you're currently reading the news digest published from 09 Dec 2019 to 16 Dec 2019



ITER control room | A new ergonomic design

Thanks to a recent design decision, ITER's main control room can be built more ergonomically, while minimizing cost. The control room will house the computer systems and displays that make it possible to pilot the ITER Tokamak, and configure and monitor the many systems that make its operation possible. A year ago, the ITER Organization made the decision to locate a main control room in a conventional control building, while locating a fallback control room in a hardened nuclear-safe building to use in the event of an earthquake or other extreme events. The new design allows for a more flexible and efficient environment for the operators to work 24/7, avoiding the bunker-like construction needed to adhere to nuclear safety standards. Nuclear-safe buildings are gloomy places to work—windowless, with thick layers of concrete to withstand earthquakes, floods and blizzards. ITER will have a more efficient and inviting control room for everyday use. A day in the life Operating an experimental tokamak is a dynamic process. Unlike nuclear or chemical plants, which run for long periods in steady state, the ITER Tokamak will run in pulses, which typically last tens of minutes. When a pulse stops, scientists analyze the data, discuss what happened during the pulse and make decisions about how to adjust subsequent pulses. 'It's important for scientists and engineers to be able to interact and discuss without disturbing operators from their important tasks,' says Ken Blackler, Deputy Head for Operations. 'To facilitate these dynamics, we've divided the room into two different spaces: one area for machine operators, the other for scientific research staff. There will be no physical barriers separating the two groups, but careful design will be used to allow communication without causing interference.' To maximize the use of the unique ITER experimental device and its research potential, planners expect to run the machine for two to three shifts a day. 'People will be coming from all around the world to run experiments on the machine, and they'll probably be working long hours while there to make the most of their time,' says Blackler. Outside the control room there will be a refreshment area and open spaces. People working long shifts can quickly step out into the dining area during a pause to have a meal without going too far from the action. Scientists can move into the open spaces to hold discussions on the progress of experiments without disturbing colleagues. The control building will also have offices and meeting rooms to prepare for the next shift and manage maintenance on the plant. The design will also take into consideration the fact that scientists can't always travel across the world to be present for a given experiment. To accommodate people working remotely, the current thinking is to have remote participation rooms in each Member country, with high-quality video equipment and direct access to the results. 'The data displays should be equivalent to being in the actual control room, so remote participants can feel like they're part of the experiments and contribute fully,' says Blackler. Ergonomics and human factors ITER benefits from a number of studies it commissioned in the past on human factors and ergonomics, which help ensure people stay focused and help prevent human error. Three of the most important considerations are lighting, temperature, and noise levels. 'The architects will perform a detailed study of the acoustics in the planned building and the control room,' says Blackler. 'They look at the walls, the windows, the surfaces, and all the materials used, then they calculate how the sound will reflect and reverberate. They need to factor in the number of people expected in the room and take into account the noisy equipment outside, such as cooling towers, and make sure the sound from outside gets filtered.' Because the main control room will sit in a conventional building it can have windows—giving operators a reference to keep their biological clocks in sync, and helping to reduce the impact working shifts might have on circadian rhythms. The number of people in the room and their roles are important considerations not only for noise, but also for seating arrangements. A normal nuclear or chemical plant may have no more than 10 people in the operating room at a time. At ITER, the peak occupancy is far higher. 'There are so many different systems on a tokamak,' says Blackler, 'systems to enable and produce the plasma, to cool the components and to take scientific measurements—and each of them will need an operator and one or more scientists to look at the data.' The design will take into account how all those people communicate and where they sit. 'We will concentrate groups of people with common interests,' says Blackler, 'then locate those groups close to other groups, all depending on the need for communication with each other.' Designers will also tackle the question of how best to display the state of the facility, using colour and graphics in the most ergonomic manner so that the operators can concentrate on the signals most important to performing their work. Such human-machine interfaces are designed by human factors engineers, who study the tasks to be performed in order to generate the most efficient and clear displays for the software developers to implement. The basis of all design considerations is: how to create an environment conducive to operating the ITER Tokamak to its maximum. 'Today we're looking at the building layout, the number of windows, the height and shape of the room, and how you get in and out,' says Blackler. 'Next year, we'll look at the detailed ergonomics—furniture layouts, exactly where people sit, the types of desks, how the desks will be laid out, and the types and positions of the screens on the walls.'

