Search

Recent progress of the ITER vacuum vessel (VV) design is presented. As the ITER construction phase approaches, the VV design has been improved and developed in more detail with the focus on better performance, improved manufacture and reduced cost. Based on the achievements of manufacturing studies being performed in cooperation with the ITER participant teams (PTs), design improvement of the typical VV sector (#1, see the legend to figure 1 in this article) has been nearly finalized. Design improvement of other sectors is in progress—in particular, of the VV sectors #2 and #3 which interface with tangential ports for the neutral beam (NB) injection. For all sectors, the concept for the in-wall shielding has progressed and developed in more detail. The design progress of the VV sectors has been accompanied by the progress of the port structures. Structural analyses have been performed to validate all design improvements.

Recent progress of the ITER vacuum vessel (VV) design is presented. As the ITER construction phase approaches, the VV design has been improved and developed in more detail with the focus on better performance, improved manufacture and reduced cost. Based on achievements of manufacturing studies, design improvement of the typical VV Sector (#1) has been nearly finalized. Design improvement of other sectors is in progress—in particular, of the VV Sectors #2 and #3 which interface with tangential ports for the neutral beam (NB) injection. For all sectors, the concept for the in-wall shielding has progressed and developed in more detail. The design progress of the VV sectors has been accompanied by the progress of the port structures. In particular, design of the NB ports was advanced with the focus on the beam-facing components to handle the heat input of the neutral beams. Structural analyses have been performed to validate all design improvements.

In this paper, we report on the experiment carried out at the Frascati Tokamak Upgrade (FTU) on the porting of the plasma control system (PCS) from a LynxOS architecture to an open source Linux real-time architecture. The old LynxOS system was implemented on a VME/PPC604r embedded controller guaranteeing successful plasma position, density and current control. The new RTAI-Linux operating system has shown to easily adapt to the VME hardware via a VME/INTELx86 embedded controller. The advantages of the new solution versus the old one are not limited to the reduced cost of the new architecture (based on the open-source characteristic of the RTAI architecture) but also enhanced by the response time of the real-time system which, also through an optimization of the real-time code, has been reduced from 150 μs (LynxOS) to 70 μs (RTAI). The new real-time operating system is also shown to be suitable for new extended control activities, whose implementation is also possible based on the reduced duty cycle duration, which leaves space for the real-time implementation of nonlinear control laws. We report here on recent experiments related to the optimization of the coupling between additional radiofrequency power and plasma.

The design and cost reduction study develop a conceptual site layout, building and plant system design for the reduced cost ITER (EU-I). This new EU-I conceptual design, that is not a scaling down of the FDR, is used to perform a cost estimate. The study has been focused on the design aspects that may result in the best potential cost saving. The scope covers the site layout, Tokamak Building and BOP system such as study state electrical power, heat rejection, liquid distribution, hot cell and waste treatment.

The use of high temperature superconductors (HTS) in long term tokamak fusion reactors is analyzed in this paper. The well-documented physical properties of high temperature superconductors are used in the evaluation. Short-sample wires and tapes of Bi2Sr2CanCun 1Oy materials, with n 1, 2 (referred to as BSCCO), and YBCO (YBa2CuO7 x) tapes approach their single-crystal performance limits. They provide a useful reference frame as well as a starting point of what may be possible in the future. In this paper, the design issues that arise when this technology is used in tokamak magnet applications will be investigated by extrapolating the properties of short sample YBCO thick films and BSCCO tapes to longer lengths. The properties of YBCO operating at elevated temperatures (\ 10 K) will also be summarized. The limitations imposed on the performance and lifetime of the HTS materials because of the fusion environment will be reviewed. The consequences of implementing an HTS configuration in a fusion environment will then be described. The use of HTS material may offer an opportunity for a fundamentally different approach to magnet design and construction leading to either lower cost or reduced maintenance. Reduced cost magnets requiring decreased shielding, with better access and easier maintenance may be feasible. © 2001 Elsevier Science B.V. All rights reserved.

This paper presents the current status of the Electron Cyclotron Emission (ECE) diagnostic on the Reduced Technical Objectives/Reduced Cost International Thermonuclear Experimental Reactor (RTO/RC ITER). It discusses the implications of the new machine design on the measurement requirements, the ability of the diagnostic technique to meet these, and the changes in the implementation imposed by the new layout. Finally, it outlines the physics studies, design and R&D work required prior to the detailed design and construction of the diagnostic. Key results are: (i) that the localisation of the measurement is similar to that in ITER–FDR (40–100 mm in X-mode, 60–200 mm in O-mode for the reference scenario), so that the relative spatial resolution degrades in this, smaller, machine, and (ii) the expected effect of transport barriers on the temperature profile in the high temperature region will be poorly resolved, because the effect of the temperature gradient on the outboard side is to degrade the resolution to (∼250 mm in X-mode, ∼350 mm in O-mode). Nevertheless ECE will be able to make a unique and useful contribution to the RTO/RC ITER measurement set.

