ITER Newsline / 13 October 2017


Crown mockup
Answering questions 3D models can't

In some areas of the Tokamak Building the steel reinforcement is so dense and the arrangement of the bars so complex, that even the most detailed 3D models are not sufficient to demonstrate full constructability. A 3D model certainly describes the position, dimension, relative angle and curvature of every steel bar needed in a construction with utmost precision. But there are important questions that a model cannot answer. What are the most efficient rebar installation sequences? Will there be enough moving room for the workers to insert the bars, manoeuver them into the right position, and tie the stirrups? And the 3D model will provide no information on how the concrete will settle into the steel lattice. This is why when things get particularly challenging, constructors choose to try their hand on a mockup. 'A 1:1-size mockup provides the ultimate demonstration of constructability,' explain Laurent Patisson and Armand Gjoklaj, from ITER's Civil Structural Architecture team. 'It's all about learning and fine-tuning procedures.' Mockups for ITER construction are like everything at ITER—large and complex. Since work began on Tokamak Complex foundations seven years ago, mockups have been erected on three occasions: in 2013 for the building's supporting slab(B2); in 2015 for the bioshield; and now one for the 'crown' that will support the combined mass (23,000 tonnes) of the machine's cryostat, vacuum vessel, magnet system and thermal shield. (Compared to the 2015 mockup, the present one includes more elements of the crown such as toroidal beams and circular wall.) Construction of the latest mockup—which has a footprint of 50 m² anda height of 3 metres—began three months ago. Reproducing a 20-degree section of the crown, the mockup's dense latticeis created from 50-millimetre-thick steel bars, a breadth not encountered anywhere else in the Tokamak Complex. The mockup will enable the Buildings Infrastructure and Power Supplies (BIPS) Project Team to demonstrate not only the feasibility of the rebar installation but also the penetration and placement of the concrete into the steel lattice. The concrete's formulation for the crown ('C90') is also unique in the Tokamak Complex. It combines fluidity when poured and extreme 'hardness' when settled. Inside the mockup, the temperature during the hardening process will be regulated and homogenized by cooling water circulating inside of thin pipes¹ and monitored by sensors distributed throughout the structure. In preparing for the actual construction of the crown, the BIPS Project Team feels confident but has decided to take no chances—the 1:1 mockup must deliver the final demonstration that, yes, it can be done. (¹) Once the process is complete, the pipes will be filled with grouting.

Expo 2017
Au revoir, Astana

Astana, Kazakhstan. Whenever you mentioned the place during dinner with friends, questioning eyes were guaranteed. That was before Expo 2017. Now, one month after the gates closed on the Astana World Fair—which was visited by four million people between 10 June and 10 September—the city is more, much more, than a dot on the world map. 'Energy of the Future' was the theme of this year's World Fair, and so it was only logical that ITER stake its claim. The ITER Project exhibition was hosted in the French Pavilion, just as the ITER Project is hosted by France. With more than 600,000 visitors, the French Pavilion—the largest of the exhibition—was one of the most frequented, and the ITER exhibition proved to be a very special attraction for tourists, political delegations, poets, activists, and even actors. Even though the vast Fair with its iconic architecture is shuttered, the images will continue to live on in visitors' minds. The buzzing opening weekend with artists on the streets and music in the air; the huge ITER model unveiled in the Chinese Pavilion with its superb animation on fusion energy; the signature of a Cooperation Agreementbetween the ITER Organization and Kazakhstan's National Nuclear Center; and finally dancers from the Cirque du Soleil defying gravity in the central Kazakhstan Pavilion. And of course the ITER exhibition itself, where the visitors stood and stared, marvelling at ITER and the promise of fusion energy before moving on. But not without turning to say: 'C'est magnifique!'

Central solenoid
A symbolic first

It was just a heavy oversized crate. But its contents had an important symbolic value for the ITER Project. The load that was delivered on Thursday 5 October contained the first shipment directly connected to one of the most spectacular of all ITER components—the 1,000-tonne central solenoid, a pillar-like magnet standing 18 metres tall at the very core of the machine. Part of US commitments to ITER, the central solenoid comprisessix cylindrical modules plusstructure subsets that will be assembled on site by the ITER Organization.Set to beginin 2019, delivery of all modules should be complete by 2021. Thecratecontains the main steel components of the central solenoid assembly platform—a thick steel structure that will be used throughout the assembly phase from early 2021 to mid-2023. The steel segments were manufactured by Robatel inGenas, near Lyon, France, under the terms of a contract from the US Domestic Agency. In addition to the centre support weldments and the platform table just delivered to ITER, the central solenoid team is also expecting nine thick, beam-like legs (the 'outriggers') to be delivered at a later date. Each outrigger will rest on a pair of seismic isolators anchored into the floor of the Assembly Hall, where all assembly operations will be performed (see drawing in the photo gallery).

