Inspecting drain tank manufacturing in the US

Across the river from Philadelphia, in the industrial suburb of Camden, New Jersey (US), manufacturing of the ITER drain tanks has begun at the Joseph Oat Corporation. Thick stainless steel plates are being welded and will soon be formed into cylinders—the largest nine and a half metres high and more than six metres in diameter, capable of holding over 227,000 litres of water.

Procured by the US Domestic Agency, the drain tanks will be installed in the „basement” (level B2) of the Tokamak Building, ready to collect the water from the cooling circuits in case of leaks or accidental situations.

Because the ITER drain tanks fall into the category of „Safety Important Components” (SIC), the ITER Organization must ascertain that manufacturing processes and procedures meet the safety requirements established by French nuclear safety regulations and, specifically, the August 1984 Quality Order (Arrêté Qualité).

„As nuclear operator, it is our responsibility to control that this set of regulations is applied throughout our whole chain of contractors and suppliers,” explains Joëlle Elbez-Uzan, acting division head for Nuclear Safety, Licensing & Environmental Protection at ITER.

An important point at this stage in the manufacturing process is to make sure that the tanks’ stainless steel is not exposed to pollution from carbon. Exposure to carbon could cause corrosion, which would put at risk the required leak-tightness of the tanks.

In Camden, Joëlle and Safety Control Section Leader Lina Rodriguez-Rodrigo noted with satisfaction that a specific „ITER zone,” clearly separated from other production and using specific tooling, had been organized within the factory.

Joëlle and Lina’s sojourn at Camden was short (two days) but fruitful. „The 1984 Quality Order is well implemented,” says Joëlle. „US ITER has done a great job in propagating its requirements down the whole chain of contractors and they have a permanent representative in the factory we visited. For us, it is a very strong guarantee.”

The Camden inspection was part of the annual audit program that ITER Safety, Quality & Security Department submits for approval to the ITER Director-General. One other inspection has already been performed this year on vacuum-vessel manufacturing in Korea; next on the agenda are the fast-discharge units, whose fabrication has begun at the Efremov Institute in Russia.

A traditional Indian blessing for the Cryostat Workshop

In the Indian pantheon, Ganesha is the one who can remove the hurdles from the path of our human endeavours. In India, anything of importance—a wedding, journey or construction project—begins with an invocation to the elephant-headed deity.

Since a small portion of the ITER platform has been made available to the Indian Domestic Agency for the construction of the Cryostat Workshop, it was natural to place this football-field-sized piece of India under the protection of the „Remover of Obstacles.”

Throwing a bridge between the high-technology world of ITER and the Indian tradition of times immemorial, Bharat Doshi, Cryostat Section leader, first explained to his guests during a ceremony held on 6 June how the giant ITER cryostat will be assembled from 54 segments manufactured in India.

He then proceeded to „break the coconut” and share the coconut meat among the guests—a ritual that is also meant to appease Mother Earth, whose tranquillity will soon be disturbed by the construction works.

Once every guest had broken a coconut, a large excavator symbolically scratched the earth where the 26-metre-high, 110-metre-long Cryostat Workshop will soon be erected.

The same Indian company (Larsen & Toubro Ltd) that will manufacture the cryostat will also build the Workshop and manage the assembly and welding activities all the way through to the final integration of the cryostat into the machine.

„We have already launched the procurement process for the raw material,” explained Philippe Tollini, Larsen & Toubro’s director for Europe and Russia. „We are presently in the manufacturing design stage, which will be completed by September. We should begin to receive the first cryostat segments from India at the end of 2014, beginning of 2015.”

„The cryostat is an essential part of the ITER installation,” explained ITER Deputy Director-General Rem Haange. „It has to be absolutely leak-tight and its assembly requires kilometres of welding. It is a tough job not only to manufacture but also to assemble.”

Last fall, Larsen & Toubro awarded the construction of the 5,500 square-metre Cryostat Workshop to the French company Spie-Batignolles, which was part of the consortium that built the adjacent Poloidal Field Coils Winding Facility.

Construction should begin in earnest in the coming weeks and take a year and half.

