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Liu, R.*; Yan, S.*; Nishio, Katsuhisa; Makii, Hiroyuki; Orlandi, R.; 17 of others*
Chinese Physics C, 50(9), p.094004_1 - 094004_6, 2026/09
Times Cited Count：0Sasamoto, Hiroshi; Arthur, R. C.*
Environmental Earth Sciences, 85(13), p.300_1 - 300_16, 2026/07
Times Cited Count：0 Percentile：0.00(Environmental Sciences)Takei, Hayanori
JPS Conference Proceedings (Internet), 45, p.011175_1 - 011175_7, 2026/06
The Japan Atomic Energy Agency is working on the research and development of an accelerator-driven nuclear transmutation system (ADS) for transmuting minor actinides. This system is a combination of a subcritical nuclear reactor and a high-power superconducting proton linear accelerator (JADS-linac). One of the challenges in developing the JADS-linac is to reduce the number of beam trips. Until now, the beam trip frequency of the JADS-linac has been estimated from the operation data of the J-PARC linac, which uses the normal-conducting acceleration (NC) cavities. Recently, data on beam trips in the superconducting acceleration (SRF) cavities of the Spallation Neutron Source of the Oak Ridge National Laboratory (SNS) have been published. These data are important for the estimation of the beam trip frequency of the JADS-linac. Rather, the SNS data are more appropriate than the J-PARC data, because the JADS-linac uses the SRF cavities. On the other hand, the calculation methods in the published data for the NC cavities of J-PARC and the SRF cavities of SNS are different, so it is not possible to simply compare the two. In this study, the mean time between beam trips (MTBT) of the J-PARC NC cavity and the SNS SRF cavity are compared using the same condition. Specifically, the MTBT of the acceleration cavities connected to a single klystron system was calculated and compared. As a result, the MTBT of the SNS SRF cavity was 5.0 and 8.8 times longer than that of the J-PARC NC cavity for 
and 
h, respectively, where 
is the beam trip duration.
Yamaguchi, Yuji; Kondo, Yasuhiro; Meigo, Shinichiro; Oguri, Hidetomo; Oi, Motoki; Saha, P. K.; Shinozaki, Shinichi; Takayanagi, Tomohiro; Yamamoto, Kazami
JPS Conference Proceedings (Internet), 45, p.011162_1 - 011162_7, 2026/06
A high-power 3-GeV proton beam from a rapid cycling synchrotron (RCS) is transported to a neutron production target at Materials and Life Science Experimental Facility (MLF) by a 3-GeV RCS to Neutron facility Beam Transport (3NBT) line in J-PARC. Recently, the design beam power of 1 MW has been achieved. By this achievement, a future plan of MLF second target station (TS2) is motivated for enhancing brightness of the secondary beams and requires a new beam transport line for the 3-GeV proton beam. The design study of the new transport line has been started based on the previous work and is being performed regarding the optics and shielding of the beamline incorporating latest beam commissioning results. In this presentation, we report a brief concept of the new transport line and current status of the design study.
Zhou, D.*; Zhang, X.*; Pang, X.*; Zhao, Z.*; Chen, X.*; Wei, S.*; Yang, C.*; Gong, W.; Harjo, S.; Li, R.*; et al.
Materials Research Letters (Internet), 14(6), p.689 - 698, 2026/06
Times Cited Count：1 Percentile：76.28(Materials Science, Multidisciplinary)Fukuda, Kodai; Obara, Toru*
Nuclear Technology, 212(6), p.1567 - 1578, 2026/06
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)
-iron at high pressures determined using 
neutron diffractionAoki, 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
Times Cited Count：1 Percentile：78.36(Materials Science, Multidisciplinary)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.
Noda, Yohei*; Kumada, Takayuki; 7 of others*
Journal of Applied Crystallography, 59(2), p.492 - 512, 2026/04
Times Cited Count：0 Percentile：0.00(Chemistry, Multidisciplinary)
Bk and 
AmWang, J. G.*; Zhang, Z. Y.*; Andreyev, A. N.; 33 of others*
Physics Letters B, 875, p.140365_1 - 140365_6, 2026/04
Times Cited Count：2 Percentile：81.50(Astronomy & Astrophysics)The new isotopes Bk and Am were investigated using the gas-filled recoil separator SHANS2. They were identified by measuring radioactive decay chains originating from Bk produced via the 
Au(
Ar,2n)Bk reaction. The energy and half-life were determined for these isotopes. A systematic analysis reveals significant discrepancies between the experimental data and the theoretical predictions for the isotopes of Bk and Am, which warrant further investigation.
