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ITER NEWSLINE 183
On 21 June, an important meeting relative to ITER's nuclear licensing took place in Fontenay-aux-Roses, outside of Paris. Representatives of the ITER Department for Safety, Quality and Security met with members of the Groupe Permanent—the safety advisory body to the French nuclear regulator ASN that is charged with the technical examination of the ITER nuclear licensing files. This was the mid-course meeting of the examination process.
During a presentation on the status of the examination, the technical advisors to the ASN (IRSN—Institut de Radioprotection et de Sûreté Nucléaire) affirmed that the quality of the answers submitted by the ITER Organization and the strict respect of deadlines opened the way for the establishment of the date for the final Groupe Permanent at the end of November 2011. This was approved by the French nuclear authorities and the president of the Groupe Permanent.
The examination process began back in July 2010. Since then, a thousand questions have been raised by IRSN on the Preliminary Safety Report (RPrS) and we have participated in three or four meetings per month.
In parallel to activities on a national level, here in the region the Local Commission for Information (CLI) is preparing its final commentary on the creation of the ITER Basic Nuclear Installation (INB) under French law. The Special Work Group created to analyze the ITER DAC files also asked more than 300 questions to members of our department in order to prepare its opinion which will be issued next month.
Lastly, the five-week Public Enquiry began on 15 June. During the Public Enquiry, the public has the opportunity to make comments on and ask questions about the ITER project, in particular its environmental impact and safety aspects. Already, many questions have been raised by the President of the Commission.
Of the 18 equatorial openings, or ports, into the ITER vacuum vessel, three will be dedicated to the testing of Test Blanket Modules (TBMs)—those ITER in-vessel components that will test viable techniques for "breeding" tritium within the fusion reactor.
ITER will provide a unique opportunity to test tritium breeding concepts. "A first version of experiments with six TBM concepts will start at the beginning of the first, pure-hydrogen phase of ITER operation," explains Luciano Giancarli, the Chief Technical Officer of the TBM Program. "and then, up to three other versions per TBM will be tested during the further phases of operation."
For the fusion power plants of the future that must be self-sufficient in tritium fuel (see box below), the data gathered from these experiments will be essential.
The Test Blanket Modules plus ancillary systems (cooling, tritium extraction, measurement ...) make up the Test Blanket Systems. Currently under design, these systems were the focus this week of a workshop attended by representatives of the seven ITER Members and the ITER Organization.
"Although each TBM design is distinct," explains Luciano, who chaired the workshop, "it is important to be on the same page for many parameters. This week's workshop focused on the interfaces that will exist between the Test Blanket Systems and ITER's instrumentation and control systems."
ITER's Test Blanket Systems will be connected to three types of control/measuring systems: CODAC, the "orchestrator" of the ITER machine; the central interlock system (CIS) dedicated to machine protection (investment protection); and the central safety system (CSS) for the protection of personnel and the environment. The interfaces with the CIS and CSS systems were the subject of discussions this week.
"As an experimental program, our TBM systems will all be equipped with measurement systems to determine how they behave—that is, after all, the research objective of this program," explains Luciano. "However, monitoring systems during accidental situations must also be agreed upon for investment protection and safety ..."
What kind of incidents might occur within the TBM systems? A loss of coolant or a decrease in the coolant rate of flow, for example, could indicate a ruptured pipe or an anomaly in the pumping system. Reacting quickly to such an incident would limit the consequences for the machine or for safety, whereas a slow reaction might result in damage and/or delay.
Measuring systems integrated into the TBM systems will transmit data by optical fibre or digital signal. "We don't need a thousand measurements," says Luciano, "but we do need measurements that are simple, reliable, and independent." In the case of serious incident, the CIS and/or CSS systems will have the ability to stop the plasma.
The goal during this week's workshop was to decide together on which events or incidents to plan for, which locations for the measuring systems would be best for detection, and what corrective actions must be planned in the case of incident.
