Evaluation Methods for Coolant Injector Performances and Severe Accident Phenomena

This report provides the numerical simulation methods of the coolant injector in the direct cooling type core catcher, and evaluation methods of the severe accident phenomena. Firstly, the numerical simulation method for two-phase flow behaviour inside coolant injectors is established. Installation of the coolant injectors in the direct cooling type core catcher is one of the concepts to deliver cooling water mixed with inert gas such as nitrogen to prevent steam explosion while effectively cooling down the corium by direct heat transfer. Secondly, the evaluation tools of the severe accident phenomena such as in-vessel accident scenario, the DCH, steam explosion, MCCI, and containment pressurization are surveyed and discussed