Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 4; Effect of BC addition on viscosity of austenitic stainless steel in liquid state

Ota, Hiromichi*; Kokubo, Hiroki*; Nishi, Tsuyoshi*; Yamano, Hidemasa   

A viscosity measurement apparatus has been developed. It is known that the measurement of the viscosity of molten alloy at elevated temperatures is difficult due to the difficulty of handling for low viscosity fluids such as the stainless steel (SS)+BC alloy. In this study, the viscosities of the molten nickel (Ni) and stainless steel (SS) were measured by the oscillating crucible method to confirm the performance of the viscosity measurement apparatus as a first step. This method is suitable for high temperature molten alloys. A crucible containing molten metal is suspended, and a rotational oscillation is given to the crucible electromagnetically. The oscillation was damped by the friction of molten metal. The viscosity is determined from the period of oscillation and the logarithmic decrement. The crucible was connected to a mirror block and an inertia disk made of aluminum, and whole of them was suspended by a wire made of platinum-13% rhodium alloy. A laser light is irradiated to the mirror. The reflection light is detected by the photo-detectors, and then, the logarithmic decrement of molten metal is determined. The viscosities of molten nickel and SS melts were measured up to 1823 K. In these results, the measured viscosity values of molten Ni and SS were close to those of the literature values of molten Ni and SS. By the equipment, the viscosity of molten SS+BC alloys are measured. The BC concentration dependence of the viscosity of molten SS+BC alloys is to be clarified.