"This workshop, which gathered more than 30 experts, was a first step toward establishing a common basis for all six Test Blanket Systems," says Luciano. "It has allowed us to identify in a coherent manner the main accidents to be dealt with, and to require similar actions from the CIS and CSS systems to mitigate them for all the six Test Blanket Systems."
Nineteen-year-olds are not often found modelling and simulating a novel design for a cooling subsystem of the giant international tokamak reactor now under constructed in southern France.
But that is exactly what Jacob Clary, a rising sophomore in chemical engineering at Auburn University, is doing as a HERE (Higher Education Research Experiences) summer intern at US ITER. Jacob is working under the guidance of mentor Juan Ferrada, a chemical engineer and specialist in cooling water systems for US ITER.
Ferrada has been at Oak Ridge National Laboratory for more than 20 years, and has taught at the University of Tennessee and the University of Santiago in Chile. Jacob has been at his computer in a small US ITER office for just 5 weeks.
"I didn't realize. I don't know if you've ever seen a picture of everything that goes inside the tokamak ... I just can't understand how all that can ever get designed and completed," Jacob enthuses. "Because it seems like it is just the most complex thing ever. I can really see why it's taking years and years to figure all this stuff out."
"Just consider this little capacitor that I am working on," he continues. "The antennae generate heat that must be transferred to a mini water cooling system. It is a relatively simple little system that is going in there. And yet there is a ton of stuff that you have to know. All the temperature changes, all the pressure drops ... and you want to know the configuration of the system, all of that. And yet what I am working on is such a small part of it. It can fit on a little table top."
Jacob is working on something quite new. Mentor Ferrada explains: "Jacob is designing the cooling loop that will take that heat and dissipate it through a heat exchanger. The relevant information for him is that the capacitor produces 1 kW of heat and that he must design a system that can transfer that 1 kW to water that comes in at 28°C." Jacob is calculating and simulating that cooling system by using FLOW and FATHOM, software he had to learn when he arrived.
Jacob must design and simulate a pump big enough to perform the job, the pipes that the cooling water will flow through, and the kind of heat exchanger device that will transfer the heat. Afterwards, the water quality is maintained by a chemical and volume control system and then pumped back in.
"What I am doing right now, I don't really have a full understanding of it," Jacob says ruefully. "I just wish I had had a fluid dynamics class at Auburn in my first year. That is the only class I wish I had already taken. Everything else I can get along with here."
That "everything else" includes the software to help him calculate and design this mini cooling system for the capacitors. FATHOM gives the young intern all the pressure drops and flow rates he needs. FLOW, developed at ORNL, pulls together all the pieces needed for the design and then simulates the cooling process.
Mentoring students such as Jacob is a compelling part of Ferrada's life in science and engineering. In his career, he has mentored more than 100 young students. "You try to give them a project that will do two things: Teach them a little about the research, so they can take it back to school and talk to their peers about it. That is the first goal, to get the student immersed in our research," Ferrada notes. "The second object is to engage them, early in their careers, in a professional project, so they feel a sense of accomplishment. That is very important for their formation as a scientist or engineer."
How has Jacob's experience been at US ITER? "The spirit here is very good," he says. "It's not been like graveyard silence. The engineers have been really welcoming and they talk to me ... will have a serious conversation with me in the halls. Everyone is very good natured."
And as to a possible future career at ITER? "It's been interesting enough that I would definitely consider it," says Jacob.
What the Japanese call "the Great East-Japan Earthquake" has caused significant damage to the JAEA Naka Fusion Research Institute, located some 300 kilometres south of the catastrophe's epicentre.
Buildings hosting ITER-related activities—notably the Superconducting Coil Test Facility Building, the Gyrotron Test Facility and the MeV-Class Ion Source Test Facility—were badly shaken. As the exact scale of damage is still being fully assessed, entrance to several buildings remains prohibited for safety reasons.
