you're currently reading the news digest published from 28 Jun 2021 to 12 Jul 2021



Integrated commissioning | The last step before plasma operations

ITER's approach to commissioning makes a clear distinction between system commissioning and integrated commissioning. Integrated commissioning is a carefully orchestrated process that occurs only after all components have been tested independently. 'If I'm going to commission the cryoplant, I need to first perform system commissioning on the water and electricity systems separately, because I need these systems during integrated commissioning,' explains Isabel Nunes, Commissioning Operations Responsible Officer in the Operations Division. 'Integrated commissioning is putting together a set of systems and making sure the integrated whole performs as expected, so we can proceed to the experimental phase.' Integrated commissioning will be performed before each stage of ITER operation, after systems and components are installed and individually commissioned. The first phase of integrated commissioning, in preparation for First Plasma, is scheduled to start on 2 January 2025 and to end on 20 December of the same year with the demonstration of First Plasma. Before First Plasma Even though integrated commissioning starts in early 2025, intense preparations are already underway. 'For me, the preparation work is the most stressful—and it has already started,' says Nunes. Nunes is currently breaking down the activities in the baseline schedule into finer detail, identifying dependencies and planning resources—both technical and human. In collaboration with different teams, she details steps and required conditions, or pre-requisites—including which investment protection functions need to be commissioned first, and which safety functions need to be active before integrated commissioning begins. Another very important part of the preparation is risk assessment, which helps minimize the impact of unexpected events through careful planning. 'My current work involves dedicated meetings with the people responsible for all the different systems that play a role in a given activity,' says Nunes. 'Take, for instance, the process of cooling down the superconducting coils to minus 268.65 °C. It sounds like a simple process, but it is actually very complicated. We are discussing the detailed steps now.' 'In general, we define the sequence of steps within a specific activity. For this process to work, all the stakeholders from the different systems need to be involved, systems such as the cryoplant, the vacuum vessel, the magnets, the safety functions and the interlock functions. It is important to consider the operating limits of the different systems at this stage. The coils cannot be cooled too fast—for example, mechanical stresses build up as a result of cooling, and there is a limit to how much of that stress the coils can handle.' The outcome of all the work Nunes and colleagues are now doing will be a set of procedures to follow during integrated commissioning. The Primavera project management tool is used to document milestones and dependencies between activities. Where there is a dependency, actions must be performed in sequence. Cool down, for example, requires the coils to be in vacuum inside the cryostat and thus can only be performed after the cryostat pump down. Integrated Commissioning officially starts when the cryostat lid is closed and responsibility is handed over to Operations. 'The first activity will be to pump down the cryostat,' says Nunes. 'Following that, we leak test the in-cryostat components. Then, we cool down the coils and thermal shields, and we condition the vacuum vessel by baking it. After that, we will be ready to start energizing the superconducting coils in preparation for the First Plasma campaign. That's when the experiments start.' After First Plasma Immediately after First Plasma comes 'Engineering Operations,' a short phase whose main purpose is to demonstrate operation of the superconducting coils at full performance. During this phase, tests will be conducted to make sure the magnets can achieve the 15 MA plasma current scenario at a toroidal field of 5.3 T, which will ultimately be used to produce 500 MW of fusion power. Engineering Operations will be followed by Assembly Phase II, where the blanket and divertor and many other components—such as diagnostics—will be installed in preparation for the first Pre-Fusion Power Operation experimental campaign. Once system components are individually commissioned, Integrated Commissioning 2 will start. 'Many of the processes will be the same as during the first phase—basic pump down, cool down and baking,' says Nunes. 'In many ways, it will be easier the second time, because we will have the experience. But we also need to consider the new components and new systems and all the new challenges we have already started to analyze.' This carefully orchestrated process will be performed after each assembly phase to bring the machine to full operational capacity. 'In summary, during integrated commissioning we build up to readiness for plasma operations by integrating all the separate systems and demonstrating that they work together.'

Magnet system | A set of spares for the long journey

In about five years, ITER will embark on a long journey through largely uncharted territory. Conditions will be harsh and—despite all the calculations, modelling, prototyping and testing—some of the components might fail. Although such a probability is low, spares must be on hand, ready to replace the faulty component and allow operations to proceed. Of all the ITER systems, the massive arrangement of coils that form the 'magnetic cage' shaping and confining the plasma is one of the most strategic. None of the elements can be allowed to fail; as a result, engineers have planned spares for all of them. When components are identical, spares are ... just spares, like a spare tire in the trunk of a car (although much more challenging to replace). This is the case for the central solenoid (six modules are needed, seven will be manufactured), for the toroidal field coils (18 are needed, 19 will be manufactured), and for the current leads and the pre-compression rings. For the poloidal field coils, which are all unique, manufacturing spares was not conceivable and a different solution was devised. Each coil has a spare double pancake embedded in its structure and is equipped with a system that allows for 'bridging' any possible faulty double pancake using jumpers outside the coil. On Thursday 8 July, the assembly sequence called for the positioning of the first of the 'identical spares' of the ITER Tokamak—an extra set of three pre-compression rings that was placed at the bottom of the assembly pit, fitting in the tight space between the bottom cylinder of the central column tool and the recently installed poloidal field coil #6. At a later stage, the set will be attached to the lower flanges of the toroidal field coils. The spare pre-compression rings have been installed early as 'captive' components under the vacuum vessel and toroidal field coils. Using them as spares to replace one, or a whole set, of faulty pre-compression rings, however, would be an extremely delicate operation that would necessitate the removal of the central solenoid and require at least six months. In addition, it would only be possible before full-power operation¹. The pre-compression rings are designed to outlive the ITER machine and the probability of a failure is extremely low. In addition, there are margins in the design that would allow the machine to operate with one failed ring or with a partial loss of pre-load from the whole set. In this context, the spare rings are a second level of back up to ensure that, whatever that the hardships encountered, the journey will continue. ¹The forces exerted on the pre-compression rings during the first phase of operations will be the same as those they will face during the full-power phase. Should a failure occur, it would be during the first few years of machine operation.

