Application of ATHLET-CD code for simulation of SBLOCA 50 cm² severe accident scenario for a generic German PWR

The improvement of the safety of nuclear power plants is a continuously on-going process. The analysis of transients and accidents by application of severe accident codes is an important research topic, which significantly contributes to safety enhancements of existing power plants. Despite continuous improvement of the severe accidents codes, the model parameters for late accident phenomena are still subject to significant uncertainties. This parameter study investigates the influence of one of those uncertain parameters in ATHLET-CD, the onset of core melt relocation to the RPV lower head, to the late in-vessel phase of accident progression. The study was performed exemplarily for a small-break loss-of-coolant severe accident with additional late coolant injection to primary circuit.