Thermal Hydraulic Analysis of JT-60SA TFC02 Complementary Quench Tests in CTF

Abstract

In the framework of JT-60SA tokamak commissioning (Japan, 2021), the 20 Toroidal Field Coils (TFC) were tested at the Cold Test Facility (CTF) at CEA-Saclay (France, 2018) and submitted to quench acceptance test (quench temperature up to 7.5 K at nominal current). Some complementary quench tests were performed on the spare coil TFC02, with different conditions, especially reduced current (at 75% and 50% of nominal current) and delayed quench detection (holding time of 0.5 s instead of 0.1 s). A numerical model was developed, with SuperMagnet (fortran, CryoSoft) coupling THEA (Thermohydraulic and electric 1-D physics of Cable In Conduit Conductor, CICC) and Flower (Thermohydraulic model of cryogenic network). The measurements are presented and compared to simulation results. The acceptance quench test of TFC02 depicted a maximal helium temperature of 27 K. During complementary quench tests, delayed quench detection induced higher helium temperature of 37 K. At 75% and 50% of nominal current, a so called “smooth” quench occurred. It is characterized by slow quench propagation and low resistive voltage which increase the quench propagation time required before triggering current discharge although it reduces the Joule energy dissipated by the coil.