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Part 2 of 2 Parts (Please read Part 1 first)
This may have been a one-off problem, but it could also have affected all the thermal shield components with Barabaschi saying that they had to assume that it was a wider problem. He explained that “The risk is too high and the consequences of a leaking thermal shield panel during operation are too dire.” He went on to say that it would be to hard to fix the issue on the assembled modules of the pit so “we have to lift out the installed module and disassemble it in order to proceed with the repairs. We are exploring different possibilities, from on-site repair to re-manufacturing in an outside facility, possibly with different pipe attachment options.
According to ITER, the problem found with the vacuum vessel sector was that when the component’s four individual segments were welded together the “deviations from nominal dimensions were more substantial than the specified limit in different locations on the component’s outer shell. “These dimensional non-conformities modified the geometry of the field joints where the sectors are to be welded together, thus compromising the access and operation of the bespoke automated welding tools.”
There had been plans to fix the issue in the assembly pit. However, Barabaschi said that “the thermal shield issue has now changed the perspective … as we need to disassemble the module to fix the thermal shield piping, the question of whether or not to repair the vacuum vessel sector in the pit becomes irrelevant. We have no other solution but to remove it”.
Repair strategies are being refined at the moment with assessments of the impact on timings and cost being drawn up. The vacuum vessel assembly has been placed on hold. ITER said in July of this year that it was already planning to revised its schedules. Most recently, the schedule for first plasma in 2025 and the start of deuterium-tritium operation in 2035. That revision to timings was partly blamed on the impact of the COVID-10 pandemic. Bernard Bigot was the longtime director of the ITER project. He died in May of this year. The revision was said not likely to be agreed until April of 2023. This was decided in order to allow time for the new director general to be appointed and decide on the timetable revision.
The ITER council features representatives from the countries involved in the ITER project. The council met in a hybrid format on the 16th and 17th of November of this year. They also urged that “the ITER Organization and Domestic Agencies to work together to ensure an appropriate project-wide quality culture to prevent any recurrence of such issues”. ITER said that the council members also reaffirmed their strong belief in the value of the ITER mission. They resolved to work together to find timely solutions to facilitate ITER’s success.
The ITER project has had many financial, administrative and hardware problems since its beginning. With some companies working on fusion research saying that they expect to demonstrate working reactor prototypes by 2030, it may turn out that ITER operation in 2035 will be too little too late.