CFD Simulations of Ballooned Regions of a Damaged Core During the Reflood Phase of a LOCA

Abstract

This study focuses on the cooling capacity of a damaged PWR reactor core during the reflooding phase of a Loss Of Coolant Accident (LOCA). Downstream the quench front, the core cooling is provided by an over-heated vapour flow carrying water droplets and may impact the ballooned fuel cladding and provide an additional cooling. The present paper will deal with the development of a CFD code to simulate such droplet dispersed flows with the final aim of carrying out sensitivity studies of blockage ratio and length on wall cooling. Adequate closure laws for the momentum and energy balances as well as for the heat transfer at droplet impact and interfacial area transport are given and some simulation results are presented.