Development of an evaluation methodology for the fuel-relocation into the coolant plenum in the core disruptive accident of sodium-cooled fast reactors

Kamiyama, Kenji  ; Tobita, Yoshiharu; Suzuki, Toru; Matsuba, Kenichi  

The objective of the present study is to develop the methodology for evaluation of molten-fuel relocation into the coolant plenum with FCIs. The evaluation methodology was developed through validations of the SIMMER code using experimental data. A series of fundamental experiments were selected for model validations in which an alloy with low melting temperature and water were used as simulant materials for the fuel and the coolant respectively. The validation required model improvements for suppression of melt-coolant interfacial area based on the results of visual observation in the experiments in order to reproduce the experimental results appropriately. Through the present model validations, the methodology to evaluate molten-fuel relocation into the coolant plenum with FCIs was successfully developed.