R&D achievements for vacuum vessel towards CFETR construction

The next generation of magnetic confinement fusion experimental facility, the China Fusion Engineering Test Reactor (CFETR), is currently undergoing physical and engineering design. The essential technology research and development projects related to CFETR manufacture are in progress. As one of the demo projects for CFETR R&D, a 1/8 full-scaled vacuum vessel (VV), which aims to solve the key technologies of forming, welding, measurement, assembly, etc in the future manufacturing process of VV, was initiated in 2015 by Institute of Plasma Physics Chinese Academy of Science (ASIPP). The fabrication of two full-scaled 22.5° toroidal sectors, which are composed of two 11.25° sectors, was successfully completed in June 2019. In the manufacturing process of the VV mockup, the progress has been made in the following six aspects: engineering design and safety evaluation of the VV mockup, the high-precision forming of the hyperbolic shell, the welding deformation control of 50 mm thick full penetration structure, the nondestructive testing of the complex welds by full volume covering, the establishment of high-precision 3D measurement fiducial network and the high-precision assembly of the VV parts. This article describes the progress and achievements of the above six aspects for the CFETR VV. (paper)