Influence of crust formation on the heat load to a reactor vessel under an in-vessel retention condition

The heat load imposed on a reactor vessel was measured with and without the crust layer under an IVR-ERVC condition. Mass transfer experiments were performed based on heat and mass transfer analogy to achieve high Raʹ_H of order 10¹⁵ with compact test rigs. Geometric configuration and thermal boundary condition of the oxide pool due to crust formation were modeled. The results showed larger Nu_up and lower Nu_dn than existing studies, which is due to the large Pr of the current experimental condition. The angular heat flux to the vessel increased monotonously with the angle regardless of the crust formation. Once the crust layer is formed, the thermal boundary condition near the vessel becomes melting temperature of the crust, which reduces the system temperature difference. The decreased buoyancy results in the decrease in both upward and downward heat transfers but the variation of the crust thickness did not show notable effect.