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Fuyushima, Takumi; Sayato, Natsuki; Otsuka, Kaoru; Endo, Yasuichi; Tobita, Masahiro*; Takemoto, Noriyuki
JAEA-Testing 2024-008, 38 Pages, 2025/03
JAEA-Testing-2024-008.pdf:2.37MB
In Japan Materials Testing Reactor (JMTR), irradiation tests had been conducted by loading specimens into capsules for irradiating fuels and materials. The thermal design calculation of capsules is significant to irradiate various types of specimens at the target temperature. The decommissioning plan of JMTR was approved in March 2021, and the Department of Waste Management and Decommissioning Technology Development is currently working on irradiation plans by foreign testing reactors as an alternative for JMTR. A one-dimensional thermal calculation code "GENGTC", which was developed at the Oak Ridge National Laboratory in U.S., is used for capsule design and irradiation tests. GENGTC has been repeatedly improved as improvements of computer performance, but there were some defects in calculation function. Therefore, we investigated the cause of the problem and changed the program from the currently used FORTRAN77 language program to a Visual Basic language program that uses the macro calculation function of Excel. In addition, the program was improved to make it easier to use the calculation code.
Co gamma irradiation test results with calculated resultsTakeda, Ryoma; Shibata, Hiroshi; Takeuchi, Tomoaki; Nakano, Hiroko; Seki, Misaki; Ide, Hiroshi
JAEA-Testing 2024-007, 33 Pages, 2025/03
JAEA-Testing-2024-007.pdf:1.63MB
Japan Materials Testing Reactor (JMTR) in Oarai Research and Development Institute of the Japan Atomic Energy Agency (JAEA) has been developing various reactor materials, irradiation techniques and instruments for more than 30 years. Among them, the development of self-powered neutron detectors (SPNDs) and gamma detectors (SPGDs) has been carried out, and several research results have been reported. In this report, we compare and verify these test results with the theoretical output results obtained by the calculation code created in the JAEA report (JAEA-Data/Code 2021-018). The comparison was made with the irradiation test results of SPGD, a cobalt-60 gamma irradiation facility. As a result, it was found that the calculation results reproduced the test results well when the emitter diameter was relatively small compared to the range of Compton scattered electrons by the gamma rays. On the other hand, when the emitter diameter is relatively large, the output current in the test results is only about half of the calculated output current. The self-shielding effect of the emitter may be one of the reasons for the difference in the emitter diameter, and a new formulation, such as incorporating the effect of self-shielding caused by a larger emitter diameter or a non-isotropic 
-ray field as a change in the mean electron range or mean minimum energy in the calculation code, is necessary. The new formulation is necessary.
Takaku, Yuhi; Kakefuda, Toyokazu*; Yashiro, Shigeo; Kimura, Hideo; Kuno, Tetsuya
JAEA-Testing 2024-006, 31 Pages, 2025/03
JAEA-Testing-2024-006.pdf:2.5MB
The Japan Atomic Energy Agency (JAEA) has a wide variety of servers across its departments, managed by on-site server administrators who are responsible for tasks including security measures. As a result, the workload and operational cost burdens are significant. Additionally, addressing the increasing frequency of security incidents in recent years, both domestically and internationally, is essential for JAEA's operations, which involve handling sensitive information. However, it is difficult for individual server administrators to take proactive measures to mitigate these risks. To address these challenges, we carried out the migration of systems that do not contain sensitive information to an external cloud environment with a focus on cost reduction. As a result, we clarified the conditions necessary for a smooth migration to an external cloud environment while achieving significant cost savings and established a foundation for implementing measures against security incidents.
Kagi, Takumi; Araki, Daisuke; Yanai, Tomohiro; Kuwabara, Ryota; Sugaya, Naoto; Nishimura, Arashi; Ebisawa, Hiroyuki; Watahiki, Shunsuke; Tanimoto, Masataka
JAEA-Testing 2024-005, 24 Pages, 2025/03
JAEA-Testing-2024-005.pdf:6.92MB
On September 9, 2019, the strong winds of Typhoon No. 15 caused the secondary cooling system cooling tower of the Japan Materials Testing Reactor (JMTR) to collapse. The cooling tower collapsed from east to west, and four secondary cooling system pipes connected to it also pulled down, and all four pipes were damaged at their riser sections. Because the exterior wall slate material (asbestos slate) covering the collapsed cooling tower contained asbestos, it was necessary to ensure the safety of the workers and to minimize the impact of asbestos on the surrounding environment during the removal work. This report describes the work plan devised while complying with the relevant laws and the results of its implementation to ensure worker safety and reduce the environmental impact of asbestos during the removal work, storage management, and transportation of the asbestos slate material from the cooling tower of the secondary cooling system.