Steady state network
US ITER completes deliveries

The Princeton Plasma Physics Laboratory (PPPL), with assistance from the Department of Energy's Princeton Site Office andthe US ITER Project Office at Oak Ridge National Laboratory, completed a $34 million, five-year project on behalf of US ITER to provide three-quarters of the components for the steady-state electrical network at ITER, the international fusion experiment site in France. The arrival of six truckloads of electrical supplies atITERon 2 October brings to a successful conclusion a massive project that will provide 120 megawatts of power—enough to light up a small city—to theITER installation in France. US ITER is providing three-quarters of the components for the steady-state electrical network (SSEN), which provides electricity for the lights, pumps, computers, heating, ventilation and air conditioning; the European Union is providing the other 25 percent.The ITER Organizationconnected the first US-sourced transformer to France's electrical grid in March. The latest shipment was the 35th and final delivery of equipment from companies all over the world, including from the United States, over the past three years. The six trucks carried a total of 63 crates of uninterruptible power supply equipment weighing 107 metric tons. The trucks took a seven-hour, 452-mile journey from Gutor UPS and Power Conversion in Wettingen, Switzerland, northwest of Zurich, to an ITER storage facility in Port-Saint-Louis-Du-Rhône, France. The equipment will eventually be used to provide emergency power to critical ITER systems in the event of a power outage. 'This represents the culmination of a very complex series of technical specifications and global purchases, and we are grateful to the entire PPPL team and their vendors for outstanding commitment and performance,' said Ned Sauthoff, director of the US ITER Project Office at Oak Ridge National Laboratory, where all US contributions to ITER are managed for the US Department of Energy's Office of Science. A separate electrical system for the pulsed power electrical network, procured by China, will power the ITER Tokamak. The first SSEN delivery in 2014 was among the first plant components to be delivered to the ITER site. The SSEN project is now one of the first US packages to be completed in its entirety, Neilson said. He noted that the final shipment arrived well ahead of deadline. See the full report on the Princeton University website.

Operational phase
Experts of the world, unite!

Late September, the ITER Project called together experts from operating tokamaks and other scientific facilities around the world in order to consider the future commissioning and operations of the ITER Tokamak and plant systems. These experts form the ITER Operations Network,established to support the ITER Organization in making the necessary detailed preparations for the operational phase of the machine. The meeting was a chance for the experts to be updated on the current status of the project and to discuss the areas for which the ITER Organization needs support and how to further involve the worldwide community in future operations.

Experts from the following institutions are currently part of the ITER Operations Network:

CEA Institute for Magnetic Fusion Research, IRFM (France)
ENEA - Frascati (Italy)
EPFL - Swiss Plasma Center (Switzerland)
Fusion for Energy (Europe)
General Atomics (US)
Instituto de Plasmas e Fusao Nuclear, IST (Portugal)
Karlsruhe Institute of Technology, KIT (Germany)
Laboratory for Plasma Physics, Ecole Royale Militaire/Koninklijke (Belgium)
Max-Planck-Institut für Plasmaphysik, IPP (Germany)
National Fusion Research Institute, NFRI (Korea)
National Institutes for Quantum and Radiological Science and Technology, QST, Naka (Japan)
Southwestern Institute of Physics, SWIP (China)
UKAEA - Culham Centre for Fusion Energy, CCFE (UK)

'The group looked at the functions and tools needed in the control room, the software that would support the operators, and control room design. The experts also considered how to plan for system commissioning, how the experimental needs lead into the definition of plasma pulses, and how the parameters are verified and loaded into the control systems. First Plasma is planned for 2025, but the first commissioning activities will start much sooner, beginning with building services and utilities, chilled water, heat rejection, and finally the cryogenic plant. These plant systems will then enter into preliminary operations to support the commissioning of the rest of the ITER plant and Tokamak. By the end of the meeting a work program for the next year was established. The process of cooperation and contribution is just getting started; in the future these experts will provide regular input to the ITER Organization, review documents, and contribute knowledge and information. Regular meetings are planned and—under the ITER Project Associate scheme—experts will also have the chance to comework at the ITER Organization for short stays or longer periods.

