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JAEA Reports

Summaries of research and development activities by using supercomputer system of JAEA in FY2022 (April 1, 2022 - March 31, 2023)

HPC Technology Promotion Office

JAEA-Review 2023-018, 159 Pages, 2023/12

JAEA-Review-2023-018.pdf:13.62MB

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 FY2022, the system was used for R&D of light water reactors, high-temperature gas reactors, and fast reactors to contribute to carbon neutrality as a priority issue, as well as for JAEA's major projects such as Various R&D related to nuclear science and technology, R&D related to the response to the accident at TEPCO's Fukushima Daiichi Nuclear Power Station, Development of technology for treatment and disposal of high-level radioactive waste, Support of nuclear safety regulation and nuclear disaster prevention, and safety research for this purpose. This report presents a great number of R&D results accomplished by using the system in FY2022, as well as user support, operational records and overviews of the system, and so on.

Journal Articles

Quantitative visualization of a radioactive plume with harmonizing gamma-ray imaging spectrometry and real-time atmospheric dispersion simulation based on 3D wind observation

Nagai, Haruyasu; Furuta, Yoshihiro*; Nakayama, Hiromasa; Satoh, Daiki

Journal of Nuclear Science and Technology, 60(11), p.1345 - 1360, 2023/11

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

A novel monitoring method for the quantitative visualization of 3D distribution of a radioactive plume and source term estimation of released radionuclides is proposed and its feasibility is demonstrated by preliminary test. The proposed method is the combination of gamma-ray imaging spectroscopy with the Electron Tracking Compton Camera (ETCC) and real-time high-resolution atmospheric dispersion simulation based on 3D wind observation with Doppler lidar. The 3D distribution of a specific radionuclide in a target radioactive plume is inversely reconstructed from line gamma-ray images from each radionuclide by several ETCCs located around the target by harmonizing with the air concentration distribution pattern of the plume predicted by real-time atmospheric dispersion simulation. A prototype of the analysis method was developed, showing a sufficient performance in several test cases using hypothetical data generated by numerical simulations of atmospheric dispersion and radiation transport.

Journal Articles

Cavitation damage prediction in mercury target for pulsed spallation neutron source using Monte Carlo simulation

Wakui, Takashi; Takagishi, Yoichi*; Futakawa, Masatoshi

Materials, 16(17), p.5830_1 - 5830_16, 2023/09

Cavitation damage on the mercury target vessel is induced by proton beam injection in mercury. The prediction method of the cavitation damage using Monte Carlo simulations was proposed taking into account of the uncertainties of the position of cavitation bubbles and impact pressure distributions. The distribution of impact pressure attributed to individual cavitation bubble collapsing was assumed to be the Gaussian distribution, and the probability distribution of the maximum value of impact pressures was assumed to be three kinds of distributions; the delta function, the Gaussian and Weibull distributions. Two parameters were estimated using Bayesian optimization by comparing the distribution of the cavitation damage obtained from experiment with that of accumulated plastic strain obtained from the simulation. It was found that the results obtained using the Weibull distribution reproduced the actual cavitation erosion phenomenon better than the other results.

Journal Articles

Modelling heterogeneous hydration behaviour of bentonite by a FracMan-Thames coupling method for the Bentonite Rock Interaction Experiment (BRIE) at $"{A}$sp$"{o}$ HRL

Sawada, Atsushi; Sakamoto, Kazuhiko*; Watahiki, Takanori*; Imai, Hisashi*

SKB P-17-06, 154 Pages, 2023/08

JAEA Reports

Reports on research activities and evaluation of advanced computational science in FY2022

Center for Computational Science & e-Systems

JAEA-Evaluation 2023-001, 38 Pages, 2023/07

JAEA-Evaluation-2023-001.pdf:1.04MB

Research on advanced computational science for nuclear applications, based on "the plan to achieve the medium- and long-term goal of the Japan Atomic Energy Agency", has been performed by Center for Computational Science & e-Systems (CCSE), Japan Atomic Energy Agency. CCSE established a committee consisting of external experts and authorities which evaluates and advises toward the future research and development. This report summarizes the results of the R&D performed by CCSE in FY2022 (April 1st, 2022 - March 31st, 2023) and their evaluation by the committee.

