Consolidated design of the HCPB Breeding Blanket for the pre-Conceptual Design Phase of the EU DEMO and harmonization with the ITER HCPB TBM program

Abstract From 2014 to 2020, the Pre-Conceptual Design phase (PCD) of the EU DEMO has taken place. The activities in the PCD phase differ from past exercises in their strong Systems Engineering methodology, as well as for the pragmatic approach in their technology choices. The Helium Cooled Pebble Bed (HCPB) is one of the 2 candidates as driver blanket for the EU DEMO in the PCD phase. Several design iterations have been required during the PCD phase in order to adjust the design to the current demanding DEMO requirements, to the very challenging systems integration and to the need to keep near-term technologies. To this respect, the design has evolved to a so-called fuel-breeder pin architecture built in single-module segments. The pins are filled with a pebble bed of a ceramic breeder mixture of Li4SiO4 + 35 mol % Li2TiO3 (60% 6Li) and are embedded in prismatic blocks of Be12Ti acting as neutron multiplier. He gas at 8 MPa is used as coolant with a temperature window of 300–520 °C. This architecture has proven to achieve a large tritium breeding performance (≈1.20), a remarkably low plant circulating power (