Establishment and validation of the penetration model of molten material in sodium environment in fast reactor

Under severe accidental condition in one subassembly of the fast reactor, the pins will be molten and soon the boiling pool of fuel and steel will be formed. After the wrapper of the pool is melt-through, it is propagation of molten material into the gap and neighbor subassemblies that upgrades the accident. To make the penetration mechanism of molten materials clear, a method of establishing model according to the mechanism is selected. conduction freezing and bulk freezing model are established separately, and they are validated on the UK SES experiment and France PV-A experiment. On the basis of validation, some conclusion about the freezing mechanism and the sodium flow is derived. After comparing and analyzing the parameters about the penetration, some conclusions about the penetration are derived as well. (authors)