Irradiation test using foreign reactor, 2; Study of irradiation test with capsule temperature control system (Joint research)

Omori, Takazumi; Fuyushima, Takumi; Sayato, Natsuki; Saito, Nagatsuki; Takabe, Yugo; Endo, Yasuichi; Inoue, Shuichi; Wojtania, G.*; Migdal, M.*; Takeuchi, Tomoaki; et al.

JAEA-Technology 2026-006, 47 Pages, 2026/06

JAEA-Technology-2026-006.pdf:3.01MB

Japan Materials Testing Reactor (JMTR), which served as the core facility for neutron irradiation research including materials research and radioisotope production, has been decommissioned. As a result, it has become difficult to continue conducting irradiation tests domestically, as well as to transfer the operational expertise and irradiation technologies associated with test reactors, to address these challenges, it was decided to initiate JMTR alternative irradiation, in which foreign irradiation reactors are utilized to partially substitute for JMTR's irradiation capabilities. As a first step, based on the "Arrangement between the National Centre for Nuclear Research and the Japan Atomic Energy Agency for Cooperation in Research and Development on Testing Reactor". The MARIA reactor (30 MW) owned by the National Centre for Nuclear Research (NCBJ) was selected as the neutron irradiation facility, a temperature control system, which is one of JMTR's irradiation technologies, was introduced into the MARIA reactor, and irradiation tests were conducted. The results of this irradiation test confirmed that the combination of the newly introduced temperature control device and the JMTR irradiation test system operates without issues even after an irradiation period exceeding 150 days, it was also demonstrated that the tests could be conducted while continuously measuring the thermocouple temperature inside the capsule during irradiation, as well as the output of the LVDT and SPGD. Furthermore, regarding the constant temperature control of the irradiation capsule at 300C constant temperature control test, which is highly demanded in materials irradiation testing, was conducted, during reactor power increases, when temperature fluctuations become significant, temperature control was maintained within 6.3C, while during power decreases, it was controlled within 26.0C. These results indicate that irradiation testing with irradiation temperature control system developed by JMTR, can also be performed in the MARIA reactor, it was confirmed that it can be offered as an alternative irradiation field.

Post Irradiation Examination (PIE) Facility for R&D of ADS and high-power target materials at J-PARC

Saito, Shigeru; Meigo, Shinichiro; Makimura, Shunsuke*; Hirano, Yukinori*; Tsutsumi, Kazuyoshi*; Maekawa, Fujio

JPS Conference Proceedings (Internet), 45, p.011177_1 - 011177_9, 2026/06

https://doi.org/10.7566/JPSCP.45.011177

A proton irradiation facility is under consideration at J-PARC to study the irradiation effects of candidate structural materials for accelerator-driven systems (ADS) and high-power target materials. In the facility, irradiation tests in liquid lead-bismuth eutectic (LBE) alloys will be performed for the candidate structural materials. Post irradiation examination (PIE) of irradiated samples will be carried out in the PIE facility to be constructed near the proton irradiation facility. In the PIE facility, PIE of the samples irradiated in the other facilities in J-PARC and in overseas accelerator facilities will also be performed. In this presentation, first, the conceptual study of the PIE facility, including the items to be tested and the test flow will be described. And then, the specifications and quantities of the facilities and the test equipment required to perform these test items will be shown. Finally, the layout of the PIE facility will be proposed.

Study on Tc separation/concentration technology from Mo by (n,) method, 4

Suematsu, Hisayuki*; Yang, Y.*; Ito, Akito*; Le, A. V.*; Su, Y.*; Kato, Suzuna*; Do, T. M. D.*; Suzuki, Tatsuya*; Osawa, Naoki*; Fujita, Yoshitaka; et al.

KURNS Progress Report 2025, P. 118, 2026/06

https://adm.rri.kyoto-u.ac.jp/pub/progressrep2/

no abstracts in English

Progressive release of long-stored carbon from tropical peatland disturbances

Koarashi, Jun; Ito, Masayuki*; Atarashi-Andoh, Mariko; Kokubu, Yoko; Matsueda, Makoto; Kusin, K.*; Jaya, A.*; Dohong, S.*; Hirano, Takashi*

Nature Communications (Internet), 17, p.4369_1 - 4369_9, 2026/05

https://doi.org/10.1038/s41467-026-72890-y

Tropical peatlands are globally important, millennia-old carbon sinks, yet unprecedented human-driven degradation is triggering alarming carbon emissions. Comprehensive quantification of carbon dynamics across the disturbance sequence, from peat swamp forests to drained and fire-impacted peatlands, remains a critical knowledge gap. Here we show that over 18 years (1996-2014), drainage and subsequent peat fires released approximately 30-41 kg C m from peatlands in Central Kalimantan, Indonesia, using radiocarbon dating of peat profiles and groundwater dissolved organic carbon. Drainage contributed 5-11 kg C m, primarily from centuries- to millennium-old, previously waterlogged peat. Fires released 23-32 kg C m from peat accumulated over the past 3,000 years, initiating progressive oxidative decomposition of older peat. Extrapolation to Indonesia's disturbed peatlands suggests a release of 0.81-3.70 Gt between 1996 and 2014, with ongoing decomposition releasing an additional 0.03-0.08 Gt C annually, accelerating the impact on the global carbon balance.

