Small steps, big results
Over the last 36 hours, another vacuum vessel sector was inserted into the ITER tokamak assembly pit. Five of nine sectors—over half of the plasma chamber—are now in place.
Great journeys are comprised of small steps. The transfer of sector module #4 into the ITER tokamak pit this week involved a meticulous lifting protocol that featured nine hours of pre-lift tests and verifications, 12 hours of transfer time to the pit, and another 15 hours of ultra-precise landing manoeuvres to ensure the component reached its final destination.
“This lift was successful because of the excellent work being done at every step of the operation,” says Mathieu Demeyere, the principal construction manager who supervised the operation for ITER. “The level of preparation and the reactivity of the teams meant we could adapt to the different challenges that arose during the lift and complete another safe landing.”
The pre-lift protocol was launched at 6:00 a.m. on Tuesday 26 May when metrology was confirmed and operators slowly increased the tension in the lines connecting the sector module to the overhead cranes. The next steps included a 90 mm test lift that allowed certain sensors to be removed. Then, the lashing securing the sector module in the sector sub-assembly tool was released and the module was given another test lift to 500 mm.
After a final metrology check confirmed there were no clashes, the module was extracted just before 3:00 p.m. on Tuesday and guided carefully to the tokamak pit and lowered by the overhead cranes. It arrived 500 mm above its final landing position at 3:00 a.m. on Wednesday 27 May. Then came the work of reconnecting sensors, installing lashing, and verifying again there were no clashes.
The final hours were spent aligning the sector module with its gravity supports, bringing it into contact with the TIPI tables (for toroidal field coil in-pit installation tool), and tightening the bolts before its full weight was finally released from the overhead cranes shortly after 6:00 p.m.
Like its predecessors in the pit, sector module #4 landed ahead of the schedule foreseen in the ITER Baseline, as lessons learned continue to contribute to greater efficiency and time saved. With sector module #7, it took 7.4 months to complete the assembly of the module from the time the vacuum vessel sector arrived in tooling to the time it landed in the tokamak pit in April 2025. With sector module #4, this process was reduced to 5.5 months.
“There is a learning curve effect that was expected but it is materializing more quickly than anticipated and we are seeing the results right now,” says Nicolas Sapet, the ITER project leader for sector module sub assembly. “The progress is thanks to the lessons learned from the experience acquired by the teams.”
This latest installation milestone brings the plasma chamber to more than half complete. Vacuum vessel sectors #4, #5, #6, #7 and #8 now stand aligned side by side in the tokamak pit. A sixth sector module is scheduled for installation this summer on the opposite side of the machine, and a seventh is expected before the end of the year.
