Reactor integration of the helium cooled pebble bed blanket for DEMO

Abstract

On the path towards the commercial use of nuclear fusion developing the technology of tritium breeding blanket is among the most challenging tasks. The EU has recognised the need for substantial progress by maintaining a long-term programme for the development of two reference designs. Recently, the EU power plant conceptual study (PPCS) triggered a design review of the helium cooled pebble bed (HCPB) blanket leading to the proposal of a novel modular design with a cellular structure of the breeding region, and substantial synergies between the two EU reference designs. The paper develops ideas of design concepts available for a DEMO reactor integration of the modular HCPB blanket. The plant layout is based on model B of the PPCS, at 3300 MW fusion power. The blanket concept proposed is radially segmented into consumable breeder region and permanent shield. Front side access for module attachment and in-bore cutting/joining of main in-vessel coolant pipes, support a quick replacement of the breeder blanket. The same is expected by a cassette system for the blanket of the upper vessel region.