Alternatives for upgrading the EU DCLL breeding blanket from MMS to SMS

•Different alternatives to upgrade the EU DCLL MMS design to a SMS architecture have been evaluated.•An electrically resistive PbLi-compatible ceramic is proposed for the BZ, enclosed by a steel case including the FW.•CO2 is a fairly good alternative to He, although possible radiological issues must be clarified.•The preliminary analyses of two proposed supporting systems point out towards the mechanical feasibility of the design.•The double wall compromises the tritium self-sufficiency. Some variants of the baseline are promising to enhance the TBR. In the last years, CIEMAT worked in the development of a low temperature DCLL breeding blanket design aimed at using conventional materials and technologies. It followed the multi-module segment (MMS) approach, which allows operating within the thermal range tolerated by EUROFER while keeping a low bulk velocity of the self-cooled liquid breeder (PbLi) in the breeding zone. Thinking in the commercial exploitation of fusion, it must be taken into account that there is risk that the foreseen availability goal in fusion reactors is not achieved. In that case, the limited net efficiency of low temperature blankets could not be sufficient to obtain a competitive cost of the electricity. For that reason, more advanced blanket solutions are being explored with the objective of developing a simpler, more reliable and more efficient design based on a single-module segment (SMS) architecture and the use of self-cooled incompressible liquid breeder. In this work, different strategies to solve interrelated aspects like the topology and electrical insulation of the breeder circuits, the first wall integration and the main neutronic responses are analysed and discussed.