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Ueda, Yuki; Kobayashi, Toru; Nakamura, Satoshi; Ban, Yasutoshi; Kaneta, Yui; Nabatame, Nozomi; Micheau, C.; Tokunaga, Kohei; Nakabe, Rintaro; Kaneko, Masashi*; et al.
Langmuir, 42(1), p.1613 - 1626, 2026/01
Times Cited Count：0 Percentile：0.00(Chemistry, Multidisciplinary)Understanding the structural factors governing the metal ions selectivity of solvent extraction systems is crucial for developing advanced processes for partitioning and transmutation of high-level radioactive waste. Here, we systematically investigated the effect of alkyl side-chain branching in nitrilotriacetamide (NTAamide) extractants on the extraction of lanthanum (La) and neodymium (Nd), chosen as representative lanthanides. Four extractants having each eight carbon atoms as one of the amide chains with identical molecular weights but different degrees of alkyl branching were examined. Distribution ratios were measured as a function of HNO
concentration, and the local coordination structures of La and Nd were analyzed by extended X-ray absorption fine structure (EXAFS), while supramolecular aggregation in the organic phase was characterized by small-angle neutron scattering (SANS). EXAFS analysis revealed that the inner-sphere coordination environment of La and Nd was essentially unaffected by the degree of alkyl branching. In contrast, SANS results showed that extractants with fewer branched alkyl groups formed larger aggregates at low HNO concentrations, particularly in the case of Nd, where aggregation was found to facilitate extraction and prevent precipitation of poorly soluble complexes. These findings demonstrate that alkyl branching strongly influences supramolecular aggregation, which in turn governs extraction behavior. This work highlights the potential of nanoscale structural control as a new design concept for improving selectivity in lanthanide and actinide solvent extraction systems.
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studied by 
Fe nuclear resonant inelastic scatteringKawachi, Shiro*; Hiraka, Haruhiro*; Yamaura, Junichi*; Iimura, Soshi*; Nakamura, Hiroki; Tsutsui, Satoshi*; Yoda, Yoshitaka*; Machida, Masahiko; Hosono, Hideo*; Kobayashi, Hisao*
Physical Review B, 113(2), p.024519_1 - 024519_7, 2026/01
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)To investigate the phonon dynamics of iron in the heavily hydride-ion-substituted region of LaFeAsOH (
), Fe nuclear resonant inelastic scattering measurements were performed over a wide temperature range from 5 to 300 K on two polycrystalline samples with 
and 0.51, which exhibit superconducting and antiferromagnetic ground states, respectively. The resulting inelastic scattering spectra revealed distinct differences between the two compositions. The Fe phonon density of states (PDOS) exhibits a pronounced peak at 15 meV for , whereas this peak is absent in 
. Density functional theory calculations support the interpretation that the PDOS peak at 15 meV is associated with the optical vibrational modes of Fe atoms along the nearest-neighbor direction, mediated by As atoms. The calculations further suggest that the suppression of the PDOS peak at 15 meV for originates from in-plane electronic inequivalence. These findings suggest that signatures of electronic nematicity may persist over a wide temperature range in the composition, which exhibits magnetic and structural order, whereas such signatures are almost absent in the superconducting composition.
Yamano, Hidemasa; Futagami, Satoshi; Sasa, Kyohei*; Nakamura, Hironori*; Tokizaki, Minako*; Kubota, Ryuzaburo*
Proceedings of 2025 International Congress on Advances in Nuclear Power Plants (ICAPP 2025) (Internet), 12 Pages, 2025/09
This study examined the application of safety design criteria (SDC) and safety design guideline (SDG) developed in the Generation-IV international forum on the passive reactor shutdown capability to sodium-cooled fast reactors (SFRs) recently designed in Japan.
Nakamura, Satoshi; Suzuki, Hideya*; Ban, Yasutoshi; Ohashi, Akira*
Progress in Nuclear Science and Technology (Internet), 8, p.228 - 232, 2025/09
To reduce volume and radiotoxicity of high-level radioactive waste, JAEA has been developing a separation process recovering minor actinides (MA) from high-level radioactive liquid-waste. In the separation process, separating trivalent MA such as Am and Cm, from RE is challenging due to their similar chemical properties. In this study, extraction properties of three different glycine-based amic-acid-type extractants for MA(III) and RE(III) were studied by a single-stage batch method. The results revealed that the distribution ratios of all metal ions increased with an increase of equilibrium pH, and all extractants showed higher distribution ratios for Am than for RE.
Takanashi, Misa*; Hidaka, Ryota*; Okubo, Kota*; Masumura, Takuro*; Tsuchiyama, Toshihiro*; Morooka, Satoshi; Maeda, Takuya*; Nakamura, Shuichi*; Uemori, Ryuji*
ISIJ International, 65(9), p.1384 - 1393, 2025/08
Times Cited Count：1 Percentile：30.65(Metallurgy & Metallurgical Engineering)Takanashi, Misa*; Hidaka, Ryota*; Okubo, Kota*; Masumura, Takuro*; Tsuchiyama, Satoshi*; Morooka, Satoshi; Maeda, Takuya*; Nakamura, Shuichi*; Uemori, Ryuji*
Tetsu To Hagane, 111(9), p.503 - 513, 2025/06
Times Cited Count：0 Percentile：0.00(Metallurgy & Metallurgical Engineering)Katsumura, Kosuke*; Takagi, Junichi*; Miyahara, Naoya*; Uchida, Shunsuke*; Koma, Yoshikazu; Karasawa, Hidetoshi; Miwa, Shuhei; Satou, Yukihiko; Nagai, Haruyasu; Kurata, Masaki; et al.
