Sensitivity of PWR ECC quenching calculations on wall heat transfer correlations

A transient numerical model of ECC quenching of a PWR fuel rod was used to study the influence of various wall heat transfer correlations on quenching predictions. A two-dimensional model for heat conduction within the fuel rod was coupled with a semi-empirical one-dimensional model of heat and mass transfer in the fluid region. Predicted cladding temperatures during quenching were analyzed. It was found that the effect of wall heat transfer in transition and film boiling regime, as well as in dispersed droplets regime were very significant, while the model was relatively little sensitive to subcooled boiling heat transfer.