A fruitful week for signatures

The presence of representatives from the ITER Members for meetings of the Management Advisory Committee last week was also the occasion to advance the ITER Organization’s procurement agenda: during „MAC week” Procurement Arrangements were successfully finalized with the United States, China and Korea.
In order to conclude the Procurement Arrangement for Standard Components, Vacuum Auxiliary Systems with the United States, a „massive” amount of work was accomplished by the vacuum team comprising ten people from the ITER Organization and five from the US Domestic Agency, according to ITER Vacuum Section Leader Robert Pearce. This Procurement Arrangement—the first to be signed with the US Domestic Agency this year—covers the manufacturing of several hundred pumps of different sizes and technologies, valves, supporting structures and connections.

„It is massive in terms of complexity—it is a highly distributed system that interfaces with about every part of the machine,” says Pearce. „And it is also massive due to the sheer number of individual components that have to be produced, assembled, tested and delivered.”

This brings to 85 the number of Procurement Arrangements signed by the ITER Organization to date out of a total of 140 planned work packages, not including about 45 Complementary Diagnostic Procurement Arrangements. Each Procurement Arrangement represents the transfer of work from the ITER Organization to the Domestic Agencies.

Three Complementary Diagnostic Procurement Arrangements were signed last week, two with the Chinese Domestic Agency and one with the Korean Domestic Agency.

China will supply equatorial port number 12 and a radial X-ray camera diagnostic for monitoring x-ray emission on ITER. Korea will supply upper port number 18. These Procurement Arrangements comprise complete port integration, including port plug, post interspace and port cell structures, diagnostics and services. The integration is a very important and challenging task which is required to ensure the proper functionality of all integrated systems, and diagnostics in particular, as well as to fulfil demands of safety, maintenance and handling.

The x-ray camera installed in equatorial port plug 12 consists of in-port and ex-port modules that are based on similar cameras on other machines, particularly JET. The hot plasma core is a strong source of x-rays. These x-rays carry information about the radiated power, electron temperature, plasma position, and plasma internal motion. Upper port 18 contains the vacuum ultra violet spectroscopy system already undertaken by the Korean Domestic Agency and completes the Korean diagnostic scope.

Let there be light!

Once the components of the ITER Tokamak are assembled and individually verified, a delicate and complex series of operations will be necessary before lighting the fire of First Plasma.

Commissioning, as this phase is called, means that all the different systems of the machine—vacuum, cryoplant, magnets—will be tested together in order to verify that the whole installation behaves as expected.

These commissioning operations all converge toward one point: the breakdown of the gas inside the vacuum vessel.

It happens in the following way: Initially, the toroidal field coils are electrically charged. Then the varying electrical current in the central solenoid and poloidal field coils generates an electric field around the torus of the tokamak causing the atoms in the gas to collide with the accelerated electrons. The gas in the vacuum vessel becomes ionized (electrons are stripped from the atoms) and reaches the state of plasma.

„At this moment,” explains Woong Chae Kim who joined ITER two months ago as Section Leader for Commissioning and Operations, „First Plasma will be achieved and the commissioning process will be over.”

ITER commissioning is expected to last more than two years and every step—from vacuum vessel leak-testing to the electrical charging of the magnets—will bring its own challenges. Woong Chae, however, is confident. „In the long history of tokamaks, start-up operations have never failed. Technically, I am not afraid. I’ve done it before …”

„Before” was five years ago, when Woong Chae was in charge of plasma commissioning at KSTAR. On 13 June 2008, following six months of commissioning operations, the large Korean tokamak (and the first to implement superconducting niobium-tin coils) achieved a First Plasma that surpassed the original target parameters.

From a technical perspective, commissioning KSTAR was close to what it will be at ITER. The difference lies in the regulatory status of the two devices—ITER is a nuclear installation, KSTAR is not—and in the inner workings of the organization.

