Last week, the ITER Organization concluded the Final Design Review for a full-tungsten ITER divertor. In this three-day assessment, which was the culmination of eighteen months of design, analysis, testing and development, the readiness and the feasibility of a full-tungsten variant capable of withstanding the extreme conditions in ITER were assessed. Challenges related to the specific nature of tungsten were identified and dealt with. "The completed design now requires some refinement with respect to the local shaping of the tungsten monoblocks," said Philippe Mertens from the Research Centre in Juelich, Germany, who chaired the review.

Almost five years ago, in its 60th issue, the ITER Newsline announced the upcoming Final Design Review of the divertor system. At that moment, the ITER approach was to begin plasma operations with carbon fibre composite (CFC) on the regions of the divertor's vertical targets that are expected to receive the highest heat loads. All other plasma-facing surfaces would have been armoured with tungsten.

So much for the non-active phases of plasma operation. The ITER approach for the following phase—nuclear operation with deuterium and tritium—was to replace the carbon-tungsten divertor with a full-tungsten variant.

Carbon presented two major drawbacks as divertor armour material: it reacts chemically with the plasma fuel tritium and it traps the fuel like a sponge, leading to enhanced material erosion and unacceptable levels of tritium retention within the machine. Tungsten (W), on the other hand, has the advantage of not absorbing tritium, but at the same time it doesn't offer the same forgiving behaviour as carbon in terms of compatibility with the plasma.

In September 2011 budget restrictions forced the ITER Organization to reconsider its Baseline divertor strategy. By launching operations with a full-tungsten divertor from day one, one of the three divertors planned for ITER's 20-year operational phase would be eliminated.

A comprehensive investigation was launched in 2011—the Tungsten Divertor Qualification Program—in consultation with the procuring Domestic Agencies in Russia, Europe and Japan. The program comprised full-scale prototype manufacturing and testing.

While many of the features of the existing CFC/W Baseline design are applicable to a full-tungsten divertor for ITER, there are some key differences. Employing metal in high heat flux areas for example requires particular attention—where carbon was known to have favorable properties for the "plasma machining" of misaligned edges (due to manufacturing and assembly tolerances) these do not to apply for tungsten.

Attention must also be paid to the global shaping of the upper baffle areas of a tungsten divertor, where off-normal events such as a sudden vertical displacement of the plasma are predicted to lead to extremely heavy heat loads. Through the slight tilting of the targets and through particular shaping of the outer baffle (very much like the shaping of the first wall of the blanket) some promising results have been obtained that were presented during the design review.

	Heavy stone   The word tungsten comes from the Swedish language, "tung sten" meaning heavy stone. In the periodic system the element with the atomic number 74 is noted under W, named after the mineral wolframite. Tungsten has the highest melting point of all the elements. Also remarkable is its high density of 19.3 times that of water, comparable to that of uranium and gold, and much higher (about 1.7 times) than that of lead.

High heat flux tests performed last year at the newly completed ITER Divertor Test Facility in Russia—with prototypes manufactured by Japanese industry that were exposed to 10 MW/m2 over 5000 cycles and 20 MW/m2 over 1000 cycles—demonstrated no macroscopic cracks, de-bonding or traces of melting. Similar tests run for 300 cycles at 20 MW/m2 have been performed by European industry with optimistic results. 

A "melt experiment" consisting in the deliberate melting of tungsten tiles has been proposed for JET this summer to better understand the behaviour of the molten layer and the consequences of operating a machine on re-solidified W layers.

"It is now expected to report the last findings on this full-tungsten divertor variant to the next ITER Council Science and Technology Advisory Committee (STAC) in October 2013, to obtain a recommendation on the divertor armour for ITER. The objective would be to implement the decision into the Baseline by the end of the year," said Frederic Escourbiac, leader of the Tungsten Divertor Section, who was clearly satisfied by the outcome of the particularly intense three-day design review.

Jörg Klora's first encounter with a computer was way back in the mid-1970s when cupboard-sized mainframes called "mini-computers" delivered the power of present-day pocket calculators. The machine belonged to his father's construction company and in 1975—the very year that Microsoft was founded—15-year-old Jörg designed his first software to do calculations for pricing and bookkeeping.

A couple of years later, while studying physics in Munich, he created his own company, producing software that addressed one of the headaches of that era: compatibility issues between computers of different brands. Thanks to 17-year-old Klora, an Amiga computer could all of a sudden "see" an IBM PC and vice versa, and the life of thousands of users was changed for the better ...

Computers and software have always been part of Jörg Klora's life. However, he never viewed these tools and techniques as an end in themselves, but rather as a convenient and efficient manner to "help people" make big things happen.

