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underwater radiation monitoring detectorJi, W.*; Lee, E.*; Ji, Y.-Y.*; Ochi, Kotaro; Yoshimura, Kazuya; Funaki, Hironori; Sanada, Yukihisa
Nuclear Engineering and Technology, 58(2), p.103933_1 - 103933_6, 2026/02
We aimed to validate the performance of an in situ underwater radiation detector, MARK-U1 (Monitoring of Ambient Radiation of KAERI - Underwater), was used to estimate 
Cs activity concentration in river and reservoir sediment at predicted sites of contamination. Additionally, underwater core samples were collected to measure the radioactivity using a high-purity germanium (HPGe) detector. To estimate radioactivity, a conversion factor was derived by comparing the measured spectrum and Cs activity in the sample. A Monte Carlo N-Particle (MCNP) simulation was conducted to determine the effective source geometry for in situ measurement. The simulation results correlated well with the on-site MARK-U1 monitoring results, with a deviation of 31.62%. These findings validate the performance of the in situ detector. This device can therefore be used to estimate Cs activity concentration in the underwater sediment via on-site monitoring, without requiring sample collection.
Ji, Y.-Y.*; Joung, S.*; Ji, W.*; Ochi, Kotaro; Sasaki, Miyuki; Sanada, Yukihisa
Journal of Radiological Protection, 45(4), p.042501_1 - 042501_11, 2025/12
This study reports the development and field validation of KAERI's UAV-based gamma-ray spectrometry system equipped with LaBr
(Ce) detectors. Joint surveys with JAEA near FDNPP showed reliable dose rate estimation after applying altitude based attenuation correction, through discrepancies occurred in sloped terrain. Incorporating terrain data is recommended to enhance accuracy for emergency response applications.
Collaborative Laboratories for Advanced Decommissioning Science; Kyoto University*
JAEA-Review 2025-020, 74 Pages, 2025/10
JAEA-Review-2025-020.pdf:5.85MB
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 FY2022, this report summarizes the research results of the "Establishment of 3-D dose dispersion forecasting method and development of in-structure survey using the transparency difference of each line gamma-ray" conducted in FY2023. We realized an electron track detecting Compton camera (ETCC) that can measure gamma-ray images (linear images) with the bijective projection. In the "Quantitative analysis of radioactivity distribution by imaging of high radiation field environment using gamma-ray imaging spectroscopy" (hereinafter referred to as the previous project) adopted in FY2018, the 1 km square area including the reactor buildings was imaged at once. In FY2021, 3-D dosimetry in the reactor building of the Institute for Integrated Radiation and Nuclear Science was carried out, and 3-D imaging of gamma-rays was successfully obtained. This project will build on the results of the previous project to develop a practical 3-D contaminant dispersion detection and prediction system for sub-mSv/h environments. In addition, a 3-D radiographic Cs distribution measurement method inside the reactor building using highly penetrating 
Cs gamma-rays will be developed. In FY2023, we fabricated a lightweight and highly effective shielding specifically for the TPC of ETCC based on simulations. In addition, by conducting calibration experiments at the FRS facility, we were also able to repair bugs in the signal processing circuit. Those meticulous advance preparations enabled us to successfully conduct a 3-D experiment within 1F in March 2024.
Collaborative Laboratories for Advanced Decommissioning Science; Tohoku University*
JAEA-Review 2025-011, 74 Pages, 2025/08
JAEA-Review-2025-011.pdf:5.31MB
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science &Z 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 a cooperative operation robot system for radiation source exploration" conducted from FY2021 to FY2023. The present study aims to develop a robot system (CORRASE: Cooperative Operation Robot system for RAdiation Source Exploration), realizing radiation source exploration with wide field of view, rapidity, and low cost. In FY2023, our research efforts focused on verification tests for radiation source exploration by summarizing the results of our previous studies. Polyhedral type gamma-ray directional detectors were fabricated from 8 BGO scintillators and shielding bodies. Radiation source exploration experiments were performed by developing a cooperative operation robot system consisting of 3 multi-legged robots carrying the gamma-ray detectors, IMUs (Inertial Measurement Units), and LiDARs (Light Detection And Ranging). An unknown test environment for the radiation source exploration was constructed by placing obstacles and a 10 MBq Cs sealed source as a simulated radioactive contamination source in a room measuring 7.8 
5.3 m
. The developed system was used to create the environmental map, to formulate the exploration plan, to create the heatmap of the radiation counts, and to image the radiation source from the calculated optimal observation position. The localization of the simulated radioactive contamination source was successfully performed with the cooperation of the 3 robot systems by displaying the image of the radiation source fused on the environmental map. It can be concluded that the initial goal of this study has been successfully achieved by developing the robot system realizing radiation source exploration.
Kimura, Yoshiki; Yamaguchi, Tomoki
Progress in Nuclear Science and Technology (Internet), 7, p.60 - 66, 2025/05
Sato, Yuki
Radiation Protection Dosimetry, p.ncaf046_1 - ncaf046_11, 2025/05
Times Cited Count：0 Percentile：0.00(Environmental Sciences)Kaburagi, Masaaki; Miyamoto, Yuta; Mori, Norimasa; Iwai, Hiroki; Tezuka, Masashi; Kurosawa, Shunsuke*; Tagawa, Akihiro; Takasaki, Koji
Journal of Nuclear Science and Technology, 62(3), p.308 - 316, 2025/03
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Sato, Yuki; Minemoto, Kojiro*; Nemoto, Makoto*
Proceedings of Waste Management Conference 2025 (WM2025) (Internet), 9 Pages, 2025/03
Miyazaki, Yasunori; Sano, Yuichi; Ishigami, Ryoya*
EPJ Web of Conferences, 317, p.01006_1 - 01006_7, 2025/01
Times Cited Count：0 Percentile：0.00(Chemistry, Inorganic & Nuclear)The gamma-ray and He
ion beam (which is simulated for alpha-ray from 
Am, for example) were irradiated on the TEHDGA adsorbent to evaluate the hydrogen gas production, leaching amount of organics in the immersed 3 M HNO solution, thermal characteristics and speciation of the degradation products. These were combined to assess the safety of the 1st run of the MA separation process from the raffinate at a dose rate of 1 kGy/h.
