If you are building a tokamak, you need to make it out of a quite special material. It must resist extraordinarily high temperatures, be structurally very strong and corrosion resistant, yet must not be very conductive or have high magnetic properties. For JET, the material chosen for the vessel is Inconel 600.

Most steel is over 90% iron, which is well-known for its excellent magnetic properties; exactly what you don’t want in a tokamak, with its huge magnetic fields and mega-amp currents. Hence Inconel 600 was chosen, a so-called super-alloy containing 72% nickel and about 15% chromium. Inconel 600 has only 8% iron in it, along with small percentages of other materials, such as niobium, silicon and sulphur which give it excellent temperature resistance and structural properties. “It will easily go up to 700 degrees Celsius before it begins to soften.” says Dr Chris Lowry, of the JET Department, “but it’s hell to machine!”

Although the resistance of Inconel 600 is quite high – its composition is similar to nichrome wire, commonly used for heating elements – it still does conduct some electricity. So, further measures have been taken in the structural design of the vessel to minimise currents in the vessel that might sap energy from the experiment. The rigid parts of the vessel are separated by corrugated sections known as bellows. There are two walls of bellows made of alloy merely 2 mm thick; 550 mm of alloy concertined into the 130 mm or so between the rigid sections. The extra length of thin alloy increases the resistance, as required, but to maintain the structural strength with such thin walls, a higher grade of alloy is required, Inconel 625, which has double the strength of Inconel 600. The strongest of all is Inconel 718, but because of its cost, it is only used in JET in a few vital spots, for example, as a tie material for some of the tiles.

This same Inconel vessel has been in place for the duration of JET’s 29 year operating life, while different internal walls and structures such as limiters and divertors have been installed and replaced. These days the duller lustres of the beryllium and tungsten based ITER-Like Wall completely obscure the bright sheen of the Inconel.

While beryllium and tungsten do have a future in the ITER vessel, Inconel does not, because of the neutron bombardment in that environment. Although Inconel has so many good properties, its downfall is that some of its components can be activated easily – nickel, cobalt, tantalum and niobium could all be problematic. Instead, for the ITER vessel, a careful selection of steels has been made, which will perform even better than a super-alloy!

Source: EFDA

DESPITE NUMEROUS DELAYS and the looming threat of budget cuts due to the poor global economy, the International Thermonuclear Experimental Reactor, an international project to prove the viability of fusion as an energy source, has reached a new stage in its development.

"We are poised to transition from design work into fabrication," said William Cahill, federal project director at the U.S. Department of Energy's Office of Science. Cahill's comment came after a fairly positive review of U.S. ITER efforts was performed by the DOE's office of project assessment.

The shift from design to production is evident from recent funding. Over the years, U.S. ITER has awarded more than $260 million in contracts, including 90 major contracts totaling more than $103 million. Much of that funding was for preliminary research and design work on various elements of the fusion reactor and supporting infrastructure. In late 2011, funding was specifically for development. For example, AREVA Federal Services was awarded $13.2 million for the fabrication of five drain tanks for the ITER cooling water system.

In another effort, the University of Tennessee magnet development lab began construction of a full-scale, wooden mock-up of a single ITER central solenoid electromagnet module along with all of the associated support structure and interfaces. Even in today's age of computer design, the wooden mock-up will be used to ensure that engineers and technicians have adequate access to assemble, inspect and maintain central solenoid components in a tight work space. "Experiencing the module at scale gives a better feel of how the design will work," said Madhu Madhukar, associate professor for mechanical, aerospace and biomedical engineering at the University of Tennessee, Knoxville. "The mock-up can also help staff identify problems that may arise during construction and installation."

Work at and around the ITER site in southern France is also picking up. At the heart of the facility is the three-building Tokamak Complex, one of which will house the reactor. This complex is being built in a seismic isolation pit with a concrete base and 493 seismic pads to shield the reactor. Last year, excavation of the reactor's site was completed and workers began to pour the building's foundation and install the pads.

In November, work started on the installation of the pylons that will carry 400-kilovolt power lines to the facility. The ITER headquarters building that will include offices for 500 people, meeting rooms and a footbridge to the ITER control room is scheduled to be completed this summer.

Even with all of this activity, the first experiment in the fusion reactor might be pushed back a year to 2020 due to consequences from last year's earthquake in Japan. Facilities in Japan that were carrying out work on the conductor to be placed in the reactor's central solenoid were damaged and some work was delayed.

Source: energybiz.com

 DOE's Princeton Plasma Physics Laboratory (PPPL) is getting an earlier-than-expected start on a $94 million, nearly three-year project as the next stage of its mission to chart an attractive course for the development of nuclear fusion as a clean, safe and abundant fuel for generating electricity.

The project will upgrade the National Spherical Torus Experiment (NSTX) facility at PPPL, over the next 30 months, with completion slated for 2014. The work will enhance the position of the NSTX as the world’s most powerful spherical torus – or tokamak – a device that controls the superheated and electrically charged gases called plasmas that create fusion power.

