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Men at work: Songtao Wu, Jens Reich, Fabien Ferlay, Jo Preble, Mark Norman, Jack Sky, Edward Daly and Brian Macklin from the various ITER divisions discussing the best way to assemble the vertical stability coils.
As part of ITER's in-vessel coil system, two vertical stability (VS) coils will provide fast control of the vertical displacement of the plasma. The circular VS coil situated in the lower segment of the vacuum vessel is the larger of the two, with a radius of 7.6 metres and a weight of 2 metric tons. The upper VS coil has a radius of 5.8 metres and weighs 1.6 metric tons.

The conductor inside of these coils—the largest of its kind ever—consists of a stainless steel jacket, magnesium oxide insulation, copper alloy to conduct current, and a water-cooling channel in the centre (also see Newsline 175 and 151).

While over the past months many discussions have taken place regarding the design of the VS coils, assembly engineers within the ITER Organization are facing a difficult challenge of their own: how to bring the bulky coil segments in through the port openings of the sealed vacuum vessel.

"We want to try to install the largest coil segments possible into the vacuum vessel to reduce the number of brazed joints to be performed on the inside of the vessel, reducing cost and schedule but more importantly increasing the reliability of the coils," explains Mechanical Engineer Brian Macklin. "The installation of the VS coils is one of the first activities to be performed after the welding of the vacuum vessel sectors. The target is to install three 120° segments. Alternatives include four 90° segments or pre-installation of the segments in the vacuum vessel sectors." However, pre-installation of the VS coils before the sector assembly is not the preferred option, because the coils would compromise the welding of the vacuum vessel. In addition, there is a risk of damaging the coil segments.

The current plan for the installation of the VS coils involves guiding 120-degree coil segments through the equatorial ports into the vacuum vessel. Once inside the vacuum vessel, the segments are to be assembled in a series of steps that include alignment, brazing, welding, non-destructive examination, vacuum-leak checking, pressure testing and electrical testing.

Easing the bulky coils into the vacuum vessel through small openings will be no easy task. Specially designed rails and handling fixtures will have to be installed to guide the bulky coils on their roller coaster ride through the port cell and the vacuum vessel port to their final destination. "I would liken the job to moving a couch into a new apartment—twisting, turning and rotating it as you climb up three flights of stairs and through several narrow hallways and a few really narrow doorways," says ITER mechanical engineer Ed Daly.

The challenge is now solved on paper: the drawings and models are finished and the objective of introducing the three segments seems feasible. But when dealing with the mechanics of assembling the world's largest fusion device you'd better double check your calculations.

That is why the ITER in-vessel coil, assembly, and integration engineers meet regularly these days in the small 3D theatre next to the Tore Supra Tokamak, where CEA/IRFM has set up a virtual reality room. With the help of advanced 3D technology and simulations prepared by CEA in the framework of a contract with the ITER Organization, the engineers can study the movement of the VS coil segments along their integration trajectory and identify potential clashes.

"And these assembly simulations are only one part of the story," says Jens Reich, engineer in ITER's Design Integration Section. "Thanks to its capability to show adjacent interfaces, this 3D tool has significantly improved the overall integration situation inside the tokamak."

"Another advantage of the virtual reality room is that we get a much better appreciation of the real size of the components," adds Brian Macklin, "which is something we often forget as we look at models of huge components on our tiny CAD screens!"

A world's first: Christopher Lefèvre (right) of CEA-Cadarache's Cell Bioenergetics Laboratory headed by David Pignol (left) succeeded in mastering the cultivation process of magnetotactic bacteria (MTB).
On the ITER side of the fence, you'll have the largest and strongest magnets in the world: some 14 metres high; some as heavy as a fully-loaded Boeing 747; some 24 metres in diameter. A stone's throw away, on the CEA-Cadarache side, their microscopic counterpart: no more than 50 nanometres in size (50 billionth of a metre!). Magnets by the hundreds of millions packed into one single drop of water.

The bulkiest among the ITER magnets, much too big to be transported along the specially adapted ITER Itinerary, will be assembled in a 257-metre-long building on site. CEA's nanomagnets are being produced naturally. Bacteria—not industry—are doing the job.

Magnet-producing bacteria are nothing new. Such microorganisms, called magnetotactic organisms, were identified and described some forty years ago. Like migratory birds, magnetotactic bacteria (MTB) biomineralize tiny crystals of magnetite, an iron oxide that acts as a built-in compass.

Birds and bacteria use this inner compass to orient themselves relative to the Earth's magnetic field. It allows birds to find their way to warmer climates and back, and bacteria to swim in one single direction rather than haphazardly, thus conserving energy in their quest for nutriments.

What is new, and what triggered several reports in science magazines throughout the world, is a double breakthrough: first, the identification of a new family of MTB that produces a different—and possibly more promising—type of nanomagnet for biotechnological applications (an iron sulphate named greigite); and second and even more important, the mastering of cultivation that could lead to mass production of MTB.

The excitement was justified. "With MTB, we have an object whose biological activity can be oriented by magnetic fields," explain David Pignol, head of Cadarache's Cell Bioenergetics Laboratory and Christopher Lefèvre, the post-doc researcher who discovered the greigite-producing bacteria and developed the cultivation method.

