4C Code Analysis of High-Margin Quench Propagation in a DEMO TF Coil

In the frame of the European DEMO reactor activities, Work Package MAG, superconducting Toroidal Field (TF) coils composed by a graded (Nb3Sn + NbTi) winding pack (WP) without radial plates, encapsulated in a steel casing, are under analysis. The ENEA WP design consists of double-layer wound rectangular cable-in-conduit conductors (CICC), for which operational as well as accidental transients must be carefully investigated. The paper presents the application of the state-of-the-art thermal-hydraulic code 4C to the analysis of the quench propagation inside the WP proposed in 2014 by ENEA. The quench is conservatively initiated at the location of the maximum temperature margin and the voltage, normal zone, hot spot temperature and maximum pressure evolutions in the WP are computed, highlighting the role of thermal coupling inside the WP