[en] Highlights: • VR technologies applied to Fusion enable better and faster understanding of integration issues. • Assembly problems are solved and validated on a numerical mockup. • Integration and accessibility issues can be identified in the earliest design on numerical mockup. • Problems are solved and validated on a physical mockup. • VR technologies are very helpful for assembly and maintenance operation simulations. - Abstract: The WEST project (Tungsten (W) Environment in Steady state Tokamak) is an upgrade of the existing fusion machine, Tore Supra. The goal is to equip the tokamak with a fully cooled tungsten divertor and to transform the machine in a test platform open to all ITER partners. The main assembly challenge of this project consists of an implementation of two magnet systems, called divertors, with an accuracy of 1 mm. Indeed, each divertor has about 4 m as diameter and has a heavy weight of 10 tons; also it introduces piece by piece in the original vessel through tight ports then assembled inside. To ensure a perfect fitting between these new components and a very constrained environment, it is necessary to use the latest CAD technologies available. Beyond conventional CAD tools, the virtual reality (VR) room of the institute provides several useful tools. Thanks to the 185″ stereoscopic 3D screen and a force feedback arm linked to clash detection software developed by the CEA LIST, a new way to carry out design and assembly studies was performed. In order to improve VR results, metrology data (3D scan) enhance simulations. Therefore, it becomes possible to be aware of the real size of a component and future difficulties in assembling it. At last, performance of such simulations is evaluated and compared to physical mockup in order to bring enhancement to the VR tools, before to be compared to the real operations on Tore Supra. The aim is to build a design tool that helps the designer since early stage of the design of complex systems, taking into consideration integration, assembly and maintenance aspects while reducing costs and schedule of a project.

[en] The actively cooled plasma facing units (PFUs) constituting the WEST lower divertor must meet strict technical specifications before their installation into the WEST tokamak. The tests performed at CEA lead mainly: to provide information on the feasibility to attach mechanically PFUs on sectors, to ensure geometrical tolerances for the welding of PFUs to water manifolds, to check the PFU vacuum tightness and to confirm the PFUs heat exhaust capability. Using high heat flux (HHF) test facilities, such as HADES at CEA-Cadarache and GLADIS at IPP-Garching, ∼ to 5% of the PFU production was tested. Infrared thermography (IR) tests were also performed (∼ to 24% of the PFU production tested). We show that PFUs are with a quality in agreement to the requirements and that the assessment of the heat exhaust capability during the series production is needed. Based on statistical approaches, this work also provides information on the methods to assess the quality of tested components using statistic process control. (authors)

[en] The design of the WEST (Tungsten-W Environment in Steady-state Tokamak) Ion cyclotron resonance heating antennas is based on a previously tested conjugate-T Resonant Double Loops prototype equipped with internal vacuum matching capacitors. The design and construction of three new WEST ICRH antennas are being carried out in close collaboration with ASIPP, within the framework of the Associated Laboratory in the fusion field between IRFM and ASIPP. The coupling performance to the plasma and the load-tolerance have been improved, while adding Continuous Wave operation capability by introducing water cooling in the entire antenna. On the generator side, the operation class of the high power tetrodes is changed from AB to B in order to allow high power operation (up to 3 MW per antenna) under higher VSWR (up to 2:1). Reliability of the generators is also improved by increasing the cavity breakdown voltage. The control and data acquisition system is also upgraded in order to resolve and react on fast events, such as ELMs. A new optical arc detection system comes in reinforcement of the V_r/V_f and SHAD systems

[en] Before the installation of the first ICRF launcher in WEST, dedicated RF, cold and hot leak tests have been performed in the TITAN test bed (Bernard a al., 2011a,b). All the water circuits have been controlled in order to avoid any in-vessel leak. The impedance matching has been checked at low level (mW range) and the high RF voltage standoff has been validated at the nominal value of 27 kV peak. During the WEST C3a campaign, the commissioning of the first antenna has been successfully performed. About 0.6 MW of power has been coupled to the plasma, and the launcher's load-resilience has been proved. (authors)

[en] One of the key missions of the Ion Cyclotron Resonant Heating (IRCH) system for WEST is to provide sufficient RF heating power in order to obtain a heat flux on the divertor target of 10 MW/m² during 1000 s and 20 MW/m² during a few tens of seconds. Based on the experience acquired in Tore Supra, the ICRH system has been upgraded for long pulse operation and Edge Localized Modes (ELM) resilience. To achieve this performance, three antennas have been designed through a European collaboration and are now under fabrication at CAS/ASIPP, at the Keye Company, Hefei, in China, within the framework of the Associated Laboratory IRFM-ASIPP. This paper describes the electrical and mechanical design of the antenna, together with the main manufacturing steps and leak test procedure used for validating the water-cooled components. Accessibility and maintenance studies on WEST have been performed with the help of virtual reality. The first ICRH antenna was delivered at Cadarache in July 2016, and is foreseen to be installed on WEST in 2017. (authors)

