Experimental and Simulation Studies of Helium Channel Reconstruction for Test Blanket Module Fabrication By High-Power Laser Welding

India is a partner in ITER and plans to test its lead lithium ceramic blanket test blanket module. This component is embedded with a large number of cooling channels of different profiles and, therefore, is a challenging component to fabricate. Cooling channel reconstruction by employing high-power laser welding provides a promising scheme to fabricate this component. Cooling channel reconstruction was demonstrated in American Society for Testing and Materials A387 Gr91 steel using high-power CO₂ laser welding. A scheme for fabrication of scale models of different subcomponents, like the first wall (FW) and inner back plate, and assembly of the two subcomponents employing the cooling channel reconstruction scheme was demonstrated. The steady-state temperature field around the weld joint was computed using the welding and heat treatment simulation solution package SYSWELD. These weld joints were characterized for microstructure at different length scales, microhardness, and room-temperature tensile properties. This paper presents the scheme used for cooling channel reconstruction and the results of the weld joint characterization. The scheme for fabrication of the scale model of the FW, the inner back plate, and joining of the two subcomponents using the cooling channel reconstruction approach is also described in this paper.