Numerical and Experimental Investigations of Solidification in an Initially Emptied Horizontal Turbulent Pipe Flow

In a reactor core meltdown under postulated severe accidents, the molten material (corium) could be ejected or relocated through existing vessel penetrations (cooling pipe connections). There exists, however, a potential for plugging of melt flow due to its complete solidification, providing the availability of an adequate heat sink. Therefore, a numerical model was created to simulate the flow of corium through an initially empty horizontal pipe. The numerical model was verified using a previously developed analytical model and validated with experimental tests with gallium. Simulations were updated for corium to conduct a sensitivity study on the Reynolds number, thermal conductivity, inlet temperature, and diameter. The study provided insight into the lower bound of the penetration distance, which was found to be 0.384 m, and the upper bound was 1.148 m when predicting the potential penetration length of corium in horizontal pipes.