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Hamdani, A.; Soma, Shu; Abe, Satoshi; Shibamoto, Yasuteru
Progress in Nuclear Energy, 185, p.105771_1 - 105771_13, 2025/07
Guembou Shouop, C. J.; Tsuchiya, Harufumi
Nuclear Instruments and Methods in Physics Research A, 1072, p.170189_1 - 170189_14, 2025/03
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)Okazaki, Nobuo*; Hattori, Takanori
CROSS Reports (Internet), 3, p.001_1 - 001_8, 2025/02
There have been requests for remote analysis of measured data at the BL11 PLANET beamline in the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), but a system to perform this analysis on a regular basis has not been established. In order to meet this demand, a system for remote analysis was established using NoMachine, which is widely used as a remote desktop connection environment. This system is built on the cloud, and users can analyze data from anywhere with an Internet environment by using the NoMachine client.
HPC Technology Promotion Office, Center for Computational Science & e-Systems
JAEA-Review 2024-044, 121 Pages, 2025/01
JAEA-Review-2024-044.pdf:7.42MB
Japan Atomic Energy Agency (JAEA) conducts research and development (R&D) in various fields related to nuclear power as a comprehensive institution of nuclear energy R&Ds, and utilizes computational science and technology in many activities. Over the past 10 years or so, the publication of papers utilizing computational science and technology at JAEA has accounted for about 20 percent of the total publications each fiscal year. The supercomputer system of JAEA has become an important infrastructure to support computational science and technology. In FY2023, the system was utilized in R&D activities that were prioritized in the Fourth Medium- to Long-Term Plan, including contributing to carbon neutrality through the development of innovative technologies such as improving safety, creating innovation by promoting diverse R&D related to nuclear science and technology, promoting R&D in response to the accident at TEPCO's Fukushima Daiichi Nuclear Power Station, steadily implementing technological developments for the treatment and disposal of high-level radioactive waste, and supporting nuclear safety regulatory administration and nuclear disaster prevention by promoting safety research for these purposes. This report presents a great number of R&D results accomplished by using the system in FY2023, as well as user support, operational records and overviews of the system, and so on.
Nagaya, Yasunobu
EPJ Nuclear Sciences & Technologies (Internet), 11, p.1_1 - 1_7, 2025/01
Japan Atomic Energy Agency (JAEA) has been developing a general-purpose continuous-energy Monte Carlo code MVP for nuclear reactor core analysis. Recently improvements to MVP have been focused on the development of an advanced neutronics/thermal-hydraulics coupling code. JAEA has also developed a new Monte Carlo solver Solomon for criticality safety analysis. Solomon aims to calculate the criticality of a damaged reactor core including fuel debris. This paper provides an overview of the capabilities and reviews recent applications of MVP and Solomon.
Tobita, Yoshiharu; Tagami, Hirotaka; Ishida, Shinya; Onoda, Yuichi; Sogabe, Joji; Okano, Yasushi
IAEA-TECDOC-2079, p.72 - 84, 2025/00
Since the fast reactor core is not in the maximum reactivity configuration, a hypothetical core disruptive accident could lead to the prompt criticality due to a change in the core material configuration, and the resulting energy generation has been one of the issues in fast reactor safety, and therefore appropriate measures are needed to mitigate and contain the effect of energy generated in the accident. In order to assess the effectiveness of these mitigative measures, a set of computer codes to analyze the event progressions and energy generation behavior in the ATWS of fast reactors have been developed, maintained, and improved under international collaboration in JAEA. Since the important physical phenomena, which govern the event progression, vary along with the progression of the accident, the whole accident process is divided into several phases in the analysis of accident, and dedicated analysis methods for each phase are provided to analyze the event progression in each phase. The organization and overview of these analysis methods are described in this paper. As a representative example of the validation approaches in applying these analysis methods to the reactor safety assessment in licensing procedure in Japan, the validation studies to confirm the applicability to reactor analysis of the SIMMER code for analyzing core material movement and reactor power, which is important to analyze the energy generation in the accident, are presented in the paper. The validation studies of the SIMMER code confirmed the applicability of SIMMER to the reactor analysis, while the critical phenomena that the effect of their uncertainty in the reactor analysis should be checked were also recognized.
