Fabrication feasibility studies for first wall of Indian LLCB TBM

Abstract

The conceptual design of the Indian Lead Lithium Ceramic Breeder (LLCB) Test Blanket Module (TBM) First Wall (FW) presents a single U-shaped component made of IN-RAFM steel having 65 square channels of 20 mm × 20 mm running along the toroidal and radial direction. There are 13 circuits; each circuit consisting of 5 channels with inlet on the 1st channel of one side and the outlet on the 5th channel of other side. The conventional machining route with innovations in the existing technique was explored to develop the method to make channel mock-ups for FW application. This developed technique includes initial pre-machining and milling of higher thickness plates, making square channels by gun drilling followed by wire-cut EDM and final milling on the external surface and then hot bending into U-shape. Modified 9Cr-1Mo steel was the structural material used for this mock-up which has two flow circuits (each circuit of 5 channels). The other dimensions of this mock-up were chosen in such a way that functional requirements of full-sized FW would be fulfilled. During manufacturing, this mock-up was subjected to a series of inspection and non-destructive tests such as helium leak test and hydro-test at 150 bar pressure as a part of in-stage and final inspections. This paper describes the main activities carried out for the fabrication and factory acceptance tests of this U-shaped 10-channels TBM FW mock-up.