Experimental and numerical evaluation of IR thermography method for Final Acceptance Tests of the ITER divertor dome

• The experiments on the assembly of the ¼ ITER divertor dome consisting of three groups of hypervapotrons with aim to prove applicability of the thermography method for detection of defective channels are performed.
• Numerical simulation of the FAT procedure on the calculation model of ½ dome is carried out.
• It is not only the flow rate difference in parallel channels caused by defective hypervapotrons but also the flow history that affects essentially the dynamics of the temperature field of the dome surface.

The divertor dome (DO), being part of the ITER divertor, is designed to extract the major part of the plasma thermal energy. As a plasma-facing component (PFC), the DO experiences high heat fluxes (up to 5.0 MW/m2). Such severe operation conditions of the DO imply stringent requirements for the DO design and its cooling system to ensure the required temperature operation regime of the dome. Hence, Final Acceptance Tests (FAT) shall be performed on each DO final assembled component with the aim to demonstrate that none of parallel coolant channels are completely or partially blocked. The paper presents the results of the analytical and experimental testing of the thermography method capability to perform the FAT. The aim is to determine defective hypervapotrons of the divertor dome. The method consists in contactless measurement of the dynamic temperature field of the PFC surface at a step-like increase (from zero to constant value) in the coolant flow rate with a temperature higher than that of the hypervapotron.