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Guembou Shouop, C. J.; Tsuchiya, Harufumi
Communications Engineering (Internet), 5, p.11_1 - 11_14, 2026/01
Collaborative Laboratories for Advanced Decommissioning Science; Kogakuin University*
JAEA-Review 2025-013, 111 Pages, 2025/10
JAEA-Review-2025-013.pdf:7.49MB
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 FY2021, this report summarizes the research results of the "Establishment of characterization method for small fuel debris using the world's first isotope micro imaging apparatus" conducted from FY2021 to FY2023. The present study aims to obtain, for the first time in the world, the important data necessary for clarifying the retrieval of small amounts of fuel debris, and to evaluate and examine them. The isotope microimaging apparatus (developed by Kogakuin University) introduced at the JAEA Fuel Monitoring Facility (FMF) can obtain local quantitative data such as isotope composition while processing cross-sections of radioactive micro-samples, which can be used to determine the properties of fuel debris. In FY2021, we improved the isotope microimaging apparatus introduced to the JAEA FMF to accommodate high radiation dose samples. In FY2022, we maintained the isotope microimaging apparatus at the JAEA FMF and succeeded in analyzing real particles containing uranium. In FY2023, we completed development to automate and remotely perform analysis routines using a prototype machine at Kogakuin University. At the JAEA FMF, although manual operations were involved, we succeeded in analyzing each Cs isotope from real particles by resonance ionization. In Nagoya University, we improved the RIMS apparatus to investigate the difference in electronic state caused by ion beam sputtering. And we succeeded in obtaining resonance ionization signals from neutral particles generated by ion beam sputtering. At the JAEA CLADS, they investigated the ionization scheme for important nuclides Nd and Gd. Those proposed ionization schemes were examined at Kogakuin University.
Collaborative Laboratories for Advanced Decommissioning Science; Osaka University*
JAEA-Review 2025-019, 95 Pages, 2025/09
JAEA-Review-2025-019.pdf:9.49MB
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 (1F), 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 FY2021, this report summarizes the research results of the "Improvement of aerosol time-of-flight mass spectrometer for on-line measurement of tiny particles containing alpha emitters" conducted from FY2021 to FY2023. The present study aims to improve Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) in order to monitor tiny particles containing alpha emitters such as U and Pu which were generated in removing debris from the reactors of 1F. We newly fabricated the improved ATOFMS quipped with a reflectron and carried out measurements for modeled tiny particles containing U. In obtained TOF spectra, ion peaks were observed for Zr
, 
U, and their oxides as well as Zr
and U. Mass resolution of the ion peak of U+ was 1,700, which demonstrates that the improved ATOFMS has sufficient mass resolution to distinguish 
Pu from U. In the development of the apparatus for preparing enriched and enlarged particles, we fabricated the apparatus consisting of PILS, a volume reduction tube, a supersonic atomizer, and an online dryer, and optimized apparatus conditions. In the optimized conditions, enlarged particles with size between 0.4 
m and 0.8 m which are detectable with ATOFMS were dominantly produced. By analyzing the enlarged particles, these were produced by taking component elements of the apparatuses used in the enlarged process. The efficiency was evaluated to be 4.5 times. From these developments, the detection concentration limits of the apparatus were evaluated to be 7.0
10
, 4.210
, and 1.310
Bq/cm
for U, 
U, and Pu, respectively. These values are below the air concentration limit.
Moon, J. Y.*; Ito, Yuta; 13 of others*
Journal of the Korean Physical Society, 87(5), p.640 - 648, 2025/09
Times Cited Count：2 Percentile：40.64(Physics, Multidisciplinary)Schury, P.*; Ito, Yuta; Wada, Michiharu*
Nihon Butsuri Gakkai-Shi, 80(2), p.72 - 78, 2025/02
The multi-reflection time-of-flight mass spectrograph has recently become of great utility in the study of superheavy nuclei. The device efficiently uses each ion and its operation is amenable to the inclusion of a decay detector being coupled into the time-of-flight (TOF) ion impact detector. In this way, TOF-decay correlation can be measured to unambiguously differentiate low-yield radioactive ions from stable molecular ions or dark counts. This will eventually allow the technique to be applied to the study of extremely low-yield nuclei such as those of 
Nh and 
Mc isotopes.
