Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Collaborative Laboratories for Advanced Decommissioning Science; Institute of Physical and Chemical Research*
JAEA-Review 2025-031, 124 Pages, 2025/12
JAEA-Review-2025-031.pdf:7.93MB
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 "Development of radiation field mapping measurement system based on high radiation tolerant solar cells for low-light illumination" conducted in FY2023. The present study aims to develop a system that can map radiation fields by applying independent and remotely operated sensors to obtain radiation information in the Primary Containment Vessel (PCV) in real time. The system will be implemented in a real environment to ensure the safety of workers and equipment by monitoring the leakage of gamma rays and neutrons, which are highly penetrating and can be a cause of accidents. A solar cell dosimeter is being developed as a compact sensor of the built-in potential drive type that utilizes a device with high radiation tolerance that has been developed as a solar cell for space use. The CIGS solar cell dosimeter is the basis for the development of a system with high functionality and systemization for 1F packaging. In FY2023, we will investigate the conditions for creating a flexible device based on the structure of a CIGS solar cell device, and clarify the initial characteristics of a prototype device using a CIGS device on a glass substrate through irradiation tests using gamma rays, electron beams, and neutron beams. In the neutron detection structure, we will explore the conditions for applying the conversion material boron, investigate the conditions for adjusting the particle size of the powder material by milling, and select the coating method and solvent conditions. In mapping measurements, we will develop a system that can display dose information by measuring multiple sensors.
Takahashi, Tone; Koizumi, Mitsuo; Yoshimi, Yuki*; Mochimaru, Takanori*
JAEA-Technology 2025-007, 26 Pages, 2025/11
JAEA-Technology-2025-007.pdf:1.6MB
To prevent the smuggling of nuclear and radioactive materials into event venues for the purpose of terrorism, it is common practice to individually inspect people and vehicles entering and exiting using radiation detectors. However, since there remains a risk of such inspections being bypassed, it is necessary to complement them with a wide-area radiation survey to ensure that no nuclear or radioactive materials have been brought in. Radiation mapping is an effective method for efficiently surveying large areas. In this method, a gamma-ray detector equipped with GPS is used to record location data and radiation dose rates while moving. By utilizing network connectivity, measurement data from multiple detectors can be aggregated at a central command post, allowing real-time monitoring of survey progress. This system helps to prevent both redundant and missing measurements and enables the prompt detection of suspicious radiation sources. Furthermore, by incorporating spectrometers into the gamma -ray detectors, it becomes possible to identify radioactive isotopes, thereby enabling appropriate responses. To enable such wide-area radiation surveys, we developed real-time mapping software. The developed software receives measurement data transmitted from GPS-equipped gamma-ray spectrometers, processes it sequentially in real time, and plots it onto pre -downloaded map data. Additionally, by integrating the spectral data collected from regions showing abnormal radiation levels can be displayed immediately. To enhance information security, the software is designed to function within local networks without requiring internet connectivity. In this report, we introduce an overview of the developed software and provide a simplified version of the source code as an appendix. The provided code is developed using open and free operating systems, libraries, and environments, making it freely available and usable by anyone.
Takahashi, Tone; Mochimaru, Takanori*; Koizumi, Mitsuo; Yoshimi, Yuki*; Yamanishi, Hirokuni*; Wakabayashi, Genichiro*; Ito, Fumiaki*
JAEA-Review 2025-039, 34 Pages, 2025/11
JAEA-Review-2025-039.pdf:2.18MB
To prevent acts of terrorism involving nuclear or radioactive materials at major public events, it is required to have surveillance technologies that either prevent these materials from being brought in or detect quickly if somebody brings them in secretly. Setting radiation gate monitors to survey pedestrians and vehicles is one of the effective methods. However, considering the possibility of individuals bypassing these monitors, complementary technologies are needed to continuously survey areas inside the gates. To survey extensive areas, radiation mapping is effective. By using multiple detectors and aggregating the data, the survey becomes much more efficient. We have developed mobile detectors capable of simultaneously measuring location data and radiation levels outdoors, with the ability to aggregate measurement results via a network and immediately visualize them on a map. For indoor environments, we have developed a technology that integrates radiation measurement results with environmental mapping created using SLAM (Simultaneous Localization and Mapping) to produce 3D maps of the surveyed areas. Additionally, we have been working on the development of a source search technology using a fast neutron detector to quickly detect neutron sources, including nuclear materials. In this report, we describe a concept of the wide area survey system and report technology development results so far.
