Reaction between molten 316 L stainless steel and Zircaloy–4 at 1450 ℃ during a core melt accident of LWR

• Oxide layers on Zircaloy suppress Zr dissolution into molten stainless steel. • Secondary oxides form at the interface due to oxygen enrichment in Zr. • A product layer with Laves phase grows between oxide layers over time. • Zr dissolution rate is modeled by time and oxide thickness. • Secondary oxide layers form rapidly and remain stable during reaction. Regarding the interaction between Zircaloy and stainless steel in the accidental conditions of light water reactors, the detailed mechanism of the eutectic liquefaction has been widely studied. However, there are seldom data on the interaction between the surface-oxidized Zircaloy and molten stainless steel, which could happen in several potential accident scenarios. The dissolution reaction rate of Zr from the surface-oxidized Zircaloy into the molten SS316L was experimentally evaluated at 1450 °C. The amount of Zr transferred externally by the Zircaloy–SS316L reaction can be formulated as m ( x , t ) A = ( − 0.0002 x + 0.115 ) · { ln ( t + 0.759 ) + 0.275 } [ g / cm 2 ] , where m ( x,t ), A, x , and t represent the amount of transferred Zr [g], reaction area [cm 2 ], thickness of oxide film on Zircaloy surface [µm], and reaction time [min], respectively.