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Tomita, Jumpei; Tomita, Ryohei; Suzuki, Daisuke; Yasuda, Kenichiro; Miyamoto, Yutaka
Journal of Nuclear Science and Technology, 63(4), p.443 - 454, 2026/04
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)
Rn/At generatorTanaka, Ko*; Shimizu, Yusuke*; Ida, Tomonori*; Washiyama, Koshin*; Nishinaka, Ichiro*; Asai, Masato; Segawa, Mariko; Yokoyama, Akihiko*
Radiochimica Acta, 114(3), p.221 - 229, 2026/04
Times Cited Count：0 Percentile：0.00(Chemistry, Inorganic & Nuclear)We are developing a Rn/At generator system to produce and deliver the medical radioisotope At. This study analyzed the dissolution of Rn in solution to investigate gas-phase recovery conditions of Rn in the Rn/At generator system. The dissolution of a Bi target in a nitric-hydrochloric acid mixture and subsequent neutralization has been shown to enhance the Rn recovery efficiency. The gas-phase Rn recovery rate reached 88%, while 50% of available At has been recovered, and further improvement can be expected in the future.
Shimada, Asako; Tsukahara, Takehiko*; Nomura, Masao*; Shimada, Taro; Takeda, Seiji; Takahashi, Hiroaki*
Scientific Reports (Internet), 15(1), p.39024_1 - 39024_10, 2025/11
Times Cited Count：0 Percentile：0.00(Multidisciplinary Sciences)Due to the accident at the Fukushima Daiichi Nuclear Power Station (FDNPS), radiocesium such as 
Cs, 
Cs, and 
Cs was dispersed over a wide area of eastern Japan and mixed with radiocesium from global fallout. The depth profiles of Cs for samples taken in 2003 before the FDNPS accident and in 2017 after the FDNPS accident in Tokai-mura (about 115 km NE of Tokyo) were both described by exponential equations from the surface up to a depth of 15 cm. Systematic grid sampling of surface soil at a depth of 5 cm was conducted at 3 sites in Tokai-mura in 2019, and distributions of the Cs concentration, Cs/Cs radioactivity ratio, and Cs/Cs isotope ratio were measured. It was found that the Cs concentration varied among sites and within individual sites, while the Cs/Cs radioactivity ratio was constant for all samples collected at 3 sites, 1.01
0.04 (2
). The Cs/Cs isotope ratio for the two sites was constant and comparable to that obtained for soil sampled near FDNPS. On the other hand, the Cs/Cs isotope ratio. For the other site varied and showed higher values (0.355-0.446), suggesting the influence of global fallout. Based on the results, the mixture percentages of radiocesium originating from global fallout and the FDNPS accident were estimated.
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; National Institutes of Natural Sciences*
JAEA-Review 2025-009, 48 Pages, 2025/07
JAEA-Review-2025-009.pdf:2.19MB
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 "Development of the continuous monitoring of tritium water by mid-infrared laser spectroscopy" conducted from FY2021 to FY2023. The present study aims to demonstrate the principle for rapid measurement of tritiated water at a concentration level of 60 Bq/cc using a cavity ring-down spectroscopy system with a mid-infrared laser. In fiscal year 2023, research focused on (1) developing the cavity ring-down apparatus and (2) evaluating hydrogen isotope composition and preparing standard samples under environmental conditions (subcontracted to Hirosaki University). For (1), an optical bench was set up at the NIFS to perform laser absorption spectroscopy of various hydrogen isotope concentrations, enabling the evaluation of measurement sensitivity and establishment of guidelines. The light amplification of a quantum cascade laser, was further developed, achieving light amplification of a 4.3 
m quantum cascade laser with an iron ion-doped medium, yielding a maximum output of 390 mW with a linewidth of less than 30 MHz. For (2), standard samples were prepared by diluting commercially available heavy water with BG water (tritium-free water) to create samples with approximately 100 Bq/L. Isotope ratio measurements were conducted indoors and outdoors using a high-time-resolution atmospheric water vapor collection system for tritium measurement, and daily measurements of the hydrogen isotope ratio (
D) were conducted. The relationship between D and tritium concentration in atmospheric water vapor in Hirosaki City was evaluated. Thus, the principle for the rapid measurement of tritiated water using a mid-infrared laser was successfully demonstrated.
