Safety Research of the 68 kA Trial-HTS Current Lead for ITER

A 68 kA trial-high temperature superconducting current lead for the ITER magnet coil had been developed and tested in parallel with a 52 kA HTS trial lead at ASIPP in Dec. 2008. In order to verify the safety and reliability of HTS section of HTS trial lead, three sub size samples cooled with a GM cooler have been fabricated and tested. Based on the successful sub size HTS module´s test results, a novel binary shunt comprising bronze and stainless steel cylinders is applied to HTS trial lead to reduce the conductional heat load to the 5 K cryogenic system and increase the burnout time after quench. This paper gives the numerical calculation of loss of flow accident (LOFA) of HTS trial lead and HTS temperature margin analysis. The measured results of the LOFA and burnout time for the 68 kA trial-HTS current lead are briefly discussed in the paper. The test results indicate the LOFA time is more than 300 s and the burnout time of 21 s is reached more than the requirement of the toroidal field coil fast discharge time of 13 s.