Thermal analysis on detailed 3D models of ITER thermal shield

Thermal shield (TS) is to be installed in ITER tokamak to minimize radiation heat load transferring from the vacuum vessel and the cryostat to the superconducting magnet operating at 4.5 K. The TS shall be properly designed so that the radiation heat load is below the specified requirement for the magnet. This paper describes how the ITER TS is modeled to verify its thermal performance. The 3D finite element (FE) models of repetitive sections of the whole TS were developed in this study. The major geometric simplifications applied to the FE models are illustrated. Passively cooled removable panel on the cryostat TS (CTS) for the in-cryostat maintenance of the magnet was modeled considering thermal contact at the joint. The boundary temperature of the CTS support was determined from the analysis of cryostat with the TS. Total heat load from the TS to the magnet was evaluated for the steady state of plasma operation. Cool-down behavior of the TS was also investigated by the transient analysis of the representative models. The maximum panel temperature and the helium outlet temperature were obtained during cool-down of TS.