Persistent rotation of particles driven by non-inertial Brownian motion

Umeda, Maki; Chudo, Hiroyuki; Imai, Masaki; Matsuo, Mamoru; Sato, Nana; Mori, Michiyasu; Maekawa, Sadamichi*; Saito, Eiji

Applied Physics Letters, 128(12), p.122402_1 - 122402_6, 2026/03

https://doi.org/10.1063/5.0320016

Continuum quasiparticle random-phase approximation for reactions on neutron-rich nuclei; Collectivity and resonances in low-energy cross sections

Saito, Teruyuki; Matsuo, Masayuki*

Physical Review C, 113(3), p.034607_1 - 034607_16, 2026/03

https://doi.org/10.1103/4ltc-ns32

Demonstration of the inherent safety feature of HTGRs through the loss-of-forced-cooling test in the HTTR

Nagasumi, Satoru; Hasegawa, Toshinari; Iigaki, Kazuhiko; Nakagawa, Shigeaki; Kubo, Shinji; Shimazaki, Yosuke; Nakajima, Kunihiro; Sakurai, Yosuke; Shinohara, Masanori; Saito, Kenji; et al.

Nuclear Engineering and Design, 446(Part A), p.114542_1 - 114542_14, 2026/01

https://doi.org/10.1016/j.nucengdes.2025.114542

To demonstrate HTGR's safety features, a loss-of-forced-cooling (LOFC) test was conducted using the HTTR. In this test, the forced cooling in the reactor core was intentionally lost by shutting down all helium gas circulators (HGCs) without reactor scram. During steady-state operation at 100% reactor power (30 MW), after the LOFC, the reactor power spontaneously decreased. This power reduction occurred due to the negative reactivity feedback effect triggered by an increase in core temperature. The power stabilized at a lower value of 1.2% after re-criticality. Additionally, the measured radioactivity concentration in the primary coolant remained nearly unchanged during this LOFC operation and during an immediately subsequent HTTR operation. This indicates no failure of the coated particle fuel, even after the increase in core temperature associated with the LOFC event. These results provide experimental evidence of the safety features of HTGRs.

Local and electronic structures of BaTiO/KNbO nanocomposite particles

Yoneda, Yasuhiro; Kobayashi, Toru; Tsuji, Takuya; Shibata, Goro; Takeda, Yukiharu*; Saito, Yuji; Khanal, G. P.*; Fujii, Ichiro*; Ueno, Shintaro*; Sato, Yukio*; et al.

Japanese Journal of Applied Physics, 64(8), p.08SP07_1 - 08SP07_8, 2025/08

https://doi.org/10.35848/1347-4065/adf4f1

It has become possible to synthesize high-quality composite nanoparticles in which a different material is grown on the surface of nanoparticle crystals. To evaluate such nanostructures, it is effective to combine different evaluation methods at various scales. We performed various structural and electronic state evaluations of BaTiO/KNbO nanocomposite particles using synchrotron radiation. From the structural evaluation, it was confirmed that the nanocomposite particles have a core of 100 nm of BaTiO covered with 20 nm of KNbO. The O-K absorption edge spectrum of the outermost surface KNbO was different from that of the bulk and nanoparticles, and it was found that the chemical bonding state changes when KNbO is made into composite particles.

U(VI) adsorption on mudstone in the presence of carbonate; Batch experiments, modeling, cryo-TRLFS and PARAFAC analysis

Mei, H.; Aoyagi, Noboru; Saito, Takumi*; Tanaka, Kazuya; Sugiura, Yuki; Tachi, Yukio

Applied Clay Science, 276, p.107944_1 - 107944_8, 2025/07

https://doi.org/10.1016/j.clay.2025.107944

Neutron diffraction study of the crystal and magnetic structures of antiferromagnetic manganese deuteride at high temperatures and high pressures

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

https://doi.org/10.1103/yf8k-cy61

The 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. Nel 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.

Electrocatalytic nitrous oxide reduction reaction at Sn-modified Pd-Pt single crystalline electrodes in acidic media

Kato, Masaru*; Zheng, J.*; Deng, Y.*; Saito, Fumie*; Unuma, Yuki*; Oka, Sayuki*; Tamura, Kazuhisa; Yagi, Ichizo*

ACS Catalysis, 15(10), p.7710 - 7719, 2025/04

https://doi.org/10.1021/acscatal.5c00379

Conceptual study of J-PARC Proton Beam Irradiation Facility

Meigo, Shinichiro; Iwamoto, Hiroki; Sugihara, Kenta*; Hirano, Yukinori*; Tsutsumi, Kazuyoshi*; Saito, Shigeru; Maekawa, Fujio

JAEA-Technology 2024-026, 123 Pages, 2025/03

JAEA-Technology-2024-026.pdf:14.22MB

Based on the design of the ADS Target Test Facility (TEF-T) at the J-PARC Transmutation Experimental Facility, a conceptual study was conducted on the J-PARC proton beam irradiation facility. This research was carried out based on the recommendations of the Nuclear Transmutation Technology Evaluation Task Force of the MEXT. The recommendations state that it is desirable to consider facility specifications that can make the most of the benefits of using the existing J-PARC proton accelerator while also solving the engineering issues of the ADS. We considered facilities that could respond to a variety of needs while reducing the facilities that were not needed in the TEF-T design. In order to clarify these diverse needs, we investigated the usage status of representative accelerator facilities around the world. As a result, it became clear that the main purposes of these facilities were (1) Material irradiation, (2) Soft error testing of semiconductor devices using spallation neutrons, (3) Production of RI for medical use, and (4) Proton beam use, and we investigated the facilities necessary for these purposes. In considering the facility concept, we assumed a user community in 2022 and reflected user opinions in the facility design. This report summarizes the results of the conceptual study of the proton irradiation facility, various needs and responses to them, the roadmap for facility construction, and future issues.

Development of high performance clarification system for spent MOX fuel reprocessing

Takeuchi, Masayuki; Takata, Takeshi; Saito, Keita*; Chikazawa, Takahiro*

Progress in Nuclear Science and Technology (Internet), 7, p.135 - 141, 2025/03

https://doi.org/10.15669/pnst.7.135

Control of insoluble sludge from fuel dissolution process is one of the important issues to secure the safety in reprocessing plant operation. In order to achieve the higher sludge recovery in the clarification stage, new clarification system which is an integrated technology of centrifugal device and filter unit has been developed for spent MOX fuel reprocessing. In this study, over-all clarification performance of this integrated system was evaluated on engineering scale. As results, total sludge recovery rate of more than 99.5 % was achieved in all test conditions by this system from the engineering test and this new clarification system showed excellent clarification performance. The sludge recovery rate of centrifugal device was influenced by test conditions and was in the range from 87 to 98 %. This study showed this technology is one of the promising clarification systems to improve the performance of sludge recovery greatly.

Stress and plastic strain partitioning behaviors and those contributions to martensitic transformation of retained austenite in medium manganese and transformation-induced plasticity-aided bainitic ferrite steels

Hojo, Tomohiko*; Koyama, Motomichi*; Kumai, Bakuya*; Zhou, Y.*; Shibayama, Yuki; Shiro, Ayumi*; Shobu, Takahisa; Saito, Hiroyuki*; Ajita, Saya*; Akiyama, Eiji*

ISIJ International, 65(2), p.284 - 296, 2025/02

https://doi.org/10.2355/isijinternational.ISIJINT-2024-268