Overview of the ITER-like wall project

Abstract

Work is in progress to completely replace, in 2008/9, the existing JET CFC tiles with a configuration of plasma facing materials consistent with the ITER design. The ITER-like Wall (ILW) will be created with a combination of beryllium (Be), tungsten (W), W-Coated CFC and Be-Coated inconel tiles, with the material depending on the local anticipated heat flux and geometry. It is part of an integrated package of JET enhancements whose aim is to develop an understanding of the ITER materials issues and develop the techniques required to operate with inductive and advanced scenarios as close as possible to ITER parameters. Over 4000 tiles will be replaced and the ILW will accommodate additional heating up to at least 50 MW for 10 s. This paper describes the scientific background to the project, the technical objectives, the material configuration selected, the R&D behind the practical realisation of the objectives and the generic problems associated with the Be tiles (power handling capacity and disruption induced eddy currents). One of the objectives is to maintain or improve the existing CFC tile power handling performance which has been achieved in most cases by hiding bolt holes, optimising tile size and profile and introducing castellations on plasma facing surfaces.

Material mixing on plasma-facing components: Compound formation

“…The investigation was focused on composition of graphite surfaces located in gaps between tiles of W-coated blocks and inside castellated grooves of the macro-brush, because these areas are considered as potential traps for vast amount of fuel retained in co-deposits formed in areas shadowed from the direct plasma impact [15]. Strong motivation for studying tungsten reactivity under plasma conditions is also related to the ITER-like wall (ILW) Project at the JET tokamak where divertor tiles will be made of bulk metal lamellae (load bearing tile) and coatings on carbon fibre composites [16].…”

Ten years of W programme in ASDEX Upgrade—challenges and conclusions

“…Clearly, not all questions posed by ITER can be answered in ASDEX Upgrade, amongst which are the effects of material mixing with Be, the melt behaviour under transients or the change of the hydrogen retention due to damage by high energy neutron irradiation [40]. Some answers may be provided by the ITER-like wall project in JET [41], but others have to be answered by dedicated experiments in other plasma devices or by modelling.…”

Current status of the JET ITER-like Wall Project

“…The basic technical design requirements and solutions were previously described at the 11th International Workshop on Plasma-Facing Materials and Components for Fusion Applications [1,2] and so will not be repeated here. Since this time there have been a number of significant developments that are outlined in the following sub-section.…”

“…The JET ITER-like Wall [1,2] will combine bulk beryllium main-chamber limiters and main protection with a full tungsten divertor. This is the materials combination now selected for the deuterium, tritium (DT) phase of ITER.…”