Design and Qualification of ITER CS and TF Cooling Inlets

Abstract

In the ITER superconducting magnets, the CIC conductors cooling is insured by supercritical helium forced flow in the central and annular parallel channels. In the Central Solenoid, with a thick square jacket conductor, the helium inlet is in the highest field region at the inner bore pancake joggle, and it has to support the high hoop force stress level with a very low stress concentration factor. In the TF magnets, a thin jacket circular conductor is wound in double pancakes, inserted into radial plates, stacked and embedded into a steel case. The helium inlets are located at the inner bore, in the limited space between the radial plates and the coil casing. The PF coils helium inlets, not studied here, are similar to the CS ones, but with a lower stress level. A complete qualification work on the CS and TF helium inlets is presented. A design optimization was performed, by FEM analysis, resulting in acceptable stress level for both helium inlets. The welding procedure was qualified and specific fatigue life mock-ups were designed, analyzed and manufactured using representative jacket materials. Fatigue life qualification at 4 K was performed in the FZK test facility applying the relevant loading and number of cycles. Hydraulic mock-ups were manufactured and qualified in the CEA test facility using GN2 at relevant Reynolds number. Pressure drop as well as flow repartition inside the conductors' petals were measured. The mechanical and hydraulic results are presented