„I participated in several design reviews for ITER components over the past four years and have had many opportunities to experience the complexity of the decision-making process within the ITER Organization. It is indeed a very complex machinery, even more than I had anticipated …”

KSTAR, which he joined in 1995 when the project was launched, taught something essential to Woong Chae: „While doing your own job on your own system or component, it is essential to have an overview of the whole device. If you don’t, coordination and interfacing becomes very, very difficult …”

Woong Chae chose to train as a fusion physicist/engineer because he felt fusion was „cool.” „It’s ideal as an energy-producing source, fascinating in terms of physics and technology and so different from the things one comes across in daily life.”

The first fusion device he encountered at graduate school in Seoul was the small tokamak SNUT-79 that Korea had developed in the late 1970s—the country’s first significant step onto the fusion stage. At the time, says Woong Chae, „the device was already a museum piece standing at the centre of the laboratory.” He then worked on the mirror machine HANBIT („Great Light”) in Daejeon, a partial reincarnation of the MIT’s 25-metre-long TARA, where he „learned how to manage big projects.”

After spending 18 years at KSTAR, Woong Chae felt that ITER was the „natural playground" for people like him—people who thrill at the challenge of „organizing men and procedures in order to make things happen.” Several ITER colleagues like Chief Engineer Joo Shik Bak or CODAC Section Leader Mikyung Park made a similar choice.

Woong Chae has moved to Aix-en-Provence with his wife, who spent a year in France as a graduate student, and their 16 year old son. They live near „Painters Ground” and have a beautiful view of Mount Sainte-Victoire. „Although I do not speak much French and am not what you would call a specialist in impressionism, I’m on familiar ground. In the early days of my marriage, we lived in Daejeon, close to restaurant named … Cézanne.”

Green light for ITER’s blanket design

After three days and 29 presentations, a comprehensive design review with probably the largest participation in the history of the ITER project was completed last week. More than 80 experts from the ITER Organization, Domestic Agencies and industry attended the Final Design Review of the ITER blanket system.

„The development and validation of the final design of the blanket system is a major achievement on our way to deuterium-tritium operation—the main goal of the ITER project,” Blanket Integrated Product Team Leader (BIPT) and Section Leader Rene Raffray concluded at the end of the meeting, obviously relieved at the success of this tremendous endeavour. „We are looking at a first-of-a-kind fusion blanket which will operate in a first-of-a-kind fusion experimental reactor.”

The ITER blanket system provides the physical boundary for the plasma and contributes to the thermal and nuclear shielding of the vacuum vessel and the external machine components such as the superconducting magnets operating in the range of 4 Kelvin (-269°C). Directly facing the ultra-hot plasma and having to cope with large electromagnetic forces, while interacting with major systems and other components, the blanket is arguably the most critical and technically challenging component in ITER.

The blanket consists of 440 individual modules covering a surface of 600 m2, with more than 180 design variants depending on the segments’ position inside the vacuum vessel and their functionality. Each module consists of a shield block and first wall, together measuring 1 x 1.5 metres and weighing up to 4.5 tons—dimensions  that not only demand sophisticated remote handling in view of maintenance requirements during deuterium-tritium operation, but also an approach to attaching the modules which is far from trivial when considering the enormous electromagnetic forces. 

The first wall is made out of shaped „fingers.” These fingers are individually attached to a poloidal beam, the structural backbone of each first wall panel through which the cooling water will be distributed. Depending on their position inside the vacuum vessel, these panels are subject to different heat fluxes. Two different kinds of panels have been developed: a normal heat flux panel designed for heat fluxes of up to 2 MW/m2 and an enhanced heat flux panel designed for heat fluxes of up to 4.7 MW/m2.

The enhanced heat flux panels are located in areas of the vacuum vessel with greater plasma-wall interaction and they make use of the hyper-vapotron technology which is similar to that used for the divertor dome elements. All panels are designed for up to 15,000 full power cycles and are planned to be replaced at least once during ITER’s lifetime. A sophisticated R&D program is currently under way in Japan for the development of remote handling tools to dismantle and precisely re-position the panels.  

Due to the high heat deposition expected during plasma operation—the blanket is designed to take a maximum thermal load of 736 MW—ITER will be the first fusion device with an actively cooled blanket. The cooling water is fed to and from the shield blocks through manifolds and branch pipes. Furthermore, the modules have to provide passage for the multiple plasma diagnostic technologies, for the viewing systems, and for the plasma heating systems.