At age 52, the career of ITER's new head of the Project Information System Section (IT) is a mix of high-level physics, big science project support and large team management ... all closely connected by the need for strong computing power and reliable software support.

Because he "liked to understand things," the young geek embraced physics and in 1988 joined the Institut Laue Langevin in Grenoble, France, to do his doctorate.

Four years later, having explored the secrets of the element Gadolinium 156, he moved on to the European Synchrotron Radiation Facility (ESRF) in Grenoble to head the Beam Line Instrument Software Support (BLISS)—an acronym, he says, that perfectly defined the atmosphere in the group.

One of the most meaningful experiences in his career as a physicist and IT specialist was his participation in the creation of ALBA, the Spanish synchrotron radiation facility. "We started from scratch in 2004—discussing notes we had jotted on a yellow post-it in a university cafeteria. We ended up with a state-of-the-art, EUR 200 million facility staffed by hundreds of international scientists."

Jörg was to spend eight years at ALBA, managing the Computing and Control Division.

"I'm just an IT guy," he likes to quip. But when you add the doctorate in nuclear physics, an executive MBA from the prestigious HEC School of Management in France, a master's degree in law from Pompeu Fabra university in Barcelona, and a brush of training in human resources you get a rather peculiar profile for an "IT guy."

What led him to explore these different and seemingly unrelated domains? "It's like opening a cupboard out of simple curiosity," he says. "You pull open the door and you find a cathedral ..."

After ALBA entered operation, ("It was a bit my baby," he admits) Jörg was ready for a new adventure, this time with what he calls "the biggest thing in the world"—the ITER project and its many-faceted challenges.

In IT as in other domains, ITER is now entering a second "age" with construction and component manufacturing well underway. "I come with plenty of ideas," says Jörg, "and I have found everyone very receptive. A tremendous amount of high quality work has been done over the past five or six years. What we need now is to create personal accountability for every project, rationalize our support and develop continuous service improvement. Basically: Tell me what problem you're having—we'll solve it."

Fusion researchers from around the world met in San Francisco from 10-14 June for the 25th IEEE Symposium on Fusion Engineering (SOFE). This year's SOFE showed a marked increase in participation from recent years, with over 300 papers presented. Anchoring the technical program were numerous plenary and invited papers on topics at the forefront of fusion research and development. In addition, the recent completion of the National Ignition Facility and the start of ITER construction have put fusion engineering in the spotlight. Not least, the San Francisco setting and superb local arrangements by Lawrence Livermore National Laboratory (LLNL) added to the event that drew many of the world's leading fusion scientists and engineers together to discuss the progress and challenges in fusion engineering.

The ITER project was well-represented at SOFE. Presenting the project's status were three of the 10 plenary papers; nine of the 45 invited papers; and dozens of contributed talks and posters from the ITER Organization and Domestic Agencies. The many ITER papers, on topics such as blankets, heating and current drive, magnets, first wall, divertors, and assembly, covered progress in nearly all of SOFE's technical areas.

Rem Haange, head of ITER's ITER Project Department, opened the meeting with a talk on "ITER Engineering Integration Challenges" that highlighted both advances in fusion technology driven by ITER requirements as well as the technical and organizational challenges of the ITER enterprise. In explaining ITER's challenges, Haange, recipient of the 2011 Institute of Electrical and Electronics Engineers Fusion Technology Award, described ITER as "a highly integrated machine with very strong interfaces between the different components."

Carlos Alejaldre, head of Safety, Quality & Security, discussed lessons learned in the ITER licensing process. He stressed ITER's significance as the first fusion nuclear facility and called the French government decree authorizing creation of the ITER facility a "historical achievement for fusion development." 

On the inertial fusion side, the symposium featured a tour of the magnificently engineered National Ignition Facility (NIF) at LLNL. Michael Dunne, director of laser fusion energy systems at LLNL, described the technical successes achieved by NIF since it went into operation several years ago. Dunne also gave a candid presentation of the gaps between the predicted and achieved target physics performance of NIF, and discussed science-based strategies aimed at closing the gaps.

ITER and NIF are moving the fusion community into a new era that is increasingly focused on the final steps to harnessing fusion energy. The 25th SOFE helped to advance the international discussion concerning next-step programs and facilities on the roadmap to realizing fusion.

Attendees received presentations on accomplishments in support of fusion next-steps from many of the world's currently operating tokamaks and stellarators. Also discussed were the construction status of the Wendelstein 7 X project in Germany and JT60 SA in Japan—devices that will come into operation later this decade. Several speakers described plans for new facilities such as WEST in France and IFMIF to attack critical fusion development problems in plasma exhaust handling and materials. Fusion program leaders from Europe, South Korea, and China described strategies, including next-step facilities and critical R&D missions, aimed at moving toward fusion-generated electricity by about mid-century.

