The launch of the largest fusion reactor on the planet has been delayed for a decade. Here are the reasons for the ITER rupture

• The original ITER itinerary assumed that the first plasma experiments would begin in 2025.

• The new ITER calendar sets the reactor’s start-up date at 2035.

Although the ITER project (International Thermonuclear Experimental Reactor) was conceived in 2006 and officially launched in 2007, the start of assembly of this titanium experimental fusion reactor has not yet begun until the end of 2020. The original route proposed by EUROfusion, the organization responsible for promoting and supporting the scientific research needed to implement the European nuclear fusion plan, called for the machine to be completed in 2025.

But that same year, another important milestone occurred: the first plasma tests began. Three years later, in 2028, ITER engineers would begin low-power tests with hydrogen and helium, and in 2032, the first high-power experiments with those two gases would begin. Finally, in 2035, ITER would be able to conduct high-power tests with deuterium and tritium. And in 2040, the experimental reactor would demonstrate the energy efficiency of nuclear fusion. Ultimately, it wouldn’t happen.

The first plasma tests are planned for 2035

ITER’s first major failure occurred in February 2022. The French Nuclear Safety Authority (ASN) identified several violations of a purely technical nature in the vacuum chamber sectors, which forced the ITER organization to react as it should have: to create a working group to satisfy additional requests from ASN and continue assembly of the reactor tokamakAt the end of April of that year, the ITER team submitted their technical proposal to ASN, and reactor assembly continued as usual.

Assembling such a complex machine as ITER is not at all easy. The vacuum chamber weighs 8,000 tons, is made of stainless steel and boron, and must remain sealed. Its assembly forced engineers to take extremely tight local tolerances of 0.1%and the chamber has a very complex shape and uses sheets up to 60 mm thick. To solve the assembly problem, technicians had to resort to the latest technologies, such as, for example, electron beam weldingthat is, electron beam welding, or the development of artificial intelligence models specifically designed to identify defects in chamber welds.

In 2022, ITER officials expected the route originally proposed for the experimental fusion reactor to undergo some changes, and that’s exactly what was consolidated during the meeting just days ago. It was attended by representatives of all countries participating in the project and fusion energy experts involved in the development of ITER. And, as we expected from the title of this article, the start of operation of the reactor and the first plasma tests will take place in 2035. Exactly a decade later than the original route.

According to those responsible for ITER, the reasons for this time lag are delays caused by the COVID-19 pandemic, which raged very strongly in 2020 and 2021, and, on the other hand, technical problems that arose due to absolutely unprecedented nature a significant portion of the components that need to be finalized for the ITER project to come to fruition. On July 3, ITER Director General Pietro Barabaschi will hold a press conference to announce all the details of the new route for what will ultimately be the most advanced experimental magnetic confinement fusion reactor on the planet. Let’s hope that this time the deadline can be met and the project can finally come to fruition.

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