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Zhang, Y.*; Marusawa, Kenji*; Kudo, Kohei*; Morooka, Satoshi; Gong, W.; Harjo, S.; Miyamoto, Goro*; Furuhara, Tadashi*
Journal of Materials Science & Technology, 275, p.250 - 259, 2026/12
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)Soma, Yasutaka; Komatsu, Atsushi; Igarashi, Takahiro
Corrosion Science, 265, p.113182_1 - 113182_13, 2026/06
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)
neutron diffraction experimentsTsuchida, Noriyuki*; Fujita, Akinori*; Hirakawa, Naoki*; Hamada, Junichi*; Ishimaru, Eiichiro*; Gong, W.; Kawasaki, Takuro; Harjo, S.
Materials Characterization, 236, p.116436_1 - 116436_13, 2026/06
Zhou, D.*; Zhang, X.*; Pang, X.*; Zhao, Z.*; Chen, X.*; Wei, S.*; Yang, C.*; Gong, W.; Harjo, S.; Li, R.*; et al.
Materials Research Letters (Internet), 14(6), p.689 - 698, 2026/06
-iron at high pressures determined using neutron diffractionAoki, Katsutoshi*; Takano, Masahiro*; Fukuyama, Ko*; Kagi, Hiroyuki*; Machida, Akihiko*; Saito, Hiroyuki*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*
Physical Review B, 113(18), p.184440_1 - 184440_6, 2026/05
Times Cited Count：1 Percentile：86.01(Materials Science, Multidisciplinary)The temperature dependence of the magnetic moment of bcc -iron was investigated over the range 300-950 K at pressures of approximately 2 and 6 GPa by neutron powder diffraction. The 
Fe isotope, whose neutron scattering length is approximately half that of naturally abundant Fe, was employed to enhance the relative contribution of magnetic scattering. Curie temperatures (
) were determined to be 946(30) K, 838(50) K and 740(40) K at 2.1, 6.0 and 6.7 GPa, respectively, defining a magnetic phase boundary described by (K) = 1043 - 49(7)
+ 1.3(1.2)
. Upon heating at 6.7 GPa, the 
structural transition was observed to follow the magnetic transition. This transition sequence indicates that the magnetic phase boundary lies on the low-temperature side of the phase boundary. Accordingly, the transition corresponds to a structural transformation from paramagnetic bcc to paramagnetic fcc iron.
Noseck, U.*; Sch
fer, T.*; Alonso, U.*; Hamamoto, Takafumi*; Havlova, V.*; Hibberd, R.*; Ishidera, Takamitsu; Kitamura, Akira; Klajmon, M.*; Missana, T.*; et al.
Applied Geochemistry, 201, p.106762_1 - 106762_23, 2026/04
Times Cited Count：0 Percentile：0.00(Geochemistry & Geophysics)Thermodynamic benchmark calculations have been performed to better understand the behavior of 
Se(VI), 
Tc(VII), 
U(VI), 
Np(V), 
Am(III), Th(IV) and 
Pu(IV)) in the evolving geochemical conditions of the Long-term In-situ Test (LIT) at the Grimsel Test Site (GTS) and corresponding mock-up experiment. It also aims to identify the status of the geochemical speciation models and databases for these elements. The experiments are simulating the near-field conditions in some radioactive waste repository concept including a bentonite engineered barrier emplaced in crystalline rock and the findings are contributing to the long-term safety assessment of these facilities.
neutron diffraction mapping measurementYamashita, Takayuki*; Nagira, Tomoya*; Gong, W.; Kawasaki, Takuro; Harjo, S.; Ushioda, Kosaku*; Fujii, Hidetoshi*
ISIJ International, 66(5), p.673 - 684, 2026/04
Times Cited Count：0 Percentile：0.00(Metallurgy & Metallurgical Engineering)Kawamura, Takuma; Shimomura, Kazuya; Idomura, Yasuhiro
Journal of Advanced Simulation in Science and Engineering (Internet), 13(1), p.29 - 43, 2026/04
This paper proposes a virtual reality (VR)-based in-situ control framework called VR IS-PBVR for simulations in computational fluid dynamics. This framework enables users to observe simulation results in an immersive VR environment while the simulation runs on a supercomputer and interactively adjust simulation conditions based on the visualization results. VR IS-PBVR enables in-situ control without disrupting simulation execution by utilizing compressed visualization particles and file-based communication. Furthermore, by extending the KVS visualization library, which forms the basis of VR IS-PBVR, with OpenXR, we achieved an implementation compatible with general-purpose head-mounted displays. The effectiveness of this framework is demonstrated through an urban wind simulation using OpenFOAM. This example shows that combining immersive VR visualization with interactive steering enables more intuitive understanding and analysis of behavior during simulation execution.