The design has progressed on the vacuum vessel and First Wall (FW)/blanket for the Reduced Technical Objective/Reduced Cost (RTO/RC) ITER. The basic functions and structures are the same as for the 1998 ITER design. The design has been improved to achieve, along with the size reduction, ∼50% target reduction of the fabrication cost. The number of blanket modules has been minimized according to smaller dimensions of the machine and a higher payload capacity of the blanket Remote Handling tool. A concept without the back plate has been designed and assessed. The blanket module concept with flat separable FW panels has been developed to reduce the fabrication cost and future radioactive waste.

Six years of joint work under the international thermonuclear experimental reactor (ITER) EDA agreement yielded a mature design for ITER which met the objectives set for it (ITER final design report (FDR)), together with a corpus of scientific and technological data, large/full scale models or prototypes of key components/systems and progress in understanding which both validated the specific design and are generally applicable to a next step, reactor-oriented tokamak on the road to the development of fusion as an energy source. In response to requests from the parties to explore the scope for addressing ITER's programmatic objective at reduced cost, the study of options for cost reduction has been the main feature of ITER work since summer 1998, using the advances in physics and technology databases, understandings, and tools arising out of the ITER collaboration to date. A joint concept improvement task force drawn from the joint central team and home teams has overseen and co-ordinated studies of the key issues in physics and technology which control the possibility of reducing the overall investment and simultaneously achieving the required objectives. The aim of this task force is to achieve common understandings of these issues and their consequences so as to inform and to influence the best cost–benefit choice, which will attract consensus between the ITER partners. A report to be submitted to the parties by the end of 1999 will present key elements of a specific design of minimum capital investment, with a target cost saving of about 50% the cost of the ITER FDR design, and a restricted number of design variants. Outline conclusions from the work of the task force are presented in terms of physics, operations, and design of the main tokamak systems. Possible implications for the way forward are discussed.

This paper describes innovative design aspects that are considered to optimise the blanket modules for the reduced technical objective/reduced cost international thermonuclear experimental reactor. The blanket modules have a vertical straight profile facing the plasma, and the first wall is built in small and flat panels. Copper may be applied only in front of the first row of cooling passages. The radial cooling of the shield block avoids a complex by-pass at the back and opens up the possibility to use cast instead of forged steel. Slits in the shield block and in the first wall reduce the electromagnetic forces enough to allow the support of the modules on the vessel and the mechanical attachment of the first wall panels.

The primary pumping system is needed not only to exhaust helium ash resulting from the DT reaction but also excess fuelling gas injected during the fusion burn, which can extend for 100's to 1000's of seconds, and to perform a variety of other functions. The prevailing environmental conditions, principally nuclear radiation, tritium exposure, magnetic fields, and the need for containment, have a significant impact on the design and selection of equipment. This paper presents the design of the Reduced Technical Objectives/Reduced Cost (RTO/RC) ITER primary pumping system with particular emphasis on the nuclear aspects of the design. Component selection and equipment layout issues to meet established requirements for the system are reviewed together with the R&D that is being undertaken to support the design. In addition, serviceability and maintainability issues related to this system are also discussed.

Recent progress in design and analysis of the vacuum vessel (VV) for the reduced technical objectives/reduced cost International Thermonuclear Experimental Reactor (RTO/RC-ITER) is presented. The basic VV design is similar to the previous ITER VV. However, because the back plate for the blanket modules could be eliminated, its previous functions could be transferred to the VV. For this option, the blanket modules are supported directly by the VV and the blanket coolant channels are structurally part of the VV double wall structure. In addition, a ‘tight fitting’ configuration is required to correctly position the modules’ first wall. Although such modifications of the VV complicate its structure and increase its fabrication cost, the design of the VV is considered to be still feasible. The structural analyses of the VV have been conducted using several FE models of the VV, including global and local models. Although further assessment is required, based on the analyses performed to date, the structural aspects of the VV for the case without the back plate appear feasible.

Instantaneous fuelling and plasma exhaust flow rates for the reduced technical objective/reduced cost version of International Thermonuclear Experimental Reactor (RTO/RC-ITER) are similar to those described in the Final Design Report (FDR) of ITER, despite the reduction in fusion power by a factor of about two. However, the reduced pulse length and the lower fraction of campaign time spent in burn mode, together with the lower integrated operating lifetime proposed, will generate cost savings in several systems of the fuel cycle. As the quantity of tritium handled per pulse is now smaller, this could be buffered, allowing systems in the tritium plant still to operate in steady state mode as in the FDR design, thereby increasing the potential for downsizing of system capacities. The lower operating time fraction will increase performance margins for some systems, for example, the Torus Exhaust Gas Processing System (TEGPS) which was designed to meet a specified daily release rate for the FDR design conditions which were more onerous than RTO/RC-ITER. As no break through of tritium into cooling water is now expected, the duties of the Water and Atmosphere Detritiation Systems are considerably reduced, and design concepts which are simpler, cheaper and more amenable to modular implementation can be adopted.