Analysis of Core Catcher Flooding Time Effect on the Temperature of Corium and Severe Accident Management

One of the most important aspects of severe accident management arises by molten corium release to containment and how to maintain the integrity of containment. In this case as a safety function, molten corium is cooled in the core catcher. Flooding is a function which used to achieve this purpose. In this paper the effect of flooding before and after vessel breach is studied. In this analysis one severe accident scenario for IR360 NPP is modeled by MELCOR which is High Pressure Melt Ejection (HPME). MELCOR is a fully integrated, engineering-level computer code whose primary purpose is to model the progression of accidents in light water reactor nuclear power plants. The forcible parameters in determining time window of flooding are containment basement corrosion, hydrogen production, corium temperature and containment pressure. From the analyses, it is concluded that in the case of flooding before vessel breach, the molten corium temperature corrosion and containment pressure addition are not so different from the case of flooding after vessel breach. But the vessel breaches later and the amount of debris which ejected through vessel breach is less. Containment basement erosion is less also. There is no hydrogen burn in the case of flooding before vessel breach.