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Thermal Shield (TS) in ITER tokamak reduces heat loads from vacuum vessel and cryostat to superconducting magnet structure. Unlike to other components in ITER tokamak, most of TS have slender structure with panel thickness of 20 mm. Due to its structural uniqueness, TS cannot be secured on packing box directly since forces caused by lashing ropes may induce undesirable deformation and structural damage during transportation environment. Therefore, transportation jigs are required to support and fasten TS. In this study, structural design and safety assessment of TS transportation jigs are presented. ‘

The main components of the ITER tokamak are assembled from the nine sub-assemblies of the 40° sectors. During the sub-assembly, the Toroidal Field coils (TFCs) are installed outside of the Vacuum Vessel Thermal Shield (VVTS) by rotation. The clearance between TFCs and VVTS is very narrow, in relation to the cooling tube end points, which are connected to the thermal shield manifolds. The dimensional analysis shows that in-situ bending of the VVTS cooling tube is required instead of pre-bending. This paper describes the development of the in-situ bending tool and its validations. The specialized tool is designed and the in-situ bending procedure is verified by structural analysis and mock-up test.

This paper describes the manufacturing study of ITER Lower Cryostat Thermal Shield (LCTS) cylinder components, which are to be delivered to ITER site. All LCTS cylinder 20 ° sectors will be assembled at the ITER site by the flange joints, which are welded to the shells. Reliability of cooling pipe welding was checked by two inspection methods: endoscopy and vacuum leak test. Pre-assembly of three 20 ° sectors is one of the important step to ensure dimensional tolerance and its process is described in details. Dimensions of the pre-assembled 60 ° sector was measured by a laser tracker. The qualification of silver coating facility was carried out using a simple well-defined plate mock-up. After the facility qualification, silver coating of LCTS cylinder 20 ° sectors had been conducted. Technical efforts to improve the coated surface quality are presented in this paper.

This paper describes the manufacturing progress of ITER Vacuum Vessel Thermal Shield (VVTS) sectors, which are on-going since the start of material buffing in October 2014. Fabrication of VVTS proceeds according to the following main processes: 1) plate cutting, 2) bending and forming, 3) welding, 4) flange final machining, 5) pre-assembly of 40 ° sector, 6) silver coating and 7) final acceptance test. All VVTS shell segments are to be assembled by the flange joints, which are welded to the shells. Two kinds of inspection methods are presented for the cooling pipe welding: endoscope and leak test. A specific endoscope is developed for a long welded cooling pipe. Vacuum leak test is performed in the test vacuum chamber with the helium pressurization of cooling pipe by 3 MPa, which is the same pressure differential with the operating condition of the VVTS. One of the dimensional inspection, 3D laser scanning is also described to see the effect of shape correction for the flange to shell welding. Silver coating jig design has been carried out, focusing on the electrode position. Structural analysis results are shown for the design of pre-assembly jig of 40 ° sector. Finally near term schedule of the manufacturing is summarized.

In the ITER tokamak, a thermal shield (TS) is installed to reduce the heat oad radiated to the superconducting magnet system from vacuum vessel (VV) and cryostat. TS has a thin silver surface to keep its emissivity below 0.05. The silver surface is achieved by electroplating. However, some vacuum vessel thermal shield (VVTS) may be imperfectly silver coated due to their complex geometry. When a segment of the VVTS is immersed in silver coating bath, electron is concentrated to the sharp edge of segment and doesn’t reach to the deep area. Also, solution in a segment surface for pre-treatment may not be removed in some point due to its geometry, and it disturbs the silver coating. In this paper, the impact of non-silver coating on heat loads from TS to magnet system is researched as following process; 1) Identification of area where the VVTS may be imperfectly silver coated – it is obtained from actual silver coating of ITER VVTS. 2) FE model/analysis condition construction of VVTS – VVTS solid element / cooling tube beam element is combined, and silver coated / non-coated area shell element with respective emissivity is applied. 3) Thermal analysis of VVTS with non-silver coated area – heat load via non-coated area of VVTS is calculated, and its impact to magnet system is estimated. According to thermal analysis of VVTS, the essential silver coating points to reduce heat load are identified. As remedial action is applied to the essential points, the heat load from VVTS to magnet system is minimized.

The role of the ITER Thermal Shields (TS) is to minimize the radiation heat load from the warm components such as vacuum vessel and cryostat to magnet operating at 4.5 K. The final design of TS was completed in 2013 and manufacturing of the vacuum vessel thermal shield (VVTS) is now on-going. This paper describes the development status of the TS in particular the design improvements, the fabrication and the requirements.

The role of the ITER thermal shield (TS) is to minimize the radiation heat load transferred from the warm components to the superconducting magnet operating at 4.5 K. Fabrication of the TS components is ongoing. Manufacturing of LCTS (Lower Cryostat TS) cylinder and VVTS (Vacuum Vessel TS) sector #6 was completed. The leak tightness of the cooling tubes, the on-site installation feasibility and the quality of the silver coated surfaces are main concerns during the manufacturing. Leak tightness of the cooling tubes is guaranteed by the test and the inspection. The surfaces of the cooling tube inside are inspected visually using the endoscope and the leak tightness has been qualified by the pressure and helium leak test. The on-site installation feasibilities are validated by the preassembly test at the factory. According to the qualified coating process, the TS panels are electro-plated with silver. This paper describes the manufacturing progress and the technical achievements.

The ITER thermal shield (TS) minimizes radiation heat loads from the vacuum vessel and the cryostat to the superconducting magnets. It is actively cooled by pressurized Helium gas. The TS Manifold (TSM) provides Helium coolant from the cold valve box (CVB) to the cooling tubes on the TS panels. Among the manufacturing of TSM, the most challenging issue is fabrication of pipe T-branches which is consisted of drilling, T-extrusion, surface milling and orbital welding. After the orbital welding the welded areas are tested by visual and x-ray examinations. Functional tests are carried out by cold shock and pressure and vacuum leak testing. This paper introduces the procedures for the fabrication and examinations for the T-Branch of the TSM.