ITER

The Iter nuclear fusion reactor that is being built in Saint-Paul-lez-Durance (Bouches-du-Rhône, France) is one of the most ambitious international projects in the energy sector. Upon completion, it will be the world’s largest nuclear fusion reactor. 35 countries are participating in the pro­ject to build the largest ever tokamak (reactor core). The aim of Iter is to demonstrate that nuclear fusion (energy from the sun and stars) can be used as a large-scale energy source to produce electri­city with no CO₂ emissions. However, the construction of this megaproject calls for extraordinary expertise and know-how. There is no place for hesitation, eve­rything has to be planned, calibrated and tested! “We have worked with Cetim on various mechanical enginee­ring projects for many years which is why we approached Cetim’s experts regarding a highly specific welding issue, explained Remi Carrat, head of welding operations. Our objective was to validate the feasibility of the orbital TIG welding method on stainless steel parts and structures planned on drawings. The major difficulties had to do with the narrowness of the welding area, the geometry of the parts and the extreme severity of the tolerancing issues. We wanted to validate several welding options with or without filler metal and at the same time make sure that no distortion exceeds the specified limits.”

Over one hundred tests and fit-up strategies 

To this end, Cetim’s experts prepared and carried out over one hundred tests on models based on various fit-up stra­tegies while ensuring that any distortions during or after treatment were less than the specified limits. “Based on the tests carried out by Cetim, we ultimately reconsidered our approach and added a part to the structure to fine-tune the joining tolerances, added Remi Carrat. The assembly will be installed by “One shot” orbital welding without filler metal.”