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.
Emori, Tatsuya; Kitatsuji, Yoshihiro; Ban, Yasutoshi
JAEA-Technology 2024-025, 20 Pages, 2025/03
JAEA-Technology-2024-025.pdf:1.65MB
Radioisotope Thermoelectric Generators (RTGs) using the decay heat of Pu-238 has been applied for outer planet missions far from Jupiter, where solar power is limited. However, no facilities are available to produce Pu-238 for space probes in Japan. Moreover, the use of nuclear materials for the space exploration is difficult in term of the regulation. Thus, we focused on Am-241 whose half-life is around 432 years as an alternative heat source for RTGs. This report describes the procedure of separating Am-241 decayed from Pu-241 in aged plutonium oxide. Two experiments were performed: one using solid-liquid extraction and the other combining liquid-liquid extraction and solid-liquid extraction. Packed columns were used in the experiments, with their number reduced by less than one-fifth in the latter experiment compared to the former. Furthermore, the time required for separation in the latter experiment was less than half that of the former. We performed the separation experiments six times, collecting a total of approximately 0.43 g of Am-241 as an oxalate salt.
Asahi, Yoshimitsu; Fukuda, Shigeki; Shiramizu, Daiki; Miyata, Koshi; Tone, Masaya; Katsuoka, Nanako; Maeda, Yuta; Aoyama, Yusuke; Niitsuma, Koichi; Kobayashi, Hidekazu; et al.
JAEA-Technology 2024-024, 271 Pages, 2025/03
JAEA-Technology-2024-024.pdf:33.98MB
JAEA-Technology-2024-024-hyperlink.zip:31.96MB
A glass melter for the vitrification process of highly active liquid waste in the Tokai Reprocessing Plant, TVF's 3rd melter, was built, and the glass of 18 vitrified waste canisters in weight was melted and poured through a cold test operation. The molten glass surface was covered by a cold cap from feeding fiberglass cartridges saturated with non-radioactive simulant liquid waste as raw material, whose components are equivalent to actual waste. Differences in inherent characteristics of the thermal behavior between the 2nd and the 3rd melter due to the difference in design were considered to establish the procedure to control the new melter. The melter's condition was stabilized at a higher glass temperature and the cooling of 1 kW less in each of the two main electrodes, compared to the 2nd one. Under 39 kW joule heating of the main electrodes with 26 Nm3/h coolant flow rate, it showed the capability to finish heating the bottom furnace in 5 hours before pouring, 2 hours shorter than the 2nd melter. Measurements of the temperature distributions in molten glass and casing surface yielded data that is efficient for developing a simulation model. After Platinum Group Elements (PGE) concentration saturates in the molten glass, feeding raw material and discharging glass were suspended to examine a holding state, indicating PGE settling could retard. During the holding test, observation of the melting process of the cold cap declared that the surface was covered by a thin layer with almost non-fluidity. It will be a reason for choosing the no-slip condition of a fluid calculation, even in the hot-top condition. The investigation of PGE discharging behavior by analyzing the elemental composition of poured glass showed the accumulated PGE amount in the 3rd melter is small compared to the 2nd melter. Inspection of the melter inside after draining out concluded that there were neither significant residual glass nor refractory fragments.
Tomioka, Dai; Kochiyama, Mami; Ozone, Kenji; Nakata, Hisakazu; Sakai, Akihiro
JAEA-Technology 2024-023, 38 Pages, 2025/03
JAEA-Technology-2024-023.pdf:1.54MB
Japan Atomic Energy Agency is an implementing organization of near-surface disposal for low-level radioactive wastes generated from research, industrial and medical facilities in Japan. Information on the radioactivity concentration of these radioactive wastes is dispensable for the design and conformity assessment of the waste disposal facilities for the licensing application of the disposal project and its safety review. Radioactive Wastes Disposal Center has been improving the radioactivity evaluation procedure for the dismantling waste generated from the research reactors based on the activation calculation. In order to investigate the applicability of the ORIGEN code (included in SCALE6.2.4), which enables more accurate activation calculations using multigroup neutron spectra, we performed activation calculations with the ORIGEN-code and the ORIGEN-S code (included in SCALE6.0), which has been widely used in the past, for the dismantled wastes from the Rikkyo University Research Reactor, where radioactivity analysis data for the structural materials around the reactor core were compiled. As a result, the calculation time difference between ORIGEN and ORIGEN-S was small and the evaluated radioactivity concentrations of the former were in the range of 0.8-1.0 times those of the latter, which was in good agreement with those of radiochemical analysis in the range of 0.5-3.0 times. The applicability of ORIGEN was confirmed. In addition, activation calculations assuming trace elements in structural materials of nuclear reactor were performed with ORIGEN and ORIGEN-S and the results were compared. The causes of the large differences among 170 nuclides that are important for dose assessment in near-surface disposal were assessed each nuclide.
