Center for Computational Science & e-Systems
JAEA-Evaluation 2021-001, 66 Pages, 2021/11
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 does research evaluation and advice for the assistance of the future research and development. This report summarizes the results of the R&D performed by CCSE in FY2020 (April 1st, 2020 - March 31st, 2021), the results expected at the end of the 3rd mid and long-term goal period, and the evaluation by the committee on them.
Hemmi, Ko; Walker, A.*; Yamaguchi, Tetsuji
Radiochimica Acta, 109(7), p.539 - 546, 2021/07
Plutonium(IV) sorption onto quartz in carbonate solutions was systematically investigated under anaerobic conditions to analyze the sorption behaviors of Pu(IV) with a non-electrostatic model (NEM). Pu(IV) sorption data was obtained from batch sorption experiments as a function of pH and carbonate concentration. The Pu(IV) sorption onto quartz showed similar tendencies to Th(IV), which is considered to be chemically analogous as a tetravalent actinoid. The distribution coefficient, d, of Pu(IV) onto quartz showed inverse proportionality to the square of the total carbonate concentration under the investigated pH conditions of 8 to 11. The modeling study, however, revealed a Th(IV) sorption model, which is SOTh(OH) and SOThOH(CO), could not be applied to simulate the Pu(IV) sorption onto quartz. It was inferred that the electrostatic repulsion between negatively charged ligands limited the formation of SOM(OH) and SOMOH(CO) for Pu(IV) with smaller ionic radii than Th(IV). The Pu(IV) sorption model was developed as SOPu(OH) and SOPu(OH). In addition, data of Pu(IV) sorption onto muscovite was obtained in order to be compared with data for quartz.
Collaborative Laboratories for Advanced Decommissioning Science; Waseda University*
JAEA-Review 2020-035, 102 Pages, 2021/01
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 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, 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 FY2019, this report summarizes the research results of the "Estimation of the In-Depth Debris Status of Fukushima Unit-2 and Unit-3 with Multi-Physics Modeling". Continuous update on understanding of the damaged Fukushima reactors is important for safe and efficient decommissioning of the reactors. This study aims to estimate the in-depth debris status of the damaged Fukushima Unit-2 and Unit-3 through multi-physics modeling, which comprises of MPS method, simulated molten debris relocation experiment and high-temperature melt property data acquision in the three-year project from FY2019.
Sugiura, Yuki; Ishidera, Takamitsu; Tachi, Yukio
Applied Clay Science, 200, p.105910_1 - 105910_10, 2021/01
Center for Computational Science & e-Systems
JAEA-Evaluation 2020-002, 37 Pages, 2020/12
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 at Center for Computational Science & e-Systems (CCSE), Japan Atomic Energy Agency. CCSE established a committee consisting of outside experts and authorities which does research evaluation and advice for the assistance of the future research and development. This report summarizes the results of the R&D performed at CCSE in FY2019 (April 1st, 2019 - March 31st, 2020) and the evaluation by the committee on them.
Chikhray, Y.*; Askerbekov, S.*; Kenzhin, Y.*; Gordienko, Y.*; Ishitsuka, Etsuo
Fusion Science and Technology, 76(4), p.494 - 502, 2020/05
Muto, Kotomi; Atarashi-Andoh, Mariko; Matsunaga, Takeshi*; Koarashi, Jun
Journal of Environmental Radioactivity, 208-209, p.106040_1 - 106040_10, 2019/11
Vertical distributions of Cs in the soil profile were observed at five forest sites with different vegetation types for 4.4 years after the Fukushima Dai-ichi Nuclear Power Plant accident, and Cs migration in the organic layer and mineral soil was analyzed based on a comparison of models and observations. Cesium-137 migration from the organic layer was faster than that observed in European forests, suggesting that the mobility and bioavailability of Cs could be suppressed rapidly in Japanese forests. The diffusion coefficients of Cs in the mineral soil were estimated to be 0.042-0.55 cmy, which were roughly comparable with those of European forest soils affected by the Chernobyl Nuclear Power Plant accident. Model predictions indicated Cs mainly distributed in the surface mineral soil at 10 years after the accident. It suggest that the Cs deposited onto Japanese forest ecosystems will be retained in the surface layers of mineral soil for a long time.