People | A new generation of Monaco-ITER Fellows

The seventh group of Monaco Fellows has joined ITER with funding from a longstanding partnership between the Principality of Monaco and the ITER Organization. The Monaco-ITER postdoctoral fellowship is designed to support young researchers in fusion science and engineering. Since 2008, five postdoctoral researchers have been chosen every two years for two-year research assignments at ITER. The latest group, from ITER Members China, India, Europe (France), and Russia, arrived between August 2020 and February 2021. Two of the Fellows have joined the Engineering Design Department, while three others are part of the Science, Controls & Operation Department. Lei Chen (China): Lei earned her PhD from the University of Innsbruck, Austria. At ITER, she analyzes the damage to plasma-facing components caused by plasma disruptions to provide key input for the limits of those components and for the ongoing updates of the ITER safety files. Her interest in fusion stems from the global energy problem and her home country's need for clean energy. She also enjoys being part of a profession that is still developing, where there are new challenges to face and puzzles to solve. Damien Colette (France): Originally from Nice, Damien has a PhD from Aix-Marseille University. His work, both in doctoral studies and at ITER, is focused on detecting the transport of impurities in plasma. Damien's passion for fusion sparked during an internship with the Swiss Federal Institute of Technology in Lausanne (EPFL). He worked with the TCV tokamak there and was drawn to fusion as he learned about its potential to solve some of the dilemmas of nuclear power—fusion creates far less radioactive waste and provides a cleaner, safer alternative to fission. William Gracias (India): William holds a PhD from University Carlos III of Madrid and Aix-Marseille University through the Fusion-DC doctoral program. He is researching detachment, a process in plasma physics that will help preserve the integrity of divertor materials as they face the heat of plasma. William is driven to study fusion for its potential as a new source of energy. During his childhood, William experienced regular power outages: 'I had to spend many a nights by candlelight as I prepared for my school and university exams.' Seeking more reliable and renewable energy, he discovered fusion. Anna Medvedeva (Russia): Anna earned her PhD in Plasma Physics from the Technical University of Munich and University of Lorraine through Fusion-DC. She creates synthetic diagnostic models, which can be used to model different stages of operation in the ITER Tokamak. Anna was inspired by a visit to an institute of nuclear physics and chose to study plasma physics because it can be applied to a wide array of real-world practices. Choosing a narrow specialization would mean eliminating other areas Anna is passionate about. Valentina Nikolaeva (Russia): With a PhD from the Institute of Plasma and Nuclear Fusion in Lisbon, Valentina's research focuses on reflectometry to study plasma density and turbulence. Her journey to fusion began before she was born, as her father aided in the construction of the Chernobyl sarcophagus. He told Valentina that humanity needed a new source of energy, one that was safer. During her academic career, Valentina kept returning to her father's words. 'Somehow, I was always choosing something related to physics,' she says. 'And then I fell in love with tokamaks.' The Monaco-ITER fellowship is a mutually beneficial relationship. The Fellows, just starting their careers, learn from specialists in their field at the most advanced fusion project on the globe. Meanwhile, ITER gains new ideas and fresh energy from these Fellows. 'The Monaco Fellowships allow the ITER Organization to match the brightest early-career professionals with issues that ITER must address,' says Chief Scientist Tim Luce. He adds that, out of the 30 Fellows who have passed through ITER, at least 16 of them are still active in the fusion community. Ten Fellows continue to collaborate with ITER with the help of their own post-doctoral students. The Fellowship has created a lasting impact on the fusion community and has formed a network that continues to multiply with each new generation of Fellows.

Central solenoid | First module ships

Having successfully completed an overland journey of 2,400 kilometres, central solenoid module #1 is now on its way across the Atlantic.   Safely secured in the hold of the OCEAN GRAND, the 110-tonne magnet coil will reach Fos-sur-Mer, France, later this month, and the ITER site in early September. A second module will leave the premises of General Atomics, contractor to US ITER, in August. US ITER oversees the entire fabrication process of the central solenoid at General Atomics and other vendors. Earlier in 2021, the first module successfully completed rigorous post-production testing that simulated the ITER operational environment, with cryogenic temperatures of 4.5 degrees Kelvin and powering to 40,000 amperes. The 5-storey tall, 1,000-tonne magnet will induce 15 million amperes of electrical current in ITER's plasma to initiate each plasma pulse and to provide vertical stability of the plasma. To accomplish this, the central solenoid will reach a magnetic field strength of 13 Tesla, about 280,000 times stronger than the Earth's magnetic field. Six modules plus one spare are in preparation; each one is 2 metres tall, 4 metres wide, and wound from 5.6 kilometres of superconducting cable provided by ITER Japan. The component left the General Atomics magnet manufacturing facility on 21 June and travelled by truck through southern California, Arizona, New Mexico and Texas. It left the port of Houston, Texas, on 7 July.


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