Journal Articles

Large-eddy simulation on gas mixing induced by the high-buoyancy flow in the CIGMA facility

Abe, Satoshi; Shibamoto, Yasuteru

Nuclear Engineering and Technology, 55(5), p.1742 - 1756, 2023/05

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Journal Articles

Validation of evaluation model for analysis of steam reformer in HTGR hydrogen production plant

Ishii, Katsunori; Aoki, Takeshi; Isaka, Kazuyoshi; Noguchi, Hiroki; Shimizu, Atsushi; Sato, Hiroyuki

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 9 Pages, 2023/05

Journal Articles

Dynamic probabilistic risk assessment of seismic-induced flooding in pressurized water reactor by seismic, flooding, and thermal-hydraulics simulations

Kubo, Kotaro; Jang, S.*; Takata, Takashi*; Yamaguchi, Akira*

Journal of Nuclear Science and Technology, 60(4), p.359 - 373, 2023/04

 Times Cited Count:3 Percentile:82.38(Nuclear Science & Technology)

Probabilistic risk assessment (PRA) is an essential approach to improving the safety of nuclear power plants. However, this method includes certain difficulties, such as modeling of combinations of multiple hazards. Seismic-induced flooding scenario includes several core damage sequences, i.e., core damage caused by earthquake, flooding, and combination of earthquake and flooding. The flooding fragility is time-dependent as the flooding water propagates from the water source such as a tank to compartments. Therefore, dynamic PRA should be used to perform a realistic risk analysis and quantification. This study analyzed the risk of seismic-induced flooding events by coupling seismic, flooding, and thermal-hydraulics simulations, considering the dependency between multiple hazards explicitly. For requirements of safety improvement, especially in light of the Fukushima Daiichi Nuclear Power Plant accident, sensitivity analysis was performed on the seismic capacity of systems, and the effectiveness of alternative steam generator injection by a portable pump was estimated. We demonstrate the use of this simulation-based dynamic PRA methodology to evaluate the risk induced by a combination of hazards.

Journal Articles

Large-eddy simulation on two-liquid mixing in the horizontal leg and downcomer (the TAMU-CFD Benchmark), with respect to fluctuation behavior of liquid concentration

Abe, Satoshi; Okagaki, Yuria

Nuclear Engineering and Design, 404, p.112165_1 - 112165_14, 2023/04

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

JAEA Reports

Quantitative evaluation of long-term state changes of contaminated reinforced concrete considering the actual environments for rational disposal (Contract research); FY2021 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; The University of Tokyo*

JAEA-Review 2022-057, 98 Pages, 2023/02

JAEA-Review-2022-057.pdf:8.5MB

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 FY2020, this report summarizes the research results of the "Quantitative evaluation of long-term state changes of contaminated reinforced concrete considering the actual environments for rational disposal" conducted in FY2021. The present study aims to construct a database for quantitative prediction of contaminated reinforced concrete inside the reactor building. In FY2021, data on deformation and water movement caused by drying and reabsorption of mortar were obtained to evaluate the mesoscale cracking behavior of concrete. A rigidbody spring model was used to develop a program that can consider changes in concrete age and temperature, water, and stress conditions. To evaluate the long-term penetration behavior of radionuclides into the factual matrix, data on sorption …

JAEA Reports

Fuel debris criticality analysis technology using non-contact measurement method (Contract research); FY2021 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Tokyo Institute of Technology*

