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Collaborative Laboratories for Advanced Decommissioning Science; Sapporo University*
JAEA-Review 2026-020, 81 Pages, 2026/09
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), has been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") from FY2019. 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 "High-speed 3D modeling for nuclear reactor environment based on feature extraction results from video images" conducted in FY2024. The present study aims to develop a methodology for 3D modeling of workspaces using video footage captured during surveys of the reactor containment vessel and reactor building at 1F. Based on features extracted from the video within a specified timeframe, the method selects a high-information-content 3D reconstruction approach while augmenting the surrounding contextual information. In fiscal year 2024, we developed a methodology to achieve high-precision photogrammetry-based 3D reconstruction within a specified time limit, using a single video sequence obtained from simulation as input. We also devised a 3D modeling algorithm based on structural grouping and concurrently implemented an optimization algorithm to reduce computation time for 3D reconstruction, thereby accelerating the overall modeling process. Furthermore, we quantitatively evaluated the generation accuracy of moving image data using generative models and continued to enhance both hardware construction and software development to further improve computational efficiency.
Takeda, Masaki; Ono, Hirokazu; Ito, Tsuyoshi*; Yotsuji, Kenji*; Fukatsu, Yuta; Sato, Tomofumi*; Tachi, Yukio
Journal of Nuclear Science and Technology, 63(9), p.1071 - 1085, 2026/09
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Fukuda, Kodai; Shiba, Shigeki*; Iwahashi, Daiki*; Gunji, Satoshi
Journal of Nuclear Science and Technology, 63(9), p.1001 - 1014, 2026/09
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Hamdani, A.; Soma, Shu; Abe, Satoshi; Shibamoto, Yasuteru
Nuclear Engineering and Technology, 58(9), p.104219_1 - 104219_9, 2026/09
Times Cited Count：0Shibata, Akira; Sugaya, Naoto; Nishimura, Arashi; Watahiki, Shunsuke
JAEA-Technology 2026-014, 36 Pages, 2026/08
JAEA-Technology-2026-014.pdf:1.23MB
At the 6th Safeguards Committee Meeting of FY2025, deficiencies in documents for IAEA random inspections were discussed, and, to prevent recurrence, the issue was shared with JOYO, DCA, FMF, and JMTR. At JMTR, IAEA random inspections are conducted with two hours advance notice on the inspection morning. This requires accurate preparation of documents shortly after work starts. One required document is a graph of reactor outlet temperature, inlet temperature and main pump output. Previously, this graph was prepared using Argus data collected from Centum. However, Argus became unusable due to malfunctions. During the random inspection on 18 July 2025, one-hour interval data were manually transcribed from Centum into Excel to create the graph. This method uses coarse data, takes time and may cause errors. Therefore, software was developed to generate inspection graphs rapidly and reliably. A data extraction tool was also developed to simplify retrieval of reactor data from Centum.
Nakayama, Masashi; Ishii, Eiichi; Aoyagi, Kazuhei; Hayano, Akira; Murakami, Hiroaki; Ono, Hirokazu; Ozaki, Yusuke; Mochizuki, Akihito; Iwai, Ryo; Kato, Yoshinari; et al.
