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Prihutami, P.*; Toda, Kanako*; Chaerun, R. I.; Oya, Yusuke*; Kikuchi, Ryosuke*; Otake, Tsubasa*; Sato, Tsutomu*; Saito, Takumi*
Applied Clay Science, 292, p.108330_1 - 108330_9, 2026/11
Times Cited Count：0Limited understanding of zinc (Zn) immobilization in altered geopolymers limits prediction of waste-form durability. This study examined the local structure and retention mechanism of Zn in a metakaolin-based potassium geopolymer by X-ray absorption spectroscopy (XAS). Zn-bearing samples were prepared from metakaolin, zinc chloride (ZnCl
) solution, potassium silicate, and potassium hydroxide, cured at 40
C and 25C for 48 h, and leached in deionized water for up to 90 days. Zn release was only 0.14%, with limited Al, Si, and Cl release. The main geopolymer framework was preserved after leaching. XAS showed that Zn was initially tetrahedrally coordinated with oxygen and linked to Si or Al tetrahedra. After leaching, Zn changed to octahedral coordination and formed a brucite-like Al-bearing co-precipitate, indicating strong Zn retention despite local structural alteration.
alteration phases under chemically complex conditionsMei, H.*; Aoyagi, Noboru; Takaki, Seiya; Saito, Takumi*
Journal of Hazardous Materials, 514, p.142804_1 - 142804_11, 2026/08
Times Cited Count：0Omori, 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.
Harada, Masahide; Tajima, Takahiro*; Ito, Taku*; Masuda, Shiho; Kinoshita, Hidetaka; Sakai, Kenji; Muto, Giichi*; Suzuki, Akio*; Haga, Katsuhiro
JPS Conference Proceedings (Internet), 45, p.011053_1 - 011053_5, 2026/06
At Materials and Life science experimental Facility (MLF) in J-PARC, a mercury target of an intense pulsed spallation neutron source is designed to be irradiated by 3 GeV and 1MW proton beams to provide high intensity neutron beams to a suit of neutron instruments. A unified mercury radioactivity monitor (UHAM) is installed to find an indication of failure of the mercury target and loop system by detecting radioactive materials leaked from the system with a gamma-ray energy analysis with Germanium semi-conductor detectors. It is composed of three units of sampling port and radiation monitors: 1) HAM for interstitial helium gas layer between the mercury vessel and surrounding water shroud of the mercury target, 2) CAM for atmosphere in the hot cell where the target loop is operated and 3) VAM for helium gas in the helium vessel where the target vessel is installed. Once any leakages of radioactive materials are detected, an alarm signal is issued immediately to the accelerator control system to stop beam operation. Software and hardware have been upgraded yearly. For example, two Ge detectors are used for HAM for redundancy, NaI Scintillation detectors are also used as supplemental for the Ge detector to keep availability of the system for high counting rate event. In addition, A gas monitor is equipped at CAM to detect tritium. Until now, several operation experiences could be obtained as the follwoing. 1) Xe-121 and Xe-123 gas could be detected at CAM. These radio-active gaseous radioactive nuclides are slightly leaked from cover gas of mercury target. 2) Humidity in the helium vessel could be detected at VAM, because detection of annihilation gamma-ray and N-15 were increased. 3) The detection of Ar-41 indicated the air mixing in helium atmosphere.
Harada, Masahide; Yamaguchi, Yuji; Hashimoto, Norimichi*; Ito, Taku*; Tajima, Takahiro*; Oku, Takayuki; Haga, Katsuhiro; Ikeda, Hiroshi*; Tamura, Satoshi*
JPS Conference Proceedings (Internet), 45, p.011184_1 - 011184_4, 2026/06
At Materials and Life Science Facility in J-PARC, 3 GeV and 1 MW pulsed proton beam hits mercury and carbon targets and intense neutron and muon beams are provided for various measurements. As samples in the measurements are activated, estimation of radioactivity of samples is very necessary for a radiation safety of user experiments. Therefore, estimation system, SAmple Radioactivity Evaluation program (SARE), is developed. SARE can estimate radioactivity of samples at each neutron and muon beam line with neutron flux and activation cross section. The neutron flux data was applied from references and the activation cross section data was obtained from DCHAIN-SP-2001. The activation of negative-muon can be also estimated from a database. SARE has a user-friendly interface of Web servlet based on JAVA and JAVA script and can select various conditions for the estimation. In the presentation, we will introduce SARE and validation results performed at BL10 with the foil-activation method.
