DTT Thermal Shield: Preliminary thermal analysis

摘要

The Thermal Shield (TS) in DTT is devoted to minimizing the heat loads from the tokamak warm components, to the superconducting magnets operating at 4.5 K. The TS is subdivided into three main regions covering respectively the vacuum vessel, the ports and the cryostat. Along the toroidal direction, the TS is arranged in 18 electrically insulated segments (20-degrees each), composed of several cooling modules. Each module consists of a double wall panel, 20 mm thick, enclosing the cooling tubes where the pressurized helium gas circulates (1.8 MPa, similar to 80-100 K). A simpler, single panel solution is envisaged as well. The present work provides a preliminary analysis of the major parameters involved in the design of the TS system. More specifically, heat loads (mainly radiative) to the TS were assessed for normal operation and backing. The introduction of multi-layer insulator was investigated for the POS scenario. Afterwards, the cooling performances of a reference module (single panel solution) was investigated. These two analyses were carried out with ANSYS Mechanical (Steady-state) commercial software. A third analysis was conducted using RELAP5-3D(C) thermohydraulic system code, in order to characterize a 10-degrees sector TS cooling circuit in terms of helium flow, temperature increment and pressure losses. The synergic use of these codes proved to be a valuable tool in support of TS design.