CSモデル・コイルの圧力損失及び流量配分

抄録

International Thermonuclear Experimental Reactor (ITER) Engineering Design Activities (EDA) have been performed in collaboration with Japan, the European Union, the Russian Federation, and the United States of America. In ITER EDA, the Central Solenoid Model Coil (CSMC) and CS insert coil have been fabricated to demonstrate the realization of ITER superconducting magnet. The conductor used in the CSMC and CS insert coil is a forced flow cable-in-conduit conductor (CICC) cooled by supercritical helium. For CICC, a pressure drop characteristic is one item of important information from the viewpoint of understanding of heat transfer in the conductor and thermodynamics design of a cryogenic system with a helium circulation pump for coil cooling. The ITER conductor has a central channel made of a spiral tube of thin stainless steel tape and a spring tube made of INCONEL in the bundle having about 1, 100 superconducting strands. The helium gas flow into the bundle and central channel in parallel and the pressure drop characteristic are determined from flow balance between the bundle region and the central channel because of different flow friction factor characteristics of both. In the past, pressure drop measurement for various bundle types of CICC composed of a few hundreds strands, such as Demo Poloidal Coil (DPC), has been well performed at 4-K supercritical helium. Recently, the friction factors of the bundle region and the central channel of the ITER conductor have been measured at room temperature. The pressure drop characteristics of an ITER relevant sub size conductor, such as QUELL have been measured at 4K. However, there are no measurement results in the practical coil operation conditions (4-K supercritical helium condition) for an ITER full-size conductor. In a CSMC experiment, the pressure drop characteristic of ITER full size conductor has been measured in a practical operation condition for the first time at an ITER CS model coil test facility in the Naka Fusion Research Establishment, Japan Atomic Energy Research Institute (JAERI).