Cf fission fragments with MRTOF-MS and detailed study of masses of neutron-rich Ce isotopesKimura, Sota*; Ito, Yuta; 8 of others*
Physical Review C, 110(4), p.045810_1 - 045810_9, 2024/10
Times Cited Count：6 Percentile：84.06(Physics, Nuclear)Collaborative Laboratories for Advanced Decommissioning Science; Kogakuin University*
JAEA-Review 2024-005, 79 Pages, 2024/06
JAEA-Review-2024-005.pdf:5.72MB
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 FY2021. 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 FY2021, this report summarizes the research results of the "Establishment of characterization method for small fuel debris using the world's first isotope micro imaging apparatus" conducted in FY2021. The present study aims to obtain, for the first time in the world, the important data necessary for clarifying the retrieval of small amounts of fuel debris, and to evaluate and examine them. SEM-EDS and TEM-EDS cannot be used for isotopic identification and analysis of Pu and B. On the other hand, bulk analysis such as ICP-MS lacks the information in a micro region.
Collaborative Laboratories for Advanced Decommissioning Science; Osaka University*
JAEA-Review 2023-040, 104 Pages, 2024/05
JAEA-Review-2023-040.pdf:5.01MB
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 FY2022. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station (1F), 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 FY2021, this report summarizes the research results of the "Improvement of aerosol time-of-flight mass spectrometer for on-line measurement of tiny particles containing alpha emitters" conducted in FY2022. The present study aims to improve Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) in order to monitor tiny particles containing alpha emitters such as U and Pu generated in removing debris from the reactors of 1F. In FY2022, we newly fabricated a prototype of the improved ATOFMS and measured collection and detection efficiencies of the particle detection unit and carried out mass measurement using the TOF part.
) cross-section measurements at n_TOF EAR2Alcayne, V.*; Kimura, Atsushi; 134 of others*
Radiation Physics and Chemistry, 217, p.111525_1 - 111525_11, 2024/04
Times Cited Count：8 Percentile：91.60(Chemistry, Physical)Collaborative Laboratories for Advanced Decommissioning Science; Osaka University*
JAEA-Review 2023-039, 71 Pages, 2024/03
JAEA-Review-2023-039.pdf:4.43MB
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 FY2021. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station (1F), 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 FY2021, this report summarizes the research results of the "Improvement of aerosol time-of-flight mass spectrometer for on-line measurement of tiny particles containing alpha emitters" conducted in FY2021. The present study aims to improve Aerosol Time-Of-Flight Mass Spectrometer in order to monitor tiny particles containing alpha emitters such as U and Pu generated in removing debris from the reactors of 1F. In FY2021, for improving mass-resolution, we designed the optimized structure of mass spectrometer with much better mass resolution and ion transmittance than commercial ATOFMS by a PC simulation. Further, design of a detection part of ATOFMS fitted to the mass spectrometer was completed.
nuclei constrain element abundancesXian, W.*; Ito, Yuta; 30 of others*
Physical Review C, 109(3), p.035804_1 - 035804_10, 2024/03
Times Cited Count：7 Percentile：84.06(Physics, Nuclear)
Mo with the new ZD-MRTOF mass spectrograph systemHou, D. S.*; Ito, Yuta; 30 of others*
Physical Review C, 108(5), p.054312_1 - 054312_10, 2023/11
Times Cited Count：9 Percentile：77.51(Physics, Nuclear)The atomic masses of 
Ag, 
Pd, Rh, Ru, and 
Mo have been measured with the ZeroDegree multi-reflection time-of-flight Mass Spectrograph (ZDMRTOF-MS) at the RIKEN RI beam factory. In most cases, good agreements between our results and available experimental data as well as the evaluated masses in AME2020. From the present results, we conclude that up to Mo there is no stabilizing shell effect corresponding to the harmonic oscillator gap at N = 70.
N(n, p)C cross section at the CERN n_TOF facility from subthermal energy to 800 keVTorres-S
nchez, P.*; Harada, Hideo; Kimura, Atsushi; 129 of others*
Physical Review C, 107(6), p.064617_1 - 064617_15, 2023/06
Times Cited Count：6 Percentile：62.65(Physics, Nuclear)Iwamoto, Hiroki; Nakano, Keita; Meigo, Shinichiro; Satoh, Daiki; Iwamoto, Yosuke; Sugihara, Kenta*; Nishio, Katsuhisa; Ishi, Yoshihiro*; Uesugi, Tomonori*; Kuriyama, Yasutoshi*; et al.
