For the second time in its history, the ITER Council Management Advisory Committee (MAC) convened for an extraordinary session in order to assess the status of the ITER project schedule and the implementation of corrective actions.
The meeting took place from 18-19 March at the headquarters of the European Domestic Agency in Barcelona with the attendance of high-level representatives of the ITER Organization and seven ITER Members.
Since the MAC meeting held in August 2012, the ITER Organization has worked closely with Domestic Agencies to complete the integration of Detailed Work Schedules (DWS) - detailed schedules that exist for every component or system. The IO and DAs completed the integration of the remaining DWS, namely main vacuum vessel, ion cyclotron antenna, poloidal field coils and toroidal field structure, which will allow for monitoring of the schedule.
MAC requested that the Unique ITER Team continue to make significant efforts to take action focusing on super-critical milestones and to take all possible measures to keep to the Baseline schedule. The ITER Organization and Domestic Agencies are committed to doing their best to implement this request.
ITER Thermal Shields
The Korean Domestic Agency signed a contract with SFA Engineering Corp. for ITER thermal shields on 28 February. The contract covers the detailed design of manifolds/instrumentation, the manufacturing design and the fabrication of the thermal shield system. "For us, this is a big step forward for the Korean contribution to ITER," said Myeun Kwon, president of the National Fusion Research Institute, after the signing.
SFA is a leading company in industrial automation with much experience in the procurement of advanced equipment related to fusion, accelerator, and space technology. SFA was deeply involved in the manufacturing and assembly of the Korean tokamak KSTAR.
The ITER thermal shield will be installed between the magnets and the vacuum vessel/cryostat in order to shield the magnets from radiation. The thermal shield consists of stainless steel panels with a low emissivity surface (<0.05) that are actively cooled by helium gas, which flows inside the cooling tube welded on the panel surface. The temperature of helium gas is between 80 K and 100 K during plasma operation. The total surface area of the thermal shield is approximately 4000 m2 and its assembled body (25 m tall) weighs about 900 tons.
The key challenges for thermal shield manufacturing are tight tolerances, precision welding, and the silver coating of the large structure. The thermal shield also has many interfaces with other tokamak components. "The Korean Domestic Agency is satisfied with this contract because the thermal shield is one of the most critical procurement items in the ITER project. We will do our best in collaboration with the ITER Organization to successfully procure the ITER thermal shield," said Hyeon Gon Lee, DDG of the Korean Domestic Agency, on the occasion of the contract signature.
ITER Blanket Design
More than 80 experts from the ITER Organization, Domestic Agencies and industry attended a 3-day Final Design Review of the ITER blanket system. "The development and validation of the final design of the blanket system is a major achievement on our way to deuterium-tritium operation - the main goal of the ITER project," Blanket Integrated Product Team Leader (BIPT) and Section Leader Rene Raffray concluded at the end of the meeting. "We are looking at a first-of-a-kind fusion blanket which will operate in a first-of-a-kind fusion experimental reactor." The ITER blanket system provides the physical boundary for the plasma and contributes to the thermal and nuclear shielding of the vacuum vessel and the external machine components such as the superconducting magnets operating in the range of 4 Kelvin (-269°C). Directly facing the ultra-hot plasma and having to cope with large electromagnetic forces, while interacting with major systems and other components, the blanket is arguably the most critical and technically challenging component in ITER.
The blanket consists of 440 individual modules covering a surface of 600 m2, with more than 180 design variants depending on the segments' position inside the vacuum vessel and their functionality. Each module consists of a shield block and first wall, together measuring 1 x 1.5 metres and weighing up to 4.5 tons - dimensions that not only demand sophisticated remote handling in view of maintenance requirements during deuterium-tritium operation, but also an approach to attaching the modules which is far from trivial when considering the enormous electromagnetic forces.
The panel nevertheless pointed out some remaining issues, including a few challenging issues that need to be addressed at the project level. But thanks to the excellent quality of work performed by the BIPT, the ITER blanket design can today be called "approved." The BIPT can now turn its focus to addressing the feedback received at the Final Design Review, applying the final touches to the design, and preparing for the Procurement Arrangements, where fabrication is handed over to the Domestic Agencies, starting at the end of 2013.