Hot Cell
Review of maintenance processes

Earlier this year, with the hot summer months fast approaching, the ITER Remote Handling & Radwaste Management Division accomplished a major milestone with the successful completion of the Conceptual Design Review for one of the principal processes of the ITER Hot Cell Complex: the Type B waste (medium activity) processing systems and in-vessel component refurbishment systems. The ITER Hot Cell Complex supports the operation, maintenance and decommissioning of the ITER Tokamak. The complex consists of three facilities: the Hot Cell itself, the Radwaste Facility and the Personnel Access Control Facility. Together, they provide a secure environment for the processing, repair or refurbishment, testing, and disposal of ITER components that have become activated by neutron exposure. Materials can also become contaminated by beryllium, tungsten and stainless steel dust, along with tritium. The success of ITER will depend to a great extent on developing reliable and safe methods of carrying out routine maintenance and repairs remotely. The in-vessel components of the ITER Tokamak are removed and transferred to the Hot Cell building by remote handling equipment. This group of components includes port plugs, cryopumps, divertor cassettes, and blanket modules. Within the Hot Cell Facility, heavy duty cleaning and refurbishment operations on these in-vessel components will be performed by remote handling systems capable of handling components up to the size of a school bus. 'The ITER refurbishment area will be unique in the world, when considering the combination of size, quantity and complexity of operations in the presence of radiation, activated dust and tritium,' explains Jean-Pierre Friconneau, in charge of the development of the remote handling systems in the Hot Cell Complex. The Hot Cell Facility will also house remote handling equipment for simulation and rehearsal of operations. In addition, the Hot Cell Facility will perform the recovery of tritium from tritiated components and materials. This operation will be housed in a safe, confined, and shielded area containing analytical systems for tritium measurement, and a detritiation system for gaseous streams in order to minimize releases and waste. The aim of the three-day design review, during whichpresentations were made to a panel of expert reviewers, was for the design team to explain the many design drivers and challenges that require strong, robust and cost-effective design solutions to be developed for the medium activity radwaste treatment and the remote refurbishment of the in-vessel components. Safety is, of course, paramount for us all and this is ingrained in all design activities. The proposed solutions were shown to be feasible, well-engineered, substantiated and justifiable with the purpose of ensuring safe and consistent operations and the promise of a safe future legacy, post operations.

Remote Handling Compatibility

A major challenge for the ITER Project is to develop and implement a remote maintenance system that can ensure a high level of Tokamak availability within the constraints of the overall ITER program objectives.

Much of the maintenance in ITER will be performed using remote handling methods, and some with combined manual and remote activities working together.

The organization and management of the ITER remote handling facilities will be of a scale unlike any other remote handling application in the world.

The success of ITER maintenance requires a high level of coordination for design activities going on across the world.

This requires the establishment of rationale and priorities for management controls and standards affecting the three key elements of ITER remote maintenance: ITER plant remote handling compatibility, the remote handling equipment itself, and remote handling operations.

'Even if the maintenance of the ITER machine is very specific, as much as we can we want to benefit from the experience and lessons learned in existing nuclear fission facilities that have been operating for decades,' explains ITER engineer Christopher Reeves, in charge of the development of the medium activity radwaste process. 'Each time we are using a proven approach and solution, we have the benefit of dozens of years of experience in terms of safety, qualification of risks, and cost.' But there are key differences between fission and fusion: nuclear fuel rods weigh kilograms, while ITER's in-vessel components weigh many tonnes. So, it is a real challenge to remotely detritiate components in large furnaces approaching 1,000 degrees Celsius, and reduce the size and volume of the waste in order to fit it into 'packages' that can be stored for a time within the facility before being sent to the Host country for final disposal. Remotely operated systems are required to handle and manage the varied waste streams, with substantial weight and reach capacity and with high dexterity. These systems, along with more traditional through-the-wall powered manipulators, work together with more conventional tooling and machinery and integrate with other newer, emerging technologies. The Type B waste processing facility will operate for many years past the operational life time of the Tokamak itself and so the systems need to be highly reliable, durable, resilient and—if necessary—capable of being removed for maintenance or remotely recovered should that be required. With the success of this Conceptual Design Review, a significant step has been achieved as it provides a first baseline description of the maintenance processes hosted within the Hot Cell.The review has given a strong level of confidence and assurance that ITER can safely and successfully manage the Tokamak waste streams in an effective and efficient manner. Accordingly, the design of in-vessel components will have to be fully compliant with the ITER remote handling maintenance requirements and the suite of remote handling tooling and services available in the Hot Cell Facility.


Segments of the cryostat leave India

On 1 October, seven large segments of the ITER cryostat left the port of Hazira, India, for their ocean crossing to France. These segments, weighing approximately 190 tonnes, form the second tier of the cryostat lower cylinder. Manufactured by Larsen & Toubro in India, they will be assembled and welded in the on-site Cryostat Workshop at ITER.


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