Nb₃Sn Strand Verification for ITER TF Conductors of CNDA

China is charged with around 7.5% of the ITER toroidal field (TF) conductor fabrication. In total about 6000 km of Nb₃Sn strands need to be supplied for Chinese Domestic Agency (CNDA), and now the TF procurement arrangement (PA) for CNDA is in the last phase, i.e., production. According to the PA, the Domestic Agency (DA) has to verify on a regular basis the room and low temperature measurements carried out by the strand suppliers. The verifications shall be performed by the reference laboratories on the strand verification samples adjacent to the samples used by the strand suppliers for critical current measurements. As the reference laboratory of CNDA, the superconducting strand test laboratory of Institute of Plasma Physics Chinese Academy of Sciences (ASIPP) is undertaking the task of Nb₃Sn strand verification. The verifications include diameter, chromium plating thickness, twist pitch direction and length, copper-to-non-copper volume ratio, residual resistance ratio (RRR), critical current (I_C) and resistive transition index (n), and hysteresis loss. The verification level was based on the requirements of the ITER PA. From the results, the supplied strands for the TF conductors fulfill well the requirements of the ITER PA.