The upgrade "will provide a huge boost to all NSTX science missions and enhance U.S. fusion research capability," said Stewart Prager, director of PPPL, which is managed by Princeton University for the DOE Office of Science and has been a leader in fusion research for 60 years. Experiments done on NSTX, he said, "will establish the physics basis to determine next steps in fusion research and development.”

Construction has been cleared by DOE officials to begin six months ahead of schedule. As with any such effort, funding for the project remains contingent on congressional appropriations.

Work on the upgrade has brought new excitement to the laboratory. "We’re building something that's one of a kind that has never been built before," said Michael Williams, associate director for engineering and infrastructure at PPPL.

Fusion takes place when the atomic nuclei in plasmas combine at extremely high temperatures and release a burst of energy. Such reactions drive the sun and the stars. But sustaining fusion in the laboratory has proven quite difficult because plasmas that leak from the confinement can halt the reaction. Controlling the plasma is thus a basic goal of fusion research.

PPPL physicists will use the upgraded NSTX facility to assess the role of compact reactors for the future development of fusion power. The spherical NSTX torus confines its plasma in the shape of a cored apple, unlike bulkier conventional tokamaks that produce doughnut-shaped plasmas and can be more costly to construct.

A key issue for the NSTX upgrade is to see if it can improve on its record-high level of a measure called "beta" — the ratio of the pressure of a plasma to the strength of the magnetic field that confines it — as the plasma grows hotter. The higher the beta, the more cost-effective the confinement.

The NSTX upgrade will furnish new tools for probing such issues and "provide ample research opportunities for years of productive research," said Michael Zarnstorff, deputy director for research at PPPL. "The whole NSTX group is quite excited by the research opportunities on this leading fusion facility."

How PPPL scientists handle the increased flux could serve as a model for ITER, a major conventional test reactor that a consortium of countries including the United States is building in the south of France. ITER aims to produce a sustained fusion reaction — or "burning plasma" — by the late 2020s that will put out ten more energy than is needed to create it.

The NSTX upgrade could also help determine the path to a possible next-generation spherical torus that would produce a burning plasma to complement the output of ITER. Such a spherical torus would be roughly twice as powerful as the NSTX upgrade, said deputy PPPL director Zarnstorff, and could be used to test components for a commercial fusionreactor by around mid century.

Provided by Princeton Plasma Physics Laboratory

Source: physorg.com

 The edition of the Geography textbook “France et Europe” by Les Edition Magnard reports on Europe’s contribution to the ITER project.

Just as French students are getting ready to return to school and face another year of different subjects ranging from mathematics to history, Les Editions Magnard have published a new edition for their Geography text book “France et Europe” aiming to raise awareness on the Europe’ s geopolitical goals and long term strategy by highlighting amongst other subjects, the ITER project.
The section reporting on the European Union starts by presenting a list of indicators about its economic competitiveness vis à vis other key players such as the US, China and Japan. Special reference is made to the EU’s leadership in development policy given the fact that it is the top contributor in this domain. Its institutional configuration is described together with the new positions created by the Lisbon Treaty.

And while the above subjects may seem fairly obvious and in line with previous publications, this year’s text book includes a new entry: fusion!

Europe’s contribution to ITER through F4E is highlighted by underlining its commitment to being a pioneer in fusion and striving to deliver a better energy mix. The role of F4E is briefly described and its brochure is included as part of the chapter’s illustrations.

The opportunity to reach out to so many young people through textbooks on the progress of the ITER experiment and its contribution towards the long term energy mix can help them evaluate options and develop opinions.

Only future will tell if tomorrow’s citizens will be fusion supporters.

Source: F4E

THE European Commission has drafted a plan ensuring cash-strapped international nuclear fusion project ITER would have funding of Euro EUR2.573 billion from 2014 to 2018. 

European Union (EU) ministers in December approved emergency spending for ITER to see the France-based research project through 2012 and 2013, and now the Commission is looking ahead for four more years' money.

It has proposed the creation of a 'Supplementary Research Programme', funded via the EU's nuclear energy wing Euratom, which would ensure Europe kept its funding bargain for ITER with the project's six other parties: China, India, Japan, South Korea, Russia, and the USA. ITER's aim is to produce a fully-functioning nuclear fusion reactor capable or commercial replication and development. However, with EU budgets under pressure, and ITER's projected costs spiralling beyond the initial EU cost contribution estimate of EUR 6.6 billion, the EU has struggled to find the necessary budgets.

Asking EU ministers to back the new plan, a European Commission note said: "An important feature of the construction of ITER is the extreme technical challenge. With its unprecedented scale and complexity, it represents a major undertaking with contributions in civil, mechanical, electrical and nuclear engineering." And it added that ITER and other large scale EU projects of interest (such as the Galileo global positioning satellite project), ITER was "disproportionately expensive in relation to the small EU budget and they tend to overrun initial cost projections."

Source: utilityweek.co.uk