Measurements of neutron capture cross-sections for nuclides of interest in decommissioning (V); Zr(n, )Zr and Zr(n, )Zr reactions at JRR-3

Nakamura, Shoji; Kimura, Atsushi; Endo, Shunsuke; Rovira Leveroni, G.; Shibahara, Yuji*

Journal of Nuclear Science and Technology, 63(6), p.653 - 666, 2026/06

https://doi.org/10.1080/00223131.2025.2586632

Assessing and tackling the barocaloric fatigue for applicable solid-state refrigeration

Xue, J.*; Huang, D.*; Hattori, Takanori; Li, L.*; Feng, Y.*; Wang, H.*; Fan, X.*; Yao, J.*; Wang, Y.*; Liu, Z.*; et al.

Applied Physics Letters, 128(20), p.201903_1 - 201903_8, 2026/05

https://doi.org/10.1063/5.0333322

The cycling fatigue and barocaloric response of NHI is directly assessed under loading--unloading cycles with stress up to 100,MPa, with the adiabatic temperature change () decaying from 15,K to approximately 0.8,K after 100 cycles. X-ray diffraction, Raman spectroscopy, and neutron diffraction concertedly reveal the existence of the residual high-pressure phase even after the first unloading, whose fraction is rapidly increased to 90% at the 100th cycle. A phenomenological model is developed to elucidate this fatigue behavior, and an excellent agreement with experimental data has been achieved. To relieve the intergranular stress and enhance the mobility of grains, we encapsulate the composite of NHI particles and silicone oil into a 3D-printed polymer shell. Such an architectural tailoring has markedly improved the cyclic stability of the barocaloric effect with rising to c.a. 4.6,K after 100 cycles. Our results establish a fundamental understanding of the barocaloric fatigue behavior and pave a feasible route to applicable barocaloric cooling technology.

Hydraulic modeling of saltwater infiltration with various concentrations into unsaturated bentonite-based buffer material

Takubo, Yusaku*; Takayama, Yusuke*; Sugita, Yutaka; Ogoshi, Minori; Ishida, Keisuke*

Environmental Earth Sciences, 85(9), p.229_1 - 229_19, 2026/05

https://doi.org/10.1007/s12665-026-12955-9

Construction of a Compton camera-equipped robotic system capable of moving autonomously towards the radiation source

Sato, Yuki; Kakuto, Takeshi*; Tanaka, Takayuki*; Shimano, Hiroyuki*

European Physical Journal; Special Topics, 235(4), p.949 - 958, 2026/04

https://doi.org/10.1140/epjs/s11734-025-01483-5

Highly water-permeable WO-containing porous hydrogel via freeze-crosslinking for efficiency and salt-robust dye Decolorization

Sugita, Tsuyoshi; Ueda, Yuki; Nakabe, Rintaro; Mori, Masanobu*; Nankawa, Takuya; Sekine, Yurina

Journal of Photochemistry and Photobiology A; Chemistry, 473, p.116773_1 - 116773_9, 2026/04

https://doi.org/10.1016/j.jphotochem.2025.116773

We developed a WO-embedded hydrogel (WFG) by freeze-cross-linking that retained high activity even in the presence of coexisting salts. Confocal laser scanning microscope revealed interconnected channels < 200 m. ensuring good water permeability, and contrast-matching small-angle neutron scattering showed that the secondary particle size of embedded WO (~300 nm) matched that in aqueous suspension. Under visible-light irradiation, WFG decolorized indigo carmine (INC) 1.5-fold increase in rate than suspended WO and 3.7-fold increase in rate than a WO-coated glass plate. Coexisting salts (NaNO, NaCl, NaSO, NaHPO) altered the decolorization efficiency; NaNO and NaSO enhanced, whereas Cl and HPO suppressed the reaction, indicating that ionic strength and anion-species affect contact efficiency and charge transfer.

Study of dissolved radon and optimization of Rn/At generator

Tanaka, Ko*; Shimizu, Yusuke*; Ida, Tomonori*; Washiyama, Koshin*; Nishinaka, Ichiro*; Asai, Masato; Segawa, Mariko; Yokoyama, Akihiko*

Radiochimica Acta, 114(3), p.221 - 229, 2026/04

https://doi.org/10.1515/ract-2025-0082

We are developing a Rn/At generator system to produce and deliver the medical radioisotope At. This study analyzed the dissolution of Rn in solution to investigate gas-phase recovery conditions of Rn in the Rn/At generator system. The dissolution of a Bi target in a nitric-hydrochloric acid mixture and subsequent neutralization has been shown to enhance the Rn recovery efficiency. The gas-phase Rn recovery rate reached 88%, while 50% of available At has been recovered, and further improvement can be expected in the future.

2D iron oxide at the graphene/SiC(0001) interface

Sakakibara, Ryotaro*; Terasawa, Tomoo; Kawauchi, Taizo*; Fukutani, Katsuyuki; Ito, Takahiro*; Norimatsu, Wataru*

Small Methods, 10(8), p.e01889_1 - e01889_12, 2026/04

https://doi.org/10.1002/smtd.202501889

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.

Synthesis report on the R&D for the Horonobe Underground Research Laboratory Project carried out between fiscal years 2020-2024

Nakayama, Masashi; Ishii, Eiichi; Aoyagi, Kazuhei; Hayano, Akira; Ono, Hirokazu; Ozaki, Yusuke; Mochizuki, Akihito; Takeda, Masaki; Kimura, Shun

JAEA-Research 2025-016, 141 Pages, 2026/03

JAEA-Research-2025-016.pdf:13.37MB

The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA). The main aim of the project is to enhance the reliability of relevant technologies for the geological disposal of high-level radioactive waste by investigating the deep geological environment within the host sedimentary rocks at Horonobe in Hokkaido, northern Japan. These investigations have been conducted in three phases: "Phase 1: Surface-based investigation", "Phase 2: Construction" (investigation during tunnel excavation) and "Phase 3: Operation" (investigation in subsurface facilities). Since the fiscal year 2020, we have been conducting R&D based on the Horonobe Underground Research Plan for the Fiscal Year 2020 Onwards, which was approved by Hokkaido Prefecture and Horonobe Town. In particular, we are working on the following key tasks with the aim of completing JAEA's 3rd and 4th Mid- and Long-Term Plans: "Study on near-field system performance in geological environments", "Demonstration of repository design options" and "Understanding of buffering behaviour of sedimentary rocks to natural perturbations". This report summarizes the R&D activities on the three above-mentioned key tasks, the goals of which were achieved between fiscal years 2020 and 2024. The results obtained from these tasks will be systematically organized as part of the "Systematic integration of technologies towards EBS emplacement" which has been in progress since fiscal year 2024. This task includes concepts related to the layout of galleries and pits, installation methods for engineered barrier materials, and methods for evaluating their containment performance.