C. Hamlyn-Harris

Structural Analysis of the ITER Thermal Shield for Final Design Verification

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.

In-service inspection and instrumentation for ITER vacuum vessel

In-service inspection (ISI) is required according to the French Order for Nuclear Pressure Equipment and also to protect plant investment and to ensure machine availability. The ITER VV maintenance and monitoring program includes Inservice Monitoring, Periodic Test and Periodic Inspection. Inservice Monitoring includes commissioning tests, continuous vacuum and water leakage monitoring and load follow-on monitoring. Periodic Test includes regular pressure tests and leak tests. For the outer shell welds of the main vessel, the equatorial region of “port #7” and lower penetrations are selected for Periodic Inspection. R&D for ISI is underway and tools and maintenance systems are being developed. Mock-ups were constructed to demonstrate its feasibility. In addition, a study of acoustic emission monitoring has started using a mock-up. The VV instrumentation is a system to monitor the VV status in normal and off-normal conditions. The VV instrumentation system includes approximately 1600 sensors, mounting devices, cables, cable holders, vacuum feed-throughs for the vessel and the cryostat, control cubicles and interrogating systems. Approximately 850 thermocouples are installed to monitor temperatures on plasma-side and cryostat-side surfaces of the vessel. Resistive and FBG strain gauges are also mounted on the vessel surfaces. Displacement sensors and accelerometers are installed to obtain data of VV movements during plasma disruptions or VDEs. These data are utilized to calculate forces on the VV. This calculation is essential to categorize plasma disruption or VDE events during the ITER operational phase.

Design and manufacture of the ITER Vacuum Vessel

The main functions of the ITER Vacuum Vessel (VV) are to provide the necessary vacuum for plasma operation, act as first nuclear confinement barrier and remove nuclear heating. The design of the VV has been reviewed in the past two years due to more advanced analyses, design modifications required by the interfacing components and R&D. Following the signature of four Procurement Arrangement (PAs), the manufacturing design of the VV sectors, ports and In-Wall Shielding (IWS) is being finalized and the fabrication of the VV sectors has been started in 2012.

Simulation of Electromagnetic Transients in ITER Thermal Shield Manifolds

A study of eddy currents and forces associated with electromagnetic (EM) transients for the event of current quench in the ITER thermal shield manifolds is presented. EM response of the tokamak passive structures with respect to their inductive coupling has been estimated using the shell approximation. The external field obtained within the model, assuming their 40-degree symmetry, has been applied to the local model of the thermal shield (TS) manifolds covering the 360-degree domain. Fields sources are modeled accurately to the input data description. At this stage of the study related to first estimates of EM loads, acting on the TS manifolds, the electric contact between the cooling tubes and adjacent TS plates was neglected. The current flow is restricted between the neighboring panels. Such simplification uncouples galvanically the manifold tubes from other TS conducting shells, which makes possible a local simulation of eddy currents and EM loads on the manifolds. Two design options with/without electrical breaks in outlet manifolds have been considered. Detailed temporal and spatial distributions of eddy currents and EM forces were obtained. The simulated results were validated in a comparison with a lumped equivalent circuit. Maximal EM loads per unit length were evaluated and found to be low.

Cryogenic Conduction Cooling Test of Removable Panel Mock-Up for ITER Cryostat Thermal Shield

Abstract This paper describes the fabrication of removable panel for ITER cryostat thermal shield (CTS) and its conduction cooling test at cryogenic temperature. Two kinds of full-scale mock-ups of the removable panels have been developed, depending on different thermal conduction designs. Passive cooling characteristics of the mock-ups are investigated with the measured data of temperature jump at the joint and maximum temperature at the panel. The passive cooling of panel with copper insertion satisfies the design requirement of temperature jump (< 3 K), even though the heat load condition in the cooling test is more severe than the design condition of CTS. It is clearly demonstrated that the copper strips bonded on the panel attenuate the temperature gradient of the panel. Different thermal behaviors at the joint are also found for the two mock-ups.

Fabrication Preparation of ITER Vacuum Vessel—Material Considerations, Regulatory Requirements, and Fabrication Plans

Abstract SS 316 L(N)-IG (ITER grade) has been selected as the main structural material for the ITER vacuum vessel (VV), considering its high mechanical strength at operating temperatures, water chemistry properties, excellent fabrication characteristics, and low cost relative to other candidates. The ITER VV is a class-2 box structure as defined in RCC-MR, 2007 edition, which was selected as the code for the design and construction. This paper describes materials, applied code and regulatory requirements, baseline fabrication procedures, and assembly on the site.

Structural analysis of the ITER Thermal Shield

The structural rigidity 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 are performed for the TS global model and detailed model such as supports and joints. TS joints in the shell model are modeled using orthogonal material properties, because using sufficiently refined joint models in the global model of TS sector is almost impossible and highly time-consuming. Joint orthogonal properties are calculated based on the periodical composite cell theory. To verify the structural rigidity for the TS, plastic collapse, buckling, ratcheting and fatigue are assessed in accordance with ASME VIII, Div. 2.