Watanabe, Kosuke*; Matsuda, Shohei; Cuevas, C. A.*; Saiz-Lopez, A.*; Yabushita, Akihiro*; Nakano, Yukio*
ACS Earth and Space Chemistry (Internet), 3(4), p.669 - 679, 2019/04
The photooxidation of aqueous iodide ions (I) at sea surface results in the emission of gaseous iodine molecules (I) into the atmosphere. It plays a certain role in the transport of iodine from ocean to the atmosphere in the natural cycle of iodine. In this study, we determined the photooxidation parameters, the molar absorption coefficient (()) and the photooxidative quantum yields (()) of I, in the range of 290-500 nm. Through the investigation of the influence of pH and dissolved oxygen (DO) on (), the subsequent emission rates of I following the photooxidation of I in deionized water solution (pH 5.6, DO 7.8 mg L) and artificial seawater solution (pH 8.0, DO 7.0 mg L) were estimated. A global chemistry-climate model employed herein to assess the I ocean emission on a global scale indicated that the photooxidation of I by solar light can enhance the atmospheric iodine budget by up to 8% over some oceanic regions.
Wan, T.; Saito, Shigeru
Metals, 8(8), p.627_1 - 627_22, 2018/08
Choi, B.; Nishida, Akemi; Li, Y.; Muramatsu, Ken*; Takada, Tsuyoshi*
Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 9 Pages, 2018/07
After the 2011 Fukushima accident, nuclear power plants are required to take countermeasures against accidents beyond design basis conditions. In seismic probabilistic risk assessment (SPRA), uncertainty can be classified as either aleatory uncertainty, which cannot be reduced, or epistemic uncertainty, which can be reduced with additional knowledge and/or information. To improve the reliability of SPRA, efforts should be made to identify and reduce the epistemic uncertainty caused by the lack of knowledge. In this study, we focused on the difference in seismic response by modeling methods, which is related epistemic uncertainty. We conducted a seismic response analysis with two kinds of modeling methods; a three-dimensional finite-element model and a conventional sway-rocking stick model, by using simulated various input ground motions, which is related to aleatory uncertainty. And then we quantified the seismic floor response results of the various input ground motions of each modeling methods. For the uncertainty quantification related to different modeling methods, we further perform a statistical analysis of the floor response results of the nuclear reactor building. Finally, we discussed how to utilize the results from these calculations for the quantification of uncertainty in fragility analysis for SPRA.
Sugita, Yutaka; Kageyama, Takeshi*; Makino, Hitoshi; Shimbo, Hiroshi*; Hane, Koji*; Kobayashi, Yuichi*; Fujisawa, Yasuo*; Makanae, Koji*; Yabuki, Nobuyoshi*
Proceedings of 17th International Conference on Computing in Civil and Building Engineering (ICCCBE 2018) (Internet), 8 Pages, 2018/06
This paper presents status of development of the iSRE (integrated system for repository engineering) as a design supporting system that enables rational designing of a geological disposal repository. The complimentary technique of construction information modeling/management (CIM) has been employed for the development of iSRE. CIM uses a shared three dimensional (3D) model of associated data through common data models. In this paper, as a design support system that conforms to the characteristics of information management about engineering technology represented by repetition of design during the disposal project period, we examined and designed the function of the "iSRE", constructed a prototype, and confirmed the function through a trial simulating actual work in the disposal project. As a result, with respect to the functions of DB and IF of the iSRE, we got a prospect that these functions can be the foundation of information management on engineering technology, and development of the prototype of the iSRE and its test run extracted issues for practical use of such system.
Sugita, Yutaka; Kawaguchi, Tatsuya; Hatanaka, Koichiro; Shimbo, Hiroshi*; Yamamura, Masato*; Kobayashi, Yuichi*; Fujisawa, Yasuo*; Kobayashi, Ichiro*; Yabuki, Nobuyoshi*
Proceedings of 16th International Conference on Computing in Civil and Building Engineering (ICCCBE 2016) (Internet), p.1173 - 1182, 2016/07
This paper presents status of development of the iSRE (integrated system for repository engineering) as a design supporting system that enables rational designing of a geological disposal repository. The complimentary technique of construction information modeling/management (CIM) has been employed for the development of iSRE. CIM uses a shared three dimensional (3D) model of associated data through common data models. The contents of this paper are the goal of the development, design requirements and required functions, the basic structure of iSRE. The main databases of the iSRE could then be designed with an interface to coordinate with external systems and other databases. Some of the databases and the interfaces were trialed and a data model was then built. A scenario of iSRE operation was also created and the applicability of iSRE using a data model was also examined. Thanks to the use of the existing software, the development process could be conducted while solving problems for realistic test cases. The prospect of the development of the iSRE for geological disposal projects was realized and the iSRE was confirmed as being a useful tool for designing a repository.