Among fusion conferences, the biennial SOFE event is unique in its strong focus on engineering issues. The first symposium, held in 1965 in Livermore, California, was called the Symposium on Engineering Problems of Controlled Thermonuclear Research. Today the scope of the series has expanded to include such topics as project management, system integration, and fusion roadmap planning, while maintaining a primary focus on fusion's challenging engineering problems and their solutions.

As fusion research has broadened internationally over the years, so has SOFE, with over two-thirds of the papers coming from outside the host country. The SOFE-2013 meeting occurred at a moment in fusion's history marked by both enormous opportunity and tremendous challenges. Participants at the Symposium agreed that fusion researchers must not let fusion's challenges cause them to lose sight of the opportunities.

Many of the ITER components that will come off of the fabrication lines in the factories of the ITER Members are particularly large and heavy. In order to permit their transport to ITER, France has adapted a special 104 kilometre-long Itinerary—widening roads, adapting roundabouts and reinforcing bridges between Port-de-la-Pointe, on the shores of the Étang de Berre, and the ITER site in Saint Paul-lez-Durance.

Work on the ITER Itinerary began in January 2008 and was completed three years later. In March 2012 the ITER Organization awarded a framework contract for the transport of the machine's components to the DAHER Group. In advance of the test convoys planned for September (technical) and October (logistics and organization) 2013, final adjustments to the ITER Itinerary were carried out between April and June this year.

On 16-20 September, travelling at night, a test convoy will be organized jointly by Agence Iter France (the CEA agency that acts as an interface between ITER and France) and the DAHER Group. After having crossed the inland sea of Étang de Berre, a dummy load made of 360 concrete blocks will be loaded onto a special self-propelled platform (88 axles) to travel the whole length of the Itinerary. Its weight and dimensions—800 tons, 40 metres long, 9 metres wide, 11 metres high—will mimic the most exceptional ITER loads.

This first test, officially a "measurement campaign," aims at verifying that the reality of bypassing 16 villages, negotiating 16 roundabouts and crossing more than 30 bridges corresponds to the engineers' calculations.

According to Agence Iter France, an "enormous technical, administrative and regulatory machine" has had to be fine-tuned in order to bring about this first campaign.

Two viewing areas—one close to Berre-l'Étang and the other in the rest area close to the village of Peyrolles-en-Provence—will allow the public to share in the event ... for many, a spectacular introduction to the exceptional dimensions of the ITER machine.

"Humans do not live by bread alone." With these words begins Fusion Physics, published in 2012 by the International Atomic Energy Agency (IAEA).

In the first chapter the book makes the case for the development of fusion as an energy source. "How is humankind going to produce the vast amount of energy it needs?" asks authors Predhiman Kaw and Indranil Bandyopadhyay from the Indian Institute of Plasma Research in Gandhinagar—two names that are also closely associated with the ITER project. Kaw and Bandyopadhyay lead a long list of prominent authors that, together, have compiled the latest on the fusion art. At over 1,100 pages, this publication provides an unparalleled resource for fusion physicists and engineers.

The idea for the book was born during preparations for the 2008 IAEA Fusion Energy Conference in Geneva. "I was considering how to commemorate the 50th anniversary of the 2nd Conference on the Peaceful Uses of Atomic Energy," writes Minh Quang Tran who, alongside Karl Lackner and Mitsuru Kikuchi, edits this fusion encyclopedia. "The intention was to be tutorial at Master's degree level to cover fusion physics and technology."

	It was natural for us to involve IAEA since the book idea was triggered by an IAEA conference and IAEA has played an important role in the development of fusion. I cannot overemphasize the importance of IAEA in the realization of this book. Minh Quang Tran

Dedicated chapters focus on the physics of confinement, the equilibrium and stability of tokamaks, diagnostics, heating and current drive by neutral beam and radiofrequency waves, and plasma-wall interactions. While the tokamak is the leading concept for the realization of fusion, helical confinement fusion and in a broader sense other magnetic and inertial configurations are also addressed in the book. Available in printed form is the first volume on fusion physics; a second volume focusing on the technological challenges is in progress.

Further reading: Newsline issues 131 and 230 

To order or download (34.15 MB) the book, please click here.

Well, not exactly ...

The opening shown in this picture, protected by plastic, is part of the path that will lead from Headquarters to the ITER Control Building. Once extended, the tunnel will take operators to the basement level of the Control Building, from where stairs or a lift will lead to the Main Control Room. Under the room's high ceiling (7 metres), work stations for some 100 operators, engineers and researchers are planned. A glass-walled viewing gallery will offer visitors a panoramic view ... and a sense of what it is like to work at harnessing the energy of the stars.