Validation of a computational model for the evaluation of fuel-coolant interaction under severe accidental condition in fast breeder reactors

A computational model for fuel-coolant interaction has been validated through calculations for a series of THINA experiments. By the experiments, it was intended to simulate a comparatively massive injection of molten core materials into sodium pool under a core disruptive accidental condition assumed for fast breeder reactors. The calculations by the SIMMER-II code showed that the current models for the fuel-coolant interaction (FeI) had the capability to well reproduce the experimental results. This means that the SIMMER-II FeI model based on the liquid particles size and the heat transfer among liquid components is valid with proper accuracy for the estimation of a Fer even without more detailed mechanistic model for Fer. In particular, the thermal-to-mechanical energy conversion rates were well predicted.