T.H. Kwon

Engineering design status of the KSTAR central solenoid structure

The central solenoid (CS) magnet system of the Korea Superconducting Tokamak Advanced Research (KSTAR) device consists of four pairs of segmented CS coils and a CS coil structure. The maximum repulsive force between CS coils is about 12 MN. The functions of the CS structure are to apply preload on the CS coils and to support the repulsive force between CS coils during operation. The designed axial compression of 15 MN at 4.5 K will be applied partly by assembling the preload structure at room temperature with preload of about 13.4 MN and partly by the thermal contraction difference between the CS coils and the structure during cool down. Additional preload will be given by minute adjustment of wedges. The structural analysis of the CS magnet system has been performed to verify the CS structure design reliability.

Design and analysis of poloidal field magnet structures for KSTAR

The poloidal field magnet system of the KSTAR consists of three pairs of coils using the cable-in-conduit conductors cooled by forced super-critical helium. The conductor of PF5 is Nb/sub 3/Sn superconductor with Incoloy 908 conduit, and that of PF6 and PF7 is NbTi superconductor with SS 316LN. The PF coils are self-supporting with regard to radial loads, and they are arranged symmetrically with respect to the equatorial plane. PF5 coil is connected to the TF coil structure at eight points by hinges, while PF6 and PF7 coils are connected at sixteen points by flexible plates to allow relative radial movements. In order to investigate the structural integrity, structural analysis has been conducted including buckling and fatigue analyses. The major design loads are dead weight, assembly loads, thermal load due to cool down, and electromagnetic loads under the critical load conditions. It is found that the PF magnet structures can safely withstand all operating conditions. In addition, AISI 316LN can be substituted for JJ1 as the material of the PF coil structures.

Structural analysis of the KSTAR central solenoid magnet system

The Central Solenoid (CS) magnet system of the Korea Superconducting Tokamak Advanced Research (KSTAR) device consists of four pairs of superconducting coils compressed with the CS coil structure. The CS coil structure is operated as a preload structure to give an axial compression on the CS coils. The required axial compression is applied partly by using the pre-compression components in assembly stage and by the thermal contraction difference between the coil winding pack and the structure during cool down stage as well. In order to investigate the structural integrities and to increase the structural reliabilities of the KSTAR CS magnet, global and local structural analyses have been performed for various operation scenarios by developing three-dimensional finite element models. From the analysis results, it has been found that the CS magnet system can safely withstand the reference operation scenarios and the structural integrity of the CS magnet complies with requirements of the design criteria for KSTAR magnet system.

Study on Seismic Analysis and Test for Seismic Qualification of 245kV GIS

Gas insulated switchgear is large-sized electric equipment for providing a reliable supply of electric power. Recently, seismic tests of electric equipment using a shaking table have been mandated because seismic performance has become an increasingly important issue. However, basic analysis methods continue to be used because some electric equipment is too large for shaking table facilities. Thus, a reliable analysis method should be developed for large-scale electric equipment. This study aims to evaluate the seismic qualification of a 245kV GIS in accordance with IEEE-693 and to validate the analysis method by comparing it with test results. Both the test and the analysis showed that the 245kV GIS has proper seismic safety. Furthermore, the differences between the analysis and the test results are less than 10% for an accurately given mass, stiffness, and input acceleration. It is expected that this study can be used for the seismic qualification of large-scale electrical structures.