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> Completed projects > Tests of locking mechanisms for ITER

Tests of locking mechanisms for ITER

Induction heating of the bolt samples. A total of 15000 thermal cycles were performed between 100 and 200 °C
Induction heating of the bolt samples. A total of 15000 thermal cycles were performed between 100 and 200 °C
Different kinds of fasteners are used in ITER for the fixation of functional and structural in-vessel diagnostic components. The fasteners should retain initial tightening preload in vacuum under neutronic irradiation, thermal cycling and vibrations. These conditions can lead to incidental unscrewing of some bolts and nuts if they are not locked properly. They shall be equipped with some locking features which in most cases shall be remote handling compatible. One of the candidates on a role of a locking mechanism is Spiralock type thread. Custom designed so called First Wall Samples (CuCrZr) with M16 fine thread and standard M8 bolts (316L) were the subject of our studies. ITER-like thermal cycling alternating with vibration tests were applied to the components. Fasteners' loosening was monitored via periodic torque audits. For comparison with the Spiralock thread, tests with normal metric threads were also performed under the same experimental conditions.

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Vibration test equipment developed by GEMS
CuCrZr first wall sample
316L M8 bolt galvanized with copper
Thermal simulation of the induction heating cycle was also performed, in order to reach the prescribed temperature difference between the bolts’ head and thread

Latest news

Jigs for the alignment of the tangential and normal outer vessel steady state magnetic sensors
Project completed!
[11 January 2022] The jigs were shipped to the ITER Organization to Cadarache, France in mid-January 2022 and they will be used for mounting of the sensors from April onwards.

Major references

GEMS Engineering is deeply involved in and fully devoted to the success of the ITER project. As a result, our main reference works are in connection with ITER, and - more closely - to its diagnostic systems.

The ITER device, currently under construction in the south of France, will study the potential of controlled nuclear fusion to provide energy for mankind. In order to study the behaviour of this device, a set of monitoring systems (referred to as Diagnostics) is required. These Diagnostics will provide the information required to understand the performance of the device.

Infrastructure development for in-vessel diagnostic signal transmission
Infrastructure development for in-vessel diagnostic signal transmission
The Erosion Deposition Monitor under the divertor dome in ITER
The Erosion Deposition Monitor under the divertor dome in ITER
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