Electron cyclotron system | First power supply delivered

Turning the key in your car causes an electrical current to be sent from your battery to your car's engine, where a small electrode (or 'spark plug') generates an electrical discharge to ignite the fuel and make your engine 'go.' ITER has an equivalent—except the spark to make the plasma 'go' is created by sending high-power microwaves (equivalent to 6,000 kitchen microwave ovens) into the vacuum vessel. All of this power creates the initial flash—like the spark plug in your car engine—that initiates each plasma pulse. As you can guess, starting the plasma in ITER is more complex than starting your car, which requires only a battery, cables, a spark plug and a switch. ITER's 'battery' is a combination of several high voltage power supplies (up to 55 kV) and a host of gyrotrons (ITER's equivalent of the microwave oven). The electron cyclotron system transmits the microwaves to the vacuum chamber using circular waveguides (50 mm pipes) followed by a series of mirrors that focus the microwaves to the centre of the vacuum chamber to create the initial 'spark.' Over the past two years, the ITER partners have made significant progress toward supplying the components needed to make ITER First Plasma. Most noticeable is the progress in manufacturing the first set of high voltage power supplies and all eight of the powerful 1 MW microwave sources (gyrotrons) used for First Plasma. Now we are one step closer, with the delivery of the first set of high voltage power supplies. There will be a total of five power supply sets used for First Plasma coming from Europe, India and Japan, with this first set delivered by the European Domestic Agency (F4E) and its supplier Ampegon (Switzerland). The power supplies are large—a single set weighs approximately 40 tonnes and requires about 250 cubic metres on two floors of the ITER Radio Frequency Building. Although massive, these power supplies represent the state of the art in high voltage power supplies, with the ability to regulate the output voltage in small steps within less than a microsecond. This is achieved by placing nearly 100 smaller power supplies in series, and switching on and off each supply to provide a controlled ramp-up of the voltage from 0 to 55 kV in roughly 100 milliseconds, then maintain a stable voltage for up to one hour. More rapid control is possible: for example, the power supplies can drop to 0 V in 10 microseconds in the event of a fault in either the gyrotron or downstream toward the machine. These smaller power supplies are made from solid-state transistors that operate with greater than 97% electrical efficiency, with the aim being to maximize the power given to the plasma. Upon arrival in October, this first power supply set was put in storage—but they will remain there for only a short time until the Radio Frequency Building is finalized on site. This coming summer, Ampegon and European Domestic Agency experts will arrive to install the power supplies. First commissioning will occur in early 2021; then the power supply will be used to power the first set of gyrotrons by the end of 2021. All of the First Plasma power supplies and gyrotrons should be installed and commissioned by mid-2024, in time to perform integrated commissioning and prepare for the first 'spark' in 2025. Read a report on the first-delivered power supply set from the European Domestic Agency here.

Sector assembly tools | Commissioning with load completed

The final test operation for the twin sector sub-assembly tools—commissioning with load—was completed in the Assembly Hall on 26 November. With the completion of commissioning, these giant tools are now cleared for operation in 2020, when the first 440-tonne vacuum vessel sectors will be delivered to ITER. The tools will suspend the sectors vertically in their centre while they are pre-assembled with toroidal field coils and thermal shield panels prior to transport to the assembly pit. The final commissioning activity was carried out using test loads of steel and concrete. Not only were these loads representative of the weight of toroidal field coils (360 tonnes), they also reproduced the coils' general shape and centre of gravity. During full load testing—which was carried out between July and November on first one tool then the other—the loads were secured on the tools' lateral wings and rotated inward, demonstrating that they are working according to specified requirements. With testing completed, the test loads have now been removed from the tools and transferred to a laydown area. They will be used again in the months to come—this time to test the upending tool, which is designed to raise ITER's largest components (vacuum vessel sectors and D-shaped toroidal field coils) to an upright position.

