Results of Mass Production of Internal Tin Nb3Sn Strand for ITER Toroidal Field Coil in Korea

Kiswire Advanced Technology (KAT) has successfully supplied 93 tons of Nb₃Sn strands produced by the internal tin process for the toroidal field coil to the ITER project, which has been procured by the Korean Domestic Agency for over five years since 2009. There are 19 restacked subelements in a strand. Each has 180 niobium filaments. There are also three different types of spacers that have different component ratios between copper and tin-titanium alloy. The spacers were symmetrically distributed among the modules. During the entire production, statistical process control (SPC) was strictly applied, and a high quality of total fabricated strands was obtained in a highly stable manner. This paper will discuss the design concept of the strand, productivity, and yield ratio in the fabrication procedure, including chromium plating and quality from the perspective of the SPC, and various results of strand performance. The test results of the cable-in-conduit conductor sample for the individual procurement execution phase at SULTAN facility will also be described.