Fabrication and characterization of SiC sandwich material for Flow Channel Inserts in HT-DCLL blanket by gel casting

Abstract

Flow Channel Inserts (FCIs) are key elements in the high temperature DCLL blanket concept since they provide the required thermal insulation between the He-cooled structural steel and the hot PbLi flowing at a maximum temperature of 700 °C, and the necessary electrical insulation to minimize magnetohydrodynamic (MHD) effects. In this paper, the use of SiC-sandwich material for FCIs consisting of a porous SiC core (thermal and electrical insulator) covered by a dense Chemical Vapor Deposition (CVD) SiC layer (protection against PbLi infiltration) has been studied. Lab-scale FCI prototypes were produced by the gel casting method and characterized in terms of thermal and electrical conductivities (the latter before and after exposure to ionizing radiation) and flexural strength. Corrosion tests under flowing PbLi at 500–700 °C in presence of a magnetic field up to 5 T were performed obtaining promising results regarding the reduction of MHD pressure drop and the compatibility of SiC and PbLi under dynamic conditions. Additionally, thermomechanical finite elements simulations were performed in a 3D channel geometry to identify black spots regarding thermal stresses.

Keywords

• Flow channel insert (FCI)
• Porous SiC
• Corrosion by PbLi
• Dual-coolant lead–lithium (DCLL) blanket
• Gel casting