Conceptual design and structural analysis of the CFETR cryostat

•The CFETR cryostat is a large vacuum container surrounding the tokamak basic machine.•Two conceptual design schemes of CFETR cryostat were proposed.•A series of structural analyses were performed for cryostat cylinder.•The design of base section is feasible for cryostat.

CFETR (China Fusion Engineering Test Reactor) is a new tokamak device, one important component of which is cryostat and it is now under designing by China national integration design group. The CFETR cryostat is a large single-wall vacuum-tight container surrounding the tokamak basic machine, which consists of top dome-shape lid, two cylindrical sections with circumferential stiffening ribs and bottom flat head. It shall provide a vacuum environment (10−4 Pa) for the operation of the superconducting coils and all the loads that derive from cryostat itself and inner components should be transferred to the floor of tokamak pit. In this paper, two schemes of cryostat were proposed and then the structural analyses including seismic response analysis, elastic stress analysis and buckling analysis were performed to validate the conceptual design of CFETR cryostat. Based on the analysis results, it can be inferred that the cryostat II has a higher stiffness and stability. The structure of cryostat I needs to be improved against buckling and it is more difficult to manufacture for cryostat II due to its complex curved surface compared with cryostat I. Finally, the structural analysis for base section was performed and the design of main support was proved to be feasible. The design of CFETR cryostat has not been finalized and structural optimization still need to be proceeded based on the analysis results.