Computational modeling and verification for hexcan wall failure under simulated core disruptive accident condition

This paper describes the improvements and verification of computational modeling for hexcan wall failures assumed to occur under core disruptive accident conditions of fast reactors. A series of out-of-pile experiments named SIMBATH has been analyzed by using the SIMMER-II code. The SIMBATH experiments used a thermite mixture to simulate fuel. The test geometry of SIMBATH ranged from single pin to 37-pin bundles. In this study, phenomena of hexcan wall failure found in a SIMBATH test were analyzed by SIMMER-II with model improvements. Although the original model of SIMMER-II did not calculate any hexcan wall failure, several model improvements made it possible to reproduce the hexcan wall melt-through with respect to the formation of an escape path for material movement as observed in the experiment. In this paper the model improvements and their significance are discussed for further model development of structure failure under the attack of molten fuel materials.