Thermal-hydraulic analysis for first wall and thermal shield of Divertor Tokamak test facility

摘要

The Divertor Tokamak Test (DTT) facility has been proposed by ENEA, in collaboration with other Italian institutions, to investigate power exhaust solutions with a machine capable to integrate all DEMO relevant physics and technology issues. The DTT machine will be able to host, in different phases of its life-time, advanced divertor magnetic configurations (snowflake, super-X, double null) and liquid metal solutions, and will be able to withstand the large loads expected in the DEMO fusion power plant. The first wall (FW) has been designed with coaxial pipes. It shall be compatible with liquid metal divertors and therefore be heated at a temperature above 200 degrees C to avoid metal condensation on the surface and, at the same time, withstand to thermal load up to 1.5 MW/m2 reached during the ramp-up. Two alternative conceptual designs are considered, one made of CuCrZr and one in stainless-steel, both coated with a W layer deposited by plasma spray (PS) technique. The possibility to use a FW without active cooling or cooled by gas or water was studied. In addition, a preliminary design optimization based on thermo-mechanical FEM analyses was carried out.To minimize the heat transferred to the superconductive coils, the vacuum vessel (VV), heated by water at 100 degrees C, is shielded by a Thermal Shield (TS) cooled with helium at 70 K. By means of a preliminary thermohydraulic analysis, the power requested to the cryogenic system has been estimated.