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The ITER design - updated

-Sabina Griffith

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It is done! The Design Review is concluded. Starting in November 2006, more than 150 leading experts from the international fusion community, divided into eight working groups, have contributed to the Design Review Process. The review was necessary because the only officially recognized documentation and technical specifications dated from 2001, while the design of the machine had developed further and outstanding issues had to be addressed. In total about 430 so called "issue cards" were reviewed, of which 186 were issues that had to be treated by more than one working group. The issues were prioritized to allow initial procurement to start.

As a result of this extraordinary effort 14 major design changes to the ITER machine have been defined, such as the insertion of ELM control coils and additional coils to improve control of the vertical stability of the plasma. No major changes were requested regarding the other magnets. Concerning safety issues it was decided that no carbon will be used in the Tritium Phase. The divertor will thus be an "all tungsten" one during this later phase of the project. The Hot Cell remains a challenge and a re-optimization of its layout is needed. In addition, the building itself will have to be redesigned in such a way that it will not perturb the performance of the magnetic fields. For the heating and current drive systems the Real Time Modulation of the Neutral Beam for advanced control scenarios will be developed as soon as possible and the RF-Heating installation will be decoupled from the assembly hall. The Tritium plant is to be completely redesigned using a new layout, with no major cost increase being incurred. Several adaptations and changes have been identified for the In Vessel components. The First Wall will be subject to some tiling adjustment in order to deal with misalignments and high heat loads.

In formulating the updates, the working groups and the Design Review Chairman Günther Janeschitz had to implement the changes without exceeding the framework of cost, scope and schedule given in the ITER Agreement and which was requested by the Interim ITER Council. Another boundary condition was to only introduce design changes where they were absolutely necessary and to adhere to the 2001 design where possible. The successful conclusion of the Design Review still leaves much detailed work to be done. However, both the ITER Organization and the Domestic Agencies are now ready to embark together on the construction of ITER.

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