Collaborative Laboratories for Advanced Decommissioning Science; Hokkaido University*
JAEA-Review 2025-028, 66 Pages, 2025/11
JAEA-Review-2025-028.pdf:3.59MB
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 FY2023, this report summarizes the research results of the "Development of a prototype shielding-free radiation-resistant diamond neutron measurement system" conducted in FY2023. The present study aims to develop a prototype of a shielding-free neutron measurement system for 1F. The system consists of diamond neutron detectors and radiation-resistant silicon integrated circuits, and has radiation resistance of more than 10 MGy and 4 MGy, respectively, at the component level in terms of integrated dose, and has a track record of stable operation under 
-ray dose rate environment of 1.5 kGy/h. Future applications are expected to include neutron detectors for debris investigation, criticality proximity monitoring monitors, and neutron detectors for dry tube investigation in pressure vessels. In this development, a prototype consisting of 100 diamond detector elements of 5 mm square will be developed to obtain system construction technology and to evaluate system performance. In addition, a subcriticality evaluation method will be developed. This development will lead to the completion of system development, development of the actual system in collaboration with the manufacturer, and introduction of the system into 1F decommissioning project.
Kawasaki, Nobuchika
JAEA-Review 2025-043, 74 Pages, 2025/10
JAEA-Review-2025-043.pdf:2.45MB
Russia is one of the most advanced countries in the civilian use of nuclear energy. However, understanding the internal mechanisms of its nuclear program remains difficult due to various reasons. Therefore, this study presents a historical overview of Russia's nuclear energy utilization, fuel supply, fuel manufacturing capabilities, and concepts regarding reprocessing and the nuclear fuel cycle. From this overview, insights have been extracted and analyzed. These insights are then organized under two strategic perspectives: "Strategic diversity and continuity in developments and demonstrations" and "Diversity in utilizations and deployments," with considerations of implications for Japan, as below. Russia's nuclear energy policy strategically utilizes a variety of reactor types and fuel cycle technologies to expand nuclear power generation both domestically and internationally. Currently, nuclear power, centered on light-water reactors (VVER series), accounts for about 20% of Russia's electricity supply, and there are plans to increase this share to 25% by 2045. A wide range of reactors, from large-scale to medium and small modular reactors, are being constructed in Russia. Russia is also actively developing fast reactor technologies, and focusing on the reprocessing and recycling of spent fuel. Internationally, VVER-1200 reactors are under construction in several countries, and cooperation with China is deepening in the field of fast reactors. Notably, Russia offers an integrated, or selectively customizable, package of nuclear technology services on the international stage. These include not only reactor deployment, but also fuel supply, reprocessing, waste management, and even the provision of radioisotopes. Rather than simply exporting products or technology, Russia fosters long-term relationships and trust by flexibly responding to the conditions and needs of partner countries. For this reason, Russia promotes the technology developments in advance within the country in areas anticipated for future overseas deployment. It carefully selects target technologies and services and systematically rolls them out. This flexible strategy, combining "technological diversity" and "strategic consistency", enables cooperation with countries across various geopolitical contexts. For Japan, this strategic approach offers valuable lessons on how to engage in comprehensive international nuclear cooperation, not merely through technology exports, but through integrated approaches that encompass the entire fuel cycle, and by combining elements such as fast reactors and RI supply.
Collaborative Laboratories for Advanced Decommissioning Science; Institute of Science Tokyo*
JAEA-Review 2025-012, 96 Pages, 2025/10
JAEA-Review-2025-012.pdf:3.99MB
JAEA/CLADS had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project. 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). Among the adopted proposals in FY2021, this report summarizes the research results of the "Uncertainty reduction of the FPs transport mechanism and debris degradation behavior and evaluation of the reactor contamination of debris state on the basis of the accident progression scenario of Fukushima Daiichi Nuclear Power Station unit 2 and 3" conducted from FY2021 to FY2023. The present study aims to elucidate the cause of the high dosage under shield plug by clarification of to the cesium behavior of migration, adhesion to structure and deposition as well as evaluate the properties of metal-rich debris predeceasing melted through the materials science approach based on the most probable scenario of accident progression of Unit 2 and 3. Through three years investigation, chemi-absorption configuration of Cs has been elucidated to change with acidity of steel surface during oxidation in humid atmosphere and Cs
O trapping compound as well as penetration depth have found to be importantly considered. For metallic debris, solid oxidation was found to be controlled by Fe
O
formation and molten state was found to tend to preferentially yield ZrO resulting in formation of slate structure during solidification. Present findings obtained are contributing to better improve the accuracy of accident progression scenario in FDNPP in viewpoint of backward analysis.
