A Preliminary study for boron mixing effect on severe accident scenario in sodium-cooled fast reactor

山野 秀将   ; 守田 幸路*

Yamano, Hidemasa; Morita, Koji*

This study is intended to investigate the effect of boron mixing in the degraded core using the eutectic reaction model between BC and SS. Two difference BC particle sizes were used to examine the effect of the boron dilution in the degraded core material mixture. The tight fluid-particle momentum coupling in the case of small size of BC particles allows boron to keep remaining in the core mixture in a longer time than in the case of nominal size of BC particles. However, this preliminary calculation showed that the upward motion of the eutectic melt in the molten core pool as well as the reactivity transient behavior caused by the molten core material relocation. This analysis indicated that the reactivity increase could be delayed thanks to the boron mixing.