Because of its low plasma-contamination properties, beryllium has been chosen as the element to cover the first wall. Other materials used for the blanket system are CuCrZr for the heat sink, ITER-grade steel 316L(N)-IG for the  steel structure, Inconel 718 for the bolts and cartridges, an aluminium-bronze alloy for the pads that will buffer the electromechanical loads acting on the segments, and alumina for the insulating layer. 

The procurement of the 440 shield blocks is equally shared between China and Korea. The first wall panels will be manufactured by Europe (50%), Russia (40%) and China (10%). Russia will, in addition, provide the flexible supports, the key pads and the electrical straps. The assembly of the blanket is scheduled for the second assembly phase of the ITER machine starting in May 2021 and lasting until August 2022. The work will be performed with the help of two in-vessel transporters working in parallel.

In assessing the work presented at the Final Design Review, Andre Grosman, deputy head of Magnetic Fusion Research Institute at CEA and chair of the review panel, enthusiastically commended the BIPT for its achievements since the Preliminary Design Review in December 2011 which were „beyond the expectation of the panel.” He added: „We have singled out the continuity and benefit of the work done by the ITER Organization and the Domestic Agencies within the BIPT framework with a sharing of risk and information among all stakeholders.”

The panel nevertheless pointed out some remaining issues, including a few challenging issues that need to be addressed at the project level. But thanks to the excellent quality of work performed by the BIPT, the ITER blanket design can today be called „approved.” The BIPT can now turn its focus to addressing the feedback received at the Final Design Review, applying the final touches to the design, and preparing for the Procurement Arrangements, where fabrication is handed over to the Domestic Agencies, starting at the end of 2013.

Propping and formwork on both slab and mockup

Take in the view and enjoy it while you can. In a couple months, the spectacular pattern formed by the 493 columns in the Tokamak Complex Seismic Pit — the emblematic image of ITER construction — will have vanished from view.

The lone scaffolding that was erected two weeks ago at the centre of the pit has already been joined by dozens of others. „Everything will be covered,” says ITER Nuclear Buildings Section Leader Laurent Patisson. Once the structures are in place, a steel rebar skeleton will be installed on top of them and pouring of the 1.5 metre-thick B2 slab will begin plot by plot (or "pour by pour") —a process which should take about nine months.

„The propping and formwork structures will support the weight of the rebar and concrete until the hardening of the concrete makes it possible to transfer the effort onto the seismic pads,” adds Laurent. „A total of 15,000 m3 of concrete will be poured, which—added  to the weight of the rebar (~ 4,000 tons)—will amount to a load of some 37,500 tons.”

Creating a reinforced slab over formwork structures that are supported by braced scaffoldings is a common technique. The very same process was implemented, two years ago, on the nuclear research reactor Jules-Horowitz (RJH) that is being constructed at CEA-Cadarache.

Every installation has its own geometry, however, which is reflected in the complex pattern of the steel reinforcement bars. „We have to demonstrate constructability prior to pouring the actual slab,” explains Laurent. „We also have to qualify the concrete and test the efficiency of the vibration techniques.”

To that effect, a 150 m2 mockup has been created on the platform to the west of the Seismic Pit. „Although 3D models of the rebar arrangements have been produced, we need a hands-on experience of the difficulties we may encounter.” Four different areas of rebar, presenting specific challenges (density, complexity), will be reproduced at 1:1 scale in the mockup. Work on the mockup began last week.

The mockup will also allow the practice installation and testing of the anchor plates that will be embedded into the concrete. These thick steel plates of various sizes, all dotted with long spikes (see picture), will reach deep into the concrete.

Once embedded into the concrete mass, the plates form an exceptionally solid base onto which equipment such as magnet feeders, drain tanks or cubicles can be welded. The Tokamak Complex will contain some 60,000 such plates.

„What is at stake beyond the B2 slab,” summarizes Laurent, „is the robustness of the whole Tokamak support, from the cryostat bearing down to the ground.”

Work progressed steadily last week on propping operations inside the Tokamak Pit and on its smaller mockup sibling nearby.

