita, Susumu; Yoshida, Hiroyuki
Journal of Nuclear Science and Technology, 62(5), p.432 - 456, 2025/05
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)We performed electrostatic simulations of a wire-mesh sensor (WMS) for a single spherical bubble and bubbly flow to clarify the accuracy of the WMS. The electrostatic simulation for the single bubble showed the electric current density distribution and the electric current path from the excited transmitter to receivers for various bubble locations. It indicated systematic errors based on the nonuniform current density distribution around the WMS. The electrostatic simulation for the bubbly flow calculated by the computational fluid dynamics code, JAEA Utility Program for Interdisciplinary Thermal-hydraulics Engineering and Research (JUPITER), indicated that the WMS had difficulty in quantitatively measuring the intermediate values of the instantaneous void fraction between 0 and 1 because they cannot be estimated by previous transformation methods from the WMS signal to the void fraction, such as linear approximation or Maxwell's equation, and have a significant deviation of the void fraction of 
0.2 for the WMS signal. However, the electrostatic simulation indicated that the time-averaged void fractions around the center of the flow channel can be estimated using linear approximation, and the time-averaged void fraction near the wall of the flow channel can be estimated using Maxwell's equation.
Fukuda, Kodai; Obara, Toru*; Suyama, Kenya
Nuclear Technology, 211(5), p.963 - 973, 2025/05
Times Cited Count：1 Percentile：0.00(Nuclear Science & Technology)Myagmarjav, O.; Tanaka, Nobuyuki; Noguchi, Hiroki; Kamiji, Yu; Ono, Masato; Nomura, Mikihiro*; Takegami, Hiroaki
Progress in Nuclear Science and Technology (Internet), 7, p.235 - 242, 2025/05
Nagatani, Taketeru; Kosuge, Yoshihiro*; Sagara, Hiroshi*; Nakaguki, Sho; Nomi, Takayoshi; Okumura, Keisuke
Progress in Nuclear Science and Technology (Internet), 7, p.41 - 46, 2025/05
neutron diffraction studyIto, Tatsuya; Ogawa, Yuhei*; Gong, W.; Mao, W.*; Kawasaki, Takuro; Okada, Kazuho*; Shibata, Akinobu*; Harjo, S.
Acta Materialia, 287, p.120767_1 - 120767_16, 2025/04
Times Cited Count：1 Percentile：0.00(Materials Science, Multidisciplinary)Nagano, Hirohiko*; Kanda, Yuki*; Suzuki, Yuri*; Hiradate, Shuntaro*; Koarashi, Jun; Atarashi-Andoh, Mariko; Guo, Z.*
Discover Soil (Internet), 2, p.27_1 - 27_9, 2025/04
C alloy measured in the electrostatic levitation furnace onboard the international space stationIshikawa, Takehiko*; Oda, Hirohisa*; Koyama, Chihiro*; Shimonishi, Rina*; Ikeuchi, Rumiko*; Paradis, P.-F.*; Okada, Jumpei*; Fukuyama, Hiroyuki*; Yamano, Hidemasa
International Journal of Microgravity Science and Application, 42(2), p.420202_1 - 420202_10, 2025/04
