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Tokamak — Watch this space

-Gary Johnson, Deputy Dir. General, ITER Tokamak Dept.

Gary Johnson, ITER DDG (Click to view larger version...)
Gary Johnson, ITER DDG
There have been several important developments in the Tokamak during the last few weeks including signing Procurement Arrangements (PA), progress on First Wall qualifications, and important developments related to magnet conductors. Related to PAs, five additional Tokamak PAs were completed and signed in June. These were: the Poloidal Field (PF) coils 2, 3, 4, 5, and 6 PA signed with the EU; the Toroidal Field (TF) conductor PA signed with the US; the upper ports PA and the divertor dome PA signed with the Russian Federation and the divertor outer target PA signed with Japan. This is an important accomplishment for the project and the Tokamak. To date, the credit value of all signed ITER PAs is ~880 kIUA which is ~30% of the total ITER credit. This is very good progress!

Several additional PAs are in the final stages of development and are expected to be ready for signature in the coming months. The most important of the next set of PAs is the Vacuum Vessel (VV) PA. This is linked to the design review where the modified reference VV design and the alternate design of the VV and blanket will be assessed. This review is scheduled for 7 to 10 July in Cadarache and will be chaired by Rich Hawryluk from the Princeton Plasma Physics Laboratory. For the modified reference design the main issue remains the Edge Localized Modes & Vertical Stability coil integration. The priority for the alternate design is still to finalize design concepts and resolve issues. After this review the decision will be made by the IO as to which design to pursue.

Another important development relates to qualification of blanket components. First wall qualification mock-ups from the Korean and Russian Federation Domestic Agencies are undergoing high heat flux testing at ~0.62 MW/m2 at the Nuclear Research Institute in Prague. Over half of the required 12000 cycles have been successfully completed. Qualification mock-ups from Chinese, Russian Federation and Japanese Domestic Agencies are being tested at ~0.87 MW/m2 at the Sandia National Laboratories in Albuquerque where ~4000 cycles have been completed. The EU and US mock ups already successfully completed tests in the US Sandia facility early this year. These tests are important because they represent the first step towards the required prequalification of the Members willing to participate in critical procurement packages. The next and final step will be the manufacturing and heat flux testing of near full-scale prototypes of First Wall panels. These prototypes will include all the main features of the corresponding ITER Blanket design and their construction is due to start early next year.

There has been a lot of progress in recent weeks, both at the ITER Organization and the Domestic Agencies, with magnet conductors. This includes: the signing of the final TF conductor PA by the US ,as I mentioned above; a successful test of the first Chinese TF conductor sample using Nb3Sn strands cabled and jacketed in China, in the Sultan facility; strand production for the TF conductor commenced at the Kiswire company in Korea and the completion of building construction on the Japanese TF and Central Solenoid conductor jacketing line in Kita Kyushu. At the time of writing Japan has already produced about 20 tons of Nb3Sn strand for the TF coils! This is about 5% of the total required. These activities and others clearly show widespread progress in this critical area. Much more has been done than mentioned here and progress is accelerating. This will be an area to watch!

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