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I in riverbank sediment after the Fukushima accidentNakanishi, Takahiro; Sakuma, Kazuyuki; Oyama, Takuya; Hagiwara, Hiroki; Suzuki, Takashi
Environmental Pollution, 355, p.124213_1 - 124213_7, 2024/08
This study investigated the transport behavior of I by riverbank surveys conducted from 2013 to 2015 in a watershed where the I/
Cs activity ratio is low in the mountainous area and high in the plain as of 2011. Until 2015, the I/Cs activity ratio of the levee crown in the studied watershed was similar to that of the surrounding area in 2011. However, the I/Cs ratios of the surface riverbank sediments were all low, indicating that radionuclides transported from the mountainous area were deposited on the riverbank in the plain. The vertical distribution of the I/Cs ratio in the riverbank sediments indicated that some I and Cs deposited during the accident remained in the lower layers, but most were eroded immediately after the accident. Based on the I/Cs ratios of sediments deposited on the riverbank, which remained constant until 2015 after the accident, the amount of I discharged to the ocean was determined from the previously evaluated Cs discharge. It was calculated that 1.8
10
Bq and 1.210
Bq of I were discharged with sediment from the studied watershed and the contaminated river watersheds (Abukuma River and Fukushima coastal rivers, including the study river), respectively. The results of this study indicate that the continuous I discharge from the river contribute little to their amount in the seafloor sediments along the Fukushima coast.
Sato, Yuki; Terasaka, Yuta; Oura, Masatoshi*
Journal of Nuclear Science and Technology, 61(7), p.856 - 870, 2024/07
Collaborative Laboratories for Advanced Decommissioning Science; The University of Tokyo*
JAEA-Review 2024-007, 83 Pages, 2024/06
JAEA-Review-2024-007.pdf:5.56MB
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 "Investigation of environment induced property change and cracking behavior in fuel debris" conducted from FY2020 to FY2022. The present study focuses on "metallic debris", which is mainly composed of elements derived from fuel cladding and control rod sheaths. This is the final year of the three years project. The findings on their material properties are as follows. Six phases are precipitated in the metallic debris according to the state diagram of the Zr-Fe-B-C system. Under high-temperature oxidation conditions, an outer film composed mainly of Zr
Fe is formed on the surface. An inner layer oxide film is also formed according to the chemical composition of the matrix phase of the debris.
-contamination visualization (Contract research); FY2022 Nuclear Energy Science & Technology and Human Resource Development ProjectCollaborative Laboratories for Advanced Decommissioning Science; Hokkaido University*
JAEA-Review 2024-006, 54 Pages, 2024/06
JAEA-Review-2024-006.pdf:2.21MB
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 FY2022, this report summarizes the research results of the "Development of elemental technologies of hand-foot-cloth monitors for -contamination visualization" conducted in FY2022. The present study aims to develop hand-foot-monitors for -contamination visualization and cloth monitors for /
-contamination visualization consisting of a portable phoswich detector for measuring /-contamination distribution and energy to ensure the safety and security of workers involved in the decommissioning project of the 1F. The possibility of practical application of new scintillator materials and devices was examined with the goal of developing such new instruments.
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.
Matsueda, Makoto; Takagai, Yoshitaka*
Bunseki (Internet), 2024(6), p.195 - 200, 2024/06
The analytical demand for radioisotopes (RI) contained in radioactive waste from the decommissioning of nuclear power plants, research activities and nuclear accidents is increasing. However, traditional analytical methods of RI are mostly complicated and time-consuming, it is necessary to be rapid, simple and automatic methods. This paper describes the rapid analytical techniques of inductively coupled plasma-mass spectrometry in recent years, which current technology, challenges and perspective for the future.
Saisu, Motofumi*; Ando, Tadahiko*; Uchiyama, Keizo*; Ueno, Toshihiro*; Takizawa, Koichi*; Endo, Yuji*; Yoshimura, Kazuya; Sanada, Yukihisa
Journal of Radiological Protection, 44(2), p.021518_1 - 021518_16, 2024/06
Mikami, Satoshi; Tokiyoshi, Masanori*; Sato, Rina*; Tanaka, Daisuke*; Yoshimura, Kazuya
Nihon Hoshasen Anzen Kanri Gakkai-Shi, 23(1), p.10 - 17, 2024/06
Taisei Corporation and Infocube LAFLA Co., Ltd. have developed the smartphone-wirelessly-connected dosemeters, aiming to apply it to real-time exposure management of multiple decontamination workers. In order to grasp the basic characteristics of the developed dosemeters, they were calibrated and tested their characteristics such as energy dependency, angle of incidence dependency, etc. at photon calibration fields in Japan Atomic Energy Agency. The results showed generally good characteristics in each test. We evaluated that the dosemeters can be effectively used for decontamination work.
Sato, Ikken; Yoshikawa, Shinji; Yamashita, Takuya; Shimomura, Kenta; Cibula, M.*; Mizokami, Shinya*
Nuclear Engineering and Design, 422, p.113088_1 - 113088_24, 2024/06
Sato, Yuki; Kakuto, Takeshi*; Tanaka, Takayuki*; Shimano, Hiroyuki*; Morohashi, Yuko; Hatakeyama, Tomoyoshi*; Nakajima, Junsaku; Ishiyama, Masahiro
Nuclear Instruments and Methods in Physics Research A, 1063, p.169300_1 - 169300_7, 2024/06
Collaborative Laboratories for Advanced Decommissioning Science; Shinshu University*
JAEA-Review 2023-053, 87 Pages, 2024/05
JAEA-Review-2023-053.pdf:4.67MB
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 "Development of environmental mitigation technology with novel water purification agents" conducted from FY2020 to FY2022. The present study aims to develop a reusable adsorbent for strontium ions with high adsorption property to contribute to the improvement of the treatment process of radioactive contaminated water generated by the Great East Japan Earthquake. As a result, reusable adsorbent materials showing excellent Sr adsorption performances were developed. The current adsorbent materials for strontium are extremely expensive and single use, so the storage and disposal of massive generation of waste have become a major problem.
