Characterization of the cooling channels of First Wall Mock-up dedicated to the HCPB TBM qualification

Abstract The First Wall (FW) of the EU Helium Cooled Pebble Bed (HCPB) Test Blanket Module (TBM) faces the fusion plasma and experiences high heat fluxes; therefore its cooling channels design is a key R&D task for qualifying the HCPB TBM for the fusion reactors ITER and DEMO. Within the manufacturing and qualification activities performed in KIT for the HCPB TBM, a First Wall Mock-up (FWM) was designed and manufactured. The objective of this study is to characterize the hydrodynamic behaviour of the FWM cooling channels by investigating the coolant pressure drop for each channel. The FWM has a shape of rectangular prism (710 mm × 405 mm × 45 mm) with 10 U-shaped cooling channels which have a square cross section (15 mm × 15 mm) with rounded corners of 4 mm radius. The FWM was integrated into a gas loop that has the relevant instruments and piping system for measuring and controlling the air (6 bar abs.) flow parameters. This paper presents experimental measurements of the pressure drop across the FWM cooling channels. The present results support the qualification of the HCPB TBM mock-ups which will be tested in the Helium Loop Karlsruhe (HELOKA) facility with fusion-relevant heat flux and helium cooling.