Poloidal field coils | A decisive year ahead

Two poloidal field coils—PF6 and PF5—must take their place in the Tokamak pit before the sectors of the vacuum vessel are lowered into place. The final activity on these magnets—cold testing—is planned next year in the European winding facility at ITER, where work is also underway on the production of a third ring-shaped coil, PF2. The year that sees the start of ITER machine assembly—2020—will also be a turning point for the European effort to procure five of ITER's six poloidal field coils*. From completing the on-site winding facility in 2012 and the installation of tooling, to the launch of qualification activities, the realization of the first production double pancake, and finally the stacking of the first coil... the road to fabricating some of ITER's largest and most technical components has been both challenging and rewarding. 'Everything about the production of these first-of-a-kind components has been challenging,' says Byung-Su Lim, who leads the ITER Poloidal Field and Correction Coil Section and interacts close with the European Domestic Agency team and contractors. 'Configuring the tooling and learning to operate it, qualifying every important production step, carrying out the manufacturing with accuracy and within tolerances, documenting every stage, working to deadline—teamwork has been a key element at every step of this process. All parties are looking forward to the important milestones that will be achieved next year.' The four largest poloidal field coils—PF2, PF3, PF4 and PF5—will come off the fabrication line in Europe's winding facility at ITER while a fifth, PF6, has been manufactured in China by the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP), under the terms of an agreement signed with the European Domestic Agency. In order of completion: PF6: The heaviest of the ring coils (although not the largest) was completed in China in September. Because it is the first poloidal field coil to be lowered into the pit, it will also be the first to be cold tested. Cold testing, which will be carried out in the European winding facility on site, will require approximately three months, counting time for the cooldown to 80 K and subsequent warm up and electrical testing at various stages. PF6 is expected at ITER early next year. PF5: This is the first coil to be produced by European contractors in the on-site winding facility. Eight double pancakes were produced for this coil and individually impregnated; now the winding pack (with all pancakes stacked and joined) is nearly ready for impregnation (photo above). During impregnation: the mould is first heated to 90 °C for 96 hours to dry the coil insulation and then cooled to 50 °C; roughly 2,200 litres of resin are injected over a period of 60 hours; the resin 'gels' for 10 hours at 110 °C; the resin "cures" for 60 hours at 140 °C. Pre-checks, mould conditioning and impregnation are scheduled to begin in February. Following cleaning, dimensional testing, and electrical testing, PF5 will be next in line for cold testing in a cryostat that has been assembled on site to match its dimensions (ø17 m). PF2: The production of PF2 is well advanced—the six double pancakes required to build the PF2 winding pack have been wound and four have been impregnated. PF2 fabrication is benefitting from lessons learned on PF5 and—as it shares the same diameter—the coil is being manufactured on the same tooling. The projected finish date for PF2 is September 2020. PF3 and PF4 are much bigger coils (ø24 m). With the winding activities completed for PF2, contractors have begun to expand the tooling to these new dimensions; work to adapt other tooling stations will follow. The commissioning of the winding line will begin in April. Next year, the first-completed coils will be removed from the winding facility and placed on temporary supports inside of the Tokamak pit (PF6 in August; PF5 in November). *The Russian Domestic Agency is procuring one of the poloidal field coils, PF1, which is installed last in the poloidal field coil assembly sequence. See a recent report on the fabrication of PF5 and PF2 on the European Domestic Agency website.

Image of the week | Crane gallery framed out

It took only nine days to install the structural modules that top the frame of the crane gallery. As one year ends and another begins, the construction teams will turn to cladding. In planning the five consecutive lift operations, the European contractors* in charge of the operation had to work around wind and rain, as well as other construction activities in the immediate vicinity. Two massive crawler cranes were required, with booms extending over 100 metres and lift capacities of 600 and 650 tonnes respectively. The complete roof structure—20 tall pillars and roof modules included—weighs approximately 2,000 tonnes. Once covered over with steel and metal cladding, the crane hall will look exactly like the Assembly Hall. Once the temporary wall between the two buildings is removed, the overhead cranes will travel back and forth through undivided space, as they deliver machine components to the Tokamak pit. Activity is underway now to create the necessary connections between the different segments of rail. *The lifting and berthing operation was performed under the responsibility of the European Domestic Agency Fusion for Energy. It was coordinated by architect-engineer Engage and implemented by contractors VFR (overall responsibility and coordination), Martifer (manufacturing and installation of the steel structure) and Vernazza (lifting operations).


Season's Greetings

The offices of the ITER Organization will be closed from 23 December through 3 January included, although work will be proceeding on the construction site. The year 2020 promises to be a special one for the ITER Project, as some of ITER's largest components arrive on site and the carefully orchestrated assembly phase for the ITER machine and plant officially kicks off. Newsline will continue to cover every aspect of ITER and the fusion world, from progress on the construction site in southern France and in component manufacturing in factories and laboratories on three continents ... to meetings, conferences and scientific breakthroughs throughout the world. See you in January. We shot a similar end-of-year photo in 2017: click here to compare the two images. View the ITER Organization's e-card here.


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