Application of RELAP/SCDAPSIM to the analysis of station blackout transient with LBLOCA for VVER-1000

This paper shows the results from a transient station blackout with LBLOCA (ID=300 mm) Using different flow models during the in-vessel phase of a severe accident. The default flow model in RELAP5/MOD3.3 is Henry-Fauske, while the flow model in RELAP/SCDAPSIM is the Ransom-Trapp choking model. The aim of this research is to compare the results and validate the RELAP/SCDAPSIM code. RELAP/SCDAPSIM is designed to describe the overall reactor coolant system (RCS) thermal hydraulic response and core behaviour under normal operating conditions or under design basis or severe accident conditions. The SCDAP portion of the code includes models to treat the later stages of a severe accident including debris and molten pool formation, debris/vessel interactions and the structural failure (creep rupture) of vessel structures. The reference power plant for this analysis is a VVER-1000/V320 Kozloduy NPP unit 6. The baseline input deck used in this study for this reactor was developed by the Institute for Nuclear Research and Nuclear Energy. (authors)