Collaborative Laboratories for Advanced Decommissioning Science; Tohoku University*
JAEA-Review 2023-048, 151 Pages, 2024/05
JAEA-Review-2023-048.pdf:8.48MB
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 "Development of a hybrid method for evaluating the long-term structural soundness of nuclear reactor buildings using response monitoring and damage imaging technologies" conducted in FY2022. The present study aims to develop an evaluation method necessary to obtain a perspective on the long term structural soundness of accident-damaged reactor buildings, where accessibility to work sites is extremely limited due to high radiation dose rate and high contamination. In FY2022, the second year of the three-year plan, some tests and other activities on the following research items were conducted following FY2021, based on the specific research methods and research directions clarified in FY2021.
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.
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.
Honda, Mitsunori; Kaneta, Yui; Muraguchi, Masakazu*; Hayakawa, Kosetsu*; Oda, Masato*; Iino, Chiaki*; Ishii, Hiroyuki*; Goto, Takuya*
AIP Advances (Internet), 14(5), p.055034_1 - 055034_6, 2024/05
This study examines the utilization of Fukushima weathered biotite(WB)as an alternative to conventional thermoelectric materials traditionally derived from rare and toxic substances. WB underwent milling, classification, and subsequent heat treatment via molten-salt treatment to produce crystals exhibiting conductivity akin to semiconductors within from 650
C to 850C range. Evaluation of WB and the derived crystal's electrical conductivity and Seebeck coefficient showcased their viability for high-temperature thermoelectric applications. Consequently, WB attained a dimensionless figure of merit (ZT) of 0.015, signaling its potential as a thermoelectric material that surpasses 650C.
Cs supply from rivers to coastal waters off Fukushima on the Cs behavior in seabed sedimentIkenoue, Tsubasa; Nakanishi, Takahiro; Shimadera, Hikari*; Kawamura, Hideyuki; Kondo, Akira*
E3S Web of Conferences (Internet), 530, p.02005_1 - 02005_10, 2024/05
The accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) caused a radioactive contamination in seabed sediment. The Cs supply from rivers could be an important process for the long-term behavior of Cs in seabed sediment. In this study, a ten-year simulation of the Cs behavior in seabed sediment was conducted using an oceanic dispersion model combined with a prediction model of Cs behavior in land and river. In the waters north of FDNPP, the simulation results suggested that the Cs supply from rivers had a great impact on the concentrations in coastal sediment due to the initial low concentrations in seabed sediment and the large supply of Cs from rivers. In the waters near FDNPP and south of FDNPP, the simulation results suggested that the impact of the Cs supply on the temporal variation of Cs concentration in coastal sediment was relatively small due to the large initial adsorption from seawater. Overall, these results indicated that Cs supply from rivers had an impact on the spatiotemporal distribution of Cs concentrations in seabed sediment on a decadal time scale and the impact was especially great in the waters north of FDNPP.
Miyazaki, Kanako*; Takehara, Masato*; Minomo, Kenta*; Horie, Kenji*; Takehara, Mami*; Yamasaki, Shinya*; Saito, Takumi*; Onuki, Toshihiko*; Takano, Masahide; Shiotsu, Hiroyuki; et al.
Journal of Hazardous Materials, 470(15), p.134104_1 - 134104_11, 2024/05
Batsaikhan, M.; Akaoka, Katsuaki; Saeki, Morihisa*; Karino, Takahiro; Oba, Hironori; Wakaida, Ikuo
Journal of Nuclear Science and Technology, 61(5), p.658 - 670, 2024/05
Times Cited Count：1 Percentile：63.33(Nuclear Science & Technology)no abstracts in English
Cs in a river-sea system boundary area after the Fukushima Dai-ichi Nuclear Power Plant accidentTakata, Hyoe*; Wakiyama, Yoshifumi*; Wada, Toshihiro*; Hirao, Shigekazu*; Aono, Tatsuo*; Nakanishi, Takahiro; Misono, Toshiharu; Shiribiki, Takehiko; Aoyama, Michio*
Marine Chemistry, 262, p.104384_1 - 104384_6, 2024/05
Sanada, Yukihisa; Oshikiri, Keisuke*; Kanno, Marina*; Abe, Tomohisa
Nuclear Instruments and Methods in Physics Research A, 1062, p.169208_1 - 169208_7, 2024/05
As part of the decommissioning work at the Fukushima Daiichi Nuclear Power Plant (FDNPP), the release of stored treated water began in 2023. In this study, we developed a practical tritium monitor to continuously monitor the concentration of tritiated water, as confirmed by batch sampling measurements at the FDNPP. The monitor is arranged with a flow cell detector comprising inexpensive plastic scintillator pellets and incorporating simultaneous measurements by three detectors, a veto detector, and lead shielding to reduce the influence of environmental 
-rays. The system reached a detection limit of 911 Bq L-1 with a measurement time of 30 min, which is lower than the discharge standard for tritiated water of 1,500 Bq L-1. The system can also qualitatively distinguish the presence of disturbances due to interfering radionuclides other than tritium or background radiation using the -ray spectrum.
