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Journal Articles

Simulation of quench tests of the central solenoid insert coil in the ITER central solenoid model coil

Takahashi, Yoshikazu; Yoshida, Kiyoshi; Nabara, Yoshihiro; Edaya, Masahiro*; Mitchell, N.*

IEEE Transactions on Applied Superconductivity, 16(2), p.783 - 786, 2006/06

https://doi.org/10.1109/TASC.2006.873254

Times Cited Count：9 Percentile：46.59(Engineering, Electrical & Electronic)

To investigate the conductor behavior during a quench, quench tests of Center Solenoid (CS) insert coils were carried out with various initial conditions in DC and pulse modes. The conductor has very similar configuration and parameters. The inductive heater, attached at the center of the length, initiated an artificial quench in DC mode. A quench has also occurred during the pulse operation with the ramping rate of 0.4-2 T/s. Simulations of electric, thermal and hydraulic behaviors of the conductor during the quench tests in both modes were carried out by using the thermohydraulic simulation code. The experimental results were compared with the simulation and good agreement was obtained. These results are described and the implication for quench detection in ITER is discussed in this paper. The voltage tap method will be used for the quench detection for the CS, and the sensitivity of the detection and the maximum temperature of the conductor during a quench are described. It is shown that the detection system could be designed with high enough detection sensitivity.

Journal Articles

Quench detection using pick-up coils for the ITER Central Solenoid

Takahashi, Yoshikazu; Yoshida, Kiyoshi; Mitchell, N.*

IEEE Transactions on Applied Superconductivity, 15(2), p.1395 - 1398, 2005/06

https://doi.org/10.1109/TASC.2005.849103

Times Cited Count：8 Percentile：43.66(Engineering, Electrical & Electronic)

The quench detection is important and necessary for the coil protection. The voltage tape method and the flow meter method are both considered for the ITER Central Solenoid (CS). The voltage tap method is primary due to its quick response. The CS consists of six pancake wound modules, which are operated with individual operating current patterns in ac mode. The induced voltage in the windings must be compensated to detect the voltage due to any normal transition during pulse operation. We have investigated the optimum configuration for pick-up coils (PC) for compensation. The results of simulations show that the compensated voltages are very low (70 mV) compared with the inductive voltage and adequate normal voltage sensitivity is obtained. The hot spot temperature in the CS during the operation was estimated from the simulation and the experimental data of the CSMC quench. The hot spot temperature estimated is about 144 K, lower than the ITER design criterion (150 K). It is shown that the detection system using the PCs could be designed with a high enough detection sensitivity.

Journal Articles

Core thermal-hydraulic design

Takada, Eiji*; Nakagawa, Shigeaki; Fujimoto, Nozomu; Tochio, Daisuke

Nuclear Engineering and Design, 233(1-3), p.37 - 43, 2004/10

https://doi.org/10.1016/j.nucengdes.2004.07.009

Times Cited Count：13 Percentile：63.86(Nuclear Science & Technology)

The core thermal-hydraulic design for the HTTR is carried out to evaluate the maximum fuel temperature at normal operation and anticipated operation occurrences. To evaluate coolant flow distribution and maximum fuel temperature, we use the experimental results such as heat transfer coefficient, pressure loss coefficient obtained by mock-up test facilities. Furthermore, we evaluated hot spot factors of fuel temperatures conservatively. As the results of the core thermal-hydraulic design, an effective coolant flow through the core of 88 % of the total flow is achieved at minimum. The maximum fuel temperature appears during the high temperature test operation, and reaches 1492 $^{circ}$ C for the maximum through the burn-up cycle, which satisfies the design limit of 1495 $^{circ}$ C at normal operation. It is also confirmed that the maximum fuel temperature at any anticipated operation occurrences does not exceed the fuel design limit of 1600 $^{circ}$ C in the safety analysis. On the other hand, result of re-evaluation of analysis condition and hot spot factors based on operation data of the HTTR, the maximum fuel temperature for 160 effective full power operation days is estimated to be 1463 $^{circ}$ C. It is confirmed that the core thermal-hydraulic design gives conservative results.