and A
value ratios for off-site transportation of small-amount of fuel debris retrieved from the Fukushima Daiichi Nuclear Power StationSakamoto, Masahiro; Okumura, Keisuke; Kanno, Ikuo; Matsumura, Taichi; Riyana, E. S.; Terashima, Kenichi; Kaneko, Junichi*; Mizokami, Masato*; Mizokami, Shinya*
Radioisotopes, 75(S-01), p.S-001_1 - S-001_5, 2026/04
Guerinoni, E.*; Ueda, Yuki; Motokawa, Ryuhei; Zemb, T.*; Pellet-Rostaing, S.*; Dourdain, S.*
Langmuir, 42(12), p.8313 - 8321, 2026/03
Times Cited Count：1 Percentile：75.13(Chemistry, Multidisciplinary)Ahn, S. Y.*; Kim, E. S.*; Jeong, S. G.*; Harjo, S.; Kawasaki, Takuro; Gong, W.; Kim, H.-J.*; Hong, S.-J.*; Hong, S. I.*; Kwon, H.*; et al.
Materials Science & Engineering A, 955, p.149839_1 - 149839_18, 2026/03
Times Cited Count：3 Percentile：91.05(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)Hiroi, Kosuke; Nakabe, Rintaro; Oku, Takayuki; Kumada, Takayuki; Motokawa, Ryuhei
Journal of Applied Crystallography, 59(1), p.69 - 79, 2026/02
Times Cited Count：0 Percentile：0.00(Chemistry, Multidisciplinary)Maruyama, Shuhei; Yamamoto, Akio*; Endo, Tomohiro*
Journal of Nuclear Science and Technology, 63(1), p.31 - 44, 2026/01
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)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.
Noh, S.*; Sugawara, Akihide*; Ishihara, Naoaki*; Konishi, Takashi*; Ueda, Yuki; Motokawa, Ryuhei; Takashima, Yoshinori*; Uyama, Hiroshi*
Advanced Science (Internet), p.e76110_1 - e76110_15, 2026/00
Times Cited Count：0 Percentile：0.00(Chemistry, Multidisciplinary)Saijo, Tomoaki; Shimazaki, Yosuke; Ishihara, Masahiro
JAEA-Technology 2025-010, 126 Pages, 2025/12
JAEA-Technology-2025-010.pdf:12.52MB
During the operation of the High Temperature Engineering Test Reactor (HTTR), thermal stress is generated in the graphite components. In addition, graphite exhibits dimensional shrinkage and creep deformation under neutron irradiation. As a result, residual stress remains in the graphite components during reactor shutdown. Therefore, in the design of the HTTR core graphite structures, stress analyses of the graphite components have previously been performed using the finite element analysis code VIENUS. In the HTTR, the graphite components are exposed to a wide range of temperature, from approximately 400
C to 1200C, depending on their location. Consequently, irradiation-induced behaviors such as material property changes and irradiation shrinkage vary among the graphite components. On the other hand, since VIENUS code evaluates stress based on thermal fluid and heat conduction analysis results, it is not suitable for parametric studies. In this study, the influence of irradiation behavior on the stress behavior of graphite components in the wide temperature range (400C to 1200C) was analyzed using simplified viscoelastic evaluation model, consisting of two beam elements, to conduct efficient parametric studies. Operational stress exhibits two distinct patterns depending on whether the irradiation temperature is below or above 800C, due to irradiation shrinkage. Residual stress approaches the thermal stress, preventing excessive increase even when irradiation shrinkage is large. Moreover good agreement in stress behavior trends was observed between the stress analysis results by the simplified viscoelastic evaluation model and VIENUS code. These results indicate that the simplified viscoelastic evaluation model is beneficial in simulating stress behavior.
Collaborative Laboratories for Advanced Decommissioning Science; Hokkaido University*
JAEA-Review 2025-037, 103 Pages, 2025/12
JAEA-Review-2025-037.pdf:7.28MB
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2023. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2023, this report summarizes the research results of the "A study on the methodology for rational treatment/disposal of contaminated concrete waste considering volume reduction of waste" conducted in FY2023. The present study aims to evaluate rational waste management strategies incorporating reuse and recycling focusing on radioactive concrete waste, which will be massively generated from dismantling. Feasibility and challenges of aggregate recycling are considered assuming a typical recycled aggregate production technique, based on the characteristics of the concrete. In 2023, the migration behaviors of radionuclides and ions in cementitious materials having interfacial transition zones (ITZ) were investigated through diffusion and leaching experiments using radioactive and non-radioactive tracers and modeled by random walk particle tracking method with a sampling technique using a probabilistic distribution model for two media with an interface. Properties of surrogate contaminated concrete samples prepared by immersing in Cs solution were examined. Migration of ions was studied for surrogate contaminated aggregates and recycled concrete using the surrogate. In addition, surrogate waste package was prepared using by-product powder to study mechanical and chemical properties as well as leaching behavior of radionuclides. Information on properties of the contaminated concrete and tools to estimate the amount of concrete were organized in order to evaluate different waste management scenarios incorporating reuse/recycling.