Crowning the cryostat from below

Columns are as old as civilization: for thousands of years, they have provided architects and engineers with a simple and sturdy solution to support heavy loads while leaving room to move around on the ground below.

This traditional and reliable solution was to be implemented in ITER: a circular arrangement of 18 steel columns was to support the cryostat ring—the thick steel component that acts as a mechanical interface between the combined mass of the cryostat and Tokamak (25,000 tons) and the Tokamak Complex basemat.

Columns do a great job supporting large, static loads. However under particular circumstances during ITER Tokamak operation, mechanical, magnetic, or thermal loads, singly or combined, could add up to generate considerable stress on the columns.

In the case of a vertical displacement event, for instance, the Tokamak could „up-lift”; in the case of a cryostat ingress cooling event, the cryostat could „shrink”…

Once refined, models and simulations showed that under certain conditions the load transfer to the basemat by way of the columns was not totally satisfying. For ITER Safety Security and Quality (SQS), this was clearly a potential safety issue. „As the Tokamak Complex basemat could not be modified, it was imperative to develop an alternate solution to the columns. In this, the expertise of Design Integration Section was fundamental,” explains head of the ITER Licensing Cell Joëlle Elbez-Uzan.

Thus began, early in 2012, a ten-month collaborative effort involving ITER’s Safety, Quality & Security; Building and Site Infrastructure; Technical Integration; Cryostat; Assembly; Safety; and Magnet teams, as well as the European Domestic Agency F4E and their Architect Engineer, Engage.

„The light eventually came from  Engage’s design project leader, Peter Sedgwick,” recounts ITER’s Nuclear Buildings Section leader Laurent Patisson. „He suggested we mobilize the resistance capacity of the three-metre-thick concrete bioshield wall that surrounds the cryostat—something we had not fully investigated …”

The exceptionally thick and strong bioshield, which stands approximately three metres away from the cryostat, held the solution indeed. „The idea is to replace the 18 steel columns with a concrete 'crown’. Every 20 degrees, the crown would be connected to reinforced concrete walls radially anchored into the bioshield. It’s a clever and efficient solution to distribute the efforts evenly…”

Faced with a similar problem, the architects of Notre Dame Cathedral, in the 13th century, developed a similar solution. „By positioning flying buttresses at regular intervals around the Cathedral’s nave, they were able to evenly distribute the loads of the edifice’s walls, explains Joëlle.

In the ITER Tokamak however, every design modification is bound to impact other components. Designers soon realized that one of the radial walls connecting the crown to the bioshield was competing for space with the magnet feeder for poloidal field coil number 4.

An early option called for compensation by way of a set of concrete beams. „However such a singularity in the crown support system would have made the structural capacity demonstration difficult,” explains Laurent.

Working closely with the Magnet and Technical Integration Divisions and the Building & Site Infrastructure Directorate, a solution was eventually reached, which resulted in the proposed cryostat support system regaining its symmetry.

All in all, as stated in the preliminary assessment on the capacity of the new cryostat support, the new design „could result in a more integral and compact solution, with many potential advantages from a mounting and constructability point of view, as well as from a global structural capacity perspective.”

The cryostat ring and the concrete crown that supports it would be connected by way of an arrangement of 18 spherical bearings acting like ball-and-socket joints. Such bearings, which are also used in large bridges, allow for the smooth transfer of horizontal and rotational forces.

Needless to say, all these components will have to retain quality and functionality in a rather harsh environment, where radioactivity will be high and cold very intense—reaching -100°C in the vicinity of the cryostat ring.

ITER Safety Security and Quality and Buildings & Site Infrastructure are now preparing the Support Robustness Demonstration document, which will be submitted to the French Safety Authority (Autorité de Sûreté Nucléaire, ASN) in January.

When the Demonstration is validated, work will resume inside the Tokamak Seismic Pit where the 1.5-metre-thick Tokamak Complex basemat will be poured.