Cu and 
Cu with accelerator neutrons by deuterons and their separation from zincNagai, Yasuki*; Kawabata, Masako*; Saeki, Hideya*; Motoishi, Shoji*; Hashimoto, Kazuyuki; Tsukada, Kazuaki; Motomura, Arata*; Ota, Akio*; Takashima, Naoki*; Hashimoto, Shintaro; et al.
Frontiers in Nuclear Medicine (Internet), 5, p.1657125_1 - 1657125_11, 2025/10
In recent years, the radionuclide pair of Cu and Cu has attracted attention as an ideal theranostic agent. We proposed a novel production method utilizing a neutron source generated by deuteron beams at an accelerator facility. By irradiating enriched 
Zn samples with this neutron source, we measured the absolute activity and radionuclidic purity of the produced Cu. The results were consistent with calculations performed using PHITS and JENDL-5 developed by the Japan Atomic Energy Agency, confirming the reliability of the calculation method and demonstrating its capability to estimate the yields of trace radionuclides that are difficult to measure experimentally. Furthermore, we successfully separated Cu from the irradiated Zn sample using our developed sublimation and column separation techniques. These findings suggest that the production of Cu and Cu can be achieved in an economically sustainable manner at multiple sites.
Engineering Services Department, Nuclear Science Research Institute
JAEA-Review 2025-018, 83 Pages, 2025/09
JAEA-Review-2025-018.pdf:4.99MB
The Engineering Services Department is in charge of operation and maintenance of utility facilities (water distribution systems, electricity supply systems, steam generation systems and drain water systems etc.) in whole of the institute. And also is in charge of operation and maintenance of specific systems (power receiving and transforming facilities, an emergency electric power supply system, an air/liquid waste treatment system, a compressed air supply system) in nuclear reactor facilities, nuclear fuel material usage facilities and usual facilities or buildings. In addition, the department is in charge of maintenance of buildings, design and repair of electrical/mechanical equipment. This annual report describes summary of activities, operation and maintenance data and technical developments of the department carried out in JFY 2023. We hope that this report may help to future work.
Sato, Yuki; Terasaka, Yuta; Ichiba, Yuta*
Journal of Nuclear Science and Technology, 62(4), p.389 - 400, 2025/04
Times Cited Count：1 Percentile：27.40(Nuclear Science & Technology)Meigo, Shinichiro; Iwamoto, Hiroki; Sugihara, Kenta*; Hirano, Yukinori*; Tsutsumi, Kazuyoshi*; Saito, Shigeru; Maekawa, Fujio
JAEA-Technology 2024-026, 123 Pages, 2025/03
JAEA-Technology-2024-026.pdf:14.22MB
Based on the design of the ADS Target Test Facility (TEF-T) at the J-PARC Transmutation Experimental Facility, a conceptual study was conducted on the J-PARC proton beam irradiation facility. This research was carried out based on the recommendations of the Nuclear Transmutation Technology Evaluation Task Force of the MEXT. The recommendations state that it is desirable to consider facility specifications that can make the most of the benefits of using the existing J-PARC proton accelerator while also solving the engineering issues of the ADS. We considered facilities that could respond to a variety of needs while reducing the facilities that were not needed in the TEF-T design. In order to clarify these diverse needs, we investigated the usage status of representative accelerator facilities around the world. As a result, it became clear that the main purposes of these facilities were (1) Material irradiation, (2) Soft error testing of semiconductor devices using spallation neutrons, (3) Production of RI for medical use, and (4) Proton beam use, and we investigated the facilities necessary for these purposes. In considering the facility concept, we assumed a user community in 2022 and reflected user opinions in the facility design. This report summarizes the results of the conceptual study of the proton irradiation facility, various needs and responses to them, the roadmap for facility construction, and future issues.
