E. Daly

Design analysis and manufacturing studies for ITER In-Vessel Coils

ITER is incorporating two types of In Vessel Coils (IVCs): ELM Coils to mitigate Edge Localized Modes and VS Coils to provide Vertical Stabilization of the plasma. Strong coupling with the plasma is required so that the ELM and VS Coils can meet their performance requirements. Accordingly, the IVCs are in close proximity to the plasma, mounted just behind the Blanket Shield Modules. This location results in a radiation and temperature environment that is severe necessitating new solutions for material selection as well as challenging analysis and design solutions. Fitting the coil systems in between the blanket shield modules and the vacuum vessel leads to difficult integration with diagnostic cabling and cooling water manifolds. The design of the IVCs is now progressing towards a final design scheduled for late CY 13. The project is a collaboration between the Princeton Plasma Physics Laboratory in Princeton NJ, the Chinese Academy of Sciences (ASIPP) in Hefei China and the ITER Organization. An extensive thermal and stress analysis to evaluate the effects of the high temperatures and electromagnetic loads on the In Vessel Coils has been undertaken. Manufacturing development is underway at ASIPP to develop the processes necessary to build ELM coil and VS Coil prototypes. This paper will outline the design and analysis issues as well as review the manufacturing development required to address these requirements and plans for prototypes.

Update on Design of the ITER In-Vessel Coils

Abstract The ITER project baseline now includes two sets of in-vessel coils, one to mitigate the effects of Edge Localized Modes (ELMs) and another to provide vertical stabilization (VS). The in-vessel location presents special challenges in terms of nuclear radiation and temperature, and requires the use of mineral-insulated conductors. An update to the preliminary design based on this conductor technology is presented for both coil designs. Results from an on-going R&D program consisting of conductor development, welding and brazing process development, electrical testing and mechanical testing in order to demonstrate manufacturability of this style of conductor are presented. Plans for two prototype coils, one of each type, are presented.

Mechanical analysis for ITER upper ELM coil

Mechanical analysis for ITER Upper ELM coil is divided into two sections, in the 1st one a FE model is built and the critical components like the conductor and jacket are analyzed, while the 2nd part analytically checks the bolt strength with the load from the previous step. Three areas representing this effort are presented: electro-magnetic, hydraulic-thermal and mechanical analysis of upper ELM coil. Electro-magnetic analysis provides the ohmic heat and electromagnetic force for hydraulic thermal and mechanical analysis respectively. Hydraulic thermal analysis is performed to get the temperature distribution of the upper ELM coil for further mechanical analysis. Mechanical analysis aids in the design of upper ELM coil while quantifying the stresses and machine loads which can be used to verify the bolts with regard to ASME and machine design handbook.

Thermal and structural analysis of the ITER ELM coils

A thermal and structural analysis of the ELM Coil design for ITER is presented. The ELM Coils are constructed using a jacketed mineral insulated conductor of CuCrZr, MgO and Inconel 625, rigidly mounted to the vacuum vessel inner shell, behind the Blanket Modules. Since the coils are not designed to be remotely maintained, a major issue is demonstrating the structural integrity against fatigue and crack propagation over an estimated 100 million cycles arising from operation at 5 hz in a high magnetic field. The temperature rises from ohmic and nuclear heating produce mean thermal stresses that further limit the allowable alternating stresses. Thermal growth also imparts large forces which must be reacted by the Vacuum Vessel. This paper presents the analysis and results with particular attention to the design criteria which is unique to the In-Vessel Coils.

Conceptual Design of ITER In-Vessel Vertical Stabilization Coil Power Supply System

ITER plasma requires the use of an internal vertical stabilization (VS) coil set as part of the system for active control of vertical position. The required peak current and voltage of VS power supply are of order of 60 kA and 2.4 kV. Also, it needs short voltage response time, less than 1 ms and highly transient power demand. This paper describes a conceptual design study for the in-vessel vertical stabilization coil power supply system to judge design feasibility and estimate its cost. Finally, the result will be used as design input data for the ITER Tokamak building and other interface systems.

