Development of phenomenological degradation models for Cr-Coated Zr alloy cladding under high-temperature oxidation conditions

Taniguchi, Yoshinori; Luu, V. N.; Tasaki, Yudai; Udagawa, Yutaka; Katsuyama, Jinya

Annals of Nuclear Energy, 231, p.112177_1 - 112177_16, 2026/06

https://doi.org/10.1016/j.anucene.2026.112177

Potential and solution conductivity inside stainless steel crevices in a very dilute bulk solution

Soma, Yasutaka; Komatsu, Atsushi; Igarashi, Takahiro

Corrosion Science, 265, p.113182_1 - 113182_13, 2026/06

https://doi.org/10.1016/j.corsci.2026.113812

Collapse of Jahn-Teller phonons in LaSrMnO with weak magnetoresistance

Sterling, T. C.*; Savici, A. T.*; Kajimoto, Ryoichi; Ikeuchi, Kazuhiko*; Khan, N.*; Weber, F.*; Reznik, D.*

Communications Materials (Internet), 7, p.121_1 - 121_11, 2026/05

https://doi.org/10.1038/s43246-026-01139-4

Spontaneous magnetization curve of -iron at high pressures determined using neutron diffraction

Aoki, 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

https://doi.org/10.1103/vdnz-y1nk

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.

Hydrogen in the Earth core inferred from neutron imaging and diffraction

Takahashi, Naoki*; Sakamaki, Tatsuya*; Hattori, Takanori; Funakoshi, Kenichi*; Arima-Osonoi, Hiroshi*; Sano, Asami; Abe, Jun*; Suzuki, Akio*

Scientific Reports (Internet), 16, p.14162_1 - 14162_13, 2026/05

https://doi.org/10.1038/s41598-026-49969-z

We performed high-pressure and high-temperature neutron diffraction and imaging experiments in situ to determine the hydrogen content in liquid iron. We observed that liquid iron contains 0.17(3) wt.% H at 3.4 GPa and 1400 K, indicating that liquid iron is hydrogenated in the magma ocean during core formation. For the hydrogen content in the liquid iron at the base of the magma ocean, we estimated that the outer and inner cores contain 0.60-0.72 and 0.30-0.44 wt.% H, corresponding to 70-85 and 1.9-2.7 times the mass of hydrogen in the ocean, respectively. This suggests that hydrogen can contribute more than half of the density deficit in the outer core. For the magma ocean equilibrating with the hydrogen-rich primary atmosphere, the study findings show that liquid iron plays a crucial role in transporting a large amount of hydrogen into the core.

Long-term variations in I seawater concentrations off Fukushima and potential of 129I as an oceanographic tracer for ALPS-treated water

Suzuki, Takashi; Otosaka, Shigeyoshi*; Takata, Hyoe*; Kuwabara, Jun; Nakanishi, Takahiro; Ikenoue, Tsubasa

Environmental Science & Technology, 60(17), p.13123 - 13131, 2026/04

https://doi.org/10.1021/acs.est.5c18263

As a results of the 2011 Fukushima Daiichi Nuclear Power Plant accident, long-lived radioactive I has been released into the environment, with additional releases beginning in 2023 through ALPS-treated water. To study its long-term variation and potential as an oceanographic tracer, I concentrations in seawater off Fukushima were measured from 2012 to 2024. The highest concentration, 44510 Bq/L, was observed in 2013 near the plant. Levels have since declined toward the pre-accident value of 1.7610 Bq/L. Spatial and temporal changes in the I/Cs ratio indicate the influence of small water masses and support its use as a tracer in areas with complex ocean circulation.

