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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.

ITER Thermal Shield (TS) reduces radiation heat loads from vacuum vessel and cryostat to superconducting magnet structure. One of the key process among the fabrication of TS is the silver electroplating to reduce the emissivity. Requirement on emissivity of TS surface after silver coating is below 0.05 at the room temperature. In practice, inevitable non-coated areas exist due to the intrinsic geometry of TS. These local defects can be repaired by attaching thin silver coated patch with spot welding. This paper treats structural characteristics on the spot welding of silver coated plates. Strength of spot welding is measured by tensile shear test. Distances between spot welding are verified by finite element analysis considering temperature deviation between TS surface and patch. Finally, thermal stress analysis for the several applications to TS main components are presented.

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.

In this paper, a full-scale prototype fabrication for vacuum vessel thermal shield (VVTS) of ITER tokamak is described and test results are reported. All the manufacturing processes except for silver coating were performed in the fabrication of 10° section of VVTS. Pre-qualification test was conducted to compare the vertical and the horizontal welding positions. After shell welding, shell distortion was measured and adjusted. Shell thickness change was also measured after buffing process. Specially, VVTS ports need large bending and complex welding of shell and flange. Bending method for the complex and long cooling tube layout especially for the VVTS ports was developed in detail. Dimensional inspection of the fabricated mock-up was performed with a 3D laser scanner and the scanning data was analyzed.

The structural integrity of the ITER thermal shield (TS) has been verified by structural analysis. In this paper, the analysis process methodology and demonstration of the structural integrity for the TS are described. The analysis is performed for the TS global models and detailed models, such as supports and joints. TS joints in the shell model are modeled using orthotropic material properties. To verify the structural reliability for the TS, plastic collapse, buckling, ratcheting, and fatigue are assessed in accordance with ASME Section VIII, Div. 2.

This paper reports a method to modify the gear tooth profile of a wind turbine gearbox to reduce the noise caused by the impact of the gear teeth. The major causes of tooth impact are the elastic deformation of the gear teeth, shafts, and case of the gearbox under loading, and the fabrication tolerances in gear manufacturing. In this study, the tooth profile was modified considering the elastic deformation of the gear tooth and the tooth lead modification to compensate for tooth interference in the lead direction as a result of shaft deformations. The method was applied to the gearbox of a 2.5MW wind turbine, and the transmission error was characterized before and after modifying the gear teeth. For the modified gear teeth, the transmission error (67.6%) was lower by 17.8%. Additionally, the gear contact stress was reduced by 6.3%, to 22.3%.

The final design of ITER vacuum vessel thermal shield (VVTS), which is planned to be procured completely by Korea, has been implemented after the procurement arrangement was signed. In this paper, the design and the supporting analysis are described for the key components of the VVTS such as joint, panel, support, and stopper. The VVTS design is revised and finalized based on the manufacturing feasibility, interface requirement and assemble feasibility. The inboard and the outboard supports of VVTS are designed in detail considering structural rigidity and assemble feasibility. The shape of in-pit joint, which is installed every 40° sector in toroidal direction for compensation of possible misalignment during sector assembly, is determined. Three types of joints are developed in accordance with their locations and assemble feasibilities are checked through the R&D. Stopper design is developed in order to prevent direct contact against adjacent components such as vacuum vessel and magnets. Structural rigidity of the whole VVTS is also validated by finite element analysis under various kinds of operating conditions, such as deadweight, electro-magnetic load, seismic load and load combinations.

The aim of the study was a quantitative analysis of elite athlete`s Dwihuryeochagi and effects of ground movements to the jumping height and kicking velocity. Eleven elite players(Taekwondo demonstration team) participated in this study. In order to get the kinetic and kinematic variables, ten Vicon cameras and a force plate were used. Foot segment velocity(FSV), vertical ground reaction force(GRF), impulse, ground time(GT) in phase 1, trunk angular velocity(TAV), vertical center of gravity(COG), flight time(FT) in phase 2 and kicking leg segment velocity(KSV) in phase 3 were measured and analyzed. Results indicated that there were similar patterns of variables among phases between subjects. Non-significant correlation(r

A full-scale mock-up of VVTS inboard section was made in order to validate its manufacturing processes before manufacturing the vacuum vessel thermal shield (VVTS) for ITER tokamak. VVTS inboard 10° section consists of 20 mm shells on which cooling tubes are welded and flange joints that connect adjacent thermal shield sectors. The whole VVTS inboard is divided into two by bisectional flange joint located at the center. All the manufacturing processes except silver coating were tested and verified in the fabrication of mock-up. For the forming and the welding, pre-qualification tests were conducted to find proper process conditions. Shell thickness change was measured after bending, forming and buffing processes. Shell distortion was adjusted after the welding. Welding was validated by non-destructive examination. Bisectional flange joint was successfully assembled by inserting pins and tightening with bolt/nut. Bolt hole margin of 2 mm for sector flange was revealed to be sufficient by successful sector assembly of upper and lower parts of mock-up. Handling jig was found to be essential because the inboard section was flexible. Dimensional inspection of the fabricated mock-up was performed with a 3D laser scanner.

ITER thermal shield, which is to be fully made by Korea, is very large system and its tolerance requirement is so tight that the precise design and manufacture are indispensable. Therefore, it is very important that the critical components of the thermal shield are tested before the manufacture of full-scale thermal shield to avoid possible risks. In this paper, mock-ups of the thermal shield components are described and the test results are reported. The weld test and the reliability test were performed for the cooling tubes. The silver coating was also tested for small specimens to investigate the quality and the process of coating. Effect of chromate treatment to prevent the discoloration on the silver coating surface was also investigated experimentally.

Thermal shield (TS) is to be installed between the vacuum vessel or the cryostat and the magnets in ITER tokamak to reduce the thermal radiation load to the magnets operating at 4.2K. The TS is cooled by pressurized helium gas at the inlet temperature of 80K. The cooling tube is welded on the TS panel surface and the composed flow network of the TS cooling tubes is complex. The flow rate in each panel should be matched to the thermal design value for effective radiation shielding. This paper presents one dimensional analysis on the flow distribution of cooling tube network for the ITER TS. The hydraulic cooling tube network is modeled by an electrical analogy. Only the cooling tube on the TS surface and its connecting pipe from the manifold are considered in the analysis model. Considering the frictional factor and the local loss in the cooling tube, the hydraulic resistance is expressed as a linear function with respect to mass flow rate. Sub-circuits in the TS are analyzed separately because each circuit is controlled by its own control valve independently. It is found that flow rates in some panels are insufficient compared with the design values. In order to improve the flow distribution, two kinds of design modifications are proposed. The first one is to connect the tubes of the adjacent panels. This will increase the resistance of the tube on the panel where the flow rate is excessive. The other design suggestion is that an orifice is installed at the exit of tube routing where the flow rate is to be reduced. The analysis for the design suggestions shows that the flow mal-distribution is improved significantly.