Design and Analysis of the ITER Vertical Stability (VS) Coils

Abstract The ITER vertical stability (VS) coils have been developed through the preliminary design phase by Princeton Plasma Physics Laboratory (PPPL). Final design, prototyping and construction will be carried out by the Chinese Participant Team contributing lab, Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). The VS coils are a part of the in-vessel coil systems which include edge localized mode (ELM) coils as well as the VS coils. The VS design employs four turns of stainless steel jacketed mineral insulated copper (SSMIC) conductors The mineral insulation is Magnesium Oxide (MgO). Joule and nuclear heat are removed by water flowing through the hollow copper conductor. The slightly elevated temperatures in the conductor and its support spine during operation impose compressive stresses that mitigate fatigue damage. Away from joints, and breakouts, conductor thermal stresses are low because of the axisymmetry of the winding (there are no corner bends as in the ELM coils).The joints, and break-out or terminal regions are designed with similar but imperfect constraint compared with the ring coil portion of the VS. The support for the break-out region is made from a high strength copper alloy, CuCrZr. This is needed to conduct nuclear heat to the actively cooled conductor and to the vessel wall. The support “spine” for the ring coil portion of the VS is 316 stainless steel, held to the vessel with preloaded Inconel 718 bolts. Lorentz loads resulting from normal operating loads, disruption loads and loads from disruption currents in the support spine shared with vessel, are applied to the VS coil. Stresses in the coil, joints, and break-outs are presented. These are compared with static and fatigue allowables. Design for fatigue is much less demanding than for the ELM coils. A total of 30,000 cycles is required for VS design.

Structural analysis work on ITER Vacuum Vessel

The structural integrity of the ITER Vacuum Vessel is verified by elastic and/or non-linear analyses. The typical loads for the Vacuum Vessel are also explained. Electromagnetic load by vertical displacement event of plasma is most serious load. Major design modifications from basic design requirement are verified.

Design and manufacture of the ITER Vacuum Vessel

The main functions of the ITER Vacuum Vessel (VV) are to provide the necessary vacuum for plasma operation, act as first nuclear confinement barrier and remove nuclear heating. The design of the VV has been reviewed in the past two years due to more advanced analyses, design modifications required by the interfacing components and R&D. Following the signature of four Procurement Arrangement (PAs), the manufacturing design of the VV sectors, ports and In-Wall Shielding (IWS) is being finalized and the fabrication of the VV sectors has been started in 2012.

R&D Activities on ITER In-Vessel Coil SSMI Conductor Fabrication

A Task Agreement (TA) “Final Design and Prototyping of the ITER In-Vessel Coils (IVCs) and Feeders” was signed and in implementation between ITER Organization and China Domestic Agency (CNDA) and Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) to advance the design of the ITER IVCs toward final design review readiness including manufacture of prototype ELM and VS coils. Based on many fruitful research results, Princeton Plasma Physics Laboratory (PPPL) is also involved into this TA and in charge of most analysis works, specifications, and electrical breakdown tests of the mineral insulated conductor during irradiation. ITER IVCs consist of Edge-Localized Mode (ELM) and Vertical Stabilization (VS) coils. Structure of Stainless Steel Jacketed Mineral Insulated Conductor (SSMIC) using Magnesium Oxide (MgO) as insulation is being developed for the IVCs manufacture. Different from the industrial products, to ensure the high purity MgO and reach as high as possible insulation performance, ASIPP has developed the compaction method for the scaled-up SSMI Conductor fabrication. After some R&D processes, final dimension ELM and VS SSMI conductor are fabricated. R&D works for SSMIC manufacture are presented in this paper.

Axisymmetric simulations of the ITER Vertical Stability coil

The ITER in-vessel coil system includes Vertical Stability (VS) coils and Edge Localized Mode (ELM) coils. There are two large VS ring coils, one upper and one lower. Each has four turns which are independently connected. The VS coils are needed for successful operation of ITER for most all of its operating modes. The VS coils must be highly reliable and fault tolerant. The operating environment includes normal and disruption Lorentz forces. To parametrically address all these design conditions in a tractable analysis requires a simplified model. The VS coils are predominately axisymmetric, and this suggests that an axisymmetric model can be meaningfully used to address the variations in mechanical design, loading, material properties, and time dependency. The axisymmetric finite element analysis described in this paper includes simulations of the bolted frictional connections used for the mounting details. Radiation and elastic-plastic response are modeled particularly for the extreme faulted conditions. Thermal connectivity is varied to study the effects of partial thermal connection of the actively cooled conductor to the remaining structure.