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Doi, Daisuke; Seino, Hiroshi; Miyahara, Shinya*; Uno, Masayoshi*
Journal of Nuclear Science and Technology, 59(2), p.198 - 206, 2022/02
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Furuyama, Taisei*; Thwe Thwe, A.; Katsumi, Toshiyuki; Kobayashi, Hideaki*; Kadowaki, Satoshi
Nihon Kikai Gakkai Rombunshu (Internet), 87(898), p.21-00107_1 - 21-00107_12, 2021/06
The effects of steam addition on the unstable behavior of hydrogen-air lean premixed flames under adiabatic and non-adiabatic conditions were investigated by numerical calculations. Adopting a detailed chemical reaction mechanism of hydrogen-oxyfuel combustion modeled by 17 reversible reactions of 8 active species and diluents, a two-dimensional unsteady reaction flow was treated based on the compressible Navier-Stokes equation. As the steam addition and heat loss increased, the burning velocity of a planar flame decreased and the normalized burning velocity increased. The addition of water vapor promotes the unstable behavior of the hydrogen-air lean premixed flame. This is because the thermal diffusivity of the gas decreases and the diffusion-thermal instability increases. The effect of adding water vapor on the instability of hydrogen premixed flames is a new finding, and it is expected to connect with hydrogen explosion-prevention measures as in NPP.
Katsumi, Toshiyuki; Yoshida, Yasuhito*; Nakagawa, Ryo*; Yazawa, Shinya*; Kumada, Masashi*; Sato, Daisuke*; Thwe Thwe, A.; Chaumeix, N.*; Kadowaki, Satoshi
Journal of Thermal Science and Technology (Internet), 16(2), p.21-00044_1 - 21-00044_13, 2021/00
Times Cited Count：5 Percentile：36.79(Thermodynamics)The effects of addition of CO
and water vapor on characteristics of dynamic behavior of hydrogen/air premixed flames were elucidated experimentally. By Schlieren photography, wrinkles on the flame surface were clearly observed in low equivalence ratios. The propagation velocity increased monotonically as the flame radius became larger and flame acceleration was found. Increasing the addition of inert gas, the propagation velocity decreased, especially in the case of CO addition. Moreover, the Markstein length and the wrinkling factor decreased. This indicated that the addition of Co or HO promoted the unstable motion of hydrogen flames, which could be due to the enhancement of the diffusive-thermal effect. Based on the characteristics of dynamic behavior of hydrogen flames, the parameters used in the mathematical model on propagation velocity including flame acceleration was obtained, and then the flame propagation velocity under various conditions was predicted.
Trianti, N.; Motegi, Kosuke; Sugiyama, Tomoyuki; Maruyama, Yu
Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 9 Pages, 2020/08
Kadowaki, Satoshi; Nogami, Masato*; Thwe Thwe, A.; Katsumi, Toshiyuki*; Yamazaki, Wataru*; Kobayashi, Hideaki*
Nihon Kikai Gakkai Rombunshu (Internet), 85(879), p.19-00274_1 - 19-00274_13, 2019/11
We dealt with three-dimensional cellular premixed flames generated by hydrodynamic and diffusive-thermal instabilities to elucidate the effects of unburned-gas temperature and heat loss by adopting the three-dimensional compressible Navier-Stokes equation. As the unburned-gas temperature became lower and the heat loss became larger, the growth rate decreased and the unstable range narrowed. With a decrease of unburned-gas temperature, the normalized growth rate increased and the normalized unstable range widened, which was because the temperature ratio of burned and unburned gases became larger. The obtained hexagonal cellular fronts were qualitatively consistent with the experimental results. As the heat loss became larger, the burning velocity of a cellular flame normalized by that of a planar flame increased. This was because diffusive-thermal effects became stronger owing to the increase of apparent Zeldovich number caused by the decrease of flame temperature.
Motegi, Kosuke; Trianti, N.; Matsumoto, Toshinori; Sugiyama, Tomoyuki; Maruyama, Yu
Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.4324 - 4335, 2019/08
Doi, Daisuke; Seino, Hiroshi; Miyahara, Shinya*; Uno, Masayoshi*
Journal of Nuclear Science and Technology, 56(6), p.521 - 532, 2019/06
Times Cited Count：1 Percentile：11.15(Nuclear Science & Technology)Sonehara, Masateru; Aoyagi, Mitsuhiro; Uchibori, Akihiro; Takata, Takashi; Ohshima, Hiroyuki; Clark, A. J.*; Denman, M. R.*
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05
In order to investigate the effect of sodium combustion, Sandia National Laboratories (SNL) and Japan Atomic Energy Agency (JAEA) have exchanged information of sodium combustion modelling and related experimental data in the framework of Civil Nuclear Energy Research and Development Working Group (CNWG). The benchmark analysis of the SNL T3 sodium spray combustion experiment and sensitivity study have been carried out using the AQUA-SF code in this paper. The sensitivity analysis clarifies the influencing factors of the multi-dimensional analysis such as turbulence models, radiation heat transfer model from sodium droplets, and momentum exchange between gas and droplets. The result shows that the turbulence effect, radiation from droplets and gas temperature increase at spray burning area affect sodium spray burning rate significantly.
Thwe Thwe, A.; Terada, Atsuhiko; Hino, Ryutaro
JAEA-Technology 2018-012, 45 Pages, 2019/01
JAEA-Technology-2018-012.pdf:4.34MB
Under long-term storage of nuclear wastes including low- and high-level wastes, hydrogen can be spontaneously generated from corrosion of metal wastes and container wall itself, and from radiolysis of water in the waste. For the sake of hydrogen safety and the risk reduction of environmental contamination, we have started to investigate the behavior and characteristics of hydrogen combustion and explosion in waste vessel. In this report, we performed numerical simulation to investigate the characteristics of methane combustion by applying OpenFOAM. For combustion scenario, FireFoam solver with LES frame was used. As the results, the average temperature increased when the container height and inlet size increased. The simulation of gas diffusion by FireFoam results showed that helium diffused faster than hydrogen and methane. By XiFoame solver, the simulation was performed to obtain flame propagation radius for hydrogen-air premixed flame.
