Summer works
A new chapter opens
9 Sep 2019
Notice anything? Yes, the giant poster (25 x 50 m) on the temporary wall of the Assembly Hall has been removed. Displaying a cutaway of the ITER Tokamak, it had been installed in June 2016 and, for more than three years, it stood as a reminder of ITER's ambition.
From the tallest heights of the Tokamak Building to the lowest depths of the machine assembly pit, intense activity is underway to prepare for the assembly phase that will officially commence in March 2020.
Little by little, as the bioshield and Tokamak Complex took shape, most of the poster disappeared from view. Its removal in late August marks a first step in the dismantling process that will see the temporary wall that separates the Assembly Hall from the Tokamak Building removed.
The poster's disappearance is just one sign that a new chapter is opening in ITER construction. Throughout the worksite, operations large and small are all heading in the same direction: preparing for the assembly phase that will officially commence in March 2020.
Following Newsline's summer recess (there is no such thing as a "summer recess" on the ITER worksite) the gallery below takes you on a tour of the major operations conducted or initiated in August—from the tallest heights of the Tokamak Building where the first pillars of the crane hall will soon be installed, to the lowest depths of the Tokamak pit where work as delicate as watchmaking is being performed on 5-tonne components.
Where there was once a large cutaway of the ITER machine affixed to the temporary wall of the Assembly Hall there is now ... nothing. Like in a scene out of "2001: A Space Odyssey," what looks like a large black monolith now towers above the Tokamak Building. And—like the monolith in the 1968 Kubrick movie—this one heralds a change in the history of humankind.
Teams do not usually paint a building's walls before completing all civil works. But worksite planners decided this summer to take advantage of the scaffolding that had been erected for concrete pouring to paint wall that stands between the Tokamak and Tritium buildings. Out of sight behind this wall are the pillars that have been erected to support the metal frame of the assembly crane hall.
For years, crane #1 has supported activities in the Tokamak Building from its central location, anchored at the bottom of the machine well. Before the end of the year it will be dismantled to allow for the installation of the metal walls and roof of the crane hall. Once the building has a roof, the temporary lid of the bioshield can be removed and the project will have reached a major milestone on the road to the official start of machine assembly.
On the platform outside of the Tokamak Complex, contractors are assembling two giant crawler cranes—one for each side of the building. These cranes, reaching more than one hundred metres in height, will be used to lift and deliver elements of the crane hall structure to the L3 level of the Tokamak Building.
Teams have been active all summer at the very bottom of the Tokamak pit, in preparation for the installation of the cryostat base. On top of the concrete crown, at the point of intersection with each of its 18 radial walls, contractors are installing a set of 18 metal bearings. (If you look closely you'll see that one has been installed in its socket and protected under black cloth, while—moving in a counter clockwise direction—other interfacing areas are in various stages of preparation.) The pedestal of the cryostat base will be supported directly by the concrete crown, with the bearing allowing for the smooth transfer of horizontal, vertical and rotational forces.
Anchored and bolted in the wall surrounding the cryostat crown, 18 of these 2.5-tonne rectangular steel pieces ("female lugs") will play a key role in transferring horizontal forces to the bioshield structure and protecting the integrity of the machine. Like mortise and tenon, they will match with the "male lugs" welded on the cryostat pedestal, allowing the machine to "breathe" outward, while countering any horizontal displacement. The precision required for the positioning is of the order of two tenths of a millimetre and will be achieved by inserting ultra-thin shims between the male and female lugs.
As a fastening system for the bearings, a steel transition piece is half embedded in the concrete crown during the first phase of pouring. Then, a high-strength top plate (3.5 tonnes of steel) is positioned on the transition piece to receive the bearings with a mechanical blocking mechanism worthy of a Swiss watch. Permitted tolerances for the different elements of the fastening system will be less the 2 mm.
Workers engaged in the installation of the cryostat support bearings call them "jewels." And when they are done with the day's operations, they wrap the 5.4-tonne component in a black, velvet-like fabric as befits a precious stone or delicate clockwork. Eighteen perfectly polished, chrome-plated semi-spherical bearings anchored deep in the Tokamak support crown under the pedestal of the cryostat will act like ball-and-socket joints to allow the smooth transfer of the tremendous forces generated during machine operation. (Read more about the bearings here: https://www.iter.org/newsline/-/2688)
ITER Organization contractors are managing equipment installation in the cooling tower zone. The infrastructure of the zone was provided by Europe; the design and fabrication of heat rejection equipment is part of India's procurement contributions to the ITER Project.
Above the hot basin, contractors are supervising the installation of large lengths of piping. Over 5 km of piping is necessary to receive cooling water from the machine and plant systems and cycle it through the cooling water system, including 20-metre-tall cooling tower cells.
When we left the sector sub-assembly tools in late July (https://www.iter.org/newsline/-/3312) the 360-tonne mock loads had just been attached to the first tool, SSAT1. Both loads have been rotated inward and the tool has performed as expected. Later this month, the mock loads will be transferred to SSAT2.