Speaker
Description
Previous studies performed for the JT-60SA TF Coils, have shown an important influence of the AC losses energy deposition, heat transfer from case to Winding Pack and cooling capacities, on the general current discharge behavior, in particular the helium pressure and temperature increase in the cooling loop.
Some parametric studies have been performed with the Fast Assessment of Operating Window (FAOW)- Superconductors Thermohydraulical and Resistive Electrical Analytical Model (STREAM), developed and used at CEA-IRFM. The results confirm, as a function of the different initial current values, the safe operation of TFC (within particular no opening of relief valves connected to cryodistribution loop).
Similar current discharge studies and analyses are presented on the EU-DEMO TFC WP4 (Winding Pack 4) design, quite similar to ITER TFC design, with radial plates. DEMO TFC WP4 comprised Nb3Sn Cable-In-Conduit Conductor (CICC) inserted into stainless steel plates, forming with pancakes and ground insulation the Winding Pack inserted into a thick stainless steel case. These FAOW-STREAM calculations and analyses show the importance of heat transfer from case to WP, as well as the convective heat exchange power (and coefficient) in case cooling channel and CICC. Also the relevance of the characteristics of cryodistribution loop and heat removal capacities in heat exchanger has been emphasized. The helium temperature and pressure increases are evaluated as well as the temperature margin, and the analyses of a potential induced quench during the current discharge (severe quench at high current, or smoothed quench at low current). Nevertheless, the calculated results show that a quench is induced, nearly 7 s after beginning of each nominal value current discharge as the helium and conductor temperature reach the current sharing temperature. These analyses demonstrate the impacts of the radial plates in the operation domain, with safety considerations.
Preliminary results and qualitative analyses are extrapolated to ITER-TF Coil current discharge with FAOW-STREAM model. Due to this model rapid execution time duration (only few minutes), compared to other numerical codes (few hours, or few tens of hours), these kind of studies can be also useful for further detailed performances analyses with possibility of real-time feed-forward calculations/control
| Submitters Country | France |
|---|
