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 (i.e., 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 components 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. They were 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 mockups 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."
Rudy Ricciotti is an architect who likes to use undulating surfaces. It is the roof that undulates at the Arts of Islam addition that recently opened at the Louvre Museum in Paris, and it is the northwest, countryside-facing facade that undulates at the ITER Headquarters ...
Together with his local colleague Laurent Bonhomme, the renowned Marseille architect designed a building that blends into its surroundings remarkably well when seen from the Vinon road. It also acts as a "visual pedestal" for the Tokamak Complex that will rise in the background on the platform side.
The new ITER Headquarters is a five-storey building which offers 19,000 m² of workspace divided in 242 offices and meeting rooms. Moving will begin this week and some 500 ITER staff and contractors will have settled into their new environment by the end of November.
With half the ITER team at Cadarache moving into the new building and the other half settling into the twin buildings B82 (the present Headquarters) and B81, the entire staff will finally be based on the ITER site. The ITER Organization will provide a number of services, such as a canteen (beginning on 29 October) and buses for commuting to work, which are presently contracted via the CEA.
Facing northwest, the view from the Headquarters will take in the rolling hills of the Durance Valley and the first peaks of the Pre-Alps further to the north. To the east, the view facing the platform will soon be dominated by the looming structure of the 60-metre Tokamak Complex.
Click here for a visual tour of the new ITER Headquarters building.
Twenty-four years ago, in September 1988, the International Atomic Energy Agency (IAEA) published the first issue of the "ITER Newsletter," an eight-page document that aimed at disseminating information on a nascent international fusion project named ITER.
Next to a rather primitive logo—the flags of the original four partners (the European Community, Japan, the USSR and the USA) arranged in a circle around a radiating Sun—a foreword expressed the essence of the project.
"The task of unravelling the secrets of how to produce useful energy from nuclear fusion has engrossed the minds and directed the efforts of significant segments of the world's scientific community for nearly thirty-five years," it read. "Steady progress has been made, so that today we are approaching an exciting threshold."
The threshold, however, was high, and passing it would require more than the "free and unselfish co-operation of scientists" that had brought fusion to where it stood in 1988. What fusion needed now was a strong political booster and also "major investments in the facilities required to test and demonstrate all the elements of fusion power production."
Three years before, the leaders of many nations had begun recognizing "the scope of the undertaking." President Reagan of the US and General Secretary Gorbachev of the USSR had provided the decisive political boost in November 1985 at the Geneva Summit. Japanese Prime Minister Takeo Fukuda, President Mitterrand of France and British Prime Minister Margaret Thatcher had all "called for increased international co-operation in the development of fusion power."
Now, under the auspices of the IAEA, the time had come to "prepare for a conceptual design for the large scientific/engineering facility" that represented the next logical step in the quest for fusion: ITER, which could be read as the acronym of International Thermonuclear Experimental Reactor but also as the Latin word for "the way" and was to be pronounced "eater." (Almost a quarter of a century later, some argue that ITER should be pronounced "/ɪtə/" with a short "e" rather than "/i:tə/" with a long one.)
The ITER that was being conceived in 1988 was a much bigger machine than the one that is being built today and its nominal fusion power was expected at 1000 MW, as opposed to 500 today.
For the next ten years, the "ITER Newsletter" reported on the project's scientific, technological, organizational, political and diplomatic progress.
In keeping with ITER Council policy, writing about personal experience was encouraged. Along with physicists, engineers and secretaries, ITER "articulate spouses" would at times write short pieces about the pleasures and hardships of adapting to a foreign environment: learning to be a Hausfrau in Garching in 1988 was no less challenging than being a femme au foyer in Manosque today ...
For the historians of ITER, present and future, the 103 issues of the original "ITER Newsletter" form a treasure trove of scientific and technical information as well as anecdotes on the daily life of an expat community in the last decade of the 20th century.
The "ITER Newsletters" (Sept. 1988-Oct. 1998) are available here.
|
From 2020 onwards, the ITER fusion reactor will demonstrate how nuclear fusion can be used as an energy source. However, inside the reactor, the plasma at a temperature of 100 million degrees presents scientists with huge challenges. Direct contact would destroy important optical instruments within a short period of time.
At the 27th Symposium on Fusion Technology (SOFT), from 24-28 September 2012 in Liège (Belgium), Jülich researchers are showing how the delicate instruments can be protected by means of new shutter and cooling systems. Among other options, they will present a patented shutter controlled by a pneumatic cylinder which was developed specifically for ultra-high vacuum.
For the first time, ITER will generate excess energy of 500 million watts for a duration of about ten minutes in order to provide us with experience for the construction of subsequent fusion power plants. Not only the burn chamber but the entire measuring technology has to be developed from scratch for this fusion experiment, which is being monitored by scientists all over the world.
Optical monitoring methods are indispensable for assessing the plasma properties and composition. However, optical elements in the vicinity of the plasma are exposed to extremely high loads. The plasma, largely composed of hydrogen and helium nuclei, erodes part of the surface material but also deposits contaminants. Thermal energy must be continuously removed in order to keep the temperature constant.
"The greatest technological challenge is to find suitable materials and designs to protect and cool the optical elements that can also be cleaned when they are installed in the machine," explains Dr. Olaf Neubauer from the Jülich Institute of Energy and Climate Research, Plasma Physics (IEK-4). Together with colleagues from Forschungszentrum Jülich and partner institutions, Neubauer organized the SOFT conference with more than 800 participants this year.