10 systems, 400 pumps pass Review

World experts on vacuum and fusion safety gathered last week at the ITER Headquarters for the Conceptual Design Review of the Vacuum Auxiliary Systems main delivery. „This is our most diverse Procurement Arrangement, covering 10 systems and including approximately 400 vacuum pumps situated all over the Tokamak Complex,” explained Vacuum Section Leader, Robert Pearce.

The design of the systems was presented in 60 presentations over 3 long days.  Liam Worth, review coordinator, expounds, „The review concludes many man-years of work by members of the ITER Vacuum team; preparations have been particularly intense over the last few months.” Such work led to a successful review and Review Chair Alastair Bell commended the Vacuum team on its high level of preparation.

Passing this Review will now allow the Vacuum teams to progress to issuing the Procurement Arrangement for the systems, which should be ready to be signed between ITER Organization and the US Domestic Agency (US-DA) early next year. „Excellent,” stated US-DA vacuum team leader Michael Hechler who attended the review with four other team members.

Planning for Test Blankets Modules radwaste

Self-sustained tritium production is essential to the future of fusion. While an experimental machine such as ITER will draw upon the tritium presently available in the market (a couple of tens of kilos), future fusion plants will have to breed their own tritium supply in a continuous manner.

Tritium, which occurs only in trace quantities in nature, can be produced through the impact of fusion-generated neutrons on lithium nuclides present in the plasma-facing components. Based on this principle, six experimental Test Blanket Modules (TBM) will be installed at the equatorial ports of the ITER vacuum vessel wall. Two of them will be procured by Europe; India, China, Japan and Korea will each contribute one. The Russian Federation and the Unites States will give support on specific technical items.

Over the years, as they are impacted by the neutron flux, the ITER TBMs will progressively become activated. „However different each TBM concept may be, we can reasonably anticipate the amount of radwaste that will be produced within the Tritium Breeding Systems (TBSs) and that we will have to manage,” explains Magali Benchikhoune, the ITER Hot Cells & Radwaste Section Leader and Chair of the Test Blanket Program Working Group on TBS RadWaste Management (TBP-WG-RWM) that has been assigned to deal with this matter.

Following three and a half months of videoconference meetings, the international players of the TBP-WG-RWM met for two days — and for the first time 'in person’ — last week at ITER.

The group comprised the ITER Members’ TBM designers, the ITER Organization TBM responsible officer, radwaste management, safety and transport specialists, legal experts from all the contributing Members and also representatives of Agence Iter France (as the interface between ITER and the host country, France).

Once the breeding experiments are completed, the activated TBMs will go back for further analysis to the ITER Member who procured them. The rest (and the largest part) of each system will go into interim storage and, eventually to a permanent disposal facility managed by the French Nuclear Waste Management Agency ANDRA.

How to approach this issue? What are the realistic options to manage and transport the irradiated components? What are the cost drivers? What can be optimized? These questions were central to the meeting that summarized and developed the work accomplished since the Working Group kick-off meeting on 19 July. „Whether from ITER, Agence Iter France, CEA or the ITER Members,” says Magali, „we all worked hard and the two-day meeting was a very motivating experience for all of us.”

The progress of the work by this Working Group will be reported to the TBM Program Committee, which heads all TBM-related activities, during its meeting in early November.
– R.A.

Designing components with remote handling in mind

With the exception of the European JET and the American TFTR which both, at one point, used the „actual fusion fuels” deuterium and tritium (DT), remote handling was never central to tokamak design.

In ITER, however, it definitely is a key issue. Beginning in 2027, ITER will be the first facility to produce DT plasmas on a regular basis and over an extended period of time. DT plasmas generate very energetic neutrons that will progressively activate (render radioactive) the components and structures they impact.

The vacuum vessel, blanket modules, divertor system, port plugs and other systems connected to the vacuum vessel (e.g. the Neutral Beam injection system) will become off-limits to human intervention as DT operation progresses. Areas of the hot cell will also become inaccessible for the same reason.

Components exposed to the neutron flux will not last forever; age and degradation will reduce their life expectancy. „A scheduled maintenance program is associated to every one of them,” explains ITER remote handling Section leader, Alessandro Tesini. „But we must also prepare for the unexpected and be ready to deploy, at short notice, the necessary tools for any componens that could fail.”

