Extra-large tool on-site assembly with millimetric precision for the 9 ITER Tokamak sectors

ITER Tokamak, currently under construction at the Cadarache site in France, is the largest experimental reactor in the world designed to produce fusion power: with a plasma radius of 6.2 m and a plasma volume of 840 m³

Key figures

800
t

metric tons lifting capacity

0. 1
mm

Positioning precision

16

personnel dedicated solely to the project

A set of tools is being built to ensure the successful handling and precise positioning of hundreds of extremely large components for the Tokamak*

* A powerful magnetic field to confine a hot plasma in the shape of a torus.

The Sector Subassembly Tool (SSAT) developed by Korean, includes two tools. Both tools will be used to pre-equip the nine 40° sectors* of the Tokamak.

* Each Tokamak sector consists mainly of portions of vacuum chamber, heat shielding and two TF coils (superconductor magnets weighing about 400 metric tons).

On-site assembly: the CNIM very large handling capacity

CNIM is responsible for the on-site assembly of this extra-large tool rising 22 m tall and weighing 880 metric tons.

The SSAT’s capability of lifting two 400 metric ton loads will enable it to suspend each Tokamak sector from the top. It will then fit, on both sides, heat shields and two toroidal field (TF) coils (superconductor magnets that will confine the plasma inside the vacuum chamber). This operation will be repeated nine times. The resulting pre-equipped sectors will then be transferred by traveling crane to the Tokamak pit for final positioning.

A tight schedule

Precision to within one millimeter is required in assembling each SSAT comprising three columns, two of which will be on rails to facilitate assembly on both sides of the sector.

The operations are performed in two main phases:

  • mechanical assembly whose final precision is critical,
  • fitting hydraulic and electrical systems for the handling of the system.

For this project, CNIM set-up a dedicated team of 16 people (project manager, methods engineers specialists , safety and quality, a site supervisor, team leaders and operational personnel). These personnel were trained in less than a month to start work on the second SSAT.

The assembly of SSAT 1 (August 2017 to March 2018) has been completed* and operating tests have started. In September 2018, work started on SSAT 2 which has been almost finalized*. Tests were due to be conducted in March 2019. Delivery of the two handling systems is scheduled for the first semester of 2019.

* On March 5th, 2019

 

Positioning to within one millimeter

The first phase is carried out with no load, in order to check that the handling tool moves as planned. The second phase is particularly impressive: each arm of the SSAT is equipped with a 400 metric ton mockup, 14 m tall and 8 m wide, representing a TF coil and weighing about the same as a bus.

CNIM teams ensure that the assembled components are possible with extreme precision, with a tolerance of about one millimeter for the component assembly of the vacuum chamber.

Since the beginning of 2019, CNIM teams have been working in similar project on contract A0, signed in December 2018, requiring the assembly of mechanic components in the Tokamak pit. Delivery is scheduled for the first quarter of 2020.