Last Tuesday, 21 June, one week after the ITER Council, Director-General Osamu Motojima paid a visit to Naka in order to see for himself the extent of the damage and discuss the recovery plan with Dr. Hiromasa Ninomiya, director general for fusion at Japan's Atomic Energy Agency.
Mitigating the consequences of the Japanese situation on the ITER schedule was a key issue in the discussion.
Impurities, in the form of particles detached from the machine components, will always find their way into a burning plasma. "They are unavoidable," explains Robin Barnsley, ITER Diagnostic Division Responsible Officer for spectroscopy. "It is important however, to detect and monitor them. Beyond certain limits, impurities would dilute the fusion fuel and degrade the reaction."
Impurities have different origins. Some are "expected," like the beryllium, tungsten, iron or carbon particles that come from the plasma-facing components of the machine. Others, like oxygen, copper or other metal particles, can originate from leaks or damage affecting other in-vessel components.
Because of the extremely high temperatures of the plasma, confined particles radiate light at specific wavelengths. They all have a "signature" that is both specific to their nature—beryllium will send a signal that is different from tungsten or copper—and to the temperature they are submitted to.
Identifying these signatures, and hence the nature and temperature of the particles, is the role of spectroscopy.
In ITER, several spectrometers will monitor different regions of the plasma in order to measure radiation and identify all relevant impurities. "Because of the very high temperature gradient in the plasma," explains Robin Barnsley, "light is emitted over the whole spectrum, from infrared,visible to ultra-violet and x-ray. No single spectrometer could survey the whole plasma in all those different wavelengths."
The vacuum ultra-violet (VUV) edge imaging spectrometer whose Procurement Arrangement was recently signed by ITER Director-General and the Head of the Korean Domestic Agency, is one of subsystems that, together, will monitor the ITER core, edge and divertor regions of the plasma. It is the first Procurement Arrangement to be signed for spectrometry diagnostic equipment.
The VUV edge imaging spectrometer , whose prototype is already under development and will be ready in two years, will be looking at a region located at the upper edge of the D-shaped plasma which is typical of the outer 10 percent of its total volume.
This is not the hottest part of the plasma: in terms of temperature (around one million degrees Celsius) and physical phenomena, this region is "very similar to the Sun's corona," says Robin Barnsley, who did his PhD in an X-ray astronomy group. "The physics and hence the instrumentation used for observation are closely related."
Data gathered in real-time by the VUV edge imaging spectrometer, along with that of other spectrometry devices observing other regions of the plasma, will enable the machine operators to adjust the plasma's parameters for optimal performance.
Prime Minister David Cameron has appointed Professor Steven Cowley, CEO of the United Kingdom Atomic Energy Authority, as a member of the Council for Science and Technology.
The Council for Science and Technology is the UK Government's top-level advisory body on science and technology policy issues. It is made up of figures from senior levels in science and engineering fields from industry, business and academia and reports directly to the Prime Minister.
Steven Cowley is a theoretical physicist who has been CEO of the UK Atomic Energy Authority since 2009. The Authority operates Culham Centre for Fusion Energy, near Oxford, which is developing nuclear fusion as a large-scale, low-carbon energy source for the future.
Before joining the Authority, Steven Cowley was a professor at the University of California Los Angeles and led the plasma physics group at Imperial College, London, where he remains a part-time professor. He has published over 140 papers and articles during his scientific career.
Professor Keith Burnett, a Board member of the United Kingdom Atomic Energy Authority, has also been appointed to the Council for Science and Technology.
Professor Steven Cowley said: "The quality of the UK's science and technology is second to none and our future prosperity depends it. I am honoured to serve on a Council dedicated to enhancing UK science and technology."
Announcing the appointment of new Council members, David Cameron said: "We have some of the world's best scientists, leading technologies, cutting edge facilities and the most innovative hi-tech companies, and it is our determination that we do all that we can to ensure the UK remains one of the world leaders in this field. That is why I am delighted that I can announce the appointment of such a high calibre team, with such a broad range of experience, to the Council for Science and Technology."