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Abe, Satoshi; Okagaki, Yuria; Ishigaki, Masahiro; Shibamoto, Yasuteru
Proceedings of OECD/NEA Workshop on Virtual CFD4NRS-8; Computational Fluid Dynamics for Nuclear Reactor Safety (Internet), 11 Pages, 2020/11
Irisawa, Keita; Garcia-Lodeiro, I.*; Kinoshita, Hajime*
Cement and Concrete Research, 128, p.105951_1 - 105951_7, 2020/02
Times Cited Count：7 Percentile：35.84(Construction & Building Technology)This study investigated characteristics of a calcium aluminate cement modified with a phosphate (CAP) by changing an amount and concentration of mixing solution with sodium polyphosphate. When the amount of mixing solution was increased with a constant amount of sodium polyphosphate, an enhanced consumption of monocalcium aluminate was observed compared with gehlenite in calcium aluminate cement (CAC). Formation of gibbsite, Al(OH)
, was also increased as a hydration product in the CAP and the possible reduction of water in the amorphous gel phase. When the amount of mixing solution was increased with a constant concentration of sodium polyphosphate, the enhanced consumption of monocalcium aluminate was not observed. Neither gibbsite nor any other crystalline hydration products were identified in this series. In addition, unreacted sodium polyphosphate remained in the system. The increased formation of gibbsite and the possible reduction of water from the amorphous gel phase appears to contribute to the improvement of the microstructure in the products.
Hamdani, A.; Abe, Satoshi; Ishigaki, Masahiro; Shibamoto, Yasuteru; Yonomoto, Taisuke
Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.5463 - 5479, 2019/08
Studer, E.*; Abe, Satoshi; Andreani, M.*; Bharj, J. S.*; Gera, B.*; Ishay, L.*; Kelm, S.*; Kim, J.*; Lu, Y.*; Paliwal, P.*; et al.
Proceedings of 12th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-12) (USB Flash Drive), 16 Pages, 2018/10
Hotta, Akitoshi*; Morita, Akinobu*; Kajimoto, Mitsuhiro*; Maruyama, Yu
Nihon Genshiryoku Gakkai Wabun Rombunshi, 16(3), p.139 - 152, 2017/09
Tochio, Daisuke; Fujimoto, Nozomu
Journal of Nuclear Science and Technology, 53(3), p.425 - 431, 2016/03
Times Cited Count：1 Percentile：10.71(Nuclear Science & Technology)The future HTGR is now designed in JAEA. The reactor has many merging points of helium gas with different temperature. It is needed to clear the mixing characteristics of helium gas at the pipe in the HTGR from the viewpoint of structure integrity and temperature control. Previously, the reactor inlet coolant temperature was controlled lower than specific one in the HTTR due to lack of mixing of helium gas in the primary cooling system. Now the control system is improved to use the calculated bulk temperature of reactor inlet helium gas. In this paper, thermal-hydraulic analysis on the primary cooling system of the HTTR was conducted to clarify the mixing behavior of helium gas. As the result, it was confirmed that the mixing behavior of helium gas in the primary cooling system is mainly affected by the aspect ratio of annular flow path, and it is needed to consider the mixing characteristics of helium gas at the piping design of the HTGR.
Moriyama, Kiyofumi; Nakamura, Hideo; Maruyama, Yu*
Nuclear Engineering and Design, 236(19-21), p.2010 - 2025, 2006/10
Times Cited Count：23 Percentile：82.01(Nuclear Science & Technology)A computer code JASMINE-pre was developed for the prediction of premixing conditions of fuel-coolant interactions and the debris bed formation behavior relevant to severe accidents of light water reactors. JASMINE-pre consists of three melt component models: melt jet, melt particles and melt pool, coupled with a two-phase flow model derived from the ACE-3D code developed at JAERI. Simulations of the FARO corium quenching experiments with a saturated water pool and with a subcooled water pool were performed with JASMINE-pre and 
. JASMINE-pre reproduced the pressurization and fragmentation behaviors observed in the experiments with a reasonable accuracy. The results by pmjet showed qualitatively the same trend with JASMINE-pre in the fragmentation behavior.
Moriyama, Kiyofumi; Maruyama, Yu; Usami, Tsutomu*; Nakamura, Hideo
JAERI-Research 2005-017, 173 Pages, 2005/08
JAERI-Research-2005-017.pdf:11.17MB
A series of experiments on the break-up of high temperature oxide and steel melt jets in a water pool was conducted. The objective was to obtain data for the jet break-up length and size distribution of the droplets produced by the jet break-up, and information on the influence of material properties. Also, we tried to obtain additional information giving a clue to the mechanism governing the melt jet break-up, such as flow intensity of the steam column surrounding the melt jet, and its relation with the droplet size. In the experiments, zirconia-alumina mixture and stainless steel melt jets with diameter 
17mm and velocity 7.8m/s at the water surface were dropped into a deep (2.1m) or shallow (0.6m) water pool with various subcool. From the results of the present experiments and also by referring other experimental data from literature, we obtained empirical correlation equations for the jet break-up length, the fraction of jet broken-up in a shallow pool where the jet was not completely broken-up, and the droplet size.