Magnetization process of the layered diluted ferromagnetic semiconductor (Ba,K)(Zn,Mn)As studied by X-ray magnetic circular dichroism

Wan, Y.*; Shibata, Goro; Takeda, Yukiharu*; Okane, Tetsuo; Saito, Yuji; Yamagami, Hiroshi; Fujimori, Atsushi*; 10 of others*

Physical Review Materials (Internet), 10(5), p.054402_1 - 054402_8, 2026/05

https://doi.org/10.1103/69sm-fz7z

Aerial monitoring around TEPCO's Fukushima Daiichi Nuclear Power Station and development of radiation monitoring technology for unmanned vehicle in fiscal year 2024 (Contract research)

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

JAEA-Technology 2025-016, 253 Pages, 2026/03

JAEA-Technology-2025-016.pdf:20.16MB

Aerial Radiation Monitoring (ARM) has been used to quickly and widely measure radiation distribution caused by the TEPCO's Fukushima Daiichi Nuclear Power Station (FDNPS) accident resulted from the tsunami accompanying the Pacific coast of Tohoku Earthquake on March 11, 2011. Since the accident, As a commissioned project of the Nuclear Regulation Authority, the Japan Atomic Energy Agency (JAEA) has continuously conducted ARM around FDNPS. This report summarizes the results of the 2024 monitoring activities, evaluates temporal changes in ambient dose rates, and identifies factors contributing to these changes. A terrain-corrected analysis was applied to improve dose rates conversion accuracy, and results with and without this correction were compared. A radon-progeny discrimination method was also used to assess its impact on manned-helicopter measurements. Furthermore, development of unmanned airplane monitoring technologies was advanced to enhance the efficiency of wide-area surveys.

Effects of non-decontamination human activities on the reduction of ambient dose equivalent rates in residential areas near the Fukushima Daiichi Nuclear Power Plant

Kim, M.; Yoshimura, Kazuya; Sakuma, Kazuyuki; Malins, A.*; Abe, Tomohisa; Nakama, Shigeo; Machida, Masahiko; Saito, Kimiaki

Journal of Environmental Radioactivity, 294, p.107931_1 - 107931_8, 2026/03

https://doi.org/10.1016/j.jenvrad.2026.107931

This study quantitatively evaluated the effects of non-decontamination human activities, such as traffic, on ambient dose rates in residential areas near the Fukushima Daiichi Nuclear Power Plant through field measurements and simulations. Field surveys showed that areas with higher traffic had greater reductions in Cs deposition, suggesting that vehicular movement may enhance cesium weathering. Monte Carlo simulations using 3D-ADRES confirmed that human activities accelerate the decrease in ambient dose rates on paved surfaces, with reductions of up to approximately 50%. These results indicate that non-decontamination human activities significantly contribute to lowering ambient dose rates.

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

Proceedings of the 10th "Conference for R&D Initiative on Nuclear Decommissioning Technology by the Next Generation"

Usami, Hiroshi; Ito, Rintaro; Sanada, Yukihisa

JAEA-Review 2025-050, 57 Pages, 2026/02

JAEA-Review-2025-050.pdf:17.19MB

The decommissioning of the TEPCO's Fukushima Daiichi Nuclear Power Station is a long-term project, and the training of young engineers and researchers who will be responsible for future decommissioning is a necessary and urgent task. Since 2016, Collaborative Laboratories for Advanced Decommissioning Science has been continuously organizing "Conference for R&D Initiative on Nuclear Decommissioning Technology by the Next Generation (NDEC)" for students who are engaged in research activities for decommissioning. NDEC is a forum for students to present their research for the purpose of human resource development and networking among young researchers, and to increase their motivation for decommissioning research. NDEC-10 was held at "Plaza-Bansho" in Tsuruga-City, Fukui Prefecture, from February 26 - 27, 2025. This proceeding compiles the contents of report papers in the conference.

Effect of nanoscale cellular structure on the mechanical properties of Inconel 718 with unique hierarchical structure fabricated by laser powder bed fusion

Cho, K.*; Yamashita, Kippei*; Kakutani, Shinnosuke*; Saito, Takuma*; Sasaki, Taisuke*; Sawaizumi, Katsuhiko*; Okugawa, Masayuki*; Koizumi, Yuichiro*; Mayama, Tsuyoshi*; Kikukawa, Taichi*; et al.

Acta Materialia, 303, p.121696_1 - 121696_18, 2026/01

https://doi.org/10.1016/j.actamat.2025.121696