Tests and analysis of quench propagation in the ITER toroidal field conductor insert

Supercond. Sci. Technol.

Bonifetto

Brighenti

et al. 2018

The ITER Toroidal Field Insert (TFI) coil is a single-layer Nb 3 Sn solenoid tested in 2016-2017 at the National Institutes for Quantum and Radiological Science and Technology (former JAEA) in Naka, Japan. The TFI, the last in a series of ITER insert coils, was tested in operating conditions relevant for the actual ITER TF coils, inserting it in the borehole of the Central Solenoid Model Coil, which provided the background magnetic field. In this paper, we consider the five quench propagation tests that were performed using one or two inductive heaters (IHs) as drivers; out of these, three used just one IH but increasing delay times, up to 7.5 s, between the quench detection and the TFI current dump. The results of the 4C code prediction of the quench propagation up to the current dump are presented first, based on simulations performed before the tests. We then describe the experimental results, showing good reproducibility. Finally, we compare the 4C code predictions with the measurements, confirming the 4C code capability to accurately predict the quench propagation, the evolution of total and local voltages, as well as of the hot spot temperature. To the best of our knowledge, such a predictive validation exercise is performed here for the first time for the quench of a Nb 3 Sn coil. Discrepancies between prediction and measurement are found in the evolution of the jacket temperatures, in the He pressurization and quench acceleration in the late phase of the transient before the dump, as well as in the early evolution of the inlet and outlet He mass flow rate. Based on the lessons learned in the predictive exercise, the model is then modified to try and improve a posteriori (i.e. in interpretive, as opposed to predictive mode) the agreement between simulation and experiment.

Section: Comparison Between 4c Code Predictions and Measurementsmentioning

confidence: 59%

“…Assuming that the cable temperature is uniform between the voltage taps VT 11 and VT 12 embracing IH02, i.e. T 1112 , the temperature of the cable in the normal zone can be extracted from the measured VD 1112 = VT 12 -VT 11 , following a well-known procedure [12], [15]. Solving for T 1112 = T hot spot the implicit equation ( 7):…”

Section: B) Simulation Resultsmentioning

confidence: 99%

Prediction, experimental results and analysis of the ITER TF insert coil quench propagation tests, using the 4C code

Supercond. Sci. Technol.

Bonifetto

Brighenti

et al. 2018

“…Mithrandir was originally developed to overcome the shortcomings of previous models where the same thermodynamic state was assumed for the helium in the central channel and in the cable bundle region of the dual-channel CICC typical of all ITER conductors. Mithrandir was validated against stability, quench and heat slug propagation data from the QUELL experiment and, more recently, against stability, quench and AC loss data of the ITER CSI coil [26][27][28] and against quench data of the ITER TFI coil [29].…”

Section: Mandm Modelmentioning

confidence: 99%

Analysis and interpretation of the full set (2000–2002) of TCS tests in conductor 1A of the ITER Central Solenoid Model Coil

Mitchell²,

Savoldi

2003

Cryogenics

The full set of T CS measurements performed during 2000-2002 on conductor 1A of the ITER Central Solenoid Model Coil (CSMC) of the International Thermonuclear Experimental Reactor (ITER) is analysed with the extensively validated M&M code. Under the assumptions of uniform strand properties and uniform current distribution among strands, the performance of this ''average'' strand in the cable is deduced from the best fit of the measured voltage-inlet temperature characteristics. Two fitting parameters are chosen: an ad-hoc additional contribution Ôe extra Õ to the longitudinal strain of the average strand in the cable, and the average-strand (or cable ''effective'') index ÔnÕ of the electric field-current density characteristic. It is shown that the average strand in the CSMC performed less well than expected from the strand database--an increasingly negative e extra being needed to reproduce the coil behaviour at increasing transport currents, and that the cable effective n is clearly below the measured n of the strand. It is argued that this average-strand performance reduction in the CSMC is most likely related to mechanical load effects.

“…However, it should be pointed out that, although quench propagation analysis with the Mithrandir code was repeatedly validated in the past against CICC data, see e.g. [28], [29] this is the first quench simulation of a NbTi CICC.…”

Section: Modelingmentioning

confidence: 96%

Preparation of the ITER Poloidal Field Conductor Insert (PFCI) Test

IEEE Trans. Appl. Supercond.

Егоров²,

Kim³

et al. 2005

Self Cite

The Poloidal Field Conductor Insert (PFCI) of the International Thermonuclear Experimental Reactor (ITER) has been designed in the EU and is being manufactured at Tesla Engineering, UK, in the frame of a Task Agreement with the ITER International Team. Completion of the PFCI is expected at the beginning of 2005. Then, the coil shall be shipped to JAERI Naka, Japan, and inserted into the bore of the ITER Central Solenoid Model Coil, where it should be tested in 2005 to 2006. The PFCI consists of a NbTi dual-channel conductor, almost identical to the ITER PF1 and PF6 design, 45 m long, with a 50 mm thick square stainless steel jacket, wound in a single-layer solenoid. It should carry up to 50 kA in a field of 6 T, and it will be cooled by supercritical He at 4.5 K and 0.6MPa. An intermediate joint, representative of the ITER PF joints and located at relatively high field, will be an important new item in the test configuration with respect to the previous ITER Insert Coils. The PFCI will be fully instrumented with inductive and resistive heaters, as well as with voltage taps, Hall probes, pick-up coils, temperature sensors, pressure gauges, strain and displacement sensors. The test program will be aimed at DC and pulsed performance assessment of conductor and intermediate joint, AC loss measurement, stability and quench propagation, thermal-hydraulic characterization. Here we give an overview of the preparatory work toward the test, including a review of the coil manufacturing and of the available instrumentation, a discussion of the most likely test program items, and a presentation of the supporting modeling and characterization work performed so far.