Enhanced work hardening in ferrite and austenite of duplex stainless steel at 200 K; neutron diffraction study

Yamashita, Takayuki*; Koga, Norimitsu*; Mao, W.*; Gong, W.; Kawasaki, Takuro; Harjo, S.; Fujii, Hidetoshi*; Umezawa, Osamu*

Materials Science and Engineering A, 941, p.148602_1 - 148602_11, 2025/09

https://doi.org/10.1016/j.msea.2025.148602

Experimental investigation of phase transformations in steel using X-ray and neutron diffraction

Tomota, Yo*; Harjo, S.; Xu, P. G.; Morooka, Satoshi; Gong, W.; Wang, Y.*

Metals, 15(6), p.610_1 - 610_19, 2025/05

https://doi.org/10.3390/met15060610

Modeling of coupled processes in full-scale engineered barrier system performance experiment at Horonobe Underground Research Laboratory, Japan

Ono, Hirokazu; Takayama, Yusuke*

Geomechanics for Energy and the Environment, 41, p.100636_1 - 100636_14, 2025/03

https://doi.org/10.1016/j.gete.2025.100636

In-situ measurement of radiation driven back-conversion from para to ortho liquid hydrogen state in cold moderators at J-PARC

Teshigawara, Makoto; Lee, Y.*; Tatsumoto, Hideki*; Hartl, M.*; Aso, Tomokazu; Iverson, E. B.*; Ariyoshi, Gen; Ikeda, Yujiro*; Hasegawa, Takumi*

Nuclear Instruments and Methods in Physics Research B, 557, p.165534_1 - 165534_10, 2024/12

https://doi.org/10.1016/j.nimb.2024.165534

At Japanese Spallation Neutron Source in J-PARC, the para-hydrogen fraction was measured by using Raman spectroscopy in-situ for an integrated beam power of 9.4 MWh at 1 MW operation, to evaluate the functionality of the ferric oxyhydroxide catalyst. This result showed that full functionality of the catalyst was retained up to the 1 MW operation. We attempted to study the effect of neutron scattering driven para to ortho-hydrogen back-conversion rate in the absence of the catalyst effect with a bypass line without catalyst. The measured increase of ortho-hydrogen fraction was 0.44% for an integrated beam power of 2.4 MWh at 500 kW operation, however, which was considered to be due to not only to neutron collisions in cold moderators but also to the high ortho-hydrogen fraction of initially static liquid hydrogen in the bypass line and passive exudation of quasi-static hydrogen in the catalyst vessel to the main loop.

Pearlite growth kinetics in Fe-C-Mn eutectoid steels; Quantitative evaluation of energy dissipation at pearlite growth front via experimental approaches

Zhang, Y.-J.*; Umeda, Takemasa*; Morooka, Satoshi; Harjo, S.; Miyamoto, Goro*; Furuhara, Tadashi*

Metallurgical and Materials Transactions A, 55(10), p.3921 - 3936, 2024/10

https://doi.org/10.1007/s11661-024-07518-1

In-situ neutron diffraction study of serration-involved ultra-cryogenic deformation behavior at 15 K

Kim, Y. S.*; Chae, H.*; Lee, D.-Y.*; Han, J. H.*; Hong, S.-K.*; Na, Y. S.*; Harjo, S.; Kawasaki, Takuro; Woo, W.*; Lee, S.-Y.*

