R. Le Barbier

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.

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.

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.

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.