Experimental and Numerical Investigation of Solidification of Gallium in an Initially Emptied Vertical Pipe

Abstract

During a severe power reactor accident, the plant core can melt. The resulting mixture of molten nuclear fuel and other in-core materials is known as corium. For a Canada Deuterium Uranium (CANDU) reactor, the corium is expected to settle at the bottom of the calandria vessel, but there is a potential for some melt to flow through connecting piping and other penetrations. The flow of corium through these structures can be contained if melt solidification and thus plugging occur. A numerical model was created to simulate the flow of molten metal through an empty vertical pipe. This model was benchmarked to a previous analytical model and validated against experimental results with gallium metal (which is a metal with low melting temperature) as an alternative for corium. The numerical model predicted the penetration length of gallium with an average percent error of 10.3% when compared to the experimental penetration length results of gallium. The model was also updated to predict the corium penetration length in cooling pipes of the CANDU reactor during a severe accident.