Study of the Primary Heat Transfer System of an hybrid EU DEMO with different Breeding Blanket concepts

The European DEMO is considered to be the nearest-term fusion reactor with the aim to generate several hundred MWs of net electricity, operate with a closed tritium fuel-cycle (achieving the tritium self-sufficiency) and qualify technological solutions for a Fusion Power Plant. Two Breeding Blanket (BB) concepts - relying on different cooling and breeding technologies - are considered for the baseline design: the Helium Cooled Pebble Bed BB and the Water Cooled Lithium Lead BB. The selection of the BB type has a strong impact on the whole DEMO plant design and, in particular, on the Balance of Plant which is mainly composed by three systems: - a Primary Heat Transfer System (PHTS) to remove the plasma generated thermal power; - a Power Conversion System (PCS) to convert the thermal power in mechanical and finally in electrical energy; - eventually a Energy Storage System (ESS) - in between PHTS and PCS - which is introduced with the purpose of buffering some energy produced by the pulsed plasma source to allow a continuous production of electricity. This paper presents a possible layout and concept design of a PHTS that, being interfaced both with Water Cooled Lithium Lead BB (WCLL BB) and Helium Cooled Pebble Bed BB (HCPB BB), has to manage helium and water at the same time. The proposed tokamak consists of 17 toroidal sectors equipped with the WCLL BB for a total power of 1816 MW and 1 sector equipped with the HCPB BB for a total power of 117 MW. The results consist in the sizing of the main components and a comprehensive set of thermo-hydraulic parameters (i.e. flow rates, temperatures, pressure drops, coolant inventory) relevant for the assessment of the design integration.