JAEA-Review 2022-043, 52 Pages, 2023/01

JAEA-Review-2022-043.pdf:3.48MB

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 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 "Fuel debris criticality analysis technology using non-contact measurement method" conducted in FY2021. The purpose of research was to improve the fuel debris criticality analysis technology using non-contact measurement method by the development of the fuel debris criticality characteristics measurement system and the multi-region integral kinetic analysis code. It was performed by Tokyo Institute of Technology (Tokyo Tech), National Institute of Advanced Industrial Science and Technology (AIST), and National Research Nuclear University (MEPhI) as the first year of four years research project. For the criticality characteristic measurement systems to be developed by the Japanese and Russian sides, …

JAEA Reports

Summaries of research and development activities by using supercomputer system of JAEA in FY2021 (April 1, 2021 - March 31, 2022)

HPC Technology Promotion Office

JAEA-Review 2022-035, 219 Pages, 2023/01

JAEA-Review-2022-035.pdf:10.94MB

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. As shown in the fact that about 20 percent of papers published by JAEA are concerned with R&D using computational science, the supercomputer system of JAEA has become an important infrastructure to support computational science and technology. In FY2021, the system was used for R&D aiming to restore Fukushima (environmental recovery and nuclear installation decommissioning) as a priority issue, as well as for JAEA's major projects such as research and development of fast reactor cycle technology, research for safety improvement in the field of nuclear energy, and basic nuclear science and engineering research. This report presents a great number of R&D results accomplished by using the system in FY2021, as well as user support, operational records and overviews of the system, and so on.

Journal Articles

A 3D particle-based simulation of heat and mass transfer behavior in the EAGLE ID1 in-pile test

Zhang, T.*; Morita, Koji*; Liu, X.*; Liu, W.*; Kamiyama, Kenji

Annals of Nuclear Energy, 179, p.109389_1 - 109389_10, 2022/12

 Times Cited Count:1 Percentile:35.78(Nuclear Science & Technology)

Journal Articles

Numerical reproduction of the seasonal variation in dissolved uranium in Lake Biwa

Saito, Tatsuo; Yamazawa, Hiromi*; Mochizuki, Akihito

Journal of Environmental Radioactivity, 255, p.107035_1 - 107035_14, 2022/12

 Times Cited Count:0 Percentile:0(Environmental Sciences)

The seasonal variation of dissolved U (DU) in Lake Biwa was reproduced by the following model and parameter research. The introduced models are the water-DU mass balance, and the ion exchange between UO$$_{2}$$$$^{2+}$$ and H$$^{+}$$ on the lakeshore soil. The optimized parameters were the CEC of the lakeshore, TU as the sum of DU and AU (soil adsorbed U), kads and kdes as the first order reaction rate coefficients during rapid soil adsorption and desorption of U, respectively. Tabulated by the chemical equilibria constituting DU and analyzed the contribution of each chemical species, it is shown that the seasonal variation of DU is caused by the seasonal variation of pH. A correction to the ion-exchange equilibrium to shift to first order rate reaction only when the daily AU ratio increased above kads or decreased below kdes, improved the reproducibility of DU measurements and reproduced the delay of the DU peak from the pH peak.

JAEA Reports

Quantitative analysis of radioactivity distribution by imaging of high radiation field environment using gamma-ray imaging spectroscopy (Contract research); FY2020 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Kyoto University*

JAEA-Review 2022-027, 85 Pages, 2022/11

JAEA-Review-2022-027.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 FY2020. 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 FY2018, this report summarizes the research results of the "Quantitative analysis of radioactivity distribution by imaging of high radiation field environment using gamma-ray imaging spectroscopy" conducted from FY2018 to FY2021 (this contract was extended to FY2021). Since the final year of this proposal was FY2021, the results for four fiscal years were summarized. In this study, ETCC, a gamma-ray imaging system, was modified to be a portable device that can be used in 1F decommissioning project and can operate in high-dose environments. ETCC is the world's first gamma-ray camera capable of complete bijective imaging, the same as an optical camera. Therefore, ETCC can make general quantitative image analysis methods applicable to radiation, …

JAEA Reports

Review of research on Advanced Computational Science in FY2021

Center for Computational Science & e-Systems

JAEA-Evaluation 2022-004, 38 Pages, 2022/11

JAEA-Evaluation-2022-004.pdf:1.38MB

Research on advanced computational science for nuclear applications, based on "the plan to achieve the mid- and long-term goal of the Japan Atomic Energy Agency", has been performed by Center for Computational Science & e-Systems (CCSE), Japan Atomic Energy Agency. CCSE established a committee consisting of external experts and authorities which evaluates and advises toward the future research and development. This report summarizes the results of the R&D performed by CCSE in FY2021 (April 1st, 2021 - March 31st, 2022) and their evaluation by the committee.