Ito, Tatsuya; Nagaishi, Ryuji; Kuwano, Ryo*; Godo, Masao*; Yoshida, Yoichi*
Radiation Physics and Chemistry, 226, p.112198_1 - 112198_5, 2025/01
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)In recent years, the use of radiation-resistant resins of polyimide and polyether ether ketone becomes increasing as vessels for irradiation and unsealed radioisotope experiments. However, in our radiolysis experiments, the possibility of interaction between radiolysis products of water and the resin was found, suggesting concerns that the resin may affect reactions in water in radiation fields. To clarify the interaction, dichromate (Cr
O
) reduction and hydrogen peroxide (HO) formation in 
-radiolysis of water were compared with and without the resin. The CrO reduction amount in aqueous solution with the resin became larger than that without the resin at the same dose, indicating the promotion of CrO reduction by the resin. On the other hand, the HO formation in pure water with and without an electron scavenger were almost independent of the presence of resin. These suggested the interaction between hydroxyl radical and the resin in contact with water in radiation fields.
Sato, Yuki; Kakuto, Takeshi*; Tanaka, Takayuki*; Shimano, Hiroyuki*
European Physical Journal; Special Topics, 10 Pages, 2025/00
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)Collaborative Laboratories for Advanced Decommissioning Science; Tohoku University*
JAEA-Review 2024-016, 61 Pages, 2024/12
JAEA-Review-2024-016.pdf:2.88MB
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 FY2022, this report summarizes the research results of the "Development of a high-resolution imaging camera for alpha dust and high-dose rate monitor" conducted in FY2022. The present study aims to develop a high-resolution imaging camera for alpha dust and a high-dose rate monitor. To realize the high-resolution imaging camera for alpha dust, we have developed novel scintillation materials with emission bands of 500-800 nm. Moreover, we have prepared several materials for the camera and software. We have also developed novel scintillation materials with emission bands of 650-1,000 nm, and simulation studies have been conducted for the high-dose-rate monitor system consisting of optical fiber.
Sumita, Takehiro*; Osawa, Takahito; Chiu, I.-H.; Ikeda, Atsushi
Analytica Chimica Acta, 1329, p.343256_1 - 343256_10, 2024/11
Times Cited Count：1 Percentile：26.64(Chemistry, Analytical)Sato, Yuki
Applied Radiation and Isotopes, 212, p.111421_1 - 111421_8, 2024/10
Times Cited Count：1 Percentile：43.12(Chemistry, Inorganic & Nuclear)Ishii, Junya*; Shimizu, Morihito*; Kato, Masahiro*; Kurosawa, Tadahiro*; Tsuji, Tomoya; Yoshitomi, Hiroshi; Tanimura, Yoshihiko; Watabe, Hiroshi*
Journal of Radiological Protection, 44(3), p.031516_1 - 031516_8, 2024/09
Times Cited Count：0 Percentile：0.00(Environmental Sciences)
Li-glass detector to gamma rays by a coincidence methodIto, Fumiaki*; Lee, J.; Hironaka, Kota; Takahashi, Tone; Suzuki, Satoshi*; Mochimaru, Takanori*; Hori, Junichi*; Terada, Kazushi*; Koizumi, Mitsuo
Nuclear Instruments and Methods in Physics Research A, 1064, p.169465_1 - 169465_9, 2024/07
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)Rodriguez, D.; Akamatsu, Shunsuke*; Rossi, F.; Suzuki, Satoshi*; Takahashi, Tone
Proceedings of 65th Annual Meeting of the Institute of Nuclear Materials Management (Internet), 9 Pages, 2024/07
Hu, X.*; Fujita, Yoshitaka; Tsuchiya, Kunihiko; Fukutani, Satoshi*; Hori, Junichi*; Suzuki, Tatsuya*
Journal of Radioanalytical and Nuclear Chemistry, 333(11), p.6057 - 6063, 2024/05
Times Cited Count：0 Percentile：0.00(Chemistry, Analytical)no abstracts in English
Ochi, Kotaro; Barker, E.*; Nakama, Shigeo; Gleizes, M.*; Manach, E.*; Vincent, F.*; Sanada, Yukihisa
Journal of Disaster Research, 19(2), p.429 - 445, 2024/04
There are no clear criteria for standardizing mapping techniques for ambient dose equivalent rate (air dose rate) distributions in different countries. Thus, in this study, manborne, carborne, and airborne radiation surveys were conducted jointly by the Japan Atomic Energy Agency and the French Institute for Radiological Protection and Nuclear Safety in the vicinity of the Fukushima Daiichi Nuclear Power Station to confirm the effectiveness of each organization's monitoring methods. For example, in the manborne survey, the discrepancy between the air dose rates measured by the two institutions was observed depending on whether or not the contribution from radionuclides with different gamma-ray energies was considered when converting the count rates obtained by the detectors to air dose rates. As in this study, comparing mapping techniques among various countries and providing feedback to each other should help to improve the accuracy of zoning scenarios after nuclear accidents.
Cantarel, V.; Chupin, F.; Ortega-Charlot, M.*; Yamagishi, Isao; Ueno, Fumiyoshi
Journal of Nuclear Materials, 592, p.154969_1 - 154969_9, 2024/04
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)