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Like in a game of musical chairs—albeit in slow motion and at a massive scale—components in the Assembly Hall are being transferred from one location to another, briefly stored in one tool before being moved again, all according to an originally unanticipated but now carefully scripted scenario. The reason behind these movements is simple: both sector sub-assembly tools (SSAT) need to be made available for repairing non-conforming vacuum vessel sectors #6 and #7 and sector #8 has to be moved to the Cryostat Workshop for heavier, partly automated interventions. Displacement operations began in late January when two toroidal field coils (TF9 and TF8) were extracted from SSAT-1 and moved to SSAT-2. Both coils were part of sector module #7, whose assembly was almost finalized when the decision to stop the process and to dismantle was taken at the end of last year. Thermal shield panels followed suit, and sector #7 now stands alone, ready to be prepared for repairs. Sector #8, in the meantime, was standing in SSAT-2, where assembly work had barely begun. On 2 May, the 440-tonne component was lifted out of the standing tool and attached, still in its vertical position, to the upending tool that with a few adaptations will now be used as "down-ending" tool. "An extraction is more than an insertion in reverse, and things were a bit more complex than anticipated," acknowledges Bruno Levesy, in charge of the machine assembly worksite. The view inside the Assembly Hall now gives a clear indication of what will happen next. To the left (facing the Tokamak pit), sector #7 stands in SSAT-1 ready for repairs. To the right, sector #8 is solidly attached to the upending tool, waiting for its move from vertical to horizontal and subsequent transport to the neighbouring Cryostat Workshop. Closer to the separating wall between Assembly Hall and Tokamak pit, SSAT-2 holds in its wings TF9 and TF8—a unique and temporary opportunity to view both toroidal field coils standing together, and take in their exceptional size and out-of-this-world aspect. In this view dated 25 January 2023, sector #8 is in the foreground, with a section of toroidal field coil visible on the right side of the photo. In the back is sector #7, still equipped with thermal shield panels. We are looking toward the entry door of the Assembly Hall. "Our priority is clearly to start working on sector #7, which will be possible at the end of the year," states Sébastien Koczorowski, acting head of the Sector Modules Delivery & Assembly Division. By then, the already installed sector module #6 will have been lifted out of the Tokamak pit (the operation is scheduled in late July) and moved to SSAT-2 to be disassembled and readied for repairs. A few weeks before this major operation, TF9 and TF8 might be "downended" with the upending tool, placed in bespoke transport platforms and put in storage. Repairing vacuum vessel non-conformities will consist first in depositing material to fill in the bevel areas that retracted out of tolerance during the manufacturing process, and second to locally machine the bevel surfaces to the required dimensions. For sectors #6 and #7, the weld deposit will be done manually; for sector #8, whose non-conformities are more severe, the process will be partially automated.  "One of the challenges is to protect both the cleanliness of the components' inner surfaces, where some equipment has already been installed, and the environment, where other activities will be ongoing," explains Levesy. Limited "enclosures," equipped with local HVAC and filtration systems, will be created to prevent the dispersion of metal particles or dust during the repairs. Things will be easier to manage in the Cryostat Workshop where more space is available. Displacement and dismantling operations offer a unique and temporary opportunity to view without obstacle two toroidal field coils (TF9 from Europe and TF8 from Japan) being held in a SSAT's wings. At this stage of the tendering process, technical and financial negotiations are being finalized with three companies, all with expertise in nuclear environments, requirements and regulations, says Koczorowski. "We are waiting for the best financial offer and we might decide to resort to more than one company." The tendering process for thermal shield repairs has also entered its final phase. In parallel, a procedure called "Delta final design review" is ongoing to validate the choice of a new steel grade for the piping and a different welding approach, and to evaluate the performance of polished steel vs silver coating for the thermal shield panels that could be refabricated. "We want to maximize the repair approach. As of today, we cannot say how many new panels need to be manufactured. It will all depend on the quality of the repairs, which we will closely analyze when the two first sets are back from the company we have selected." The critical task of repairing three vacuum vessel sectors and replacing 23 kilometres of thermal shield cooling pipes will soon begin. In the words of °ÄÃÅÁùºÏ²Ê¸ßÊÖ Director-General Pietro Barabaschi, its impact on the project's schedule and cost "will not be insignificant," but fortunately this setback occurs "at a moment when we can fix it."

