Laser Trackers Perform Critical Role In Tokamak Vacuum Vessel ‘Big Lift’

“THE BIG LIFT” as it is called is the first lifting that took place at the ITER construction site located in Cadarache, France of the first sector of the Vacuum Vessel (VV) that completes the first piece for the construction of an experimental reactor for nuclear fusion.

The highly complex handling task lasted more than a one and a half days and allowed the first sector of the Vacuum Vessel , with its 1,380 tonnes, to arrive inside the Tokamak Pit.

GEATOP S.r.l., a company specialized in applied metrology and dimensional inspection and a partner of Ansaldo Nucleare, support the DYNAMIC group in the assembly of the Tokamak, for this important milestone teamed up with the ORYS company, working at the forefront of lifting and handling monitoring of the sector, using critical software and instrumentation for this important achievement.

An extraordinary challenge for metrology in fact. Due to a study carried out in the preliminary stage through virtual simulation, GEATOP were able to carry out the metrological control activity in the field through the use of more than 30 CatEyes and SMRs, detected simultaneously by three Leica Absolute Tracker AT960 LT, obtaining a quality result in a short time.

The developed know-how was developed within the Spatial Analyzer measurement software that allowed GEATOP to drive the alignment to the final position of the sector, with a cycle time between measurement, analysis and displacement calculation, of less than 2 minutes.

The entire metrological control operation achieved a landing site positioning result below 0.1 mm and with a final Sector positioning error below ±0.5mm.

The “piece” of the ITER machine lowered represents one-ninth of the toroidal plasma chamber. It is a modular assembly, formed from one 40° vacuum vessel sector fitted with silver-coated thermal shields, and two D-shaped vertical superconducting electromagnets called toroidal field coils. Eight other similar assemblies will form the complete chamber and surrounding toroidal field coil superstructure. The ITER team had been actively preparing for this important lift operation for many months. The creation of the modular assembly took place on specialized tooling in the ITER Assembly Hall.. The components were first lifted to vertical on a specially adapted ‘upending’ cradle and transferred to a standing tool capable of docking the vacuum vessel sector in its centre and rotating the other components in on its wings. Dedicated rigging elements—veritable tools in themselves, capable of controlling the load’s centre of gravity and controlling the rotation of the component to align with the waiting supports in the Tokamak pit—were tested singly and in tandem.

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