The ITER machine is extremely complex; its 'innards’ are so densely packed that remote handling cannot be improvised. „Remote handling needs to be an intrinsic feature of a component’s design. It is essential that component designers and remote handling engineers enter a structured dialogue as early as possible in the process and proceed hand in hand until the process is complete.”

Since the consequences of a non-maintainable tokamak are unacceptable for the project, the efficiency of this relationship needs to be closely monitored, with the remote handling compatibility of each design being assessed on a regular basis.

An important milestone in this process was the Conceptual Design Review (CDR) for the Neutral Beam remote handling system in July this year. The CDRs for the Blanket remote handling system and the Divertor remote handling system were held in February 2011 and June 2011 respectively.

To prepare for this CDR, the ITER remote handling section worked closely with the ITER Neutral Beam section. It was also supported by F4E and the Culham Centre For Fusion Energy (CCFE), which has accumulated a great deal of experience in tokamak remote handling at JET.

While ITER managed the configuration and integration of the Neutral Beam remote handling system in the tokamak building, F4E managed the design progress and deliverables, with CCFE providing the system design and analysis results. This joint effort was behind the successful completion of the CDR.

The CDR Review Panel was particularly impressed by the virtual reality animations — realistic 3D sequences used to assess the equipment trajectories in the complex Neutral Beam cell environment. „Like in a flight simulator, these animations provide a lot of information with minimum effort, highlighting, for example, where and when a clash between equipment and structures could occur”.

In addition, physical mock-ups may be used to simulate situations where component deflection and/or relative friction play a role that cannot be modelled in virtual reality.

„The CDR for the Neutral Beam remote handling system concluded that the system’s conceptual design satisfactorily answers the requirements while respecting the interfaces,” says Tesini. „We are now engaged in the CDR follow-up work to address the issues raised by experts during the review. We will then write the final specification which will form the core of the procurement agreement to be signed between the ITER Organization and the European Domestic Agency.”

Manufacturing of the Neutral Beam remote handling system is expected to start around 2016-2017 so it can be installed in early 2019. Years before it is required for remote maintenance, the system will be put to work to assemble the Neutral Beam components inside the neutral beam cell. „From a topological point of view,” says Tesini, „there is no other solution.”

ITER "conductor community" meets in Moscow

The traditional International Conductor meeting was held in Moscow on 10-13 September, 2012. The regular meeting was attended by representatives from the ITER Organization, experts from the ITER Domestic Agencies of Europe, China, Japan, Republic of Korea, Russia and USA, as well as specialists from the DAs’ suppliers.

Such meetings are particularly important since the ITER magnetic system, with conductors forming its core, is one of the ITER tokamak’s key elements. The manufactured conductors, which are designed to withstand super high current in continuous mode, have to meet the IO’s strict requirements.

At the moment, 10 out of the 11 conductor Procurement Agreements, are either well into the production phase or are completing the qualification/pre-production phase. This is particularly true for the Toroidal Field conductors, where 75 percent of the required Nb3Sn strands and one third of the cable-in-conduit conductor unit lengths have been completed. Also, a technical solution has been found for the Central Solenoid conductors that are being implemented by the ITER Japanese partner.

„This is a clear indication  that the ITER project is moving ahead and is able to keep schedule”, says the meeting’s Chair Arnaud Devred, ITER Superconductor Systems and Auxiliaries Section Leader.

In Devred’s opinion, „in spite of the difficulties of coordinating work with about 30 suppliers and six DAs around the world, the ITER conductor community has always tried to work in a cooperative and synergetic manner, and the conductor meetings have always been a great opportunity for sharing experience and tackling difficult interface issues.

The conductor meeting is also an opportunity to showcase the work done in the Russian Federation and for the DAs involved in coils procurement to visit the conductor production facility”. Russia is responsible for the procurement of 22 kilometres of conductors, destined for Toroidal field (TF) coils, and 11 kilometres destined for the Poloidal field (PF) coils of the ITER magnet system. TF coils include more than 90 tons of superconducting Nb3Sn strands; PF coils include 40 tons of Nb-Ti strands.

