[en] The WEST (Tungsten Environment in Steady-state Tokamak) project in France is crucial for reaching sustainable fusion energy by simulating reactor-like conditions. WEST provides a unique facility to integrated and test technologies for Long Pulse Operations. Previous operation on Tore Supra, and numerous studies showed that all components receiving convective heat flux from particles and thermal radiations from the plasma must be water-cooled. Key components such as the divertors and limiters were identified for their high thermal load. Their design has been studied for many projects and is well documented. The integration process involved rigorous design and manufacturing standards, particularly focusing on over 2000 Copper/Stainless Steel junctions critical for preventing water leaks during operation. Additionally dedicated models were developed to compute thermal loads on all components within WEST Vacuum Vessel (VV), including the VV inner shell, ports walls, diagnostics… It was shown that depending on the plasma scenario and the reflectivity hypothesis of the surfaces, temperatures can significantly vary, forcing the design teams to take into account conservative envelop cases. Dedicated water cooled protection panels were integrated to shield the larger surfaces of the VV. Actively cooled protections on some of the most loaded diagnostics inside the ports were developed. These upgrades were installed during several annual shutdowns. The current WEST configuration includes more than 98% of the VV surface with actively cooled components. Innovative technologies are not indispensable, however all components must be manufactured and installed under high quality requirements, and stringent tightness control methods to prevent any risk of leak over the years from the numerous welds and hundreds of meters of cooling channels. However, some areas were too complex to cool down, for two main reasons: either it was too difficult to integrate water cooled components, or it was too complex to route water pipes to feed these components and to perform all welds with the required quality. Those aspects cannot be overlooked since they can severely affect the operational domain for long pulse operations. The remaining inertial structures are monitored with thermocouples and IR diagnostics. Flowmeter and thermocouples are installed in all water loops and a dedicated calorimetry diagnostic was developed. The energy balance is closed with an imbalance of about 10% of the total injected energy for most of the campaigns. Those diagnostics are mandatory to monitor the behaviour of poorly cooled components, to check that the cooling remains efficient during long pulse operation (no flow perturbation or critical flux…) and allow assessing the lifetime of inertial components. Yet, degassing occurred during long pulse operation, leading to an increase of plasma density and eventually disruptions. This is likely caused by overheating of surfaces. Indeed, thermocouples show that the temperature is steeply rising on some areas around the WEST upper divertor, reaching values above 300°C after 300s pulses and 1GJ injected. Some inertial areas not controlled by thermocouple temperature measurement may also have caused this outgassing. The path to high power continuous operation in WEST still requires improvements of protection of its internal components.

[en] The Interactive Robotics Laboratory of CEA LIST is in charge of the development of remote handling technologies to meet energy industry requirements. This paper reports the research and development activities in advanced robotics systems for inspection or light intervention in hazardous environments with limited access such as blind hot cells in the nuclear industry or the thermonuclear experimental Tokamak fusion reactor. A long-reach carrier robot called the articulated inspection arm (AIA) and diagnostics and tools for inspection or intervention are described. Finally experimental field tests are presented and actual challenges in modeling the robot's flexibilities are discussed. (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