Kinase, Masami
Radioisotopes, 74(2), p.233 - 238, 2025/07
no abstracts in English
Kimura, Yoshiki; Yamaguchi, Tomoki
Progress in Nuclear Science and Technology (Internet), 7, p.60 - 66, 2025/03
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：82.41(Physics, Nuclear)Idomura, Yasuhiro
Physics of Plasmas, 31(10), p.102504_1 - 102504_10, 2024/10
Times Cited Count：0 Percentile：0.00(Physics, Fluids & Plasmas)Hydrogen isotope mixing phenomena in tokamak plasmas are analyzed using global full-f gyrokinetic simulations. Model plasma parameters are chosen based on the hydrogen isotope pellet experiments on JET, in which hydrogen isotope mixing in the time scale of the energy confinement time occurred after injecting deuterium (D) pellets into hydrogen (H) plasmas. Two numerical experiments are conducted using plasma profiles before and after the D pellet injection. In both cases, turbulent fluctuations in the plasma core are characterized by ion temperature gradient driven turbulence, while in the latter case, trapped electron mode turbulence also exists in the outer region. In the former case, the density profile of bulk H ions is kept in a quasi-steady state, and the particle confinement time of bulk H ions is an order of magnitude longer than the energy confinement time. In the latter case, the density profiles of bulk H ions and pellet D ions show transient relaxation in the time scale of the energy confinement time, indicating the fast hydrogen isotope mixing. In the toroidal angular momentum balance, it is found that the hydrogen isotope mixing is driven by the toroidal field stress.
Iwata, Yoshihiro; Miyabe, Masabumi; Wells, S. R.*; Yamamoto, Yuta*; Hasegawa, Shuichi*
Proceedings of International Topical Workshop on Fukushima Decommissioning Research 2024 (FDR2024) (Internet), 4 Pages, 2024/10
In this study, triple and double resonance ionization schemes of atomic Ca were developed, aiming for the separation of odd isotopes by (i) laser polarization-dependent selection rules, and (ii) large isotope shifts of odd Ca isotopes in the Rydberg levels. Separation of odd isotopes was confirmed under the orthogonal condition. Suppression of non-resonant ionization of 
Ca by the electric field in the ionization region could further improve the optical isotope selectivity of 
Ca.
Collaborative Laboratories for Advanced Decommissioning Science; Kogakuin University*
JAEA-Review 2024-015, 99 Pages, 2024/09
JAEA-Review-2024-015.pdf:5.42MB
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, 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 FY2022. 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.
Battulga, B.; Munkhbat, D.*; Matsueda, Makoto; Atarashi-Andoh, Mariko; Oyuntsetseg, B.*; Koarashi, Jun; Kawahigashi, Masayuki*
Environmental Pollution, 357, p.124427_1 - 124427_10, 2024/09
Times Cited Count：2 Percentile：20.20(Environmental Sciences)The occurrence and characteristics of plastic debris in aquatic and terrestrial environments have been extensively studied. However, there is still limited information on the properties and dynamic behavior of plastic-associated biofilms in the environment. In this study, we collected plastic samples from an inland river system in Mongolia and extracted biofilms from the plastics to uncover the characteristics of the biofilms using analytical, isotopic, and thermogravimetric techniques. Mixtures of organic and mineral particles were detected from extracted biofilms, revealing the plastic as a carrier for exogenous substances including contaminants in the river ecosystem. The present study provides insights into the characteristics and environmental behavior of biofilms which are useful to elucidate the impact of plastic-associated biofilms on organic matter and material cycling in the aquatic ecosystems.
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; i-Lab*
JAEA-Review 2023-029, 77 Pages, 2024/05
JAEA-Review-2023-029.pdf:3.98MB
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, 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 FY2020, this report summarizes the research results of the "Challenge to advancement of debris composition and direct isotope measurement by microwave-enhanced LIBS" conducted from FY2020 to FY2022. The present study aims to increase the emission intensity of LIBS (laser-induced breakdown spectroscopy) by superimposing MW (microwave) and apply it to uranium isotope measurement. In FY2022, we improved the cooling method and reduce unnecessary functions in of the semiconductor microwave oscillator, and apply the optimized conditions obtained from simulations to the LIBS experiment for the microwave antenna gave better results.
Iwata, Yoshihiro; Miyabe, Masabumi; Akaoka, Katsuaki; Wakaida, Ikuo; Hasegawa, Shuichi*
Journal of the Optical Society of America B, 41(1), p.119 - 126, 2024/01
Times Cited Count：3 Percentile：46.87(Optics)Calcium Rydberg levels are of significant interest for efficient and isotope-selective resonance ionization of trace radionuclides such as calcium-41 (Ca). In this study, we report novel measurement data on the energy level shifts of calcium-43 (
Ca) for 4sns 
S
and 4s(n-1)d D
(n=40, 45, 50, 55, 60) Rydberg levels due to hyperfine-induced singlet-triplet mixing specific to isotopes with an odd mass number.