Zheng, X.; Ito, Hiroto; Tamaki, Hitoshi; Maruyama, Yu
Journal of Nuclear Science and Technology, 53(3), p.333 - 344, 2016/03
Soler, J. M.*; Landa, J.*; Havlova, V.*; Tachi, Yukio; Ebina, Takanori*; Sardini, P.*; Siitari-Kauppi, M.*; Eikenberg, J.*; Martin, A. J.*
Journal of Contaminant Hydrology, 179, p.89 - 101, 2015/08
Matrix diffusion is a key process for radionuclide retention in crystalline rocks. An in-situ diffusion experiment in granite matrix was performed at the Grimsel Test Site (Switzerland). Several tracers (HTO, Na, Cs) were circulated through a borehole and the decrease in tracer concentrations was monitored for 2.5 years. Then, the borehole section was overcored and the tracer profiles in the rock were analyzed. Transport distances in the rock were 20 cm for HTO, 10 cm for Na and 1 cm for Cs. The dataset was analyzed with diffusion-sorption models by different teams using different codes, with the goal of obtaining effective diffusivities (De) and rock capacity factors. There was a rather good agreement between the values from different teams, implied that De and capacity factors in the borehole damaged zone are larger than those in the bulk rock. However, HTO seems to display large discrepancies between measured and modeled results.
Polevoi, A. R.*; Loarte, A.*; Hayashi, Nobuhiko; Kim, H. S.*; Kim, S. H.*; Koechl, F.*; Kukushkin, A. S.*; Leonov, V. M.*; Medvedev, S. Yu.*; Murakami, Masakatsu*; et al.
Nuclear Fusion, 55(6), p.063019_1 - 063019_8, 2015/05
Garcia, J.*; Hayashi, Nobuhiko; Baiocchi, B.*; Giruzzi, G.*; Honda, Mitsuru; Ide, Shunsuke; Maget, P.*; Narita, Emi*; Schneider, M.*; Urano, Hajime; et al.
Nuclear Fusion, 54(9), p.093010_1 - 093010_13, 2014/09
Hosokawa, Masanari*; Loarte, A.*; Huijsmans, G.*; Takizuka, Tomonori*; Hayashi, Nobuhiko
Europhysics Conference Abstracts (Internet), 38F, p.P5.003_1 - P5.003_4, 2014/06
Hayashi, Nobuhiko; Takizuka, Tomonori; Sakamoto, Yoshiteru; Fujita, Takaaki; Kamada, Yutaka; Ide, Shunsuke; Koide, Yoshihiko
Plasma Physics and Controlled Fusion, 48(5A), p.A55 - A61, 2006/05
no abstracts in English
Hayashi, Nobuhiko; Takizuka, Tomonori; Ozeki, Takahisa
Nuclear Fusion, 45(8), p.933 - 941, 2005/08
We have investigated profile formation and sustainment of current hole (CH) plasma by 1.5D transport simulations with current limit model inside CH based on Axisymmetric Tri-Magnetic-Islands equilibrium. Sharp reduction of anomalous transport in RS region can reproduce JT-60U experiments. The transport becomes neoclassical-level in RS region, which results in autonomous profile formation of ITB and CH through large bootstrap current. ITB width determined by neoclassical-level transport agrees with that in JT-60U. Energy confinement inside ITB agrees with JT-60U scaling. The scaling means that core plasma inside ITB is governed by MHD equilibrium limit, i.e., autonomous limitation of energy confinement. The plasma with large CH is sustained with full current drive by bootstrap current. The plasma with small CH and small bootstrap current fraction shrinks due to penetration of inductive current. This shrink is prevented and CH size can be controlled by appropriate external CD. CH plasma is found to respond autonomically to external CD. Application of CH plasma to reactor is discussed.