JAEA-Review 2026-023, 64 Pages, 2026/08
JAEA-Review-2026-023.pdf:6.33MB
The Horonobe Underground Research Laboratory Project is being pursued by the Japan Atomic Energy Agency to enhance the reliability of relevant technologies for geological disposal of high-level radioactive waste through investigating the deep geological environment within the host sedimentary rocks at Horonobe Town in Hokkaido, north Japan. In the fiscal year 2026, we continue R&D on "Study on near-field system performance in geological environment" and "Demonstration of repository design options". These are identified as key R&D challenges to be tackled in the Horonobe underground research plan for the fiscal year 2020 onwards. In the "Study on near-field system performance in geological environment", dismantling experiment will be conducted on the full-scale engineered barrier system performance experiment in the 350 m depth gallery. Regarding the "Demonstration of repository design options", tracer tests will be conducted in fractures surrounding the 250 m depth gallery and within the excavation damaged zone (EDZ) of the 500 m depth gallery in order to evaluate containment performance at both tunnel and pit scales. Vertical boreholes will be drilled from the floor of the 500 m depth gallery to assess the extent of the EDZ and the volume of water flow, which will inform the selection of the test pit location. A monitoring and assessment plan will then be established to evaluate the EDZ during pit excavation, including analytical approaches for EDZ characterization and their application to tunnel support design. Based on the outcomes of hydraulic disturbance tests performed in the 350 m depth gallery, an assessment will be conducted to evaluate the resistance of pre-existing fractures and faults to displacement. In addition, while continuing to collect the data required to address the issues outlined above, operational monitoring and maintenance inspections of the underground facility equipment will be conducted. Furthermore, we continue R&D on the following three tasks in the Horonobe International Project; Task A: Solute transport experiment with model testing, Task B: Systematic integration of repository technology options, and Task C: Full-scale engineered barrier system dismantling experiment.
Futemma, Akira; Kudo, Tamotsu; Takahashi, Fumiaki
JAEA-Research 2026-002, 51 Pages, 2026/07
JAEA-Research-2026-002.pdf:3.35MB
Rapid assessment of wide-area dose rate distributions is essential in aerial radiation monitoring during a nuclear emergency. Under contract with the Nuclear Regulation Authority, JAEA has developed a real-time data transmission system to receive gamma-ray count rates and positional information from crewed helicopters. However, the conventional system only displayed position and count-rate data on a map and did not support either real-time dose rate conversion or mapping. In this study, a real-time analysis method was developed for aerial radiation monitoring data acquired via satellite communication at approximately 30-second intervals and implemented in the existing system. The method integrates dose rate conversion at 1 m above ground level, automatic extraction of valid flightline data, and dose rate mapping. Cosmic-ray and airborne radionuclide corrections were simplified based on previous monitoring data. A machine-learning model based on aircraft flight behavior was developed to automate flight-line data extraction, which had relied on visual inspection using GIS. IDW interpolation and mapping procedures suitable for 30-second interval data were determined. Comparison with conventional post-flight analysis showed that the method reproduced the main trends of dose rate distributions. Operational testing confirmed normal operation from data reception to map display and delivery of results within several seconds. These results provide a technical basis for real-time dose rate mapping from satellite-transmitted aerial monitoring data during nuclear emergencies.
Matsumoto, Chihiro*; Tanabe, Shota*; Chika, Yamamoto*; Zhao, T.*; Sawano, Toyoaki*; Nonaka, Saori*; Kato, Hideyuki*; Yamaguchi, Fumie; Takahara, Shogo; Tanaka, Tomoaki*; et al.
Journal of Radiological Protection, 46(3), p.032501_1 - 032501_10, 2026/07
Times Cited Count：0 Percentile：0.00(Environmental Sciences)Harada, Masahide; Yamaguchi, Yuji; Hashimoto, Norimichi*; Ito, Taku*; Tajima, Takahiro*; Oku, Takayuki; Haga, Katsuhiro; Ikeda, Hiroshi*; Tamura, Satoshi*
JPS Conference Proceedings (Internet), 45, p.011184_1 - 011184_4, 2026/06
At Materials and Life Science Facility in J-PARC, 3 GeV and 1 MW pulsed proton beam hits mercury and carbon targets and intense neutron and muon beams are provided for various measurements. As samples in the measurements are activated, estimation of radioactivity of samples is very necessary for a radiation safety of user experiments. Therefore, estimation system, SAmple Radioactivity Evaluation program (SARE), is developed. SARE can estimate radioactivity of samples at each neutron and muon beam line with neutron flux and activation cross section. The neutron flux data was applied from references and the activation cross section data was obtained from DCHAIN-SP-2001. The activation of negative-muon can be also estimated from a database. SARE has a user-friendly interface of Web servlet based on JAVA and JAVA script and can select various conditions for the estimation. In the presentation, we will introduce SARE and validation results performed at BL10 with the foil-activation method.
