부산대학교 도서관

The International Thermonuclear Experimental Reactor (ITER) is a full superconducting coil tokamak. The tail is a critical element of the bottom or top double pancakes of the Poloidal Field (PF) coil. The main functions of the tail are to withstand the electromagnetic force of the conductor. The electrical isolation is provided by the strap. The connections of the tail to the last but one turn and conductor terminal are both carried out through the welds. Moreover, this welding is further complicated as it is performed in overhead position due to the narrow operational space, one welding procedure should be developed and qualified to satisfy the ITER requirements. This paper focuses on the assessment and qualification of the weld for PF6 coil tail. One new special J-style groove with the thickness of 10 mm was designed and two full-size samples were prepared by simulating the actual working condition. Meanwhile, one welding procedure was developed and applied to control the weld deformation and welding temperature, etc. Finally, the sample 1 was destructively inspected in two sections after a five cycle thermal test, and no obvious defects appeared. In addition, a fatigue test of sample 2 was carried out with a load range of (60–600) kN at 4 Hz and 77 K. Finally, sample 2 successfully passed 30 000 cycles, validating that the fatigue properties of the PF6 coil tail weld satisfy the ITER requirement for the PF6 coil production.