and A
value ratios for off-site transportation of small-amount of fuel debris retrieved from the Fukushima Daiichi Nuclear Power StationSakamoto, Masahiro; Okumura, Keisuke; Kanno, Ikuo; Matsumura, Taichi; Riyana, E. S.; Terashima, Kenichi; Kaneko, Junichi*; Mizokami, Masato*; Mizokami, Shinya*
Radioisotopes, 75(S-01), p.S-001_1 - S-001_5, 2026/04
Sakakibara, Ryotaro*; Terasawa, Tomoo; Kawauchi, Taizo*; Fukutani, Katsuyuki; Ito, Takahiro*; Norimatsu, Wataru*
Small Methods, 10(8), p.e01889_1 - e01889_12, 2026/04
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)Group for Fukushima Mapping Project
JAEA-Technology 2025-013, 206 Pages, 2026/03
JAEA-Technology-2025-013.pdf:34.64MB
This report presents results of the investigations on the distribution-mapping project of radioactive substances conducted in FY2024. Car-borne and walk surveys, a measurement using survey meters, and an unmanned helicopter survey were carried out to obtain air dose rate data on land to create their distribution maps, and temporal changes of those air dose rates were analyzed. In order to confirm the applicability of unmanned aircraft to monitoring in mountainous areas, a basic performance of unmanned aircraft was investigated in mountainous areas. Surveys on depth profile of radiocesium and in-situ measurements as for radiocesium deposition were performed. These measurement results were published on the WEB site. Based on these measurement results, effective half-lives of the temporal changes in the air dose rates and the deposition were evaluated. Using the Bayesian hierarchical modeling approach, we obtained maps that integrated air dose rate distribution data acquired through surveys such as car-borne and walk surveys. Radiation monitoring and analysis of environmental samples owing to the comprehensive radiation monitoring plan were carried out. Representative life patterns that can be expected after the return to the evacuation-designated restricted area were set, and the cumulative exposure doses were evaluated for the local governments and residents in the area. Score maps to classify the importance of the measurement points were created, and the temporal changes in the score were analyzed. A system to report the tritium concentration level in seawater to the Nuclear Regulation Authority was operated, and the variation of tritium concentration before and after the discharge of ALPS treated water to the ocean was analyzed. Monitoring data in coastal area performed owing to the comprehensive radiation monitoring plan until FY2024 was analyzed.
Terasawa, Tomoo; Katsube, Daiki*; Yano, Masahiro; Ozawa, Takahiro*; Tsuda, Yasutaka; Yoshigoe, Akitaka; Asaoka, Hidehito; Suzuki, Seiya
Chemistry of Materials, 38(6), p.2933 - 2945, 2026/03
Times Cited Count：0 Percentile：0.00(Chemistry, Physical) neutron diffraction at cryogenic temperaturesYamashita, Takayuki*; Harjo, S.; Gong, W.; Kawasaki, Takuro; Morito, Shigekazu*; Morooka, Satoshi; Fujii, Hidetoshi*; Tomota, Yo*
Journal of Alloys and Compounds, 1056, p.186668_1 - 186668_11, 2026/02
underwater radiation monitoring detectorJi, W.*; Lee, E.*; Ji, Y.-Y.*; Ochi, Kotaro; Yoshimura, Kazuya; Funaki, Hironori; Sanada, Yukihisa
Nuclear Engineering and Technology, 58(2), p.103933_1 - 103933_6, 2026/02
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)We aimed to validate the performance of an in situ underwater radiation detector, MARK-U1 (Monitoring of Ambient Radiation of KAERI - Underwater), was used to estimate 
Cs activity concentration in river and reservoir sediment at predicted sites of contamination. Additionally, underwater core samples were collected to measure the radioactivity using a high-purity germanium (HPGe) detector. To estimate radioactivity, a conversion factor was derived by comparing the measured spectrum and Cs activity in the sample. A Monte Carlo N-Particle (MCNP) simulation was conducted to determine the effective source geometry for in situ measurement. The simulation results correlated well with the on-site MARK-U1 monitoring results, with a deviation of 31.62%. These findings validate the performance of the in situ detector. This device can therefore be used to estimate Cs activity concentration in the underwater sediment via on-site monitoring, without requiring sample collection.
