29th Symposium on Fusion Technology (SOFT 2016)

P2.089 Performance of JT-60SA toroidal field coils in light of strand and conductor test results

6 Sep 2016, 14:20

1h 40m

Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Board: 89

Poster E. Magnets and Power Supplies P2 Poster session

Speaker

Daniel Ciazynski (IRFM/STEP)

Description

The Toroidal Field system of the JT-60SA tokamak is composed of 18 NbTi superconducting coils. Half of them are provided by France within the Broader Approach Agreement. These coils are manufactured by General Electric (ex-Alstom) at Belfort, France. Each TF coil is composed of 6 cable-in-conduit conductor lengths, wound in double-pancakes, carrying a nominal current of 25.7 kA at a temperature of 4.5 K. These coils are being tested in the single coil configuration at the so-called Cold Test Facility (CEA/IRFU Saclay, France). The test program includes a progressive operating temperature increase at nominal current up to quench for the first coil of each series and a DC operation at nominal current for 1 hour slightly below the expected quench temperature for all coils. In addition, a fast safety discharge is triggered at nominal current and 4.5 K for all coils. The test of the first coil (C10) has shown that the coil casing was hard to cool-down and remained at about 20 K during the test, which puts in competition for quench location either the central pancakes (peak field) or the side-pancakes (warmer). The test procedure was modified so as to trigger the quench at peak field, but the quench location at 7.46 K helium inlet temperature was identified on a side double-pancake in C10. The paper presents the CEA analyses for the French coils tested in the first half of 2016 in light of the NbTi strand superconducting properties coming from the strand characterization program, of the unit lengths hydraulic tests carried out by F4E, and of the full-size conductor tests carried out by CEA in the SULTAN facility. These analyses involve cable thermal and electrical modelling developed at CEA and already used in ITER R&D, design and characterization programs.