Experimental study of molten metal penetration and freezing behavior in pin-bundle geometry

Molten metal penetration and freezing phenomena were studied during the interaction with reactor core structures from the view point of the safety analysis of heavy liquid metal cooled reactor. For the determination of the fundamental mechanisms underlying the penetration and freezing behavior of molten metal flowing through a seven-pin channel was the main objectives of this study. The present series of simulant experiments, therefore, has been performed to study the freezing phenomena of molten metal (wood's metal) which focus on fuel pin-bundle geometry under the various thermal conditions of molten metal and pins. The liquid penetration length into the flow channel and the proportion of adhered frozen metal onto the pin surfaces were measured in the present series of experiments. Visual information was also obtained by using a digital video camera. The comparison between the atmosphere and the water-coolant experiments shows that characteristics of penetration and freezing behavior will significantly change due to heat transfer from melt to coolant. The present results will be utilized to create a relevant database for the verification of reactor safely analysis codes.