TFC-PREDIM: A FE dimensioning procedure for the TF coil system of a DEMO tokamak reactor

Abstract

Abstract The equatorial plane of the inner leg of a toroidal field (TF) coil is the most stressed part of the TF coil system and optimal usage of the radial space in this region is crucial for the design of the DEMO tokamak reactor. A procedure for initial dimensioning (pre-dimensioning) of this region developed earlier [ 1 ] is based on a simplified 2D geometry of the TF coil cross-section and a semi-analytical approach to estimate stresses in the TF coil case and the conductor jackets with limited capabilities for optimization. This work presents a new procedure named TFC-PREDIM which features a detailed 2D finite element (FE) generalized plane strain model. The model gives very accurate results within a short calculation time and allows additional options for layout optimization. The FE model for the cross-section is generated automatically from the input geometrical parameters of the given layout allowing any of the conductor design options currently investigated for DEMO. The post-processing of the results is also automated, consisting in the determination of the maximum values of the membrane and membrane + bending Tresca stresses for each conductor jacket and for the TF coil case. Two strategies for the optimization of the cross-section are presented: minimization of the TF coil radial build with a predefined maximal toroidal field and maximization of the maximal toroidal field for a predefined radial space.