ITER Cryostat
There is already one facility on site for the fabrication of ITER components that are too large for transport and there's soon to be another. Ground breaking begins in May for a temporary workshop where the four main sections of the cryostat will be assembled from 54 smaller segments manufactured by India.
Like the largest poloidal field coils, the size and weight of the main cryostat segments makes travel along the ITER Itinerary impossible. The cryostat base section - 1250 tons - is the single largest load of ITER Tokamak assembly; the other three cryostat sections (lower cylinder, upper cylinder and top lid) weigh in the range of 600-800 tons each. Within the on-site Cryostat Workshop, assembly activities will take place on two huge steel platforms built to support the weight of the components, jigs and fixtures.
As a high vacuum component, the cryostat is subject to strict quality requirements. Two types of testing will be carried out in the Workshop: an examination of each weld through non-destructive means (ultrasonics or radiography) and the vacuum leak testing of each joint (helium mass spectrometer leak detection). Dimensions and tolerance control will be achieved using sophisticated alignment and metrology equipment. Approximately 50 people are expected to manage the machining, alignment, welding and testing operations during assembly of the cryostat segments.
As soon as the Tokamak and Assembly buildings (and their heavy-lift crane) are available, the cryostat base must be ready ... and the lower cryostat cylinder soon after that. The Indian Domestic Agency is procuring two transporter platforms so that work can be carried out in the Cryostat Workshop on the two sections simultaneously. A gap of about two years will then follow before the upper cylinder and top lid can be assembled in the pit.
The contract for the design, fabrication and assembly of the cryostat was awarded in August 2012 by the Indian Domestic Agency to Larsen & Toubro Ltd - this contract also includes the set-up of the Cryostat Workshop, workshop assembly activities, and in-pit assembly (integration of cryostat main sections, welding, etc.). In the autumn, Larsen & Toubro awarded the construction of the Workshop to the French company SPIE Batignolles TPCI (part of the consortium that built the ITER Poloidal Field Coils Winding Facility). Work on the steel-framed structure is scheduled to last 18 months.
ITPA
The 10th Integrated Operation Scenarios (IOS) International Tokamak Physics Activity (ITPA) meeting was held in the ITER Council Chamber from 15-18 April 2013. There were 30 external participants from the ITER Members and a number of representatives from the ITER Organization. The external participants include representatives from the main magnetic fusion devices and modellers from the ITER Members.
The purpose of the meeting was to discuss the experiments and modelling being carried out around the world in support of the ITER design and plasma operation as well as to align the priorities for future R&D with the latest ITER priorities. The IOS Topical Group (TG) is one of seven topical groups in the ITPA whose main role is to integrate plasma operation scenarios for burning plasma experiments, particularly for ITER, including inductive, hybrid, and steady-state scenarios. The IOS-TG also recommends physics guidelines and methodologies for the operation and design of burning plasma experiments. The ITPA topical groups all meet every six months in one of the countries of the ITER Members. This was the first time the IOS-TG met at ITER, allowing the members and experts of the IOS-TG to see first-hand the progress in ITER construction.
Experimental and modelling results were presented from Alcator C-Mod, ASDEX-Upgrade, DIII-D, JET, JT-60U, and KSTAR of ITER-relevant plasma operational scenarios. Experimental results concentrated on inductive and hybrid scenarios; modelling of steady-state scenarios was also presented. Modelling of burning plasma and energetic particle physics were presented as well as plasma rotation in ITER and their impact on operational scenarios. The predicted plasma rotation profiles in hybrid scenarios were strongly peaked with rotation up to nearly 200 km/s, corresponding to about 4 kHz rotation in ITER in the centre. The effects of the Edge Localized Mode (ELM) coil fields on fast ion losses comparing vacuum fields and the plasma response were also shown, indicating that when the plasma response is included, the fast ion losses are acceptable even at high performance with the maximum ELM coil current.