EPJ Web of Conferences, 284, p.01023_1 - 01023_4, 2023/05
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)For accurate prediction of neutronic characteristics for accelerator-driven systems (ADS) and a source term of spallation neutrons for reactor physics experiments for the ADS at Kyoto University Critical Assembly (KUCA), we have launched an experimental program to measure nuclear data on ADS using the Fixed Field Alternating Gradient (FFAG) accelerator at Kyoto University. As part of this program, the proton-induced double-differential thick-target neutron-yields (TTNYs) and cross-sections (DDXs) for iron, lead, and bismuth have been measured with the time-of-flight (TOF) method. For each measurement, the target was installed in a vacuum chamber on the beamline and bombarded with 107-MeV proton beams accelerated from the FFAG accelerator. Neutrons produced from the targets were detected with stacked, small-sized neutron detectors for several angles from the incident beam direction. The TOF spectra were obtained from the detected signals and the FFAG kicker magnet's logic signals, where gamma-ray events were eliminated by pulse shape discrimination. Finally, the TTNYs and DDXs were obtained from the TOF spectra by relativistic kinematics. The measured TTNYs and DDXs were compared with calculations by the Monte Carlo transport code PHITS with its default physics model of INCL version 4.6 combined with GEM and those with the JENDL-4.0/HE nuclear data library.
Rosenbusch, M.*; Ito, Yuta; 24 of others*
Nuclear Instruments and Methods in Physics Research A, 1047, p.167824_1 - 167824_12, 2023/02
Times Cited Count：30 Percentile：96.16(Instruments & Instrumentation)A new MRTOF mass spectrograph was assembled following the ZeroDegree spectrometer at RIKEN RIBF. By using a pulsed-drift-tube technique to modify the ions' kinetic energy in a wide range, we directly characterized the dispersion function of the system for optimizing the voltages applied to the electrostatic mirrors. This enabled us to achieve a mass resolving power of 10
within a total time-of-flight of only 12.5 ms, making the spectrometer capable of studying short-lived nuclei possessing low-lying isomers.
Yogo, Akifumi*; Lan, Z.*; Arikawa, Yasunobu*; Abe, Yuki*; Mirfayzi, S. R.*; Wei, T.*; Mori, Takato*; Golovin, D.*; Hayakawa, Takehito*; Iwata, Natsumi*; et al.
Physical Review X, 13(1), p.011011_1 - 011011_12, 2023/01
Times Cited Count：43 Percentile：96.85(Physics, Multidisciplinary)U(n,f) cross section from n_TOF (CERN) from 18 meV to 10 keVMastromarco, M.*; Amaducci, S.*; Colonna, N.*; Kimura, Atsushi; 118 of others*
European Physical Journal A, 58(8), p.147_1 - 147_13, 2022/08
Times Cited Count：7 Percentile：63.46(Physics, Nuclear)-ray analysisMaeda, Makoto; Segawa, Mariko; Toh, Yosuke; Endo, Shunsuke; Nakamura, Shoji; Kimura, Atsushi
Scientific Reports (Internet), 12(1), p.6287_1 - 6287_8, 2022/06
Times Cited Count：2 Percentile：9.43(Multidisciplinary Sciences)Collaborative Laboratories for Advanced Decommissioning Science; Osaka University*
JAEA-Review 2021-074, 104 Pages, 2022/03
JAEA-Review-2021-074.pdf:4.91MB
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 FY2020. 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 FY2019, this report summarizes the research results of the "Basic study for on-line monitoring of tiny particles including alpha emitters by aerosol time-of-flight mass spectroscopy" conducted in FY2019 and FY2020. Since the final year of this proposal was FY2020, the results for two fiscal years were summarized. The present study aims to conduct a feasibility study of Aerosol time-of-flight mass spectroscopy (ATOFMS) to on-line measurement of tiny particles containing alpha emitters which might be dispersed in cutting the debris in reactors of the Fukushima Daiichi Nuclear Power Station for realizing their real-time monitoring.
NpRovira Leveroni, G.; Katabuchi, Tatsuya*; Tosaka, Kenichi*; Matsuura, Shota*; Kodama, Yu*; Nakano, Hideto*; Iwamoto, Osamu; Kimura, Atsushi; Nakamura, Shoji; Iwamoto, Nobuyuki
Journal of Nuclear Science and Technology, 59(1), p.110 - 122, 2022/01
Times Cited Count：5 Percentile：41.70(Nuclear Science & Technology)