Preliminary evaluation of ALFRED revised concept under station blackout

The Advanced Lead Fast Reactor European Demonstrator (ALFRED) was conceived in the framework of the LEADER (Lead-cooled European Advanced DEmonstration Reactor) project since 2010. Recently, a revised concept of the Reactor Coolant System (RCS) is ongoing to solve some identified issues such as thermal stratification and others. To verify the improvements of the ALFRED design the authors developed a detailed nodalization scheme of the reactor using RELAP5-3D© code. This paper provides a summary of the main improvements introduced in the revised concept of ALFRED reactor and a detailed discussion of the thermal-hydraulic analysis performed with RELAP5-3D©. The nodalization scheme is described in detail together with transient boundary conditions and timing of events. The numerical activity demonstrates the improvements of the revised configuration of the reactor that avoid the establishment of relevant thermal stratification phenomena in both normal and accidental operations. The effect of two relevant parameters is also investigated, highlighting that safety conditions are maintained in the whole spectrum of the sensitivity analysis.