[en] Robotic operations are one of the major maintenance challenges for ITER and future fusion reactors. CEA has developed a multipurpose carrier able to realize deployments in the plasma vessel without breaking the Ultra High Vacuum (UHV) and temperature conditioning. A 6 years R and D programme was jointly conducted by CEA-LIST Interactive Robotics Unit and the Institute for Magnetic Fusion Research (IRFM) in order to demonstrate the feasibility and reliability of an in-vessel inspection robot relevant to ITER requirements. The Articulated Inspection Arm robot (AIA) is an 8-m long multilink carrier with a payload up to 10 kg operable between plasma under tokamak conditioning environment; its geometry allows a complete close inspection of Plasma Facing Components (PFCs) of the Tore Supra vessel. Different tools are being developed by CEA to be plugged at the front head of the carrier. The diagnostic presently in operation consists in a viewing system offering accurate visual inspection of PFCs. Leak detection of first wall based on helium sniffing and laser compact system for carbon co-deposited layers characterizations or treatments are also considered for demonstration. In April 2008, the AIA robot equipped with its vision diagnostic has realized a complete deployment into Tore Supra and the first closed inspection of the vessel under UHV conditions. During the upcoming experimental campaign, the same operation will be performed under relevant conditions (10^-6 Pa and 120 deg. C) after a conditioning phase at 200 deg. C to avoid outgassing pollution of the chamber. This paper describes the different steps of the project development, robot capabilities with the present operations conducted on Tore Supra and future requirements for making the robot a tool for tokamak routine operation.

[en] Robotic operations are one of the major maintenance challenges for ITER and future fusion reactors. In particular, in-vessel inspection operations without loss of conditioning will be mandatory. In this context, an Articulated Inspection Arm (AIA) is currently developed by the CEA within the European work programme framework, which aims at demonstrating the feasibility of a multi-purpose in-vessel Remote Handling inspection system using a long reach, limited payload carrier (up to 10 kg). It is composed of 5 segments with 8 degrees of freedom and a total range of 8 m. The first in situ tests will take place by the end of 2007 on the Tore Supra Tokamak at Cadarache (France). They will validate concepts for operations under ITER relevant vacuum and temperature conditions. After qualification, the arm will constitute a promising tool for various applications. Several processes are already considered for ITER maintenance and will be demonstrated on the AIA robot carrier: - The first embedded process is the viewing system. It is already manufactured and will allow close visual inspection of the complex Plasma Facing Components (PFC) (limiters, neutralisers, RF antenna, diagnostic windows, etc.). - In situ localisation of water leakage based on a helium sniffing system is also being studied to improve and facilitate maintenance operations. - Finally a laser ablation system for PFC detritiation, developed in CEA laboratories, is being fitted to be implemented on the robot for future operation in Tore Supra. This paper deals with the integration of the robot into Tore Supra and the progress in the development of the processes listed above. It also describes the current test campaign aiming to qualify the robot performance and reliability under vacuum and temperature conditions

[en] Highlights: • CEA have developed a dedicated test-bed for testing RF contact in ITER relevant conditions (vacuum, temperature, RF current). • A prototype of RF contacts have been designed and manufactured, with copper lamellas brazed on a titanium holder. • This RF contact prototype failed at RF current larger than 1.8 kA. • Extensive R&D is foreseen with new RF contact designs. - Abstract: Embedded RF contacts are integrated within the ITER ICRH launcher to allow assembling, sliding and to lower the thermo-mechanical stress. They have to withstand a peak RF current up to 2.5 kA at 55 MHz in steady-state conditions, in the vacuum environment of the machine. The contacts have to sustain a temperature up to 250 °C during several days in baking operations and have to be reliable during the whole life of the launcher without degradation. The RF contacts are critical components for the launcher performance and intensive R&D is therefore required, since no RF contacts have so far been qualified at these specifications. In order to test and validate the anticipated RF contacts in operational conditions, CEA has prepared a test platform consisting of a steady-state vacuum pumped RF resonator. In collaboration with ITER Organization and the CYCLE consortium (CYclotron CLuster for Europe), an R&D program has been conducted to develop RF contacts that meet the ITER ICRH launcher specifications. A design proposed by CYCLE consortium, using brazed lamellas supported by a spring to improve thermal exchange efficiency while guaranteeing high contact force, was tested successfully in the T-resonator up to 1.7 kA during 1200 s, but failed for larger current values due to a degradation of the contacts. Details concerning the manufacturing of the brazed contacts on its titanium holder, the RF tests results performed on the resonator and the non-destructive tests analysis of the contacts are given in this paper.