Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Ohira, Hiroaki; Ara, Kuniaki
JNC TN9400 2003-044, 68 Pages, 2003/09
JNC-TN9400-2003-044.pdf:5.13MB
As it is reported that a fluid with dispersed nano-particles shows extremely high over-all heat transfer coefficient, it is expected to be used as a coolant of the next generation reactor. Although the adaptablity of the nano-fluid technology to the liquid sodium coolant is not studied, the mitigation of sodium-water and sodium-oxygen reaction with the interfacial phenomena between the dispersed nano-particles and liquid sodium can be expected. If these phenomena are confirmed, this technology is expected to be greatly contributed to the enhancement of FBR safety. In this study, metal nanofluid, the liquid sodium containing nano-particles, was prepared and the chemical reactivity and the viscosity were evaluated. The results of this study were summarized as follows; 1)It was realized to prepare the liquid sodium with metal nano-particles(Ni, Co, Fe, Mn and Si). 2)With the evaluation of sodium-water reaction, it was confirmed that Ni nano-particles dispersed into sodium mitigated the reaction. The mitigation of the reaction showed less the chemical reactivity of sodium-water by the finer Ni-particle. 3)At350deg,the Ni-nanofluid did not show extreamly high viscosity in comparison with liquid sodium.
;
JNC TN9400 2002-058, 40 Pages, 2002/11
JNC-TN9400-2002-058.pdf:1.51MB
Advanced electromagnetic components are investigated in Feasibility Studies on Commercialized FR Cycle System to apply to the main cooling systems of Liquid Metal Fast Reactor. Although a lot of experiments and numerical analysis were carried out on both high Reynolds numbers and high magnetic Reynolds numbers, the complex phenomena could not be evaluated in detail. As the first step of the development of the numerical methods for the liquid metal magnetohydrodynamics, we investigated numerical methods that could be applied to the electromagnetic components with both complex structures and high magnetic turbulent field. As a result, we selected GSMAC (Generalized-Simplified MArker and Cell) method for calculating the liquid metal fluid dynamics because it could be easily applied to the complex flow field. We also selected the vector-FEM for calculating the magnetic field of the large components because the method had no iteration procedure. In the high magnetic turbulent field, the dynamic-SGS models would be also a promising model for the good estimation, because it could calculate the field directly without any experimental constant. In order to verify the GSMAC and the vector-FEM, we developed the 2D numerical models and calculated the magnetohydrodynamics in the large electromagnetic pump. It was estimated from these results that the methods were basically reasonable, because the calculated pressure differences had the similar tendencies to the experimental ones.
Hirabayashi, Masaru; ;
JNC TN9400 2002-016, 72 Pages, 2002/05
JNC-TN9400-2002-016.pdf:1.54MB
Utrasound Doppler Velocimetry technique (UDV) applying Doppler effect has been developed for measuring velocity distributions of sodium flow. As Doppler shift frequency is proportional to velocity of microparticles carried by flowing liquid, it is possible to evaluate velocity distributions of flowing liquid from Doppler shift frequency. In this report, a technique applying cross-correlation processing is proposed to derive Doppler shift frequency from the echoes of ultrasonic pulses. Verification studies of the proposed technique are conducted based on simulated echoes and actual echoes in water tests. Mahl results are as follows: (1)As the result of verification studies conducted based on the simulated echoes, relative error estimated by the proposed technique is about 1 percent. (2)The proposed technique is an effective measures fbr the reduction of noise signals. (3)The velocity distributions of water flowing in a pipe are evaluated in the experiments. The velocity distributions evaluated by the proposed technique is almost equivalent to that of turbulent flow evaluated by 1/7th power law.