ASTEC investigations of severe core damage behaviour of VVER-1000 in case of loss of coolant accident along with Station-Black-Out

Abstract Severe accident analysis of a reactor is an important aspect for evaluation of source term. Analyses have been carried out for VVER-1000 V320 reactor following LOCA along with Station-Black-Out using the severe accident code ASTEC. The predictions of different severe accident parameters like vessel rupture time, hydrogen and corium production and radioactivity release to containment have been compared for three break sizes. Since these predictions are dependent on different core degradation parameters and models, a sensitivity analysis is also carried out to study the effect of different core degradation parameters and models on severe core damage progression. LOCA analyses show a variation of degradation parameters which is a consequence of steam-rich and steam-starved conditions. All these calculations of VVER-1000 scenarios show that the ASTEC V2 code gives reliable and consistent results on this type of reactor, including its specifics like Zr1%Nb clad material and horizontal steam generators.