Takahatake, Yoko; Watanabe, So; Watanabe, Masayuki; Sano, Yuichi; Takeuchi, Masayuki
Progress in Nuclear Science and Technology (Internet), 7, p.195 - 198, 2025/03
Extraction chromatgraphy technology for trivalent minor actinide (MA(III) ; Am(III) and Cm(III)) recovery from the solution generated by an extraction process in reprocessing of spent nuclear fuel has been developed. A fine particle is generated in the solution. The fine particle must be removed before MA recovery operation, because that leads clogging of the extraction chlomatography column. In order to prevent clogging the column, filtration system utilizing porous silica beads packed column has been designed. In this study, a fine particle trapping system was developed and particle removal performance of the system was experimentally evaluated using alumina particles as simulated fine particle. Column experiments revealed that the fine particle with the particle size from 0.12 to 15 
m is cause of clogging of the filtration column. Since simulated fine particles were trapped on filtration experiments, a filtration system using the porous silica beads column is practical,
Fukahori, Tokio
JAEA-Conf 2024-002, p.6 - 11, 2024/11
The author has been keeping relationship with Japanese Evaluated Nuclear Data Library for around 38 years. During this period, he has been contributing code developments, for example, Preequilibrium Nuclear Reaction Calculation Code (ALICE-F) and Particle and Heavy Ion Transport Code System (PHITS). The author has also been assisting for EXFOR activities and promoting Evaluated Nuclear Data Processing Code (FRENDY) and Multiphase Multicomponent Detailed Thermal Fluid Analysis Code (JUPITER). In this paper, introduced are the outline of the author's works. Also reported are the author's perspective and challenge for the future form of nuclear data.
Sc, 
Cu, Zn, 
Ag, and 
InNakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Rovira Leveroni, G.; Kimura, Atsushi
Journal of Nuclear Science and Technology, 61(11), p.1415 - 1430, 2024/11
Times Cited Count：3 Percentile：65.33(Nuclear Science & Technology)Neutron capture cross-sections of nuclides targeted for decommissioning are necessary to contribute to the evaluation of radioactivity produced. The present study, Sc, Cu, 
Zn, Ag and In nuclides were selected as target ones, and their thermal-neutron capture cross-sections were measured by an activation method at Kyoto University Research Reactor. The thermal-neutron capture cross-sections were obtained as follows: 27.18
0.28 barn for Sc(n, )
Sc, 4.340.06 barn for Cu(n, )Cu, 0.7190.011 barn for Zn(n, )Zn, 4.050.05 barn for Ag(n, )
Ag and 8.530.27 barn for In(n, ) 
In
. The results for Sc and Zn nuclides supported evaluated values within the limits of uncertainties, while those for the other nuclides were slightly different from evaluated ones. The obtained results are useful not only for the evaluation of production amount, but also for the monitor selection other than Au and Co by considering those nuclides as flux monitors.
Mikhail, M. A. G.*; Kin, Tadahiro*; Eto, Taisei*; Tsukada, Kazuaki
Scientific Reports (Internet), 14, p.27132_1 - 27132_10, 2024/11
Times Cited Count：0 Percentile：0.00(Multidisciplinary Sciences)We have studied a straightforward and robust single-step cation exchange separation method to isolate medical copper radioisotopes Cu and Cu produced in the 
Zn(n, x) reaction with an accelerator neutrons technique. This study revealed the key role of a phosphate buffer pre-treatment of the cation exchange column in the separation process. It was found that incorporating the phosphate buffer into the column pre-treatment markedly enhances the retention of copper isotopes within the column throughout the separation procedure. This approach yields a high-purity radioactive copper sample with a high extraction efficiency of 94.4% of the initially produced copper, all within a relatively short experimental time frame of approximately 5 h for 100 g of starting material.
