Y. Utin

Conceptual design and integration of a diagnostic neutral beam in ITER

In ITER, one of the key issues to achieve 400 s driven-burn operation at Q about 10 (Technical Basis for the ITER-FEAT Outline Design-Section I-3.2.2.IAEA) is helium ash accumulation. As a result, the real-time measurement of the thermalised helium density profile in the confinement region is of fundamental importance. This paper outlines the design of a modulated, 100 keV, hydrogen, diagnostic neutral beam (DNB), together with preliminary calculations of the performance for the measurement of helium ash by charge exchange recombination spectroscopy (CXRS). The DNB uses a negative ion beam as the primary beam to achieve a required performance with acceptable system efficiency (a higher neutralisation efficiency and smaller beam divergence). This uses the same negative ion source as the ITER HC as a consequence, the DNB has to share the vacuum vessel access through a single port with one of the H&CD injectors

Structural analysis work on ITER Vacuum Vessel

The structural integrity of the ITER Vacuum Vessel is verified by elastic and/or non-linear analyses. The typical loads for the Vacuum Vessel are also explained. Electromagnetic load by vertical displacement event of plasma is most serious load. Major design modifications from basic design requirement are verified.

Final design and start of manufacture of the ITER Vacuum Vessel ports

The ITER Vacuum Vessel (VV) features upper, equatorial and lower ports. Although the port design has been overall completed in the past, the design of some remaining interfaces was still in progress and has been finalized now. As the ITER construction phase has started, the procurement of the VV ports has been launched. The VV upper ports will be procured by the Russian Federation DA, while the equatorial and lower ports will be procured by the Korean DA. The main industrial suppliers were selected and development of the manufacturing design is in progress now. Since the VV is classified at nuclear level N2, design and manufacture of its components are to be compliant with the French code RCC-MR and regulations of nuclear pressure equipment in France. These regulations make a strong impact to the port design and manufacturing process, which is in progress now.

Fabrication Design and Code Requirements for the ITER Vacuum Vessel

The ITER vacuum vessel (VV) is a double walled torus structure and one of the most critical components in the fusion reactor. The design and fabrication of the VV as nuclear equipment shall be consisted with the RCC-MR code based on French fast breeder reactor. The VV is a heavy welded structure with 60 mm thick shells, 40 mm ribs and flexible housing of 275 mm diameter. The welding distortion should be controlled since the total welding length is over 1500 m. To satisfy the design requirement, the electron beam welding (EBW) and narrow gap gas tungsten arc welding (GTAW) techniques are to be applied and developed through the fabrication of mock-ups. The fabrication design has been developed to manufacture the main vessel and port structures in accordance with the RCC-MR code. All fabrication sequences including welding methods are also established to meet the demanding tolerance and inspection requirement by HHI as a supplier.Copyright

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.

Integration of diagnostics on ITER

Diagnostics play a very important role in the modern Tokamak where optimum performance is essential. To achieve this, the device must be equipped with reliable and robust sensors and instrumentation that allow the operation envelope to be fully explored. Development of these diagnostics to maintain this reliability is necessary. Further to the development, the systems must be integrated in a way that maintains their performance while simultaneously satisfying the key requirements needed for safety and tokamak operation. ITER will have 50 diagnostics; almost all of which are utilized primarily for the real-time operation of the tokamak. While there is still much work to do, to date, significant progress has been made in the development of these systems. The work load for the developments is shared across all the ITER partners. This paper focuses on the challenges for the integration of the systems.