Abstract
The dynamics of molten core-material freezing into colder flow channels during core disruptive accidents (CDAs) is important for the safety design of liquid-metal cooled reactors (LMRs). In this study, some typical experiments relating to freezing characteristics of solid-liquid mixtures have been analyzed by the fast reactor safety analysis code, SIMMER-III, to demonstrate its applicability to such complex and highly transient multiphase flow situations. In the experiments a low-melting-point metal alloy (viz., Wood's metal) and its mixtures with solid metal particles were used as a simulant melt, while a stainless-steel seven-pin bundle was used as a flow channel. The melt penetration length and the proportion of frozen mass distribution into the flow channel were measured. SIMMER-III simulations show good agreement with the measured penetration length. For the relocation of molten metal, SIMMER-III also represents only one freezing mode of all melt adhesion with pin surface for pure molten metal, whereas in molten-metal/solid particle mixtures two freezing modes of melt separation with rich solid particles is reproduced as well as melt adhesions with pin surface. Their transient behaviors are also in good agreement with the experimental results.
