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Tamai, Hidesada; Yoshida, Hiroyuki; Masuko, Kenji*; Akimoto, Hajime
Proceedings of 4th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-4), p.230 - 236, 2004/12
no abstracts in English
Yoshida, Hiroyuki; Nagayoshi, Takuji*; Tamai, Hidesada; Takase, Kazuyuki; Akimoto, Hajime
Proceedings of 4th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-4), p.264 - 269, 2004/12
no abstracts in English
Yoshida, Hiroyuki; Ose, Yasuo*; Takase, Kazuyuki; Akimoto, Hajime
Proceedings of 4th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-4), p.270 - 276, 2004/12
no abstracts in English
Sagayama, Yutaka; Enuma, Yasuhiro; Sakamoto, Yoshihiko; Kotake, Shoji
Paper No.103, 0 Pages, 2004/11
Focusing on the cover layer materials (as the Radon Barrier Materials), which could have the effect to restrain the radon from scattering into the air and the effect of the radiation shielding, we produced the radon barrier materials with crude bentonite on an experimental basis, using the rotary type comprehensive unit for grinding and mixing, through which we carried out the evaluation of the characteristics thereof.
Shibamoto, Yasuteru; Yonomoto, Taisuke; Nakamura, Hideo; Nishikizawa, Tomotoshi
Proceedings of 4th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-4), p.210 - 214, 2004/11
no abstracts in English
Uchibori, Akihiro; Ohshima, Hiroyuki; Yamaguchi, Akira
Proceedings of 4th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-4), p.51 - 55, 2004/11
To evaluate the feasibility of several candidate techniques for a nuclear fuel cycle process, a numerical simulation program using an eXtended Finite Element Method (X-FEM) was developed. The X-FEM is an excellent numerical simulation method for a melting/solidification phenomenon which is a moving boundary problem. The validity of the numerical simulation program was demonstrated through the analysis of an one-dimensional melting/solidification problem.
Ito, Kei; Sakai, Takaaki; Ohshima, Hiroyuki; Yamaguchi, Akira
Proceedings of 4th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-4), p.155 - 162, 2004/00
Gas entrainment due to free surface vortex is one of important phenomena to be solved for its onset condition to design the innovative fast breeder reactor because the reactor has the high coolant velocity. The free surface vortex must be studied in detail by both experiments and numerical simulations to make clear the complicated behavior of the vortex gas entrainment. However, an applicability of a numerical simulation to the free surface vortex has not been clear yet. In this paper, numerical simulation for the free surface vortex was conducted to study the sensitivity of some parameters on the simulation accuracy. Moreover, the effect of the horizontal mesh size on the simulation accuracy is discussed because the effect is important to determine the mesh size for the accurate simulation. As a result of the simulation, it became clear that the horizontal mesh size near the vortex center has a significant sensitivity on the simulation accuracy near the vortex center rather than the vertical mesh size. Agreement of the simulation result with the experimental one is highly improved with the decrease of the mesh size. An equation for evaluating simulation accuracy was derived from the extension vortex theory. The relationship between the mesh size and the simulation accuracy was quantified with this equation. The equation showed good agreement with the simulation results in terms of the effect of the horizontal mesh size on the simulation accuracy and was verified to have capability to evaluate the simulation accuracy.
Sakai, Takaaki; Eguchi, Yuzuru*; Iwasaki, Takashi*; Ohshima, Hiroyuki; Yamaguchi, Akira
Proceedings of 4th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-4), p.171 - 178, 2004/00
Design method to prevent the gas entrainment from a steady vortex in a cylinder is discussed. The gas core length of the surface vortex dimple is used as a measure of the criterion of the gas entrainment. Burgers vortex model is applied compensationally to predict the gas core length with the practical CFD method. Practical CFD method that did not consider the liquid surface deformation was validated. Macroscopic flow parameters predicted by the CFD method showed reasonable agreements with the measured data in a cylindrical tank. In addition, predicted gas core lengths by using the CFD results showed conservatively longer length than the measured data. The criterion of the gas core length to prevent the gas entrainment was tried to evaluate for the Baum data in order to see the prospects of the design method. In conclusion, it may say that the CFD method has a possibility to evaluate the gas entrainment from a surface vortex.