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Ono, Ayako; Yamashita, Susumu; Sakashita, Hiroto*; Suzuki, Takayuki*; Yoshida, Hiroyuki
Dai-26-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 4 Pages, 2022/07
JAEA is implementing a simulation of a two-phase flow in the reactor core by TPFIT and JUPITER which are developed by JAEA based on the surface tracking method. However, it is impossible to simulate a boiling on the heating surface in the large-scale domain by this type of simulation method since the simulation of boiling based on the surface tracking method needs the fine mesh which sufficiently resolves the initiation of boiling. Therefore, JAEA started to develop the simplified boiling model applied for the two-phase flow in the fuel assemblies. In this study, the simulation results of the convection boiling on a vertical heating surface and the comparison between the simulation results and experimental results are shown.
Ono, Ayako; Yamashita, Susumu; Suzuki, Takayuki*; Yoshida, Hiroyuki
Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 16 Pages, 2022/03
JAEA is developing the methodology to predict the critical heat flux based on a mechanism in order to reduce the cost for full mock-up test. The evaluation method based on a mechanism is expected to be able to predict in the wide range of parameter under the unexpected conditions including the severe accident. In this study, the JUPITER code developed by JAEA is examined to apply for the two-phase flow simulation of LWR fuel assembly with the spacer grid. The benchmark data of single-phase flow in the bundle with the spacers by KAERI were used to validate the simulation result by JUPITER. Moreover, the single-phase flow simulation was conducted by another simulation method, STAR-CCM+, as a supplemental analysis to consider the effect of the different simulation methods. Finally, the two-phase flow simulation for the bundle with the spacer was conducted by JUPITER. The effect of the spacer with a vane on the bubble behavior is discussed.
4 simulated bundleOno, Ayako; Yamashita, Susumu; Suzuki, Takayuki*; Yoshida, Hiroyuki
Mechanical Engineering Journal (Internet), 7(3), p.19-00583_1 - 19-00583_12, 2020/06
JAEA is implementing the 3D detailed nuclear-thermal-coupled analysis code to analyze the transition state of the core and to reduce the likelihood of the design. In the development plan, the computational fluid dynamics code based on the VOF method, JUPITER, is applied for TH part of the 3D detailed nuclear-thermal-coupled analysis code.
Ono, Ayako; Yamashita, Susumu; Suzuki, Takayuki*; Yoshida, Hiroyuki
Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.666 - 677, 2019/08
An evaluation methodology of critical heat fluxes (CHFs) based on a mechanism for fuel assemblies in light water reactors (LWRs) is needed in order to design and evaluate the safety for the fuel assemblies in LWRs. In our study, the numerical simulation with surface-tracking will be applied for the two-phase flow in fuel assemblies in order to obtain the detail data relating to the size and velocity of bubbles in the subchannel, which is needed to predict the CHF based on the mechanism. In this study, the numerical simulation of two-phase flow in 44 bundle was implemented by using JUPITER in order to establish the evaluation method of the size and velocity of bubbles by the numerical simulation, which is the multi-physics simulation code and enable to track the gas-liquid surface. The simulation results are validated by the curve of flow regime for air-water under the adiabatic condition. The bubble and velocity of bubbles obtained by simulation results are analyzed.
Ota, Masakazu; Kwamena, N.-O. A.*; Mihok, S.*; Korolevych, V.*
Journal of Environmental Radioactivity, 178-179, p.212 - 231, 2017/11
Times Cited Count：20 Percentile：46.51(Environmental Sciences)Environmental transfer models assume that organically-bound tritium (OBT) is formed directly from tissue-free water tritium (TFWT) in environmental compartments. Nevertheless, studies in the literature have shown that measured OBT/TFWT ratios are variable. The importance of soil-to-leaf HTO transfer pathway in controlling the leaf tritium dynamics is not well understood. A model inter-comparison of two tritium transfer models (CTEM-CLASS-TT and SOLVEG-II) was carried out with measured environmental samples from an experimental garden plot set up next to a tritium-processing facility. The garden plot received one of three different irrigation treatments - no external irrigation, irrigation with low tritium water and irrigation with high tritium water. The contrast between the results obtained with the different irrigation treatments provided insights into the impact of soil-to-leaf HTO transfer on the leaf tritium dynamics. Concentrations of TFWT and OBT in the garden plots that were not irrigated or irrigated with low tritium water were variable, responding to the arrival of the HTO-plume from the tritium-processing facility. In contrast, for the plants irrigated with high tritium water, the TFWT concentration remained elevated due to a continuous source of high HTO in the soil. Calculated concentrations of OBT in the leaves showed an initial increase followed by quasi-equilibration with the TFWT concentration. In this quasi-equilibrium state, concentrations of OBT remained elevated and unchanged despite the arrivals of the plume. These results from the model inter-comparison demonstrate that soil-to-leaf HTO transfer significantly affects OBT/TFWT ratio in the leaf regardless of the atmospheric HTO concentration, only if there is elevated HTO concentrations in the soil. The results of this work indicate that assessment models should be refined to consider the importance of soil-to-leaf HTO transfer to ensure that dose estimates are accurate and conservative.
