Experimental and numerical investigations of heat transfer in the first wall of Helium-Cooled-Pebble-Bed Test Blanket Module – Part 1: Presentation of test section and 3D CFD model

• Design of the test section for investigation of heat transfer in the first wall is presented.
• Manufacturing details and providing of operational ready mock-up are given.
• Corresponding 3D CFD model of the test section is described.

This paper deals with cooling of the first wall of Helium-Cooled-Pebble-Bed Test Blanket Module (HCPB TBM) for ITER. The first wall cooling is an important investigation issue due to an extreme asymmetry of heat loads: heat flux on the plasma facing side is several times stronger than the one on the side which faces breeding units. Our preliminary 3D CFD analysis revealed that under such conditions the heat transfer coefficient is significantly lower than predicted by common heat transfer correlations (see Ilić et al., 2006). For an experimental validation of these results HETRA (HEat TRAnsfer) test section has been designed and built at the Institute for Neutron Physics and Reactor Technology in Karlsruhe Institute of Technology. The HETRA test section involves in full scale one U-pass of the cooling channel in the first wall of HCPB TBM Version 1.1 (see Meyder et al., 2005). The HCPB TBM relevant experimental conditions have been provided: test channel made of Eurofer steel, helium coolant at pressure of 8 MPa and inlet temperature of 300 °C and heat flux of 270 kW/m2 at the channel surface representing plasma facing side of the first wall. Test channels with hydraulically smooth and with hydraulically rough walls have been built. At each test channel the temperature of Eurofer walls has been measured at ∼60 positions. For numerical investigations the 3D CFD modelling with the code STAR CD has been applied. This paper is the first report on this study and presents the development of the test section and of the 3D CFD model. The analyses of the obtained experimental and computational results are presented in the second report (see Ilić et al., 2014).