"We can imagine tweaking their DNA and transferring an extra biological function to their genome, such as the capacity to degrade pesticides or other toxic molecules. Then, we'll have the ability to guide this added biological function with a simple magnet."

The achievement was part of a larger quest that also involved Pr. Dennis Bazylinski at the University of Nevada at Las Vegas; researchers from the French Centre National de la Recherche Scientifique (CNRS); several universities in France, the US, Brazil and Hungary; and a group of scientists from the Ames Laboratory of the US Department of Energy.

Greigite-producing bacteria, which Christopher Lefèvre isolated in the brackish waters of Badwater Basin on the edge of Death Valley National Park (USA), could open the way to a wide field of application.

Genetically-modified MTB could be used for environmental clean-up or as intelligent contrasting agents in medical imaging techniques such as Magnetic Resonance Imaging (MRI): NeuroSpin, a CEA research centre on neuroimaging, has begun exploring this technique on lab rodents and will soon extend it to monkeys. Cancer therapy is another potential application, by way of a technique called hyperthermia in which heated crystals could be directed to burn cancer cells.

The difficulty, until now, was to cultivate and eventually mass-produce MTB. "Christopher succeeded in mastering the cultivation process," says Pignol with pride. "It's a world's first."

The genome of the most promising of these magnetotactic bacteria has been sequenced and the bioreactors at CEA-Cadarache Institute of Environmental Biology and Biotechnology are now teeming with magnetic bacteria life.

"There is still a lot of work to be done in optimizing the cultivation method," adds Lefèvre. The challenge now is to turn the tame bacteria into mass producers—a difficult task but a highly promising prospect.

More information in The Scientist, ZeitNews and The National Science Foundation web sites.

For the fifth time, ITER employees this week elected their representatives.
This week, for the fifth time since the inauguration of the ITER Organization, ITER staff members were invited to the polls to elect their representatives.

The key mission of the Staff Committee is to represent the professional interests of all ITER employees, including employment and work conditions, safety and general welfare, and to act as an intermediate body facilitating communication between the Director-General and the staff on these matters. Some 320 employees, representing 67.9 percent of ITER staff, took the chance on Wednesday to elect their new board of representatives.

The EAST tokamak has been extensively upgraded during its recent shutdown. The picture shows the first wall of the machine, whose tiles were changed from graphite to molybdenum at the beginning of this year.
With the advent of significantly augmented auxiliary heating and operational capabilities, the Experimental Advanced Superconducting Tokamak (EAST), situated in Hefei, China, is starting this year's experimental campaign. The campaign aims at exploring the boundary and understanding the physics of the EAST operational space with favorable stability and confinement, and developing suitable means to expand this space toward steady-state operation.

To these ends, the campaign is focusing on ion cyclotron resonance heating (ICRH) and lower hybrid current drive (LHCD) physics, MagnetoHydroDynamics (MHD) and edge localized mode control (ELM), L-H transition and pedestal physics, divertor physics and emerging plasma-surface interaction (PSI) issues under long pulse operational conditions, and developing integrated scenarios that integrate high performance with advanced divertor steady-state operation.

For further information on the campaign and its organization, press here.
here for online submission of experiment proposals. 

Most of Europe, and quite exceptionnaly balmy Provence (here, the ITER platform on February 1st) were under a severe cold spell last week. The French power grid operator RTE feared a collapse that, fortunately, did not happen.
As bitter cold swept across most of Europe this week, France's electricity demand reached a record high of 101,700 megawatts (MW), equivalent to the total production of approximately 100 nuclear reactors. The previous record dated from 2010, when a peak of 100,500 MW was reached on 15 December.

The French power grid operator Réseau de Transport d'Électricité (RTE) feared a collapse, especially in the "weak" regions of Provence-Alpes-Côte d'Azur (PACA) and Brittany where production barely covers 90 percent of the local demand. The situation in the PACA region was particularly tense as electricity is transported by one single west-east 400 kV power line.

Fortunately, the collapse didn't happen as France hastily imported thousands of megawatts from neighbouring Germany.

As temperature falls by one degree Celsius, electricity demand in the whole of continental Europe increases by 5,000 MW—the equivalent of the combined consumption of Paris and Lyon.

France, with only 60 million inhabitants out of a population of 350 million continental Europeans, accounts for half of this added consumption. The reason for such "gluttony" is historical: when France decided to "go nuclear" in the late 1970s, authorities strongly promoted electrical heating in order to reduce imports of heating oil.

Now, some 35 years later, nuclear plants account for more than 75 percent of French electricity production; the French kilowatt is among the cheapest in Europe and about a third of French households depends on electrical heating exclusively.

Hence the "fragility" of the country in terms of electricity supply, when temperatures drop as they have since the first days of February.

Thirty-two years ago, on 19 December 1978, the failure of a 400 kV power cable in eastern France caused a general blackout that affected 80 percent of the country. Under the pressure of falling temperatures, demand for electricity had increased to 38,000 MW, caused the collapse of the power cable.

There's some simple math to do here: French population at the time was 53 million and the peak consumption per person on 19 December reached 720 W. Thirty-two years later, the French are 63 million and the overload threshold has been pushed to about 100,000 MW. In other words, peak electricity consumption per person on a very cold day in France is now 1,565 W.

In a little more than three decades, consumption has more than doubled...