Futemma, Akira; Sanada, Yukihisa; Nakama, Shigeo; Sasaki, Miyuki; Ochi, Kotaro; Sawahata, Yoshiro*; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; Haginoya, Masashi*; et al.
JAEA-Technology 2024-022, 170 Pages, 2025/03
JAEA-Technology-2024-022.pdf:15.09MB
On March 11, 2011, the 2011 off the Pacific coast of Tohoku Earthquake caused a tsunami that led to the Fukushima Daiichi Nuclear Power Station accident, releasing radioactive material into the environment. Since then, Aerial Radiation Monitoring (ARM) using manned helicopters has been employed to measure radiation distribution. As a commissioned project from the Nuclear Regulation Authority, the Japan Atomic Energy Agency (JAEA) utilizes this technology for emergency monitoring during nuclear facility accidents, aiming to provide prompt results by pre-arranging information on background radiation, topography, and control airspaces around nuclear power plants nationwide. In fiscal year 2023, the commissioned project included conducting ARM around the Sendai Nuclear Power Station and preparing related information. To enhance effectiveness during emergencies, ARM and the first domestic training flight of Unmanned Aerial Vehicles (UAVs) were conducted during the FY2023 Nuclear Energy Disaster Prevention Drill. Furthermore, UAVs radiation monitoring technology was advanced by selecting UAVs and investigating their performance. This report summarizes the results and technical issues identified providing insights to improve emergency preparedness.
Futemma, Akira; Sanada, Yukihisa; Nakama, Shigeo; Sasaki, Miyuki; Ochi, Kotaro; Nagakubo, Azusa; Sawahata, Yoshiro*; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; et al.
JAEA-Technology 2024-021, 232 Pages, 2025/03
JAEA-Technology-2024-021.pdf:25.79MB
The 2011 off the Pacific coast of Tohoku Earthquake on March 11, 2011, caused a tsunami that led to the TEPCO's Fukushima Daiichi Nuclear Power Station (FDNPS) accident, releasing a large amount of radioactive material into the surrounding environment. Since the accident, Aerial Radiation Monitoring (ARM) has been used to quickly and widely measure radiation distribution. As a commissioned project from the Nuclear Regulation Authority, the Japan Atomic Energy Agency (JAEA) has continuously conducted ARM around FDNPS using manned and unmanned helicopters. This report summarizes the monitoring results for fiscal year 2023, evaluates changes in dose rate from past results, and discusses the factors contributing to these changes. Additionally, an analysis considering terrain undulation was conducted to improve accuracy for converting ARM data into dose rate. Furthermore, a method to discriminate airborne radon progeny was applied for ARM results to evaluate its impact. Moreover, to perform wide-area monitoring more efficiently, we advanced the development of unmanned airplane monitoring technology.
Hatakeyama, Yuichi; Hirai, Koki; Ikegami, Yuta*; Sano, Naruto; Tomita, Takeshi; Usami, Koji; Tagami, Susumu
JAEA-Technology 2024-020, 33 Pages, 2025/03
JAEA-Technology-2024-020.pdf:2.21MB
The Waste Safety Testing Facility (WASTEF) is a facility that began operation in December 1982 with the aim of conducting safety testing research on the long-term storage and subsequent geological disposal of high-level radioactive waste generated by the reprocessing of spent fuel. This facility is composed of five concrete cells, one lead cell, six glove boxes, and seven hoods, and is a large-scale facility capable of using nuclear fuel materials including uranium and plutonium, as well as radioisotopes such as neptunium and americium. The facility is equipped with an automatic fire alarm system for the entire building in accordance with the Fire Service Act and regulations on technical standards for facilities used. This is an important aspect of safety management, and it is required that the equipment be sufficiently sound and reliable. However, after more than 30 years of use since its installation, the fire receiving panel, one of the components of the automatic fire alarm system, has deteriorated significantly. Furthermore, many of the parts used have been discontinued and are no longer available, making it difficult to procure them, making it difficult to maintain the equipment's performance. Therefore, in order to ensure the safe and stable operation of WASTEF, the fire receiving panel was updated. This report summarizes the update of the fire receiving panel among the automatic fire alarm equipment that was implemented in FY2022.
