ナトリウム冷却高速炉条件における炭化ホウ素とステンレス鋼の共晶反応可視化基礎実験

抄録

This paper describes basic visualization experiments on eutectic reaction and relocation of boron carbide (B₄C) and stainless steel (SS) under a high temperature condition exceeding 1500°C as well as the importance of such behaviors in molten core during a core disruptive accident in a Generation-IV sodium-cooled fast reactor (750MWe 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 B₄C-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 B₄C 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 B₄C-SS eutectic in upper part of the solidified test piece due to the density separation.