Shibamoto, Yasuteru
JAERI-Research 2005-016, 127 Pages, 2005/08
JAERI-Research-2005-016.pdf:4.54MB
no abstracts in English
Uchida, Shunsuke*; Sato, Tomonori; Morishima, Yusuke*; Hirose, Tatsuya*; Miyazawa, Takahiro*; Kakinuma, Nagao*; Sato, Yoshiyuki*; Usui, Naoshi*; Wada, Yoichi*
Proceedings of 12th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors (CD-ROM), p.19 - 29, 2005/00
Static and dynamic responses of stainless steel specimens exposed to H
O and O in high temperature water were evaluated by analyzing ECP and FDCI (frequency dependent complex impedance). The oxide films on the specimens were characterized by multilateral surface analyses, e.g., LRS, SIMS, XPS and direct electric resistance measurement. As a result of evaluation, it was confirmed that (1) corrosive condition of BWR normal water chemistry (NWC) was simulated by 100 ppb HO without co-existing O, while that of hydrogen water chemistry (HWC) was simulated by 10 ppb HO, (2) ECP under HWC was as high as that under NWC, while dissolution rate of oxide film under HWC was much lower than that under NWC, (3) combination effects of electric resistance and dissolution rate of oxide caused same level ECP for both NWC and HWC, and (4) distinct weight loss of the specimen exposed to 100 ppb HO was observed.
Matsunaga, Takeshi; Nagao, Seiya*; Ueno, Takashi; Takeda, Seiji; Amano, Hikaru; Tkachenko, Y.*
Applied Geochemistry, 19(10), p.1581 - 1599, 2004/10
Times Cited Count：39 Percentile：56.11(Geochemistry & Geophysics)The association of dissolved 
Sr, 
Pu and 
Am with natural colloids was investigated in surface waters in the Chernobyl nuclear accident area by means of ultrafiltration. Results suggest that Pu and Am isotopes were preferentially associated with dissolved humic substances (HS) of high molecular size. A model calculation of the complexation of Pu and Am with HS also supported the above. This study has expanded our understanding of the general role of natural organic colloids in dictating the chemical form of actinides in the surface aquatic environment.
Yamazawa, Hiromi
Environmental Modelling & Software, 16(8), p.739 - 751, 2001/12
no abstracts in English
Nakamura, Hiroshi; Ida, Mizuho*; Nakamura, Hiroo; Nakamura, Hideo; Ezato, Koichiro; Akiba, Masato
JAERI-Research 2000-068, 30 Pages, 2001/02
JAERI-Research-2000-068.pdf:3.88MB
no abstracts in English
Yamazawa, Hiromi
KURRI-KR-61, p.100 - 105, 2000/00
no abstracts in English
Noguchi, Hiroshi; Fukutani, Satoshi*; Yokoyama, Sumi; Kinouchi, Nobuyuki
KURRI-KR-61, p.18 - 25, 2000/00
no abstracts in English
Ito, Kazuhiro*; Tsuji, Yoshiyuki*; Nakamura, Hideo; Kukita, Yutaka*
9th Int. Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-9)(CD-ROM), 16 Pages, 1999/00
no abstracts in English
Takahashi, Tomoyuki; ; Kimura, Hideo; Matsuzuru, Hideo
JAERI-M 91-216, 31 Pages, 1992/01
no abstracts in English
JAERI-M 83-199, 83 Pages, 1983/11
no abstracts in English
Yoshida, Hiroyuki; Nagatake, Taku; Nemoto, Yoshiyuki; Kaji, Yoshiyuki
no journal, ,