Group for Fukushima Mapping Project
JAEA-Technology 2024-017, 208 Pages, 2025/03
JAEA-Technology-2024-017.pdf:27.32MB
This report presents results of the investigations on the distribution-mapping project of radioactive substances owing to TEPCO Fukushima Daiichi Nuclear Power Station (FDNPS) conducted in FY2023. Car-borne surveys, a measurement using survey meters, a walk survey and an unmanned helicopter survey were carried out to obtain air dose rate data to create their distribution maps, and temporal changes of the air dose rates were analyzed. Surveys on depth profile of radiocesium and in-situ measurements as for radiocesium deposition were performed. Based on these measurement results, effective half-lives of the temporal changes in the air dose rates and the deposition were evaluated. Score maps to classify the importance of the measurement points were created, and the temporal changes in the score were analyzed. A system to report the tritium concentration level in seawater to the Nuclear Regulation Authority was operated, and the variation of tritium concentration before and after the discharge of ALPS treated water to the ocean was analyzed. Monitoring data in coastal area performed owing to the comprehensive radiation monitoring plan until FY2023 was analyzed. Using the Bayesian hierarchical modeling approach, we obtained maps that integrated air dose rate distribution data acquired through surveys such as car-borne and walk surveys. Representative life patterns that can be expected after the return to the evacuation-designated restricted area were set, and the cumulative exposure doses were evaluated for the local governments and residents in the area. The measurement results for FY2023 were published on the Web site and measurement data were stored as CSV format. Radiation monitoring and analysis of environmental samples owing to the comprehensive radiation monitoring plan were carried out.
Kokubu, Yoko; Takeuchi, Ryuji; Nishio, Kazuhisa*; Ikeda, Koki
JAEA-Review 2024-066, 67 Pages, 2025/03
JAEA-Review-2024-066.pdf:8.25MB
The Tono Geoscience Center of the Japan Atomic Energy Agency has undertaken backfilling and restoration activities at the Mizunami Underground Research Laboratory (MIU) site since fiscal year 2020. These activities are being conducted in accordance with "The MIU Project from FY2020 Onwards," outlining the procedures for backfilling, restoration, and environmental monitoring at the MIU site. The backfilling activity was completed in January 2022, and thereafter, the observation of the backfilled shafts was commenced. On November 6, 2023, the settlement of the backfilled surface was observed in the Main Shaft and the Ventilation Shaft. By December 5, 2023, the depth of the settlement reached 12.9 m in the Main Shaft and 27.7 m in the Ventilation Shaft. After an evaluation by the MIU safety confirmation committee, which assessed the settlement condition and recommended countermeasures, the affected areas were backfilled for safety reasons. This report summarizes the observed settlement of the backfilled surface, the subsequent rebackfilling efforts, and the condition of the surface settlement areas. The condition of the backfilled sections has been confirmed up to June 2024.
Abe, Kazuhide
JAEA-Review 2024-065, 26 Pages, 2025/03
JAEA-Review-2024-065.pdf:2.55MB
The Japan Atomic Energy Agency's research reactor, JRR-3, resumed operations on February 26, 2021, after nearly a decade. As a shared-use facility, JRR-3 is operated to accommodate external users as well. The procedures, from research proposal submissions to final report submissions, are conducted through the online system JRR-3 RING (Research Information NaviGator) (https://jrr3ring.jaea.go.jp/). RING enables integrated management of proposal submissions, schedule adjustments, data sharing, and report submissions, and it has been upgraded in preparation for the resumption of JRR-3 operations. RING is specifically designed to enhance the convenience of beamline users, featuring simplified application processes, improved flexibility in schedule coordination, and enhanced data management capabilities. With the implementation of this system, users can conduct their research more efficiently and securely. Moving forward, JRR-3 aims to expand its role as a platform for neutron research, accessible to a diverse range of researchers both domestically and internationally. The resumption of operations and the expansion of RING mark a significant step toward revitalizing neutron research and fostering collaboration with industries and academia.
