When the next refurbishment and enhancement phase of the JET Facilities starts this year, the staff of the Remote Handling group will be extremely busy. The whole task is carried out by remote manipulation, a technique in which JET has acquired a unique expertise over many years. Remote Handling is not a fully robotic system. There is always an operator involved.

Operator in action in the Remote Handling control room

The task is to replace about 4,500 tiles within the vessel of Europe’s largest fusion device, JET. The operator in the control room uses the handles of a servo-manipulator master called MASCOT. His actions are performed by the slave which is positioned inside the Torus using a 10 metre long articulated boom. The surface of the new tiles is made predominantly of beryllium which is a relatively fragile material. Scratches or marks cannot be not tolerated. He feels the weight of the tile he lifts although he has nothing but the manipulator in his hands. A quick button push and the computer removes the virtual weight from his arms. The smoothness of the system helps him to forget how far he is from the scene of action. In addition, his imagination is enhanced by Virtual Reality. The operator feels as if he is standing inside the torus, but he is actually in the Remote Handling control room, using more than 20 different camera views to follow his actions. So, Remote Handling isn’t a fully robotic system. Automation is used in a minimum number of tasks. In all the rest there is always a man-in-the-loop.

Assembly work during boom extension

This scenario will happen this year during the next shutdown of the fusion device: 7 days a week, 20 hours a day with two shifts and three teams handing over to each other. “Shutdown means the period where we close the machine down and undertake maintenance and refurbishment,” explains Tony Loving, Remote Handling Group Leader at JET. He continues, “so we can have new experiments pushing fusion forward”.

This shutdown is centred on the installation of an ITER-like wall in JET. ITER, the next generation fusion experiment, will use beryllium and tungsten as first wall materials within the torus. This combination of materials has never been tested in a tokamak with a geometry and plasma parameters close to those of ITER. A key aim of the experiments with the ITER-like wall will be to develop regimes of operation for ITER compatible with beryllium and tungsten as first wall materials.

Virtual Reality Simulation showing the Remote Handling Mascot Manipulator carrying a Poloidal Limiter inside the Vacuum Vessel of the Joint European Torus facilities in 2006

Thirty nine people work in the Remote Handling group with a wide range of different skills sets. The work needs mechanical, operational knowledge as well as electrical, electronical and software development expertise. The preparation of this “ITER-like wall shutdown” has taken more than 18 months. Tony explains how many tasks his group is involved in, “Our experience has to go into the design of the components, of the tooling, and in the management of the delivery of all these different bits”. Alan Rolfe, Remote Handling group leader at JET for 20 years and since 2000 Managing Director of Oxford Technologies Ltd, divides this technique in two aspects: technology and management. “Apart from the boom which is a completely novel design,” he says, “the manipulators and other systems are designs based on proven and reliable technologies integrated in a rational and efficient way”. In this regard Virtual Reality is an impressive example. In the beginning, this technique was nothing more than green cathode ray tubes. Since then it is developed into multicoloured almost three-dimensional images of the JET torus. This development is being driven by the games market. “Remote Handling is for me,” Alan continues, “the integration and management of all: the technology, the people, and the structure. That makes Remote Handling what it is.”

The Mascot Servo-manipulator (coloured) inside the JET vessel

The first time Remote Handling was used fully during a shutdown at JET was in 1998. Alan Rolfe remembers:”The whole fusion community was looking and a lot of them said it couldn’t be done.” But the group succeeded. “We developed the set up, which means how to organise it, from nothing”, he adds. Tullio Raimondi started his career at the very beginning of JET in 1973. The engineer, who retired in 1997 as leader of the Remote Handling Development group, remembers:”My enthusiastic assistant during the design phase was the late Tom Arthur and our mini-group was irreverently referred to by some sceptical engineers, who were struck by the size of the task, as Don Quixote and Sancho Panza.” Nowadays the whole group has gained an international reputation and self confidence.

The forthcoming shutdown is the fifth Tony Loving has been involved in. “Historically,” he says, “our operations were on time. So I’m confident that we will be equally successful this time”.

Tony Loving, Remote Handling Group Leader

The preparation of the ITER-like wall shutdown started with an assessment of how to improve the procedures that have to be followed. During this stage the idea of extending the capabilities of the second boom emerged. The task of the second boom is to serve as the equipment or tooling deliverer for the working manipulator. The vast benefit for JET is saving time. Tony explains: “What we are going to do now is bringing the store to the man, remotely. We developed a container with a cabinet of trays to store the tools the manipulator needs.” With the second boom the shutdown needs up to 30 per cent less time; this allows 30 per cent more time to do research. Tony adds: “And this might even be a pessimistic amount. There is some evidence that we might be better than that”.