Tokamak—watch this space

There have been several important developments in the Tokamak Department during the last few weeks including signing Procurement Arrangements, progress on first wall qualifications, and important developments related to magnet conductors.

Related to Procurement Arrangements, five additional Arrangements related to the Tokamak were completed and signed in June for: the poloidal field coils 2, 3, 4, 5, and 6 (signed with Europe); the toroidal field conductor (signed with the US); the upper ports and divertor dome (signed with the Russian Federation); and the divertor outer target (signed with Japan). This is an important accomplishment for the project and the Tokamak Department. To date, the credit value of all signed ITER Procurement Arrangements is ~880 kIUA which is approximately 30 percent of the total ITER credit. This is very good progress!

Several additional Procurement Arrangements are in the final stages of development and are expected to be ready for signature in the coming months. The most important of these is the Vacuum Vessel Procurement Arrangement. This is linked to the design review where the modified reference vacuum vessel design and the alternate design of the vacuum vessel 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 integratin of Edge Localized Modes (ELM) and vertical stability coils. 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 ITER Organization as to which design to pursue.

Another important development relates to qualification of blanket components. First wall qualification mockups 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 12,000 cycles have been successfully completed. Qualification mockups from Chinese, Russian Federation and Japanese Domestic Agencies are being tested at ~0.87 MW/m² at the Sandia National Laboratories in Albuquerque where ~4,000 cycles have been completed. The European and US mockups 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 Toroidal Field Conductor Procurement Arrangement by the US, as I mentioned above; a successful test at the SULTAN facility of the first Chinese toroidal field conductor sample using Nb3Sn strands cabled and jacketed in China; strand production for the toroidal field conductor commenced at the Kiswire company in Korea and the completion of building construction on the Japanese toroidal field and central solenoid conductor jacketing line in Kita Kyushu. At the time of writing, Japan has already produced about 20 tonnes of Nb3Sn strand for the toroidal field coils! This is about 5 percent 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!