-, 
- and X-ray spectraOshima, Masumi*; Goto, Jun*; Hayakawa, Takehito*; Asai, Masato; Shinohara, Hirofumi*; Suzuki, Katsuyuki*; Shen, H.*
Journal of Nuclear Science and Technology, 10 Pages, 2025/00
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)The spectrum determination method (SDM) is the method to determine radioactivities by analyzing full spectral shape of - or rays through least-squares fitting by referring to standard - and spectra. In this paper, we have newly applied the SDM to a unified spectrum composed of two spectra measured with a Ge detector and a liquid scintillation counter. By analyzing the unified spectrum, uncertainties of deduced radioactivities have been improved. We applied this method to the unified spectrum including 40 radionuclides with equal intensities, and have deduced their radioactivities correctly.
Fukuda, Kodai
Annals of Nuclear Energy, 208(1), p.110748_1 - 110748_10, 2024/12
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Miyakawa, Kazuya; Ishii, Eiichi; Imai, Hisashi*; Hirai, Satoru*; Ono, Hirokazu; Nakata, Kotaro*; Hasegawa, Takuma*
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 31(2), p.82 - 95, 2024/12
no abstracts in English
Wakui, Takashi; Saito, Shigeru; Futakawa, Masatoshi
Jikken Rikigaku, 24(4), p.212 - 218, 2024/12
Irradiation damage is one of the main factors determining the lifetime of the mercury target vessel for spallation neutron source in J-PARC. To understand material degradation of the used vessels, it is planned to conduct an evaluation using inverse analyses with indentation tests on the structural materials of the used vessels and numerical experiments. This evaluation technique was applied to two kinds of ion-irradiated materials with different displacement damage doses, in which the irradiation condition was simulated. It could be confirmed that the ultimate strength increased, and the total elongation decreased with increasing irradiation. These trends are like the material degradation behaviors which have been reported by using small specimen's tensile tests.
Wakui, Takashi; Saito, Shigeru; Futakawa, Masatoshi
Materials, 17(23), p.5925_1 - 5925_14, 2024/12
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)The ductile properties of irradiated materials are one of the important indicators related to their structural integrity. Indentation tests are used for evaluating the ductile properties easily and rapidly. Constants in the material constitutive equation were identified via inverse analysis using the Kalman filter, such that the numerical experimental results reproduced the indentation test results. Numerical tensile experiments were conducted using stress-strain curves with the identified constants to obtain nominal stress-strain curves. Furthermore, two methods were proposed for evaluating the total elongation. Evaluated minimum total elongation was 10 %. The evaluation results of ion-irradiated materials were similar to the tensile test results of irradiated materials.
Materials Sciences Research Center
JAEA-Review 2024-037, 141 Pages, 2024/11
JAEA-Review-2024-037.pdf:13.08MB
Fifteen neutron beam experimental instruments managed by JAEA are installed in JRR-3 (Japan Research Reactor No.3) and are available for internal use including upgrading of instruments and for external users to produce various research results. This report summarizes the progress of internal application research and technical development such as upgrading of neutron beam instruments in the fiscal years 2021 and 2022 after the restart of operation.
Collaborative Laboratories for Advanced Decommissioning Science; Tokai National Higher Education and Research System*
JAEA-Review 2024-027, 77 Pages, 2024/11
JAEA-Review-2024-027.pdf:6.0MB
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2022. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2022, this report summarizes the research results of the "Development and evaluation of a real-time 3D positioning embedded system combining wireless UWB and camera image analysis" conducted in FY2022. The present study aims to realize an embedded system that combines two of the latest popular technologies, "wireless UWB (Ultra Width Band)" and "multi-camera object recognition," with the goal of simple realtime 3D positioning with less than 10 cm accuracy by a human or robot for measuring air doses in nuclear reactor buildings.
Koizumi, Mitsuo; Ito, Fumiaki*; Lee, J.; Hironaka, Kota; Takahashi, Tone; Suzuki, Satoshi*; Arikawa, Yasunobu*; Abe, Yuki*; Wei, T.*; Yogo, Akifumi*; et al.