Tokumitsu, Shun*; Matsumiya, Masahiko*; Sasaki, Yuji
Separation and Purification Technology, 382(Part 2), p.135631_1 - 135631_9, 2026/02
Times Cited Count：0 Percentile：0.00(Engineering, Chemical)Maruyama, Shuhei; Yamamoto, Akio*; Endo, Tomohiro*
Journal of Nuclear Science and Technology, 63(1), p.31 - 44, 2026/01
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Iwasawa, Yuzuru; Shibamoto, Yasuteru; Maruyama, Yu
Nuclear Engineering and Design, 446(Part B), p.114599_1 - 114599_16, 2026/01
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Yoneyama, Kai; Nitta, Ayako; Tanaka, Yasuyuki; Kodaka, Noriyasu; Kikuchi, Riku; Sakano, Takuma; Furuse, Takahiro; Sato, Soichi; Sambongi, Mitsuru; Tanaka, Kosuke
JAEA-Technology 2025-008, 44 Pages, 2025/12
JAEA-Technology-2025-008.pdf:4.3MB
At the TEPCO's Fukushima Daiichi Nuclear Power Station (1F), an investigation inside the reactors has been carried out. In order to safely carry out the decommissioning work such as fuel debris retrieval and building demolition, it is important to estimate the contamination in primary containment vessel for control the decommissioning planning and the worker radiation exposure levels. Therefore, the analysis of the deposit inside the penetration for the 1F Unit 2 primary containment vessel ("X-6 penetration") was performed to clarify the components and activity. The smears from the deposit were used for the analysis. Non-destructive analysis such as gamma-ray spectrometry, X-ray Fluorescence (XRF) and Scanning Electron Microscope-Energy dispersive X-ray spectroscopy (SEM-EDX) for the smear-samples were performed to determine the gamma-nuclides and the morphology of elements in the deposit. Furthermore, in order to evaluate the nuclides and nuclide composition of the deposit in detail, the smear-samples were dissolved and the quantitative analysis of gamma-nuclides, Sr-90, alpha-nuclides in the dissolved solution were conducted. The results (non-destructive analysis and quantitative analysis) were compared with the results of samples collected at different locations in the X-6 penetration in 2020. In the gamma-ray spectrometry as non-destructive analysis where the smears were analyzed directly, Co-60, Sb-125, Cs-134, Cs-137, Eu-154, Eu-155 and Am-241 were detected. In XRF results, Fe originating from construction material was detected as a major element and small amount of U and Zr originating from the fuel and fuel cladding were also detected. In SEM-EDX results, O and Fe were found as a major element of the deposit and U particles coexisting with Fe, Si, Cr, Ni and Zr were also found. These results were consistent with the SEM-EDX results of the samples collected in 2020. In radioactivity analysis, quantitative values for gamma-nuclides (Co-60, Sb-125, Cs-134, Cs-137, Eu-154, Eu-155), Sr-90, Pu-238, Pu-239+240, Am-241, Cm-244, U-235 and U-238 were obtained. Using the results, the ratios of radioactivity based on Cs-137 and U-238 were calculated. Both sets of the ratios were compared to the calculated value of the Unit 2 fuel composition from ORIGEN.
Collaborative Laboratories for Advanced Decommissioning Science; Hokkaido University*
JAEA-Review 2025-037, 103 Pages, 2025/12
JAEA-Review-2025-037.pdf:7.28MB
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2023. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2023, this report summarizes the research results of the "A study on the methodology for rational treatment/disposal of contaminated concrete waste considering volume reduction of waste" conducted in FY2023. The present study aims to evaluate rational waste management strategies incorporating reuse and recycling focusing on radioactive concrete waste, which will be massively generated from dismantling. Feasibility and challenges of aggregate recycling are considered assuming a typical recycled aggregate production technique, based on the characteristics of the concrete. In 2023, the migration behaviors of radionuclides and ions in cementitious materials having interfacial transition zones (ITZ) were investigated through diffusion and leaching experiments using radioactive and non-radioactive tracers and modeled by random walk particle tracking method with a sampling technique using a probabilistic distribution model for two media with an interface. Properties of surrogate contaminated concrete samples prepared by immersing in Cs solution were examined. Migration of ions was studied for surrogate contaminated aggregates and recycled concrete using the surrogate. In addition, surrogate waste package was prepared using by-product powder to study mechanical and chemical properties as well as leaching behavior of radionuclides. Information on properties of the contaminated concrete and tools to estimate the amount of concrete were organized in order to evaluate different waste management scenarios incorporating reuse/recycling.