Motegi, Kosuke; Shibamoto, Yasuteru; Hibiki, Takashi*; Tsukamoto, Naofumi*; Kaneko, Junichi*
JAEA-Review 2024-039, 45 Pages, 2024/09
JAEA-Review-2024-039.pdf:2.23MB
Several heat transfer correlations have been reported related to single-phase opposing flow; however, these correlations are based on experiments conducted in various channel geometries, working fluids, and thermal flow parameter ranges. Therefore, establishing a guideline for deciding which correlation should be selected based on its range of applicability and extrapolation performance is important. This study reviewed the existing heat transfer correlations for turbulent opposing-flow mixed convection. Furthermore, the authors evaluated the predictive performance of each correlation by comparing them with the experimental data obtained under various experimental conditions. The Jackson and Fewster, Churchill, and Swanson and Catton correlations can accurately predict all the experimental data. The authors confirmed that heat transfer correlations using the hydraulic-equivalent diameter as a characteristic length can be used for predictions regardless of channel-geometry differences. Furthermore, correlations described based on nondimensional dominant parameters can be used for predictions regardless of the differences in working fluids.
Collaborative Laboratories for Advanced Decommissioning Science; Tokyo Institute of Technology*
JAEA-Review 2024-010, 112 Pages, 2024/08
JAEA-Review-2024-010.pdf:6.49MB
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 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 "Uncertainty reduction of the FPs transport mechanism and debris degradation behavior and evaluation of the reactor contamination of debris state on the basis of the accident progression scenario of Fukushima Daiichi Nuclear Power Station Unit 2 and 3" conducted in FY2022. The present study aims to elucidate the cause of the high dosage under shield plug by clarification of to the cesium behavior of migration, adhesion to structure and deposition as well as evaluate the properties of metal-rich debris predeceasing melted through the materials science approach based on the most probable scenario of accident progression of Unit 2 and 3. In this fiscal year, the followings were achieved.
Nagatsuka, Kentaro; Noguchi, Hiroki; Nagasumi, Satoru; Nomoto, Yasunobu; Shimizu, Atsushi; Sato, Hiroyuki; Nishihara, Tetsuo; Sakaba, Nariaki
Nuclear Engineering and Design, 425, p.113338_1 - 113338_11, 2024/08
Times Cited Count：15 Percentile：97.90(Nuclear Science & Technology)HTGR has a potential to contribute to decarbonization of hard-to-abate industries by supplying a large amount of hydrogen and high temperature heat or steam without carbon dioxide emission. JAEA has been conducting R&Ds for HTGR technologies with High Temperature Engineering Test Reactor (HTTR). This paper shows that HTTR's tests including the loss of core cooing test as a joint the OECD/NEA international research project and a HTTR heat application test plan which demonstrate hydrogen production by coupling the HTTR with a hydrogen production test facility. Additionally, aiming for operation start from the latter half of 2030s, the basic design of the HTGR demonstration reactor has been shown. The Japan's HTGR technology capabilities established by the HTTR project will be fully utilized for the construction of HTGR demonstration reactor.
Watanabe, Tomoaki; Yamane, Yuichi
Journal of Nuclear Science and Technology, 61(7), p.958 - 966, 2024/07
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)The total fission energy released in a criticality accident involving fissile solution boiling tends to be high because the relatively high fission power continues during boiling. Simulating fission power change correctly during boiling seems essential to estimate the total fission energy. Fission power during boiling changes depending on fissile concentration and volume as the solution evaporates. In this study, we investigated the effect of concentration and volume change on estimated total fission energy for a long time of boiling. We introduced a model calculating the evaporation of fissile solution into the modified quasi-steady-state method to simulate power change during boiling. Three CRAC experiments and the Idaho Chemical Processing Plant (ICPP) criticality accident in 1959 were analyzed. As a result, the calculated energy considering concentration and volume change during boiling reproduced the measured energy well.
Sato, Yuki; Terasaka, Yuta; Oura, Masatoshi*
Journal of Nuclear Science and Technology, 61(7), p.856 - 870, 2024/07
Times Cited Count：10 Percentile：88.86(Nuclear Science & Technology)Lan, Z.*; Arikawa, Yasunobu*; Mirfayzi, S. R.*; Morace, A.*; Hayakawa, Takehito*; Sato, Hirotaka*; Kamiyama, Takashi*; Wei, T.*; Tatsumi, Yuta*; Koizumi, Mitsuo; et al.
Nature Communications (Internet), 15, p.5365_1 - 5365_7, 2024/07
Times Cited Count：11 Percentile：87.29(Multidisciplinary Sciences)