Moriyama, Kiyofumi; Nakamura, Hideo; Maruyama, Yu
Proceedings of 6th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operations and Safety (NUTHOS-6) (CD-ROM), 18 Pages, 2004/10
A steam explosion simulation code JASMINE is under development at JAERI for the assessment of steam explosion impacts on the integrity of containment vessel during severe accidents in light water reactors. Selected alumina and corium steam explosion experiments, KROTOS-44, 42, 37 and FARO-L33 were simulated with JASMINE code. The experimentally observed difference of the steam explosion intensity with the two materials, alumina and corium, was reproduced in the simulations without changing the model parameters related to the fine fragmentation process, but based on the difference in the premixing behavior predicted by the simulations. The simulation of corium experiments showed more fraction of the melt droplets frozen during premixing, as well as more void fraction, and those two points were likely to be the primary reasons of weak interactions in corium experiments.
Kasahara, Mikio*; Ma, C.-J.*; Okumura, Motonori*; Kojima, Takuji; Hakoda, Teruyuki; Sakai, Takuro; Arakawa, Kazuo
JAERI-Review 2003-033, TIARA Annual Report 2002, p.270 - 272, 2003/11
A snow crystal scavenges earozol particles and trasfer various elements in atomosphere through heterogenious nucleation. The snow has many complicated crystal shapes which results in difficulty in comparison of its environmental purification function directly with that of raindrops. The replica of individual snow crystal grain was prepared by their immobilization on the collodion film. The replica samples were analized by micro-PIXE at JAERI and PIXE st Kyoto university. The following results are obtained: (1) Size(circumscribed diameter) of individual snow crystal are in the range of 0.12-2.5mm, (2)snow crystal grows from hexagnal plate to dendritic sectored plate, (3) major elements captured by a snow crystal are Si,S,K,Ca,Fe,S, (4)there is relation between snow crystal size and captured-element masses. The result leads us to presume the chemical inner-structure and the elemental mixing state in/on single snow crystal.
Moriyama, Kiyofumi; Nakamura, Hideo; Hirano, Masashi
Nihon Kikai Gakkai Dai-8-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu, p.209 - 214, 2002/06
Through a review of experimental works on steam explosions and consideration on the uncertainty in the methodology for plant scale analysis of each stage of the phenomena, it was identified that the molten jet breakup process in premixing has an important uncertainty caused by lack of experimental knowledge. Based on this perspective, an experimental work are under planning at Japan Atomic Energy Research Institute (JAERI), in which the premixing stage of steam explosions in a deep water pool is modeled by high temperature oxide melts. Melt material and scale of the experiment were examined in terms of the simulation capability of the jet breakup mechanism in a plant scale phenomena. Materials and geometrical scale considered adequate were found.
Moriyama, Kiyofumi; Maruyama, Yu*; Nakamura, Hideo
Journal of Nuclear Science and Technology, 39(1), p.53 - 58, 2002/01
Times Cited Count：8 Percentile：47.9(Nuclear Science & Technology)no abstracts in English
Iwai, Yasunori; Yamanishi, Toshihiko; Nishi, Masataka
Journal of Nuclear Science and Technology, 36(1), p.95 - 104, 1999/01
Times Cited Count：12 Percentile：66.16(Nuclear Science & Technology)no abstracts in English
; Moriyama, Kiyofumi; Maruyama, Yu; H.Park*; Y.Yang*; Sugimoto, Jun
Nucl. Eng. Des., 189(1-3), p.205 - 221, 1999/00
Times Cited Count：4 Percentile：34.81(Nuclear Science & Technology)no abstracts in English
Watanabe, Tadashi; Ebihara, Kenishi
Nucl. Eng. Des., 188(1), p.111 - 121, 1999/00
Times Cited Count：6 Percentile：45.57(Nuclear Science & Technology)no abstracts in English
A.R.Antariksawan*; Moriyama, Kiyofumi; H.Park*; Maruyama, Yu; Y.Yang*; Sugimoto, Jun
JAERI-Review 98-012, 66 Pages, 1998/09
JAERI-Review-98-012.pdf:3.36MB
no abstracts in English
Yamazawa, Hiromi; Furuno, Akiko; Chino, Masamichi
Atmospheric Environment, 32(24), p.4343 - 4349, 1998/00
Times Cited Count：5 Percentile：17.42(Environmental Sciences)no abstracts in English
Yamazawa, Hiromi; Chino, Masamichi; Furuno, Akiko
ETEX Symp. on Long-Range Atmospheric Transport,Model Verification and Emergency Response, p.191 - 194, 1997/00
no abstracts in English
SiO
crystals*; *
Opt. Rev., 4(6), p.683 - 685, 1997/00
Times Cited Count：0 Percentile：0.01(Optics)no abstracts in English
Abe, Hiroaki; Naramoto, Hiroshi; Hojo, Kiichi; Furuno, Shigemi
JAERI-Research 96-047, 18 Pages, 1996/09
JAERI-Research-96-047.pdf:0.96MB
no abstracts in English
