Subscribe options

Select your newsletters:

Please enter your email address:

@

Your email address will only be used for the purpose of sending you the ITER Organization publication(s) that you have requested. ITER Organization will not transfer your email address or other personal data to any other party or use it for commercial purposes.

If you change your mind, you can easily unsubscribe by clicking the unsubscribe option at the bottom of an email you've received from ITER Organization.

For more information, see our Privacy policy.

News & Media

Latest ITER Newsline

  • Bookmark | "ITER: the Giant Fusion Reactor," second edition

    'Is ITER the 'star of science' whose creation has been made possible by humankind's sophisticated mastery of the laws of nature and the powers of technology? Or [...]

    Read more

  • Fusion world | ITER and ASDEX Upgrade in the monastic quiet

    The ASDEX Upgrade tokamak in Germany has been helping to establish the scientific basis for the optimization of the tokamak approach to fusion energy since 1991 [...]

    Read more

  • On site | There goes the long-standing crane

    In October 2014, close to ten years ago, five giant cranes were installed on and around the Tokamak Complex basemat slab. As work progressed to erect the Comple [...]

    Read more

  • Portfolio | Sector repair has started

    Built up against vacuum vessel sector #7, the scaffolding reaches almost 20 metres in height and masks the massive component. Streaks of blinding light, filtere [...]

    Read more

  • Fusion world | Public/private consortium is building the DTT tokamak

    The Divertor Test Tokamak in Italy is creating a new model for engagement with industry in fusion research. ITER helped to pave the way. The Divertor Test Tokam [...]

    Read more

Of Interest

See archived entries

Welding

Cryostat base and lower cylinder are now one

Procured by India, the ITER cryostat is composed of four sections: the base, the lower and upper cylinders, and the top lid. Once positioned inside the assembly pit, the different sections are welded together in order to form the perfectly leak-tight vacuum chamber that will act as a thermos, insulating the ultra-cold superconducting magnets from the outside environment.

The welding of the lower cylinder to the cryostat base began in October 2020 and was completed in the last week of March 2021. ''Throughout this six-month operation we were never outside tolerance,'' says mechanical engineer Vikas Dube. (Click to view larger version...)
The welding of the lower cylinder to the cryostat base began in October 2020 and was completed in the last week of March 2021. ''Throughout this six-month operation we were never outside tolerance,'' says mechanical engineer Vikas Dube.
Protected in a sealed cocoon, the upper cylinder has been in storage on the platform since April 2020. The cryostat base was lowered into the pit in May 2020, followed by the lower cylinder in August. As for the top lid, its 12 segments are being assembled and welded in the Cryostat Workshop.

The first in-pit welding operation—the welding of the lower cylinder to the cryostat base—began in October 2020 and lasted six months, including testing. Like all previous cryostat welding operations, it was performed by India's contractor MAN Energy Solutions (sub-contractor of cryostat segment manufacturer Larsen & Toubro).

Following a first phase of root welding by way of a technique known as "double operator" welding (one working from the inside, the other from the outside), nine specialists continued working simultaneously on the 90 metres of circumference, using more than 1.5 tonnes of filler material in the process.

Distortion monitoring was performed on a regular basis by way of 50 metrology targets distributed on the inner surface of the components. "Because of the heat that the welds generate, deformation inevitably occurs, but we have ways to minimize that. Margins are included by manufacturing design and throughout this six-month operation we were never outside tolerance," says Vikas Dube, a mechanical engineer in ITER In-Cryostat, Cryostat Thermal Shield, Auxiliaries Section.

A weld, however, is not considered final until it is tested. Beginning with visual inspection, the non-destructive examination process implements a series of tests ranging from the simple, like dye penetrant test examination, to the ultra-sophisticated like helium leak tests.

The final check consists of a dimensional inspection that compares the data from the welded components to the data that was recorded before the start of welding, as well as to the requirements from the manufacturing drawings. There again, "everything was within the limits," says Vikas.



return to the latest published articles