Simple technique for the preparation of uranium-impregnated porous silica particles and their application as working standard particles for analysis of the safeguards environmental samples

Tomita, Jumpei; Tomita, Ryohei; Suzuki, Daisuke; Yasuda, Kenichiro; Miyamoto, Yutaka

Journal of Nuclear Science and Technology, 63(4), p.443 - 454, 2026/04

https://doi.org/10.1080/00223131.2025.2557376

Background aerial monitoring and UAV radiation monitoring technology development for emergency response and preparedness in the fiscal year 2024 (Contract research)

Futemma, Akira; Ochi, Kotaro; Sasaki, Miyuki; Nakama, Shigeo; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; Haginoya, Masashi*; Matsunaga, Yuki*; Sanada, Yukihisa; et al.

JAEA-Technology 2025-015, 171 Pages, 2026/03

JAEA-Technology-2025-015.pdf:11.43MB

On March 11, 2011, the 2011 off the Pacific coast of Tohoku Earthquake and tsunami caused the Fukushima Daiichi Nuclear Power Station accident, releasing radioactive material. Since then, Aerial Radiation Monitoring (ARM) with manned helicopters has been used to assess radiation distribution quickly. In FY2024, the Japan Atomic Energy Agency (JAEA), under commission from the Nuclear Regulation Authority, conducted ARM around the Shimane Nuclear Power Station, producing background dose rate maps validated against ground and other data. During a nuclear emergency drill, UAV training flights complemented manned monitoring, confirming the effectiveness of real-time communication and rapid mapping. The UAV data system was developed and demonstrated for real-time analysis and multi-platform use. Skill training for multicopters was also conducted to strengthen operational capability. Additionally, joint monitoring with the U.S., France, South Korea, and Canada provided insights into international technologies and practices, emphasizing the value of information sharing. This report summarizes the results and technical challenges from these FY2024 activities, contributing to the advancement of emergency radiation monitoring.

Annual report of Nuclear Science Research Institute, JFY 2024

Nuclear Science Research Institute

JAEA-Review 2025-061, 183 Pages, 2026/03

JAEA-Review-2025-061.pdf:4.01MB

Nuclear Science Research Institute (NSRI) was composed of Planning and Management Department and six departments, namely Department of Operational Safety Administration, Department of Radiation Protection, Engineering Services Department, Department of Research Reactor and Tandem Accelerator, Department of Criticality and Hot Examination Technology, and Department of Decommissioning and Waste Management, and each department manages facilities and develops related technologies to achieve the "Medium- to Long-term Plan" successfully and effectively. On November 1, NSRI unified Department of Research Reactor and Tandem Accelerator, and Department of Criticality and Hot Examination Technology, newly organized Department of Research Infrastructure Technology Development. And, Planning and Management Department was reorganized to Promotion Office. Continuously, four research centers which are Advanced Science Research Center, Nuclear Science and Engineering Center, Nuclear Engineering Research Collaboration Center and Materials Sciences Research Center, belong to NSRI. In order to contribute to future research and development, and to promote management business, this annual report summarizes information on the activities of NSRI of JFY 2024 as well as the activity on research and development carried out by Collaborative Laboratories for Advanced Decommissioning Science, Nuclear Safety Research Center and activities of Nuclear Human Resource Development Center, using facilities of NSRI.

Risk communication activity which used "YUME Chisoukan" in the Horonobe Underground Research Center (FY 2024)

Hoshino, Masato; Sasaki, Yoshifumi; Horikoshi, Hidehiko*; Tani, Kosuke*

JAEA-Review 2025-047, 122 Pages, 2026/03

JAEA-Review-2025-047.pdf:3.75MB

Horonobe Underground Research Center managed by Japan Atomic Energy Agency (JAEA) is the Japan's best environment to understand the project of geological disposal of high-level radioactive waste, because there is an Underground Research Laboratory (URL) in the center besides an exhibition facility which explains the content of research conducted in the URL. In the area of the center, there is also an exhibition facility for the full-scale model of engineered barrier system of geological disposal. JAEA takes advantage of this opportunity to conduct public hearing including questionnaire research regarding the questions, anxieties and comments by the visitors for geological disposal project. This report summarizes the result of statistical analysis of 2,830 visitors from April 2024 to January 2025.