NG-TIG welding technology research on 1/8 Sector of CFETR vacuum vessel

Abstract With the development of the China Fusion Engineering Test Reactor (CFETR) engineering design, a 1/8 vacuum vessel (VV) sector prototype is conducted as one of the major R&D projects of CFETR. The welding structure between VV sectors in field assembly is modeled in this prototype, and narrow-gap tungsten inert gas (NG-TIG) welding, which has small welding deformation, high-quality welds, and excellent adaptability to this structure, is taken as an applicable welding strategy. All-position welding system solutions are provided in this paper, and the welding experiments, including flat, vertical, and over-head welding, are performed. Relevant test results, including nondestructive testing, mechanics performance testing, macro and micro weld detection, permeability testing, and the optimal process parameters, are obtained. Finite element analysis (FEA) by SYSWELD is executed, and the results are compared with the actual measurements. The NG-TIG welding system is used to perform the local VV double-wall structural welding experiment and the welding of four 1/32 sectors. These results show that the welding system and the process scheme are feasible.