/Pu
couple in NaCl-2CsCl meltHayashi, Hirokazu; Minato, Kazuo*
Journal of Radioanalytical and Nuclear Chemistry, 335(6), p.4233 - 4240, 2026/06
Times Cited Count：0 Percentile：0.00(Chemistry, Analytical)Anhydrous plutonium trichloride (PuCl
) was synthesized by a solid-state reaction of plutonium nitride with cadmium chloride. The lattice constants of hexagonal PuCl were refined from its powder X-ray diffraction pattern to be a = 0.7394 
0.0006 nm and c = 0.4244 0.0006 nm, which are close to the reported values. Using the synthesized PuCl sample, electrochemical behavior of plutonium in NaCl-2CsCl melt at 823-923 K was investigated by cyclic voltammetry and open-circuit chronopotentiometry after polarization. The results show that Pu ions are reduced to Pu metal by single-step mechanism in the NaCl-2CsCl melt. The apparent standard potentials of Pu/Pu redox couple were determined to be E
(Pu/Pu) = -3.514 + 8.60
10
T vs. Cl
/Cl
(V). The activity coefficients of Pu ions were determined using the previously reported Gibbs free energy of formation for PuCl in the supercooled liquid state.
Sr
MnO
with weak magnetoresistanceSterling, T. C.*; Savici, A. T.*; Kajimoto, Ryoichi; Ikeuchi, Kazuhiko*; Khan, N.*; Weber, F.*; Reznik, D.*
Communications Materials (Internet), 7, p.121_1 - 121_11, 2026/05
Takubo, Yusaku*; Takayama, Yusuke*; Sugita, Yutaka; Ogoshi, Minori; Ishida, Keisuke*
Environmental Earth Sciences, 85(9), p.229_1 - 229_19, 2026/05
Times Cited Count：0 Percentile：0.00(Environmental Sciences)Noda, Yohei*; Kumada, Takayuki; 7 of others*
Journal of Applied Crystallography, 59(2), p.492 - 512, 2026/04
Times Cited Count：0 Percentile：0.00(Chemistry, Multidisciplinary)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：1 Percentile：0.00(Nuclear Science & Technology)Nuclear Science Research Institute
JAEA-Review 2025-061, 183 Pages, 2026/03
JAEA-Review-2025-061.pdf:4.01MB
Nuclear Science Research Institute (NSRI) was composed of Planning and Management Department and six departments, namely Department of Operational Safety Administration, Department of Radiation Protection, Engineering Services Department, Department of Research Reactor and Tandem Accelerator, Department of Criticality and Hot Examination Technology, and Department of Decommissioning and Waste Management, and each department manages facilities and develops related technologies to achieve the "Medium- to Long-term Plan" successfully and effectively. On November 1, NSRI unified Department of Research Reactor and Tandem Accelerator, and Department of Criticality and Hot Examination Technology, newly organized Department of Research Infrastructure Technology Development. And, Planning and Management Department was reorganized to Promotion Office. Continuously, four research centers which are Advanced Science Research Center, Nuclear Science and Engineering Center, Nuclear Engineering Research Collaboration Center and Materials Sciences Research Center, belong to NSRI. In order to contribute to future research and development, and to promote management business, this annual report summarizes information on the activities of NSRI of JFY 2024 as well as the activity on research and development carried out by Collaborative Laboratories for Advanced Decommissioning Science, Nuclear Safety Research Center and activities of Nuclear Human Resource Development Center, using facilities of NSRI.