Battulga, B.; Atarashi-Andoh, Mariko; Matsueda, Makoto; Koarashi, Jun
Environmental Science and Pollution Research, 30(31), p.77226 - 77237, 2023/05
Times Cited Count：4 Percentile：24.77(Environmental Sciences)The global survey for the presence of microplastics (MPs) in aquatic environments has attracted widespread scientific attention over the past decade. This study demonstrates a multidimensional analytical approach, including isotopic and thermogravimetric analyses to evaluate characteristics and behavior of MPs in the environment. The MP samples were collected in two contrasting coastal areas of Japan. The 
C values of field-collected polyethylene (PE), polypropylene (PP), and polystyrene (PS) MPs were ranged from -25.6 to -31.4, -23.4 to -30.9, and -27.3 to -28.6 per mil, respectively. The differences in C signature between MPs with the same polymer types (i.e., PE and PP) but different colors. Through thermal analysis, the single-step endothermic process was observed for environmental PE and PS-MPs. The results reveal that degradation may play a significant role in the behavior and characteristics of MP debris in the aquatic environment.
Collaborative Laboratories for Advanced Decommissioning Science; i-Lab*
JAEA-Review 2022-042, 67 Pages, 2023/01
JAEA-Review-2022-042.pdf:7.42MB
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 FY2020, this report summarizes the research results of the "Challenge to advancement of debris composition and direct isotope measurement by microwave-enhanced LIBS" conducted in FY2021. The present study aims to increase the emission intensity of LIBS (laser-induced breakdown spectroscopy) by superimposing MW (microwave) and apply it to uranium isotope measurement. In FY2021, after confirming that there was no problem in terms of specifications including noise leakage by downsizing the semiconductor MW oscillator and evaluating it as a single unit, the possibility of uranium isotope measurement was examined by applying it to the LIBS experiment. In addition, the optimized design of the MW antenna was carried out. By applying them, we confirmed the actual performance, …
Battulga, B.; Atarashi-Andoh, Mariko; Nakanishi, Takahiro; Koarashi, Jun
Science of the Total Environment, 849, p.157758_1 - 157758_11, 2022/11
Times Cited Count：12 Percentile：54.67(Environmental Sciences)Characterizing plastic-associated biofilms is key to the better understanding of organic material and mineral cycling in the "Plastisphere"-the thin layer of microbial life on plastics. In this study, we propose a new method to extract biofilms from environmental plastics, in order to evaluate the properties of biofilm-derived organic matter through stable carbon (C) and nitrogen (
N) isotope signatures and their interactions with radionuclides especially radiocesium (Cs). After ultrasound-assisted separation from the plastics, biofilm samples were successfully collected via a sequence of syringe treatments. Biofilm-derived organic matter samples (14.5-65.4 mg) from four river mouths in Japan showed Cs activity concentrations of 
75 to 820 Bq kg
biofilm (dw), providing evidence that environmental plastics, mediated by developed biofilms, serve as a carrier for Cs in the coastal environment. Significant differences in the (C and N signatures were also obtained for the biofilms, indicating the different sources, pathways, and development processes of biofilms on plastics.
Collaborative Laboratories for Advanced Decommissioning Science; The University of Tokyo*
JAEA-Review 2022-014, 106 Pages, 2022/08
JAEA-Review-2022-014.pdf:10.42MB
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 FY2018, this report summarizes the research results of the "Development of technology for rapid analysis of strontium-90 with low isotopic abundance using laser resonance ionization" conducted from FY2018 to FY2021 (this contract was extended to FY2021). Since the final year of this proposal was FY2021, the results for four fiscal years were summarized. The present study aims to develop a rapid analysis technique for strontium-90 using diode laser-based resonance ionization with elemental and isotopic selectivity. Strontium-90 is one of the major difficult-to-measure nuclides released into the environment due to the accident at TEPCO's Fukushima Daiichi Nuclear Power Station.
Yb for producing 
Lu with high radionuclide purity by Yb(
)LuNagai, Yasuki*; Kawabata, Masako*; Hashimoto, Shintaro; Tsukada, Kazuaki; Hashimoto, Kazuyuki*; Motoishi, Shoji*; Saeki, Hideya*; Motomura, Arata*; Minato, Futoshi; Ito, Masatoshi*
Journal of the Physical Society of Japan, 91(4), p.044201_1 - 044201_10, 2022/04
Times Cited Count：6 Percentile：51.58(Physics, Multidisciplinary)Recently, Lu is considered as one of the most important medical RIs for treating neuroendocrine tumors. A plan to produce Lu with high purity by using enriched Yb samples with irradiation of deuteron beams in accelerators has been discussed. However, since the other Yb isotopes contained in the Yb sample interacts with deuterons, Lu isotopes other than Lu are produced as impurities. Since the purity of Lu is important for medical use, a method to evaluate the impurity of Lu has been required. In this study, we proposed a new method to estimate production yields of each Lu isotopes in Yb samples with arbitrary isotopic compositions by using excitation functions of Yb()Lu reactions and the particle transport calculation code PHITS. The method plays an important role in discussing the isotopic composition of enriched samples to produce high-purity Lu using accelerators.