Safety Division, J-PARC Center
JAEA-Review 2024-060, 139 Pages, 2025/03
JAEA-Review-2024-060.pdf:5.78MB
This annual report describes the activities on radiation safety and general safety in Japan Proton Accelerator Research Complex (J-PARC) in FY 2023. Activities on radiation safety such as radiation control in each facility, environmental monitoring, individual monitoring, maintenance of monitoring instruments and other activities on radiation matters are represented. Activities on general safety such as safety committees, meetings, lectures, trainings and periodical checks are described. In addition, activities on promotion of safety culture and the technological developments etc., including research activities and noteworthy safety managements on safety issues, are also summarized in each separate section.
Taniguchi, Takumi; Matsumoto, Saori; Hiraki, Yoshihisa; Sato, Junya; Fujita, Hideki*; Kaneda, Yoshihisa*; Kuroki, Ryoichiro; Osugi, Takeshi
JAEA-Review 2024-059, 20 Pages, 2025/03
JAEA-Review-2024-059.pdf:1.0MB
The basic performance required for solidifying waste into cement, such as fluidity before curing and strength after curing, is expected to be affected by the chemical effects of substances and components contained in the waste. The fluidity before curing and the strength properties after curing are greatly influenced by the curing speed of the cement. We investigated existing knowledge with a focus on chemical substances that affect the curing speed of cement. In this report, chemical substances that affect fluidity are broadly classified into inorganic substances such as (1) anion species, (2) metal elements such as heavy metals, (3) inorganic compounds as cement admixtures, and (4) organic compounds as cement admixtures. Based on the investigation, we actually added chemicals and measured the setting time. As a result, it was found that there are multiple mechanisms contributing to accelerated hardening. We investigated chemical substances that inhibit the curing reaction of cement, and were able to compile information to consider ingredients that are contraindicated in cement curing.
Nuclear Science Research Institute
JAEA-Review 2024-058, 179 Pages, 2025/03
JAEA-Review-2024-058.pdf:7.42MB
Nuclear Science Research Institute (NSRI) is 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. And, 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 the future research and development and to promote management business, this annual report summarizes information on the activities of NSRI of JFY 2023 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.
Nuclear Science Research Institute
JAEA-Review 2024-057, 178 Pages, 2025/03
JAEA-Review-2024-057.pdf:8.51MB
Nuclear Science Research Institute (NSRI) is 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. And, 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 the future research and development and to promote management business, this annual report summarizes information on the activities of NSRI of JFY 2022 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.
Department of Radiation Protection, Nuclear Science Research Institute; Nuclear Facilities Management Section, Aomori Research and Development Center
JAEA-Review 2024-056, 113 Pages, 2025/03
JAEA-Review-2024-056.pdf:3.1MB
This annual report describes the activities in the 2023 fiscal year of Department of Radiation Protection in Nuclear Science Research Institute, Sector of Nuclear Science Research, Harima Synchrotron Radiation Radioisotope Laboratory and Nuclear Facilities Management Section in Aomori Research and Development Center, Sector of Nuclear Fuel, Decommissioning and Waste Management Technology Development. The activities described in this repots are environmental monitoring, radiation protection practices in workplaces, individual monitoring, maintenance of monitoring instruments, and research and development of radiation protection. At these institutes the occupational exposures did not exceed the dose limits. The radioactive gaseous and liquid discharges from the facilities were well below the prescribed limits. The research and development activities produced certain results in the fields of radiation protection technique.
Kokubun, Yuji; Hosomi, Kenji; Nagaoka, Mika; Seya, Natsumi; Inoue, Kazumi; Koike, Yuko; Uchiyama, Rei; Sasaki, Kazuki; Maehara, Yushi; Matsuo, Kazuki; et al.
JAEA-Review 2024-054, 168 Pages, 2025/03
JAEA-Review-2024-054.pdf:2.73MB
The Nuclear Fuel Cycle Engineering Laboratories conducts environmental radiation monitoring around the reprocessing plant in accordance with the "Safety Regulations for Reprocessing Plant of JAEA, Part IV: Environmental Monitoring". This report summarizes the results of environmental radiation monitoring conducted during the period from April 2023 to March 2024 and the results of dose calculations for the surrounding public due to the release of radioactive materials from the plant into the atmosphere and ocean. In the results of the above environmental radiation monitoring, several items were affected by radioactive materials emitted from the accident at the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company, Incorporated (changed to Tokyo Electric Power Holdings, Inc. on April 1, 2016), which occurred in March 2011. In addition, environmental monitoring plan, analysis and measurement methods, monitoring data and their chronological change, meteorological data after statistical processing, status of radioactive waste release and evaluation results of the data over the normal range are included as appendices.