Nakayama, Masashi; Ishii, Eiichi; Aoyagi, Kazuhei; Hayano, Akira; Ono, Hirokazu; Ozaki, Yusuke; Mochizuki, Akihito; Takeda, Masaki; Kimura, Shun
JAEA-Research 2025-016, 141 Pages, 2026/03
JAEA-Research-2025-016.pdf:13.37MB
The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA). The main aim of the project is to enhance the reliability of relevant technologies for the geological disposal of high-level radioactive waste by investigating the deep geological environment within the host sedimentary rocks at Horonobe in Hokkaido, northern Japan. These investigations have been conducted in three phases: "Phase 1: Surface-based investigation", "Phase 2: Construction" (investigation during tunnel excavation) and "Phase 3: Operation" (investigation in subsurface facilities). Since the fiscal year 2020, we have been conducting R&D based on the Horonobe Underground Research Plan for the Fiscal Year 2020 Onwards, which was approved by Hokkaido Prefecture and Horonobe Town. In particular, we are working on the following key tasks with the aim of completing JAEA's 3rd and 4th Mid- and Long-Term Plans: "Study on near-field system performance in geological environments", "Demonstration of repository design options" and "Understanding of buffering behaviour of sedimentary rocks to natural perturbations". This report summarizes the R&D activities on the three above-mentioned key tasks, the goals of which were achieved between fiscal years 2020 and 2024. The results obtained from these tasks will be systematically organized as part of the "Systematic integration of technologies towards EBS emplacement" which has been in progress since fiscal year 2024. This task includes concepts related to the layout of galleries and pits, installation methods for engineered barrier materials, and methods for evaluating their containment performance.
Nishihara, Kenji; Fukushima, Masahiro; Abe, Takumi; Katano, Ryota; Yee-Rendon, B.; Iwamoto, Hiroki; Sugawara, Takanori; Obayashi, Hironari; Saito, Shigeru
JAEA-Research 2025-013, 125 Pages, 2026/03
JAEA-Research-2025-013.pdf:4.68MB
A conceptual design for a pilot Accelerator Driven subcritical System (ADS) was developed as a precursor to a commercial ADS aimed at partitioning and transmutation of minor actinides. The output of the pilot ADS was set at 200 MW. Based on safety assessment results, the design incorporates deep subcriticality and safety rods. Core design, accelerator design, target design, and in-vessel equipment design were performed, clarifying the specific concept.
Okamoto, Naritoshi; Komeno, Akira; Seya, Atsumasa; Inaba, Hideki*; Terakado, Shinichi*; Higuchi, Masashi*
JAEA-Data/Code 2025-022, 497 Pages, 2026/03
JAEA-Data-Code-2025-022.pdf:18.06MB
The Plutonium Fuel Third Development Laboratory of the Nuclear Fuel Cycle Engineering Laboratories has applied for a change of use permit (hereinafter referred to as "license") for plutonium fuel facilities. For the criticality safety design of gloveboxes and equipment/instruments handling mixed oxide (MOX), various criticality calculation codes are used. The most recent employs the 3D Monte Carlo calculation code KENO-V.a embedded in the SCALE 4.4 code system, along with the 27-group ENDF/B-IV neutron cross-section library. SCALE 4.4 was released by the Oak Ridge National Laboratory (ORNL) in the US in 1998, and has now been in use for 27 years. ORNL has continuously improved its functionality, with SCALE 6.3.2 released in 2024. When designing and constructing new MOX fuel facilities, it is desirable to obtain a license using criticality calculation codes based on the latest knowledge. However, it is necessary to verify that these codes have sufficient reliability. Therefore, in 2018, benchmark calculations were performed using the 252-group ENDF/B-VII.1 neutron cross-section library (v7-252n) for two versions of the criticality calculation sequences KENO-V.a and KENO-VI from SCALE 6.2.3, based on past criticality experimental setups. The estimated critical-limiting multiplication factor was calculated. The results indicate that these codes can be used with sufficient confidence for criticality safety design of MOX fuel facilities.
Guerinoni, E.*; Ueda, Yuki; Motokawa, Ryuhei; Zemb, T.*; Pellet-Rostaing, S.*; Dourdain, S.*
Langmuir, 42(12), p.8313 - 8321, 2026/03
Times Cited Count：1 Percentile：75.13(Chemistry, Multidisciplinary)Hiroi, Kosuke; Nakabe, Rintaro; Oku, Takayuki; Kumada, Takayuki; Motokawa, Ryuhei
Journal of Applied Crystallography, 59(1), p.69 - 79, 2026/02
Times Cited Count：0 Percentile：0.00(Chemistry, Multidisciplinary)