Parametric Thermal and Flow Analysis of ITER Diagnostic Shield Module

Authors: A. Khodak, Y. Zhai, W. Wang, R. Feder, G. Loesser, D. Johnson

Abstract: As part of the diagnostic port plug assembly, ITER Diagnostic Shield Module (DSM) is designed to provide mechanical support and the plasma shielding while allowing access to plasma diagnostics. DSM 3 located in Equatorial Port Plug 9 and housing ITER Toroidal Interferometer and Polarimeter, (TIP) diagnostics was considered in current analysis.

Thermal and hydraulic analysis was performed using conjugated heat transfer approach, in which heat transfer was resolved in both solid and liquid parts, and simultaneously fluid dynamics analysis was performed only in the liquid part. This approach includes interface between solid and liquid part of the system. In such interface conservation of the heat flux is assumed together with the non-slip wall boundary conditions for the liquid. Since the flow in the cooling system is for the most part turbulent, non-slip wall boundary conditions take the form of wall functions.

ITER Diagnostic First Wall (DFW) and cooling tubing of the EPP09 DSM3 were also included in the analysis. This allowed direct modeling of the interface between DSM and DFW, and also direct assessment of the coolant flow distribution between the parts of DSM and DFW to ensure DSM design meets the DFW cooling requirements. Combined model of 2 DFWs and a DSM was imported in ANSYS Workbench. The model meshed contained 25 million elements, allowing accurate representation of the model details, as well as layers of elements on the fluid side of the fluid-solid interface. Temperature dependent material properties were used in the analysis. Design of the DSM included voids filled with Boron Carbide pellets, allowing weight reduction while keeping shielding capability of the DSM. These voids were modeled as continuous solid with smeared material properties using analytical relation for thermal conductivity

Results of the analysis lead to design modifications improving heat transfer efficiency of the DSM. These modifications include rearrangement of the cooling channel sequence, and elimination of Boron Carbide beds in the front portion of the DSM to avoid local overheating. Analysis of the modified design showed that temperature does not exceed allowable values for DSM and DFW. Effect of design modifications on thermal performance as well as effect of Boron Carbide will be presented.

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