Nihon Genshiryoku Gakkai-Shi ATOMO
, 67(2), p.128 - 132, 2025/02
no abstracts in English
Nakamura, Satoshi; Ishii, Sho*; Kato, Hitoshi*; Ban, Yasutoshi; Hiruta, Kenta; Yoshida, Takuya; Uehara, Hiroyuki; Obata, Hiroki; Kimura, Yasuhiko; Takano, Masahide
Journal of Nuclear Science and Technology, 62(1), p.56 - 64, 2025/01
Times Cited Count：1 Percentile：20.46(Nuclear Science & Technology)A dissolution method for analyzing the elemental composition of fuel debris using the sodium peroxide (Na
O) fusion technique has been developed. Herein, two different types of simulated debris materials (such as solid solution of (Zr,RE)O and molten core-concrete interaction products (MCCI)) were taken. At various temperatures, these debris materials were subsequently fused with NaO in crucibles, which are made of different materials, such as Ni, AlO, Fe, and Zr. Then, the fused samples are dissolved in nitric acid. Furthermore, the effects of the experimental conditions on the elemental composition analysis were evaluated using inductively coupled plasma-atomic emission spectroscopy (ICP-AES), which suggested the use of a Ni crucible at 923 K as an optimum testing condition. The optimum testing condition was then applied to the demonstration tests with Three Mile Island unit-2 (TMI-2) debris in a shielded concrete cell, thereby achieving complete dissolution of the debris. The elemental composition of TMI-2 debris revealed by the proposed dissolution method has good reproducibility and has an insignificant contradiction in the mass balance of the sample. Therefore, this newly developed reproducible dissolution method can be effectively utilized in practical applications by dissolving fuel debris and estimating its elemental composition.
Hori, Junichi*; Sano, Tadafumi*; Takamiya, Koichi*; Fukutani, Satoshi*; Nakamura, Shoji; Nauchi, Yasushi*; 3 of others*; 10 of others*
KURNS-EKR-21, p.10 - 14, 2025/01
no abstracts in English
Sm synchrotron-radiation-based M
ssbauer and 
SR studies of Sm
Ru
Ge
Tsutsui, Satoshi; Ito, Takashi; Nakamura, Jin*; Yoshida, Mio*; Kobayashi, Yoshio*; Yoda, Yoshitaka*; Nakamura, Jumpei*; Koda, Akihiro*; Higashinaka, Ryuji*; Aoki, Dai*; et al.
Interactions (Internet), 245(1), p.55_1 - 55_9, 2024/12
Sm synchrotron-radiation-based Mssbauer spectroscopy of Sm-based heavy fermion compoundsTsutsui, Satoshi; Higashinaka, Ryuji*; Mizumaki, Masaichiro*; Kobayashi, Yoshio*; Nakamura, Jin*; Ito, Takashi; Yoda, Yoshitaka*; Matsuda, Tatsuma*; Aoki, Yuji*; Sato, Hideyuki*
Interactions (Internet), 245(1), p.9_1 - 9_10, 2024/12
Ishikawa, Akihisa; Tanaka, Hiroki*; Nakamura, Satoshi*; Kumada, Hiroaki*; Sakurai, Yoshinori*; Watanabe, Kenichi*; Yoshihashi, Sachiko*; Tanagami, Yuki*; Uritani, Akira*; Kiyanagi, Yoshiaki*
Journal of Radiation Research (Internet), 65(6), p.765 - 775, 2024/11
Times Cited Count：3 Percentile：47.62(Biology)Hayakawa, Satoshi*; Hagiwara, Hiroyuki*; Imamura, Akira*; Onoda, Yuichi; Tanaka, Masaaki; Nakamura, Hironori*
Proceedings of 13th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS13) (Internet), 8 Pages, 2024/11
In a sodium-cooled fast reactor, a cover gas region filled with argon gas is located above the sodium pool in the main vessel to prevent the hot sodium from contacting the structures. This region involves heat transportation by natural convection of the cover gas, radiation among liquid surface and structures, and sodium phase change between mist and vapor. In this study, the numerical evaluation method has been developed with a commercial CFD code, Fluent, incorporating the sodium mist transport and growth models, and the radiation scattering model. Simulations of a laboratory scale test with a cylindrical cover gas region was carried out for the validation of the method and showed that the temperature distribution and sodium mist concentration in the cover gas region are in good agreements with the test results. A simulation of a pool-type sodium cooled fast reactor has also conducted and the basic aspect of physical phenomena taking place in the cover gas region were evaluated.
