Within the framework of the European DEMO blanket study programme, CEA and the JRC of ISPRA develop a water cooled lithium-lead blanket concept. Considering the low breeding coverage ratio of the DEMO-1 reactor configuration currently specified in the E-C programme, the use of beryllium was envisaged in order to reach the tritium self-sufficiency which corresponds to an equivalent tridimensional Tritium Breeding Ratio (TBR) above 1.05. This beryllium is either directly immersed in the liquid metal (Pb-17Li) or completely separated from it.