What weighs more than 700 small cars, stands taller than the Louvre Pyramid, and can embrace the cross-section of the ITER Headquarters building in its wingspan? The largest tool in ITER's assembly arsenal. This giant yet highly precise piece of technology has passed factory acceptance tests in Korea and is ready to take to the sea.
A milestone achieved at Taekyung Heavy Industries (THI) in Changwon in early May brings the ITER Project one step closer to the start of its tokamak assembly phase.
The first vacuum vessel sector sub-assembly tool (SSAT) has demonstrated all functional performance in factory acceptance tests conducted in the presence of observers from the ITER Organization and the Korean Domestic Agency. The tool has now been taken down and packed for shipment to the ITER site—over 800 tonnes of metal plus auxiliary components packed into 90 shipping crates that will ship in five batches.
The first batch, containing lower elements plus all hydraulic activators and accessories, shipped this weekend and is expected to arrive on 30 June.
From their location in one area of the ITER Assembly Building, two identical SSAT tools will support the weight of 440-tonne vacuum vessel sectors within the triangle formed by three large columns, as lateral wings slowly rotate thermal shielding and two 310-tonne toroidal field coils into place. The challenge of the operation—reflected in the careful design
and prototyping phase of the tools—is in assembling large and very heavy components to extremely unforgiving tolerances. (More on the tool's hydraulic system and actuators here
The first of the twin tools was manufactured in segments by the Korean contractor THI and then assembled completely at the factory for inspection and testing (see the video
in this issue). Lessons learned on the realization of the first tool will serve in the fabrication of the second, which has started now in Korea.
In a ceremony held on 11 May the head of the Korean Domestic Agency, Kijung Jung, celebrated the completion of the first tool: "This is a step forward for procurement efforts for ITER in Korea and for the project as a whole. Like all ITER Members, Korea's participation in ITER contributes to our industrial and scientific capabilities and positions our nation to be a future player of consequence in the promising domain of fusion."
The months ahead will be a busy time in the Assembly Hall and adjacent Cleaning Facility at ITER. On the reinforced slab that has been prepared for the SSAT tools, contractors have already embedded anchor bolts onto which the rail base plates will be mounted when access to the Assembly Hall becomes possible in mid-August. A few metres away, in the Cleaning Facility, a large storage area is in the planning stages for the components that will arrive starting late June from Korea. In the shape of a 10-metre tall enclosed "box," the storage unit will protect the SSAT components from ambient dust and the other activities underway in the building. When access is possible for the first assembly operations (mid-September), Taekyung Heavy Industries, as the main contractor, and subcontractor CNIM (France) will proceed by first installing the rail components on the basemat and then moving on to assembly of the structural elements of the tool.
Three months will be necessary, meaning that by the end of the year the first SSAT tool will be standing tall in the Assembly Building.
The largest tools of the Assembly Building
In this image, the Tokamak Building has been finalized and the temporary wall that now closes off the Assembly Building has come down. We see the 170-metre crane bay, with the machine assembly area in the background. The vacuum vessel subassemblies will be picked up from one of the two SSAT tools and delivered by overhead crane for installation.
Stands on three legs, has wings
The sector sub-assembly tool is seen here in its construction pit at Taekyung Heavy Industries during factory acceptance testing. In dark grey are the dummy load sets (27 tonnes each) that were used to check that the tool performs required movements without jamming or malfunction and that the required alignment can be reached.
SSAT #1: successful manufacturing, assembly and testing
On 11 May, a ceremony was held in Changwon, South Korea, to mark the end of the factory acceptance test phase for the first sector sub-assembly tool. That same evening, workers began to disassemble the tool for shipment to ITER.
First component batch has shipped
Disassembled over the weekend, the first SSAT tool will ship in five batches. The first is already on route.
Dedicated assembly area
22 metres high, 800 tonnes—contractor Taekyung Heavy Industries started assembling the first SSAT tool eight metres below ground in a dedicated "pit." A sliding warehouse structure was on hand to cover the work in progress in the case of inclement weather.
A giant, seen from above
Three main columns will support the weight of each vacuum vessel sector while the lateral wings rotate inward ... ever so carefully ... to bring segments of thermal shielding or toroidal field coils into alignment with millimetre-level tolerances.
The tool and its full charge = 2,000 tonnes
The tool's inboard and outboard columns were machined in sections and bolted together, with interior ribs that add structural strength. All told, the tool is designed to support the weight of one vacuum vessel sector, two toroidal field coils and thermal shielding ... or 1,200 tonnes. The tool itself weighs another 800 tonnes.
A vacuum vessel sector is seen suspended within the triangle formed by the three main columns. The tool will arrive in 90 shipping crates (five shipments) between June and August; installation activities will kick off in the Assembly Building in September, with the installation of the base rails; and the complete tool will be in place by the end of the year.