A Preliminary Study on Criticality Evaluation of Corium Re-arranged in the 1400MWth PWR Core Catcher

The concept of the core catcher, which is a representative provision against the core melting accident, was developed in Europe. The core catcher has the function of corium retention in the core melting accident. The reaching to the criticality of corium re-arranged in the core catcher can cause the severe secondary accident. Therefore, the criticality in the core catcher should be properly evaluated. To calculate the criticality in the core catcher, some possible corium conditions were assumed in this study. The orienting parameters, which can affect a possible return to the criticality of corium, were determined. The corium criticalities in the core catcher were evaluated with the changes of porosity in corium, average enrichment of uranium and density of water using MCNP5 code