Severe Accident Modelling Inside a Calandria Tank in Caiser Code

Abstract

From the demands about accurate and realistic severe accident codes in the PHWR safety analysis, a new integrated severe accident code called CAISER has been developing at KAERI for a support of Korean regulatory body. The core degradation phenomena in a fuel channel, which is treated in CAISER, includes all kinds of heat transfer, steam-Zr oxidation, a fuel rod slumping (fuel rod movement below because of the weakness of spacer, bearing pad in high temperature condition), melting & relocation of main components and thermal interaction of relocated mass with pressure tube. And, the main phenomena in a calandria tank treated in CAISER include all kinds of heat transfer, sagging of a fuel channel, debris bed formation caused by a fuel channel failure, the molten pool formation and the calandria tank wall failure, which is modeled with the ablation of wall by molten corium, creep rupture failure mechanism.