Preliminary analysis of severe accident in sodium-cooled fast reactor using eutectic reaction model of boron-carbide control-rod material

Yamano, Hidemasa   ; Morita, Koji*

This study applied the SIMMER-IV code with the newly developed model to a preliminary SA analysis of the SFR. The analysis results show that the eutectic reaction is caused by the contact between the liquid SS and the broken BC pellets which are released to the coolant channel after the failure of cladding which is melted by the mixture of liquid SS and fuel particles coming from the neighboring fuel assemblies. The liquid eutectic material formed by the reaction moves from the control assembly to the neighboring fuel assemblies. The lower density of the eutectic melt than molten SS drives the upward motion of the eutectic in the molten core pool. This analysis indicated that the SIMMER-IV code using the eutectic reaction model has successfully simulated the eutectic reaction and the relocation of the eutectic melt as well as the reactivity transient behavior caused by the molten core material relocation.