Al
Higashinaka, Ryuji*; Iwami, Takuma*; Saito, Kosuke*; Ito, Takashi; Tabata, Chihiro; Kaneko, Koji; Ohara, Takashi; Kiyanagi, Ryoji; Nakao, Akiko*; Nakamura, Jumpei*; et al.
Journal of the Physical Society of Japan, 95(6), p.063702_1 - 063702_5, 2026/06
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)Nishihara, Kenji; Fukushima, Masahiro; Abe, Takumi; Katano, Ryota; Yee-Rendon, B.; Iwamoto, Hiroki; Sugawara, Takanori; Obayashi, Hironari; Saito, Shigeru
JAEA-Research 2025-013, 125 Pages, 2026/03
JAEA-Research-2025-013.pdf:4.68MB
A conceptual design for a pilot Accelerator Driven subcritical System (ADS) was developed as a precursor to a commercial ADS aimed at partitioning and transmutation of minor actinides. The output of the pilot ADS was set at 200 MW. Based on safety assessment results, the design incorporates deep subcriticality and safety rods. Core design, accelerator design, target design, and in-vessel equipment design were performed, clarifying the specific concept.
O
precursors on solid-state formation reactions of (K
Na)NbO
Shoji, Takuma*; Nam, H.*; Ye, J.*; Ito, Daiki*; Takagi, Yuka*; Yoneda, Yasuhiro; Nagata, Hajime*
Journal of the American Ceramic Society, 109(3), p.e70657_1 - e70657_9, 2026/03
Times Cited Count：1 Percentile：0.00(Materials Science, Ceramics)(K,Na)NbO (KNN)-based ceramics have been hesitant to be used in practical piezoelectric devices due to their poor chemical homogeneity, despite their excellent piezoelectric characteristics. In this study, we revealed that the role of NbO precursors varies depending on the processing approaches and is strongly correlated with the chemical homogeneity of KNN with the use of soft X-ray absorption spectroscopy. Therefore, the choice of NbO precursor is a dominant factor in the fabrication of KNN.
Ito, Tatsuya; Ogawa, Yuhei*; Gong, W.; Kawasaki, Takuro; Shibata, Akinobu*; Harjo, S.
Scripta Materialia, 273, p.117084_1 - 117084_6, 2026/03
Times Cited Count：5 Percentile：60.79(Nanoscience & Nanotechnology)
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
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)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
Times Cited Count：10 Percentile：82.42(Materials Science, Multidisciplinary)
, I
and HDO onto pre-Neogene sedimentary rocksHou, L.*; Fukatsu, Yuta; Okamoto, Shunichi*; Toda, Kanako*; Nakata, Kotaro*; Nohara, Shintaro*; Ishidera, Takamitsu; Saito, Takumi*
Journal of Nuclear Science and Technology, 62(11), p.1121 - 1134, 2025/11
Times Cited Count：1 Percentile：46.18(Nuclear Science & Technology)Yildirim, A. C.*; Mei, H.*; Toda, Kanako*; Aoyagi, Noboru; Saito, Takumi*
Applied Clay Science, 274, p.107853_1 - 107853_9, 2025/09
Times Cited Count：1 Percentile：0.00(Chemistry, Physical)Toda, Kanako*; Motokawa, Ryuhei; Saito, Takumi*
Journal of Physical Chemistry C, 129(36), p.16261 - 16271, 2025/09
Times Cited Count：2 Percentile：23.54(Chemistry, Physical) neutron diffraction and digital image correlation strain analysisKawasaki, Takuro; Harjo, S.; Gong, W.; Mao, W.*; Yamashita, Takayuki*; Ito, Tatsuya; Aizawa, Kazuya
Review of Scientific Instruments, 96(9), p.093901_1 - 093901_6, 2025/09
Times Cited Count：5 Percentile：79.44(Instruments & Instrumentation)
neutron diffraction study on the strength and ductility enhancement mechanism of hydrogen-charged SUS310S stainless steelIto, Tatsuya; Ogawa, Yuhei*; Gong, W.; Mao, W.*; Kawasaki, Takuro; Okada, Kazuho*; Shibata, Akinobu*; Harjo, S.