Arnaud Devred highly praised the progress achieved by the Russian suppliers saying that „The Russian Domestic Agency has now entered full TF conductor and PF cable production. It is a proactive partner, eager to play collectively and to assume its role within the ITER collaboration”.

The next regular meeting is planned for March 2013 in Cadarache.

Conductors for six out of 18 Toroidal Field coils manufactured

The production of superconducting cables for ITER’s large and powerful Toroidal Field (TF) coils is making remarkable progress: as of today, 330 tons of strands made out of Nb_SUBSCRIPT_3_/SUBSCRIPT_Sn, a special alloy made of niobium and tin, have been produced in factories in China, Europe, Japan, Korea, Russia and the United States. In the pre-ITER world, global production was 15 tons a year. „The current production status represents 75% of the total required TF strands”, reports Arnaud Devred, Section Leader for ITER’s Superconducting Systems. "Out of these strands, conductors for six out of the machine’s 18 TF coils have been produced."

The 18 TF coils will produce a magnetic field around the ITER torus helping to confine and control the plasma inside. The coils are designed to achieve operation at magnetic fields up to 13 Tesla. They are made of cable-in-conduit superconductors, in which a bundle of superconducting strands is cabled together and contained in a structural jacket. Unit lengths of theses cables — measuring 760 metres or 415 metres depending on their position within the coil – are then spooled into a D-shaped double spiral called a „double pancake” giving the structure the characteristic shape of ITER’s TF coils.

As of today, a total of 30 760-m Unit Lengths and 13 415-m Unit Lengths have been manufactured by the procuring agencies in Japan, Korea, Russia and Europe which adds up to the material required for six of the 18 TF coils.

„Quality tests”, says Devred, „are currently underway to confirm that these unit lengths can be accepted for coil winding”.


Cooling water: last preliminary design review

Nearly all of the heat generated during ITER operation, whether it be from the fusion reaction, auxiliary systems, electrical cabinets, (or even warm bodies!) will be collected by the Component Cooling Water System (CCWS) or the Chilled Water System (CHWS). These systems subsequently reject the heat to the atmosphere, either directly or via ITER’s Heat Rejection System (HRS).

Although the CCWS and CHWS systems use standard, proven technology, the design of the systems is highly complex. The systems will serve a wide variety of clients, all with different requirements and with designs at different levels of maturity. Approximately 200 unique interface documents are required to define the CCWS and CHWS interfaces with clients, buildings, and services. 

The design and procurement of these systems is under the responsibility of the Indian Domestic Agency. On 11-14 June, the preliminary design review for the CCWS and CHWS cooling water systems was held in Cadarache, gathering representatives from the ITER Organization, the Indian Domestic Agency, and experts in the field. One of the experts was Warren Curd, former Cooling Water Section leader, who travelled from China where he is currently a construction coordinator for two of the first Westinghouse AP1000 reactors to be built.

Sekhar Basu, chief executive at the Department of Atomic Energy in India, was chairman of the Design Review. During a meeting of the review panel on the final day of the review, he received a phone call informing him that he had just been appointed Director of the Bhabha Atomic Research Centre (BARC), India’s premier nuclear research facility, based in Mumbai.  This announcement was greeted with a spontaneous round of applause and congratulations from the panel members.

One of the important topics discussed during the review was the approach taken to seismic design of the system piping which will crisscross the site and be installed in nearly every building. „While the analytical approach we took was satisfactory, this meeting gave participants the opportunity to ensure agreement on assumptions and inputs so that safety, regulatory, and investment protection goals are met,” says Prashant Wani, project engineer for Tata Consulting Engineers, who performed preliminary design on behalf of the Indian Domestic Agency.

A few other key issues, inherent to this stage of design, were identified during the review. Following the resolution of these issues and one last review of interfaces, the next step will be for ITER-India to launch a call for tender to select an engineering and procurement contractor to perform final design and procurement of piping and equipment.

The first shipment of piping is due on site in the summer of 2014.

The preliminary design review of the Tokamak Cooling Water System (TCWS) and the Heat Rejection System (HRS) took place in March 2012.