The IOS-TG also concentrates on plasma control including experiments and modelling of profile control as well as development of the preliminary design of the ITER plasma control system (PCS). A review of the PCS conceptual design was presented as well as an action plan for how the experimental and modelling programs within the ITER Members can contribute to developing the PCS preliminary design for First Plasma and early hydrogen and helium plasma operation. Modelling of control of the entry into a burning plasma regime was also presented. A proposal was made to integrate experiments and modelling of plasma control schemes for ITER in existing experiments so that these control schemes can be developed before ITER operation to reduce run time on ITER for control scheme development. A request was made for the ITPA to provide control priorities for the ITER actuators starting with a few phases of plasma operation. As part of the ITPA response to the question of starting ITER with an all-tungsten divertor, the IOS-TG discussed the effect of a tungsten divertor on operational scenarios. Reports from DIII-D, ASDEX Upgrade, and C-Mod compared operation with carbon walls and metal walls. Although there were some differences, it was generally believed that ITER would be able to learn how to operate with beryllium walls and an all tungsten divertor.
Modelling of ITER and JET current ramps were also presented indicating the differences between operation with carbon walls and with the ITER-like wall on JET. Since the peak in radiation for tungsten occurs around a temperature of 1 keV, the radiation from tungsten will be peaked near the edge in ITER. There is still a question about whether or not the tungsten transport into the core can be controlled to a sufficiently small value.
Modelling of steady-state fusion plasma scenarios was also presented to understand how the present heating and current drive systems should perform as well as what upgrades might be required to meet the long-pulse goals of the ITER program. The modelling includes simulation of sawtooth control, kinetic integrated modelling, and parameter scaling from existing experiments to ITER steady-state regimes. An update was also given on the latest proposed changes to the steering of the electron cyclotron heating and current drive system that was followed by extensive discussion.
In summary, the meeting provided valuable information on recent experiments and modelling of ITER plasma operation scenarios. Actions for the ITPA members and experts to help define the preliminary design of the ITER plasma control system were agreed upon. Continued experiments and modelling to demonstrate ITER operational scenarios for the inductive, hybrid, and steady-state scenarios were presented. A special report on the impact of an all-tungsten divertor on ITER operational scenarios was also discussed at length.
Korean ITER Meetings
An important week of meetings took place recently in Korea for the ITER vacuum vessel and thermal shield—for both of these key components industrial suppliers have been selected and manufacturing, pre-manufacturing or kick-off works have begun.
The 52nd ITER Vacuum Vessel Integrated Product Team (IPT) meeting and Domestic Agency collaboration meeting held on 8-10 April brought together over 30 experts from the ITER Organization, the European, Indian, Korean and Russian Domestic Agencies, and Korean industry (Hyundai Heavy Industry & AMW). During meetings hosted at the National Fusion Research Institute (NFRI) and at Hyundai Heavy Industry, participants shared the technology and experience of fabrication of the ITER vacuum vessel, ports and in-wall shielding, and discussed the development pathway for fabrication issues.
During a bilateral collaboration meeting held on 11 April, participants from the Korean and European Domestic Agencies - plus industrial suppliers Hyundai Heavy Industry and AMW - focused more particularly on the new technologies for fabrication of ITER vacuum vessel sectors, especially welding, nondestructive examination (NDE) and optical dimensional measurement. All parties agreed that such valuable collaboration would be continued in the future.
On Friday 12 April, the kick-off meeting for the ITER thermal shield was held—this key component will be installed between the magnets and the vacuum vessel/cryostat in order to shield the magnets from radiation. The contract for the design and fabrication of the thermal shield was awarded by the Korean Domestic Agency in February to SFA Engineering Corp, which is also the supplier selected by Korea for ITER's assembly tooling. SFA presented the implementation plan for the procurement of the thermal shield during the meeting.
More than 20 responsible persons from the Korean Domestic Agency, SFA and the ITER Organization were present including Domestic Agency head Kijung Jung, SFA Chief Operating Officer Myung Jae Lee, and head of the ITER Vacuum Vessel Division Carlo Sborchia. Prior to the kick-off meeting, representatives from ITER and the Korean Domestic Agency agreed to collaborate closely to solve urgent design change requests related to assembly and interface issues.
"The thermal shield is one of the most critical procurement items in the ITER project. We will do our best in collaboration with the ITER Organization for its successful procurement," stressed Kijung Jung.