Koda, Yuya; Nakamura, Yasuyuki; Iguchi, Yukihiro*; Yanagihara, Satoshi*
Proceedings of 31st International Conference on Nuclear Engineering (ICONE31) (Internet), 10 Pages, 2024/11
"Fugen" has been proceeding with decommissioning work since receiving approval for the decommissioning plan in 2008, and is currently in the second step of dismantling the reactor peripheral equipment. In decommissioning, project management is important to select strategies and optimize processes, waste, safety, costs, etc. In Japan, it is expected that decommissioning work for nuclear facilities will become more serious in the future, and the knowledge and project management data obtained from the decommissioning work carried out at "Fugen" to date will be useful for planning. Since the dismantling and removal of the main turbine equipment and the peripheral equipment in preparation for the reactors have been completed so far, the actual data has been organized and analyzed and compiled into unit work coefficients. The project management data, collected during the decommissioning work carried out at "Fugen" is organized and calculated as a unit work coefficient.
shetta lakes in the Soya Coast region and their paleoenvironmental significance with glacial isostatic adjustment in East AntarcticaInoue, Genki*; Honda, Eisuke*; Ito, Keisuke*; Kang, I.*; Seto, Koji*; Tani, Yukinori*; Watanabe, Takahiro; Kashima, Kaoru*; Otani, Shuji*; Yamanaka, Toshiro*; et al.
Quaternary Science Reviews, 338, p.108822_1 - 108822_18, 2024/08
Times Cited Count：0 Percentile：0.00(Geography, Physical)We studied Holocene paleolimnological changes inferred from biomarkers and microscopic observation of microalgae and cyanobacteria in sediment cores from Rundvshetta lakes (Maruwanminami-ike and Maruwan o-ike) in the Soya Coast of East Antarctica, along with sedimentary facies and radiocarbon dating. Coastal marine environment: Maruwanminami-ike (147-72.5 cm, 5,010-2,590 cal BP) and Maruwan-oike (226-47.2 cm, 5,700-3,190 cal BP) were characterized by low biological production with the predominance of diatoms. Transition period of stratified brackish lake environment: Maruwanminami-ike (72.5-65.6 cm, 2,590-2,500 cal BP) and Maruwan-oike (47.2-28.8 cm, 3,190-2,890 cal BP) were characterized by stratified conditions with marine water overlain by freshwater, and a chemocline developed together with an anoxic layer in the bottom of photic zone.
Ishikado, Motoyuki*; Takahashi, Ryuta*; Yamauchi, Yasuhiro*; Nakamura, Masatoshi*; Ishimaru, Sora*; Yamauchi, Sara*; Kawamura, Seiko; Kira, Hiroshi*; Sakaguchi, Yoshifumi*; Watanabe, Masao; et al.
JPS Conference Proceedings (Internet), 41, p.011010_1 - 011010_7, 2024/05
Linh, B. D.*; Corsi, A.*; Gillibert, A.*; Obertelli, A.*; Doornenbal, P.*; Barbieri, C.*; Duguet, T.*; G
mez-Ramos, M.*; Holt, J. D.*; Hu, B. S.*; et al.
Physical Review C, 109(3), p.034312_1 - 034312_15, 2024/03
Times Cited Count：6 Percentile：79.47(Physics, Nuclear)no abstracts in English
Koyama, Shinichi; Ikeuchi, Hirotomo; Mitsugi, Takeshi; Maeda, Koji; Sasaki, Shinji; Onishi, Takashi; Tsai, T.-H.; Takano, Masahide; Fukaya, Hiroyuki; Nakamura, Satoshi; et al.
Hairo, Osensui, Shorisui Taisaku Jigyo Jimukyoku Homu Peji (Internet), 216 Pages, 2023/11
In FY 2021 and 2022, JAEA perfomed the subsidy program for "the Project of Decommissioning and Contaminated Water Management (Development of Analysis and Estimation Technology for Characterization of Fuel Debris (Development of Technologies for Enhanced Analysis Accuracy, Thermal Behavior Estimation, and Abbreviated Analysis))" started in FY 2021. This presentation material summarized the results of the project, which will be available shortly on the website of Management Office for the Project of Decommissioning, Contaminated Water and Treated Water Management.
Misaki, Satoshi*; Miwa, Hiroko*; Ito, Takashi; Yoshida, Takefumi*; Hasegawa, Shingo*; Nakamura, Yukina*; Tokutake, Shunta*; Takabatake, Moe*; Shimomura, Koichiro*; Chun, W.-J.*; et al.
ACS Catalysis, 13(18), p.12281 - 12287, 2023/09
Times Cited Count：12 Percentile：49.50(Chemistry, Physical)
OKondo, Yosuke*; Achouri, N. L.*; Al Falou, H.*; Atar, L.*; Aumann, T.*; Baba, Hidetada*; Boretzky, K.*; Caesar, C.*; Calvet, D.*; Chae, H.*; et al.
Nature, 620(7976), p.965 - 970, 2023/08
Times Cited Count：53 Percentile：95.82(Multidisciplinary Sciences)no abstracts in English