Dated April 2023, this new image of the °ÄÃÅÁùºÏ²Ê¸ßÊÖ "planet" places the construction site squarely in the middle. One kilometre long, 400 metres wide, the °ÄÃÅÁùºÏ²Ê¸ßÊÖ construction platform is the focal point of project activity, where some three dozen buildings and technical areas house equipment that will be needed during °ÄÃÅÁùºÏ²Ê¸ßÊÖ's operation phase. Approximately 60 kilometres north of Marseille and the Mediterranean Sea, the worksite is represented here as the centre of the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Planet, surrounded by forest and farmland. A little right of centre is the machine assembly theatre—two contiguous buildings where the principal machine components are delivered and installed. At 5 o'clock from that point are two elements of the °ÄÃÅÁùºÏ²Ê¸ßÊÖ cryostat, the top lid and upper cylinder, wrapped in white protective coverings. Plant buildings are distributed along grid-like roads and alleys, and a huge electrical switchyard is visible at left. This drone image can be downloaded as a printable image. A "Planet °ÄÃÅÁùºÏ²Ê¸ßÊÖ" brochure, with labelled buildings, will soon be available in Publications. (Photo °ÄÃÅÁùºÏ²Ê¸ßÊÖ Organization - EJF Riche)

To accommodate the first real-time system integrated with the °ÄÃÅÁùºÏ²Ê¸ßÊÖ control system, new components of the data archiving system have been deployed. Data archiving, an essential requirement of °ÄÃÅÁùºÏ²Ê¸ßÊÖ, is carried out by a collection of integrated software components. The continuous archiving system has been in place to collect and store data since the beginning of the project. To support the first real-time system—the reactive power compensation system—another component was introduced in 2022 to enable archiving of fast data. Fast data is real-time data emitted by even-driven applications and that usually needs to be analyzed quickly. In any case, it needs to be stored as it comes. The data archiving system now operates in "quasi" real time, meaning it closely approximates real time operation. The quasi real-time data archiving system collects and stores data immediately, and it does so at rates of up to 37 GB per second. The structure of the data, the amount of data, and the frequency with which data is output varies from one system to another. "We have slow and continuous systems, which produce sparse data, and we have fast systems, which produce dense data," says Lana Abadie, Data Service Coordinating Engineer in the Data, Connectivity and Software Section. "The way of processing the output from the different types of systems is different, with different needs for both storage space and computing power." Data archiving is important in all phases of the project. Currently, for example, engineering and test data from the commissioning and early operation of plant systems is being stored. This data helps in the evaluation of performance in the short term, and it is stored for the long term to keep a record of how the machine was built for future analysis and to inform future designs. Data is also used to find tiny problems that might not otherwise manifest themselves for weeks or months. "During commissioning, sometimes you look for defects that are not directly measurable," says Bertrand Bauvir, leader of °ÄÃÅÁùºÏ²Ê¸ßÊÖ's Central Control Integration Section. "You operate for a long time, and you archive all the data. Sometimes finding a problem is like looking for a needle in the haystack." As an example, a motor and a pump might be mechanically misaligned. This might be spotted through higher-than-expected electrical current measurements or features in the data from vibration sensors. Data collected on the electrical current consumption in the motor, the rotation speed, and the pressure inside the compressor can be used by the commissioning engineers to determine whether equipment is operating as expected. In the cryoplant, where a lot of gaseous helium is stored, a tiny leak cannot be detected immediately. But as the tanks fill up with gas over several months, some of the physics measurements taken inside the tanks will drift slowly, providing a clue. Here too, stored data is valuable in the interpretation of tiny features over very long periods of time. Once operations begin, diagnostic data will be archived during each pulse to help scientists learn from experiments. The data will be analyzed minutes and days after each pulse—and it will be stored for future analysis and shared with scientists around the world. It will probably be useful for decades to come. Data will also help operators adjust configurations for subsequent pulses, and scientists and engineers to conduct post-pulse analyses—an important endeavor not only when failure occurs, but under normal circumstances to compare real-life behaviour with that predicted by simulators. Most of all, though, the data will lead to new and surprising discoveries.

Listen to physicist Hartmut Zohm from Germany's Max Planck Institute of Plasma Physics (IPP) as he addresses what in his view are the five most common misconceptions about fusion research: 1) Fusion energy is always 30 years away; 2) With the money flowing into fusion research right now, a fusion power plant can be built in 10 years; 3) Using alternative fuels circumvents all the challenges; 4) Your Q values are not correct; 5) In fusion research, every success is a breakthrough. The 20-minute talk""5 Myths About Nuclear Fusion" is available in English and German.