Basic visualization experiments on eutectic reaction between boron carbide and stainless steel under sodium-cooled fast reactor conditions

Yamano, Hidemasa   ; Suzuki, Toru; Kamiyama, Kenji  ; Kudo, Isamu*

This paper describes basic visualization experiments on eutectic reaction and relocation of boron carbide (BC) and stainless steel (SS) under a high temperature condition exceeding 1500C as well as the importance of such behaviors in molten core during a core disruptive accident in a Generation-IV sodium-cooled fast reactor (750 MWe class) designed in Japan. At first, a reactivity history was calculated using an exact perturbation calculation tool taking into account expected behaviors. This calculation indicated the importance of a relocation behavior of the BC-SS eutectic because its behavior has a large uncertainty in the reactivity history. To clarify this behavior, basic experiments were carried out by visualizing the reaction of a BC pellet contacted with molten SS in a high temperature-heating furnace. The experiments have shown the eutectic reaction visualization as well as freezing and relocation of the BC-SS eutectic in upper part of the solidified test piece due to the density separation.