Sample of EDF-R&D 2009-2012 core design studies on: Heterogeneous sodium-cooled fast reactors with low sodium void effect

• The use of axial or radial heterogeneities allows to reach negative global sodium void worth: → 600 MWe radially heterogeneous cores can be designed (no annual shape, reasonable core size). But the constraint on the fissile radius might be the reason why current performances are not a breakthrough... → Other interesting configuration exists (standard 2 diabolos, etc.). • Complexity versus intrinsic safety: where should the line be drawn? → On 1200 MWe cores, it was shown that very good features can be reached. But very complex designs are needed. • Core design studies are still going on... → The precision of global optimization method will be improved and new safety indicators added. → Optimization studies will be led on the CEA CFV design. → (Little) time should be spent on alternative design options