Dai-45-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2024/11
Doi, Daisuke
International Journal of Hydrogen Energy, 91, p.1245 - 1252, 2024/11
Times Cited Count：1 Percentile：0.00(Chemistry, Physical)Aoyagi, Kazuhei; Ozaki, Yusuke; Tamura, Tomonori; Ishii, Eiichi
Proceedings of 4th International Conference on Coupled Processes in Fractured Geological Media; Observation, Modeling, and Application (CouFrac2024) (Internet), 10 Pages, 2024/11
In high-level radioactive waste disposal, it is crucial to estimate the transmissivity of gallery excavation-induced fractures, i.e., excavation damaged zone (EDZ) fractures, because EDZ fractures can be a radionuclide migration pathway after the backfilling of the facility is completed. From previous research, the transmissivity of the fracture can be estimated through the empirical equation using the parameter ductility index (DI), which corresponds to the effective mean stress normalized to the tensile strength of the rock. In this research, we performed a hydromechanical coupling analysis of a gallery excavation at the Horonobe Underground Research Laboratory to estimate the transmissivity of the EDZ fracture before the excavation. At first, we simulated the gallery excavation at 350 m and showed that the measured transmissivity was within the range of the estimated transmissivity using the DI. After that, we also predicted the excavation of a gallery at 500 m by setting the hydromechanical parameters acquired from the laboratory tests before the excavation. The estimated transmissivity at 500 m was one order of magnitude less than that at 350 m. This result might be related to the closure of the fracture under high-stress conditions and low rock strength.
Brear, D. J.*; Kondo, Satoru; Sogabe, Joji; Tobita, Yoshiharu*; Kamiyama, Kenji
JAEA-Research 2024-009, 134 Pages, 2024/10
JAEA-Research-2024-009.pdf:2.45MB
The SIMMER-III/SIMMER-IV computer codes are being used for liquid-metal fast reactor (LMFR) core disruptive accident (CDA) analysis. The sequence of events predicted in a CDA is often influenced by the heat exchanges between LMFR materials, which are controlled by heat transfer coefficients (HTCs) in the respective materials. The mass transfer processes of melting and freezing, and vaporization and condensation are also controlled by HTCs. The complexities in determining HTCs in a multi-component and multi-phase system are the number of HTCs to be defined at binary contact areas of a fluid with other fluids and structure surfaces, and the modes of heat transfer taking into account different flow topologies representing flow regimes with and without structure. As a result, dozens of HTCs are evaluated in each mesh cell for the heat and mass transfer calculations. This report describes the role of HTCs in SIMMER-III/SIMMER-IV, the heat transfer correlations implemented and the calculation of HTCs in all topologies in multi-component, multi-phase flows. A complete description of the physical basis of HTCs and available experimental correlations is contained in Appendices to this report. The major achievement of the code assessment program conducted in parallel with code development is summarized with respect to HTC modeling to demonstrate that the coding is reliable and that the model is applicable to various multi-phase problems with and without reactor materials.
Naoe, Shota*; Tanaka, Ayumi*; Kanzaki, Norie; Takenaka, Reiju*; Sakoda, Akihiro; Miyaji, Takaaki*; Yamaoka, Kiyonori*; Kataoka, Takahiro*
Acta Medica Okayama (Internet), 78(5), p.387 - 399, 2024/10
Shibayama, Yuki; Hojo, Tomohiko*; Koyama, Motomichi*; Akiyama, Eiji*
International Journal of Hydrogen Energy, 88, p.1010 - 1016, 2024/10
Times Cited Count：1 Percentile：0.00(Chemistry, Physical)Yanagisawa, Kayo; Yokota, Hiromi*; Fujimoto, Katsushige*; Takagai, Yoshitaka*
Bunseki Kagaku, 73(9), p.515 - 522, 2024/09
On-line isotope dilution-laser ablation-inductively coupled plasma-mass spectrometry (on-line ID-LA-ICP-MS) is capable of quantification for each point ablated by laser, then the quantitative mapping of elements can be also conducted by reconstruction of the obtained each point data. The volume of data obtained as flow peaks in this system as a flow injection analysis, will be multiplied by each data such as number of m/z, scan time, time resolution and measurement position, and the total amount of data is enormous, resulting in a large human power and time consumption for data processing. In this paper, an original application software using Python to improve the efficiency of data processing in on-line ID-LA-ICP-MS was developed. To discriminate between the time-to-peak intensity and the background noise, an automatic peak detection using penalized asymmetric least squares was developed.