Sonehara, Masateru; Aoyagi, Mitsuhiro; Uchibori, Akihiro; Takata, Takashi; Ohshima, Hiroyuki; Clark, A. J.*; Denman, M. R.*
Proceedings of 11th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-11) (Internet), 5 Pages, 2018/11
no abstracts in English
Bentaib, A.*; Chaumeix, N.*; Grosseuvres, R.*; Bleyer, A.*; Gastaldo, L.*; Maas, L.*; Jallais, S.*; Vyazmina, E.*; Kudriakov, S.*; Studer, E.*; et al.
Proceedings of 12th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-12) (USB Flash Drive), 11 Pages, 2018/10
Matsumoto, Toshinori; Sato, Masatoshi; Sugiyama, Tomoyuki; Maruyama, Yu
Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 6 Pages, 2017/07
Masaki, Kei; Sugiyama, Kazuyoshi*; Tanabe, Tetsuo*; Goto, Yoshitaka*; Tobita, Kenji; Miyo, Yasuhiko; Kaminaga, Atsushi; Kodama, Kozo; Arai, Takashi; Miya, Naoyuki
Nihon Genshiryoku Gakkai Wabun Rombunshi, 2(2), p.130 - 139, 2003/06
no abstracts in English
Masaki, Kei; Sugiyama, Kazuyoshi*; Tanabe, Tetsuo*; Goto, Yoshitaka*; Miyasaka, Kazutaka*; Tobita, Kenji; Miyo, Yasuhiko; Kaminaga, Atsushi; Kodama, Kozo; Arai, Takashi; et al.
Journal of Nuclear Materials, 313-316, p.514 - 518, 2003/03
Times Cited Count：55 Percentile：94.93(Materials Science, Multidisciplinary)Detailed tritium profiles on the JT-60U W-shaped divertor and first wall tiles were examined by Tritium Imaging Plate Technique (TIPT) and full combustion method. The tritium deposition image obtained by TIPT was consistent with the distribution measured by combustion method. The highest tritium concentration was 60 kBq/cm
at the dome top tile. However, deposition layer was not obviously observed on the dome top tile. The tritium concentration in the inner divertor target tile was lower (2 kBq/cm) even with the thick deposition layer of 
60 
m. This tritium distribution can be explained by energetic triton particle loss due to ripple loss. According to the simulation using the OFMC code, 31% of the triton particles produced by D-D nuclear reaction is implanted deeply to the wall without fully losing the initial energy of 1 MeV.
Inaba, Yoshitomo; Nishihara, Tetsuo; Moriyama, Koichi*; Nakamura, Masashi*
JAERI-Data/Code 2002-014, 255 Pages, 2002/07
JAERI-Data-Code-2002-014.pdf:21.69MB
One of the most important safety design issues for an HTGR hydrogen production system is to ensure reactor safety against fire and explosion accidents in the hydrogen production plant because a large amount of combustible fluid is dealt with in the system. JAERI has the demonstration test plan to connect the hydrogen production system with the HTTR. In the plan, we considered effective measures against the fire and explosion accidents in the HTTR hydrogen production system, which were applicable to the HTGR hydrogen production system of a commercial base, and also developed the P2A code system to analyze event sequences and consequences in detail, on assumed fire and explosion accidents in the HTGR hydrogen production system and the HTTR hydrogen production system. The P2A can analyze the process of leakage, dispersion, ignition, and combustion including deflagration and detonation of the combustible fluid in the internal and external area of the reactor building. In this report, we describe the outline and the usage of the P2A, and the results of preliminary calculations.
Inaba, Yoshitomo; Nishihara, Tetsuo; Inagaki, Yoshiyuki
Proceedings of 14th Hydrogen Energy Conference (WHEC 2002) (CD-ROM), 9 Pages, 2002/06
The Japan Atomic Energy Research Institute (JAERI) has the demonstration test plan to connect a hydrogen production system by steam reforming of methane with the High Temperature engineering Test Reactor (HTTR). One of the most important safety design issues for the HTTR hydrogen production system is to ensure reactor safety against fire and explosion accidents. Therefore, we developed the P2A code system to analyze event sequences and consequences in detail, on assumed fire and explosion accidents in the HTTR hydrogen production system. It is possible that the P2A analyzes the process of leakage, dispersion and combustion including deflagration and detonation of the combustible fluid in the internal and external area of the reactor building. This paper describes the outline of the P2A and the results of preliminary calculations.
L.Chan*; Watanabe, Kazuo; Ito, Mitsuo
JAERI-Research 95-061, 13 Pages, 1995/09
JAERI-Research-95-061.pdf:0.52MB
no abstracts in English
Uchiyama, Gunzo; Maeda, Mitsuru; Fujine, Sachio; *; *; *
Journal of Nuclear Science and Technology, 31(3), p.228 - 239, 1994/03
Times Cited Count：8 Percentile：60.22(Nuclear Science & Technology)no abstracts in English
Uchiyama, Gunzo; Maeda, Mitsuru; *; Fujine, Sachio; *; *
Proceedings of 4th International Conference on Nuclear Fuel Reprocessing and Waste Management; RECOD '94, Vol.3, 0, p.1 - 15, 1994/00
no abstracts in English
Uchiyama, Gunzo; Maeda, Mitsuru; Fujine, Sachio; *; *
JAERI-M 93-213, 204 Pages, 1993/10
no abstracts in English
