An improved analysis method for assessing the nuclear-heating impact on the stability of toroidal field magnets in fusion reactors

Abstract

The superconducting magnet system of a fusion reactor plays a vital role in plasma confinement, a process that can be disrupted by various operational factors. A critical parameter for evaluating the temperature margin of superconducting magnets during normal operation is the nuclear heating caused by D–T neutrons. This study investigates the impact of nuclear heating on a superconducting magnet system by employing an improved analysis method that combines neutronics and thermal hydraulics. In the magnet system, toroidal field (TF) magnets are positioned closest to the plasma and bear the highest nuclear-heat load, making them prime candidates for evaluating the influence of nuclear heating on stability. To enhance the modeling accuracy and facilitate design modifications, a parametric TF model that incorporates heterogeneity is established to expedite the optimization design process and enhance the accuracy of the computations. A comparative analysis with a homogeneous TF model reveals that the heterogeneous model improves accuracy by over 12%. Considering factors such as heat load, magnetic-field strength, and cooling conditions, the cooling circuit facing the most severe conditions is selected to calculate the temperature of the superconductor. This selection streamlines the workload associated with thermal-hydraulic analysis. This approach enables a more efficient and precise evaluation of the temperature margin of TF magnets. Moreover, it offers insights that can guide the optimization of both the structure and cooling strategy of superconducting magnet systems.