All the components in ITER's burn chamber can essentially only be serviced by remote-controlled tools or robots. At the conference, Jülich plasma researchers are presenting a new fast shutter for a spectrometer that protects the optical instruments when they are not in use for measurements, in particular during ignition when most of the contaminating particles are mobile.
"In designing the structure, the main problem was that the shutter is exposed to even higher loads than the optical instruments themselves. Furthermore, a movement mechanism had to be invented that could cope with the extreme plasma conditions and the ultra-high vacuum," says David Castaño Bardawil, an engineer in Neubauer's working group. Conventional bearings cannot be used because of their abrasion and the Jülich solution therefore makes use of flexible arms. They are operated by an actuator that was specially developed and patented, into which helium is fed under pressure.
Electric drives cannot be used in the burn chamber due to the strong, disturbing magnetic fields. "The shutter is additionally protected by a molybdenum screen, which reflects the thermal radiation. Together with a sophisticated combination of thermally conducting and insulating materials this maintains an acceptable temperature," says Bardawil.
At SOFT 2012, other Jülich scientists are presenting new concepts for uniformly cooling the instrument mirrors under extreme conditions. "Large temperature differences arise on the mirror surface close to the cooling channels. With the aid of simulations, we optimized the cooling channels in order to minimize divergences," explains Andreas Krimmer, who also works in the field of fusion technology. The temperature-related high pressure of the coolant causes other deformations. At the moment, researchers are testing various elastic materials in order to even out the deformations thus ensuring that in 2020 the fusion plasma can be ignited in Cadarache.
Source: Forschungszentrum Jülich
Click here to read the Press Release.
Through their respective Appropriations Committees, the United States Senate and House of Representatives oversee the billions of federal dollars allocated to different projects.
While projects are closely monitored by way of regular reports and meetings, it is important for the US legislators to get a concrete experience of their reality. This is even more necessary when a project is located outside the US and is part of a larger international collaboration, like ITER.
Senators and Congresspeople, however, are very busy and often rely on close aides to "see on the ground" the projects they have to assess.
Three of these congressional and senatorial aides, plus a press secretary in the House of Representatives, visited ITER last week, met with Director-General Osamu Motojima and ITER Organization senior management, and were given an extensive tour of the work site. They were all highly impressed by what they saw.
"When we deal with our participation in the ITER Project," explained one of the visitors, "we naturally focus on the components that are procured by the US Domestic Agency, so we never quite realized until today the sheer size of the project, and the state of development it has reached already. Also, it was important for us to see beyond the US contribution to the project and take full measure of the international dimension of ITER."
Seven years ago, about a year before Newsline published its first issue, a 27-year old student at the Jožef Stefan Institute (JSI) in Ljubljana, Slovenia, sat frustrated in front of his computer. Googling the word "ITER," this "mind-blowing" project some of his colleagues were in contact with, didn't return much relevant information. For internet-savvy David Jezeršek, this was an injustice to be repaired.
"Here we had this fantastic project aiming at artificially recreating physical reactions similar to those occurring in the Sun and stars," he remembers fuming, "and there was almost nothing on the Web to help people understand what it was all about..." The creation, in September 2005, of the Unofficial ITER Fan Club website was David's answer to this paradox.
"The idea," he explains, "was to collect the meagre ITER-related news that was published here and there in news portals and websites. I didn't have grand ambitions, I just thought this would be a way to keep in touch with the project, monitor its progress and share that information with whoever connected to the site."
The Unofficial ITER Fan Club website soon developed into a patchwork of news, announcements, quotes and book reviews. Membership rose steadily until—a victim of its own success!—spamming and "some automatic scripts that create accounts without human intervention" forced David to close the registration process.
The 430 "confirmed members" (65 students, 81 engineers, one actor, two historians, etc.) who are listed on the site's front page are the original fans and their number does not reflect the actual traffic generated by the site. As this article was being written, more than 20 people were connected and, according to Google Analytics, the Unofficial ITER Fan Club website has been visited by more than 100,000 people since October 2006, 22 percent of them coming from the US; 17 percent from Germany; and 10 percent from the UK. "Quite surprisingly," says David, "France ranks only 4th, with 7 percent of the total visits."
As a revamped ITER official website was launched in May 2009, traffic to its unofficial counterpart inevitably declined. For David, it was both "unfortunate" and inevitable. The lone, enthusiastic student had done his part; now the official institution was taking over. "Iter.org became more and more informative," he recalls, "which was a very good thing for the project."
As for the present, David acknowledges that, considering the amount and quality of the information Iter.org provides, "the need for a separate, unofficial ITER website has diminished." This does not mean, however, that his creation is obsolete. "The site could be a good base for community building—a forum where ITER enthusiasts would meet and discuss."
Seven years ago, when he created the Unofficial ITER Fan Club website, David was a graduate student preparing a diploma in physics and later material science, which left him a reasonable amount of spare time. Now, as a post-doc at the Elettra Synchrotron in Trieste, Italy, the situation is different: "I can't find time to administer the website properly. I need a forum administrator—I hope that a web-literate fusion enthusiast reading this interview will contact me for the job ..."
Whatever the future holds for the Unofficial ITER Fan Club and its website, David's creation will remain as a testimony of a time, pre-dating the establishment of the ITER Organization, when communicating the ITER Project relied almost exclusively on enthusiasm, goodwill and personal initiative.
|
