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.

On 29 November, F4E signed a contract (EUR 12 million) for the supply of nine pre-compression rings for the ITER magnet system with EADS CASA Espacio in Spain. By holding tightly to the toroidal field coils at the top and bottom, these 5-metre-diameter fibreglass composite rings (in pink, at right) will reduce the fatigue on the magnet structures caused by electro-magnetic forces—consequently prolonging their operational life from ten to over twenty years.

The nine pre-compression rings will be the largest composite structures ever built for operation in a cryogenic environment.

The following week, on 5 December, F4E concluded the contract (EUR 160 million) for the supply of 70 radial plates with a consortium made up of SIMIC S.p.A. (Italy) and CNIM (France).

The radial plates are large, D-shaped stainless steel structures with grooves machined on both sides. Europe is responsible for delivering 10 of ITER's 18 toroidal field coils; as part of this in-kind procurement, 70 radial plates will be necessary to hold the conductor of the toroidal field coils. Prior to the contract signature, both companies had successfully completed radial plate prototypes.

Read the F4E press releases on the pre-compression ring contract and the radial plate contract.

In the early hours of Monday, 29 October 2012, the last of 633 massive stainless steel forgings for the ITER vacuum vessel left the KIND premises in rural Gummersbach, Germany. Their destination: Hyundai Heavy Industries in Ulsan, South Korea.

The forgings, made from highly refined F316L(N) IG steel, will be used for the construction of the first two sectors of the ITER vacuum vessel. The vacuum vessel is a hermetically-sealed steel container that contains the fusion plasma and acts as a first safety containment barrier. The manufacturing of the vessel is divided between Europe, which will supply seven sectors, and Korea, which will supply two sectors.

"We are very proud of being able to deliver these very special and tailor-made components for ITER on time," said Markus Kind, commercial managing director of the family-run company that is well-known for its experience in custom-made forgings (whether the 2,000 pieces manufactured for the Large Hadron Collider at CERN or the 15-ton propeller shaft of a super yacht).

It took two full days to load the precious goods weighing 360 tons into 20 shipping containers.

The cargo Don Giovanni is now headed for Ulsan, South Korea, where the fabrication of the first two vacuum vessel sectors is in full swing. 

"The start of vacuum vessel sector welding is a historical moment for the ITER project as it marks the manufacturing of the first fully licensed vacuum vessel for a fusion reactor in the word," said Alexander Alekseev, director of the ITER Tokamak Directorate during a recent visit to the Hyundai facility. "The Korean Domestic Agency and Hyundai Heavy Industries have done a great job. I know that it was not easy ... I appreciate very much the work done. This is a good start; we are quite confident that Korea will deliver all the sectors according to schedule."

Deuterium is the heavy twin brother of hydrogen; however, it is more than 20 times rarer than identical twins. It accounts for only 0.015 percent of natural hydrogen and is twice as heavy as the light isotope.

There is no chemical difference between the two isotopes: both deuterium and ordinary hydrogen react with oxygen to form water. Its double mass allows researchers to lay a trail to elucidate chemical reactions or metabolic processes, however. They dispatch a compound containing deuterium into the processes and analyze in which conversion product it turns up. And this is only one of the tasks that deuterium fulfils in research. It may even become an inexhaustible and climate-neutral fuel in future.

This would be the case if nuclear fusion becomes so technically mature that energy is generated on Earth using the same process that also occurs in the Sun. This produces much less radioactive waste than nuclear fission.

In a cooperation established within the DFG German Research Foundation's priority program "Porous Metal-Organic Frameworks" (SPP 1362), a team of scientists from the Max Planck Institute for Intelligent Systems in Stuttgart, Jacobs University Bremen and the University of Augsburg have now been able to enrich deuterium contained in hydrogen more efficiently than with conventional methods.

The findings are reported in the journal Advanced Materials. The researchers discovered that a certain metal-organic framework, abbreviated MOF, absorbs deuterium more easily than common hydrogen at temperatures below minus 200 degrees Celsius.

Read more here. 

As if on cue, snow began to fall minutes before Roger Pizot, the mayor of Saint-Paul-lez-Durance and Osamu Motojima, Director-General of the ITER Organization, proceeded to light the ITER Christmas tree last Friday.

The large tree was a gift from the municipality of Saint-Paul (pop. 800), which hosts the ITER installation. At its last meeting in November, the ITER Council resolved that when referring to the location of the ITER project, official correspondence would from now on bear the name "Saint-Paul-lez-Durance" instead of "Cadarache," which is not a village but a mere lieu-dit (locality).

This, of course, made Mayor Pizot very happy. Back in 2001, he was instrumental in mobilizing local governments to commit financial support to the project to the tune of EUR 467 million.

Last Friday, he assured the assembled ITER staff that the village of Saint-Paul will "continue to support the project, which has brought substantial economic benefits to the whole Provence region."

As the snow continued to fall, traditional vin chaud (mulled wine) was served.