Study on Assembly of TF Coil and Vacuum Vessel for Fusion DEMO

Abstract

ITER is in the integration phase and a fusion DEMO is being designed conceptually. The size of the DEMO will be around 1.5 time larger than the ITER and the weight will be about three times larger than the ITER. The TF coil and the vacuum vessel of the DEMO will become very heavy and extremely large. Although the central support structure will be used in the ITER for the assembly of TF coils and vacuum vessels, the central cylinder concept is proposed in this study to avoid the huge concentrated load at the center of the device floor during assembly. In addition, the welding joint between the vacuum vessels is discussed under the limited conditions supposed on the DEMO. Since the vacuum vessel will become the nuclear boundary, all weld lines will be expected to be examined by ultrasonic testing and/or radiographic testing to ensure the soundness of the welds.

Conceptual Design of Plasma Vacuum Vessel for Fusion DEMO Considering Integration of Core Components

“…Figures 4 and 5 illustrate the top view and the cross-sectional image of the assembly process. These figures are modifications of those in [4]. As mentioned above, it was supposed that one TF coil and one VV sector weigh about 1,200 and 1,700 tons, respectively.…”

“…The major radii of JA and EU DEMOs are about 1.37 and 1.45 times larger than that of the ITER, and the fusion output increases 3 or 4 times. Therefore, when the fusion DEMO size is supposed to be 1.5 times larger than the ITER and the global density is the same as the ITER, the total weight of the fusion DEMO will become around 77,500 tons by considering the 23,000 tons of the ITER [4]. In case that the fusion DEMO has 16 TF coils and 8 VV sectors, the weight of one TF coil and one VV sector will become around 1,200 tons and 1,700 tons, respectively.…”

“…The image of the weld joints between VV sectors is shown in Fig. 2 which is a modification of the figure in [4]. Since the VV is a nuclear boundary, a volumetric non-destructive test (NDT) must be carried out for all weld joints.…”