Fluid dynamic and thermal analyses of a HCPB TBM Breeder Unit mock-up

In the frame of the WP08 EFDA Goal Oriented Training Program (GOTP) EUROBREED [1], the Working Package 1 is aimed at the design and procurement of a prototype of a Helium Cooled Pebble Bed Test Blanket Module Breeder Unit (HCPB TBM BU) and its testing in a dedicated experiment in a medium scale (<50 g/s) helium loop. This paper presents the design and analyses studies of the helium coolant fluid dynamics and of the thermal field in a HCPB TBM BU. After several design iterations, the helium coolant mass flow distribution has been improved between 3% and 7%. The analysis of the thermal field of the improved design has been performed. Considering steady state conditions with a heat flux deposed on the first wall equal to 500 kW/m2 and a neutron wall load of 0.78 MW/m2, the maximum temperature reached in the BU is 560.9 °C, about 2% above the maximum design temperature of the structural material (550 °C). As this maximum temperature is localized in a zone where there are not foreseen high stresses and the assumption for the analyses is conservative, the design presented for the Cooling Plates is considered as the reference for the production of the full scale BU mock-up.