°ÄÃÅÁùºÏ²Ê¸ßÊÖ

During a recent tour of industrial contractors and sub-contractors, the head of the Korean Domestic Agency Kijung Jung and staff members were able to photograph manufacturing progress on two procurement packages that fall under Korean scope—assembly tooling and the °ÄÃÅÁùºÏ²Ê¸ßÊÖ thermal shield.   The group first visited Taekyung Heavy Industry in Changwon, where manufacturing activities are underway on the Sector Sub-Assembly Tool. Six stories high, made of 800 tonnes of steel each, two Sector Sub-Assembly tools will work side by side in the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Assembly Building to equip the nine sectors of the vacuum vessel before their transfer to the Tokamak Pit. The contractor has finished all of the roll-bending procedures for the main columns of the first tool and has begun welding the first segments of bended rolls (pictured). Taekyung is a sub-contractor to SFA Engineering, which is main supplier of the Sector Sub-Assembly Tools.   The team from °ÄÃÅÁùºÏ²Ê¸ßÊÖ Korea stands in front of a 40° sector of the °ÄÃÅÁùºÏ²Ê¸ßÊÖ thermal shield. The Director of the Korean Domestic Agency, Kijung Jung, is fourth from right. The second visit was to Sam Hong Machinery in Changwon to verify manufacturing progress on the °ÄÃÅÁùºÏ²Ê¸ßÊÖ thermal shield, which will be installed between the vacuum vessel and the cryostat to minimize heat loads transferred by thermal radiation. Sam Hong Machinery, which is working under contract with the main supplier SFA, is responsible for welding, machining, silver coating and pre-assembly activities. The fabrication is progressing simultaneously on all nine 40° thermal shield sectors.   Next month, the cooling tube will be welded on the inboard section of sector #6—one of the first components of the thermal shield scheduled for delivery to °ÄÃÅÁùºÏ²Ê¸ßÊÖ. A special facility has also been constructed at Sam Hong Machinery for silver coating operations. Coating baths measuring 9 x 3 x 6 metres—the largest in the world—will be used to apply low-emissivity silver coating to both sides of the shield plates. Silver coating of the first sectors will begin in November.

Like a lunar module checking its landing coordinates one last time, the cylindrical tank with six metal feet hovered silently over the Tritium Building. The event was significant. Part of °ÄÃÅÁùºÏ²Ê¸ßÊÖ's water detritiation plant system, the tank had the honour of being the first component to be installed in the Tokamak Complex. Both a "captive component" (once installed, it cannot be removed) and a Protection Important Component (PIC), the holding tank that was lowered into the Tritium Building on the morning of Tuesday 29 March is part of a set of four that will play a key part in the detritiation process of the °ÄÃÅÁùºÏ²Ê¸ßÊÖ installation.   In the Tokamak Building, tritium needs to be removed from the atmosphere of different "spaces" such as the vacuum vessel, the port cells, the neutral beam injector, etc.   Both a "captive component" and a Protection Important Component (PIC), the holding tank will play a key part in the detritiation process of the Tokamak Complex. Tritiated air is extracted and passed through a shower (the "scrubber columns") to become tritiated water, which is stored in holding tanks. Following storage, the tritiated water is submitted to electrolysis to recuperate the highly valuable tritium in the °ÄÃÅÁùºÏ²Ê¸ßÊÖ fuel cycle.   Three years ago the design of the tanks was launched and progressed in parallel with the design of the finer details of the Tritium Building—such as defining the precise position of the anchors for the tanks.   As interfaces perfectly locked into place, Tuesday's operation marked an important and symbolic moment in the progress of construction.

The °ÄÃÅÁùºÏ²Ê¸ßÊÖ cryolines are a system of complex, multi-process, vacuum-insulated pipes that connect cryogenic components in the Cryoplant and Tokamak buildings—some 3.5 kilometres of piping in all. Their function is to provide helium at 4.5 K and 80 K to the machine's superconducting magnet system, the thermal shields and the cryo-vacuum pumps.   On a recent mission to India, the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Vacuum Section reviewed one of two full-size prototypes of the cryoline sections that will feed the torus cryopumps. Pictured here at the Institute of Plasma Research in Gandhinagar are Biswanath Sakar (°ÄÃÅÁùºÏ²Ê¸ßÊÖ India) and Eamonn Quinn (°ÄÃÅÁùºÏ²Ê¸ßÊÖ vacuum team).

