IVR-ERVC effectiveness assessment for large-size advanced PWR severe accident

As a key severe accident management strategy for light water reactors (LWRs), in-vessel retention (IVR) through external reactor vessel cooling (ERVC) has been the focus of relevant studies for decades. This paper addressed the IVR-ERVC issues from a transient perspective using the severe accident code MELCOR for large-size advanced passive nuclear power plant, Current analysis was mainly focused on the transients in severe accident including core degradation and relocation, molten pool formation, growth and heat transfer within, together with external flow and heat transfer analysis. MELCOR calculations for lower head heat flux were then compared with critical heat flux (CHF) of lower head to assess the effectiveness of IVR-ERVC. The results suggest that lower head heat flux is well below the CHF value. Thus, the IVR-ERVC strategy is considered to be physically effective. (authors)