Sensitivity Analysis of Ex-Vessel Corium Coolability Models in MAAP5 Code for the Prediction of Molten Corium–Concrete Interaction after a Severe Accident Scenario

A postulated progressing severe accident scenario has been simulated using MAAP5 code with the focus on ex-vessel cooling of molten corium in reactor cavity. Various parameters associated prediction corium–concrete interaction (MCCI) are identified. Accordingly, a sensitivity analysis is performed to assess impact these predicted cavity floor erosion depth during this MCCI accident. The index each variable parameter determined Cotter indices method and Sobol′ method. At early stage accident, found be highly sensitive downward heat transfer coefficient 94% 50%, respectively. late phase however, becomes melt eruption (Cotter 40%), water ingression 13%), particulate bed 15%) alongside 16%) becoming dominant. Thus, code′s predictions can minimized by improving physical models parameters. Moreover, used model developers identify unimportant bid reduce dimension problem aim current predictive capabilities conduct MCCI-related safety analyses.