In the 257-metre-long Poloidal Field Coils Winding Facility, the newly installed tools occupy only half of the building's length. This leaves a lot of free space that can be used for other purposes, such as storing four 155-tonne, 47-metre long girders for the Assembly Hall overhead cranes. Manoeuvring such long and heavy pieces of steel into storage is a slow and delicate process. Every movement of the 32-wheel modular trailer that carries each beam must be carefully planned and executed with utmost precision.   Twice last week, the operation was performed to perfection: the two girders that were delivered on 18 and 25 March are now safely stored inside the winding facility; two more will join them in April.   The storage will be of relatively short duration, however, as the girders and their trolleys will be installed in the Assembly Hall in June.

At 2:21 a.m. on Thursday 18 March, a convoy carrying a load as long as four buses passed the gates of the °ÄÃÅÁùºÏ²Ê¸ßÊÖ site. The load was the first of four girders for the Assembly Hall cranes (provided by Europe) to be delivered in the weeks and months to come. Manufactured by REEL in Avilès, on the Atlantic coast of Spain, the 155-tonne, 47-metre long steel beam had travelled four nights along the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Itinerary instead of the standard three.   Due to the length and weight of the convoy (67 metres, 330 tonnes) the transport took place at a leisurely 2 to 5 kilometres per hour. Negotiating curves and roundabouts, passing bridges and cutting across the A51 thruway was a particularly complex task whose preparation required 3D modelling.   However delicate, the task was performed to perfection by all actors involved—global logistics provider DAHER, Agence Iter France, and the French authorities who provide a large security detachment to every °ÄÃÅÁùºÏ²Ê¸ßÊÖ convoy.   View the image gallery below.

By Raphael Rosen The world of fusion energy is a world of extremes. For instance, the center of the ultrahot plasma contained within the walls of doughnut-shaped fusion machines known as tokamaks can reach temperatures well above the 15 million degrees Celsius core of the sun. And even though the portion of the plasma closer to the tokamak's inner walls is 10 to 20 times cooler, it still has enough energy to erode the layer of liquid lithium that may be used to coat components that face the plasma in future tokamaks. Scientists thus seek to know how to prevent hot plasma particles from eroding the protective lithium coating. Physicist Tyler Abrams has led experiments on a facility in the Netherlands called Magnum-PSI that could provide an answer. The research, published in Nuclear Fusion in December 2015, found that combining lithium with the hydrogen isotope deuterium substantially reduced the erosion. Abrams conducted the research as a doctoral student in the Princeton Program in Plasma Physics substantially based at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL). He currently is a postdoctoral research fellow at General Atomics. The research was funded by the DOE Office of Science. Read the full article on the PPPL website.

The European Domestic Agency has developed a new numerical model that represents °ÄÃÅÁùºÏ²Ê¸ßÊÖ's 18 toroidal field magnets with remarkable detail. The model will be used to compute the magnetic fields produced by the coils and the resulting electromagnetic forces on the magnet system, which are the result of the interaction between electrical currents and the magnetic field. "It's the first time we have a complete model of the entire °ÄÃÅÁùºÏ²Ê¸ßÊÖ toroidal field system to such a level of detail," says Gabriele D'Amico, the technical support officer responsible for the development of the model. "The level of complexity of the tool is outstanding. For example there are more than 1,500 bolts connecting the different pieces of the toroidal field magnet system, and the model allows us to predict the behaviour of each one during operations." The model, which took six months to develop, will allow the European Domestic Agency and the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Organization to simulate different scenarios using an approach that integrates the 18 coils and all major subsystems. Scientists will be able to study the occurrence of an electrical fault during operation, for example, or the impact of possible misalignment in the assembly of the coils on the behaviour of the whole system. Read the full article on the European Domestic Agency website.