Materials Science & Engineering A, 899, p.146453_1 - 146453_7, 2024/05

https://doi.org/10.1016/j.msea.2024.146453

Interactive steering on in situ particle-based volume rendering framework

Kawamura, Takuma; Hasegawa, Yuta; Idomura, Yasuhiro

Journal of Visualization, 27(1), p.89 - 107, 2024/02

https://doi.org/10.1007/s12650-023-00945-z

Interactive in-situ steering is an effective tool for debugging, searching for optimal solutions, and analyzing inverse problems in fast and large-scale computational fluid dynamics (CFD) simulations. We propose an interactive in-situ steering framework for large-scale CFD simulations on GPU supercomputers. This framework employs in-situ particle-based volume rendering (PBVR), in-situ data sampling, and a file-based control that enables interactive communication of steering parameters, compressed particle data, and sampled monitoring data between supercomputers and user PCs. The parallelized PBVR is processed on the host CPU to avoid interference with CFD simulations on the GPU. We apply the proposed framework to a real-time plume dispersion analysis code CityLBM on GPU supercomputers. In the numerical experiment, we address an inverse problem to find a pollutant source from the monitoring data, and demonstrate the effectiveness of the human-in-the-loop approach.

Deformation-induced martensitic transformation at tensile and compressive deformations of bainitic steels with different carbon contents

Ueji, Rintaro*; Gong, W.; Harjo, S.; Kawasaki, Takuro; Shibata, Akinobu*; Kimura, Yuji*; Inoue, Tadanobu*; Tsuchida, Noriyuki*

ISIJ International, 64(2), p.459 - 465, 2024/01

https://doi.org/10.2355/isijinternational.ISIJINT-2023-253

Deformation mechanism of a strong and ductile maraging steel investigated using X-ray synchrotron diffraction

Li, H.*; Liu, Y.*; Zhao, W.*; Liu, B.*; Tominaga, Aki; Shobu, Takahisa; Wei, D.*

International Journal of Plasticity, 165, p.103612_1 - 103612_20, 2023/06

https://doi.org/10.1016/j.ijplas.2023.103612

In order to clarify the strength properties of Co-free maraging steel, tensile experiment using high energy synchrotron X-ray diffraction was performed. Diffraction profiles from the martensitic and austenitic phases were obtained, and their strength and width were observed to vary as loading. Analysis of the diffraction profiles showed that the content of martensite in the as-aged material decreased slowly at low stress levels and decreased rapidly at high stress levels. On the other hand, the austenite phase in the as-solution materials was significantly transformed the martensite phase as the stress increased. It was clarified to be responsible for their respective strength properties.

Development of an continuous air monitor for the measurement of highly radioactive alpha-emitting particulates (-aerosols) under high humidity environment

Tsubota, Yoichi; Honda, Fumiya; Tokonami, Shinji*; Tamakuma, Yuki*; Nakagawa, Takahiro; Ikeda, Atsushi

Nuclear Instruments and Methods in Physics Research A, 1030, p.166475_1 - 166475_7, 2022/05

https://doi.org/10.1016/j.nima.2022.166475

In the long-lasting decommissioning of the Fukushima Daiichi Nuclear Power Station (1F), the dismantling of nuclear fuel debris (NFD) remaining in the damaged reactors is an unavoidable but significant issue with many technical difficulties. The dismantling is presumed to involve mechanical cutting, generating significant concentrations of particulates containing -radionuclides (-aerosols) that pose significant health risk upon inhalation. In order to minimize the radiation exposure of workers with -aerosols during the dismantling/decommissioning process at 1F, it is essential to monitor the concentration of -aerosols at the point of initial generation, i.e. inside the primary containment vessels (PCV) of the damaged reactors. Toward this end, an monitoring system for -aerosols ( alpha air monitor: IAAM) was developed and its technical performance was investigated under the conditions expected for the actual environments at 1F. IAAM was confirmed to fulfill four technical requirements: (1) steady operation under high humidity, (2) operation without using filters, (3) capability of measuring a high counting rate of -radiation, and (4) selective measurement of -radiation even under high radiation background with /-rays. IAAM is capable of selectively measuring -aerosols with a concentration of 3.3 10 Bq/cm or higher without saturation under a high humid environment (100%-relative humidity) and under high background with /-radiation (up to 100 mSv/h of -radiation). These results demonstrate promising potential of IAAM to be utilized as a reliable monitoring system for -aerosols during the dismantling of NFD, as well as the whole long-lasting decommissioning of 1F.