Freezing Model of Double Constitute Molten Mixture in Fast Reactor Severe Accident

Under serious accidental conditions in fast reactors,the fuel pins will be molten which finally lead to formation of molten pool and boiling pool.Later on,the molten material will break the wrapper of the subassembly.In order to understand the penetration mechanism of the molten material,two mechanism mod-els are established to simulate the penetration process: the conduction-freezing model and the bulk-freezing model.And they are validated on the UK SES out-of-pile experiments.In comparison with the single-material freezing model which is validated on GEYSER experiments,the influence of steel on freezing process is ana-lyzed,and finally some conclusions relative to the penetration are derived.