European Lead-cooled SYstem core design: an approach towards sustainability

The paper deals with the neutronic design of ELSY (the European Lead-cooled SYstem), a 600 MWe Fast Reactor developed within the 6th EURATOM Framework Programme. The overall core layout, an open square-lattice configuration mostly defined by complying with mechanical and seismic constraints, is optimized to achieve a flatten power/Fuel Assembly distribution. The power-to-flow ratio is locally adjusted by changing the fissile (Plutonium) enrichment at different radial positions in the core. Three independent scram sets have been introduced in order to achieve the required reliability for reactor shutdown and safety system. Eight traditional concept Control Rod assemblies together with two systems of sparse control “Finger Absorber” Rods, small B4C rods that can be inserted, in principle, in the centre of each FA. A trade-off between a fuel Burn UP as high as 100 GWd/t and an acceptable Breeding Ratio is achieved. It is shown the possibility to realize an “adiabatic” reactor, i.e. a reactor self-sustainable in Plutonium and burning its own generated Minor Actinides. This is in compliance with the sustainable goals of the Generation IV systems: ELSY would base its operation upon the net “conversion” of either Natural or Depleted Uranium into Fission Products only.