Hamon, 35(3), p.129 - 133, 2025/08
/KNbO nanocomposite particlesYoneda, Yasuhiro; Kobayashi, Toru; Tsuji, Takuya; Shibata, Goro; Takeda, Yukiharu*; Saito, Yuji; Khanal, G. P.*; Fujii, Ichiro*; Ueno, Shintaro*; Sato, Yukio*; et al.
Japanese Journal of Applied Physics, 64(8), p.08SP07_1 - 08SP07_8, 2025/08
Times Cited Count：1 Percentile：28.15(Physics, Applied)It has become possible to synthesize high-quality composite nanoparticles in which a different material is grown on the surface of nanoparticle crystals. To evaluate such nanostructures, it is effective to combine different evaluation methods at various scales. We performed various structural and electronic state evaluations of BaTiO/KNbO nanocomposite particles using synchrotron radiation. From the structural evaluation, it was confirmed that the nanocomposite particles have a core of 100 nm of BaTiO covered with 20 nm of KNbO. The O-K absorption edge spectrum of the outermost surface KNbO was different from that of the bulk and nanoparticles, and it was found that the chemical bonding state changes when KNbO is made into composite particles.
Ito, Ayumi*; Kanno, Tatsuya*; Iwama, Takayuki*; Ueda, Shigeru*; Sato, Takumi; Nagae, Yuji
Annals of Nuclear Energy, 217, p.111333_1 - 111333_14, 2025/07
Times Cited Count：2 Percentile：70.03(Nuclear Science & Technology)In the Fukushima Daiichi Nuclear Power Station Unit 2, the formation of a metallic pool, mainly comprising Fe and Zr, has been proposed as a mechanism contributing to the failure of the reactor pressure vessel. This study focuses on material interactions during the early core degradation that led to metallic pool formation in the late phase of the in-vessel degradation process. Initially, two compositions, Fe-87Zr and Fe-15Zr (at%), were heated to the liquidus temperature of 1723 K, dropped onto SS at lower temperatures, and the metallographic structure of the reaction products was examined. Subsequently, the Fe-87Zr melt at temperatures ranging from 1723 to 1873 K was dropped onto oxidized SS to evaluate the influence of the oxide layer on degradation. This study confirmed that the liquidus temperatures of all intermetallic compounds were below 2000 K, and the metallic debris could be a source of the "metallic pool formation" predicted by recent severe accident analysis.
Mei, H.; Aoyagi, Noboru; Saito, Takumi*; Tanaka, Kazuya; Sugiura, Yuki; Tachi, Yukio
Applied Clay Science, 276, p.107944_1 - 107944_8, 2025/07
Times Cited Count：4 Percentile：75.87(Chemistry, Physical)Mao, W.*; Gong, W.; Kawasaki, Takuro; Gao, S.*; Ito, Tatsuya; Yamashita, Takayuki*; Harjo, S.; Zhao, L.*; Wang, Q.*
Scripta Materialia, 264, p.116726_1 - 116726_6, 2025/07
Times Cited Count：3 Percentile：46.97(Nanoscience & Nanotechnology)