Recent Development and Qualification of Materials for ITER

Full text: The material development together with the important qualification of each individual material and joint are continuously providing new data. Results are provided for ITER components contributing to the First Wall/Blanket, the Divertor and the Vacuum Vessel. The work has been organized by EFDA and F4E together with EURATOM associations and industry. Assessment of data including the interfaces to the primary heat transfer systems under ITER operational conditions is highlighted in the presented paper. Historically it is well known that corrosion has caused high costs to nuclear power plants and efforts aimed at avoiding similar situations for ITER have been made or are currently ongoing. Due to the complex geometry and component assembly it is of great importance to understand the corrosion aspects. The initial activity was aimed at identifying possible weak points, such as crevices, joints and welds, within the primary heat transfer systems. Taking into account highlighted corrosion issues along with results from previous and presently ongoing work it is possible to make an assessment of fundamental corrosion parameters. The assessment is done by analysis and simulation, which is followed up by experiments under ITER relevant operational conditions. The drying sequence of the vacuum vessel using hot nitrogen and hot dry sTeam was simulated using the computer code MELCOR. Radiolysis calculations were reviewed in a task to determine how the corrosion potential (ECP) changes during the plasma burning cycles. Even if the corrosion effects are found to emerge slowly it is important to follow up the margins against corrosion during the expected lifetime of ITER. The knowledge gathered from these studies also enables preventive actions to be available during operation. A new grade of carbon fibre composite (CFC), DMS 814 MEGGAGARD, was developed by Meggitt UK. The CFC is used as a plasma facing material for the Divertor and it was concluded that this grade can be manufactured to meet ITER requirements. The ITER Organization has identified a lack of materials data concerning the copper alloy CuCrZr and stainless steel 316L(N)-IG and especially the CuCrZr/316L(N)-IG joints. Several studies have been launched as an effort to increase the available materials data. The studies on the CuCrZr/316L joints are contributing to the development of the First Wall. (author)