JAEA Reports

Assessment report of research on development activities in FY 2021 Activity; "Computational Science and Technology Research" (Result and in-advance evaluation)

Center for Computational Science & e-Systems

JAEA-Evaluation 2022-003, 61 Pages, 2022/11

JAEA-Evaluation-2022-003.pdf:1.42MB
JAEA-Evaluation-2022-003-appendix(CD-ROM).zip:6.16MB

Japan Atomic Energy Agency (hereinafter referred to as "JAEA") consults an assessment committee, "Evaluation Committee of Research Activities for Computational Science and Technology Research" (hereinafter referred to as "Committee") for result and in-advance evaluation of "Computational Science and Technology Research", in accordance with "General Guideline for the Evaluation of Government Research and Development (R&D) Activities" by Cabinet Office, Government of Japan, "Guideline for Evaluation of R&D in Ministry of Education, Culture, Sports, Science and Technology" and "Regulation on Conduct for Evaluation of R&D Activities" by the JAEA. In response to the JAEA's request, the Committee assessed the research program of the Center for Computational Science and e-Systems (hereinafter referred to as "CCSE"). The Committee evaluated the management and research activities of the CCSE based on explanatory documents prepared by the CCSE, and oral presentations with questions-and answers.

Journal Articles

Accurate estimation of spectral density of LCS gamma-ray source

Omer, M.; Shizuma, Toshiyuki*; Hajima, Ryoichi*; Koizumi, Mitsuo

Dai-43-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 3 Pages, 2022/11

JAEA Reports

Experimental and numerical study on energy separation in vortex tube with a hollow helical fin (Joint research)

Kureta, Masatoshi; Yamagata, Yoji*; Miyakoshi, Ken*; Mashii, Tatsuya*; Miura, Yoshiaki*; Takahashi, Kazunori*

JAEA-Research 2022-007, 28 Pages, 2022/09

JAEA-Research-2022-007.pdf:8.17MB

To enhance energy separation in a counter-current Ranque-Hilsch vortex tube, a newly designed hollow helical fin was inserted into the hot tube of the vortex tube. In this study, the effect of the fin on the energy separation was investigated using three types of the vortex tube, and then computational fluid dynamics (CFD) simulation has been conducted to understand the experimental results and discuss the flow structure in the vortex tube with the hollow helical fin. As a result, it was found from the experimental data that the fin effectively enhanced energy separation, and that the tube length could be shorten. When the inlet air pressure was 0.5 MPa, the maximum temperature difference from the inlet to the cold exit was 62.2$$^{circ}$$C. The CFD code employing the Reynolds Stress Model (RSM) turbulence model was used to analyze the fluid dynamics in the vortex tube. As a result, it was confirmed that the temperature, velocity, and pressure distributions changed significantly at the stagnation point, and that the distributions in the tube with the fin were completely different from those without the fin. It was thought that a strong reversing helical vortex flow with small recirculating vortex structure formed between the fin end and the stagnation point on the cold exit side would enhance energy separation in the vortex tube with the hollow helical fin.

Journal Articles

Calculating off-axis efficiency of coaxial HPGe detectors by Monte Carlo simulation

Omer, M.; Shizuma, Toshiyuki*; Hajima, Ryoichi*; Koizumi, Mitsuo

Radiation Physics and Chemistry, 198, p.110241_1 - 110241_7, 2022/09

 Times Cited Count:1 Percentile:59.27(Chemistry, Physical)

556 (Records 1-20 displayed on this page)