Posted on: 15th February 2009
How was the first group for Remote Handling established?
Tullio: Initially my task was to participate in the design of the toroidal system, paying particular attention to assembly/disassembly problems which ultimately, in radioactive conditions, would have to be performed remotely. I used to spend most of the time in the drawing office where the various sub-systems were taking shape under the constant supervision of Paul Henri Rebut (Editor’s note: JET director from 1985 to 1992). There I put forward suggestions for easy to operate connections, welding and handling methods suitable for a dexterous servo manipulator. I started familiarising the designers with the capabilities of such robotic devices and we worked out connection methods which were later formally included in the Remote Handling Manual. An important and novel project started at that time was the welding and cutting of the vacuum joint between octants, which required a laborious development of an automatic tool deployable by the manipulator. Such was the quality of the automatic welds achieved, this device was used in first assembly.
The rather scary subject of robotics had virtually no place in the early managerial discussions which were focused on the JET basic design. The management had the foresight, however, to allocate an engineer to this task from the start and I carried on feasibility studies of the remote handling equipment and assembly methods which were inserted in the first official reports of JET. 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. In 1978, after the construction of JET was approved the newly appointed Director, Hans Otto Wüster (Editor’s note: first JET director from 1978 to 1985), and deputy director Paul Henri Rebut supported new recruitments and I became leader of a group called Engineering of Assembly and Remote Handling. A major problem was how to handle the 125 ton octants. Having specified an accurate control of the main crane I proposed a C-shaped lifting frame which proved adequate to the task.
In 1983 the group became quite large, as the design of robotics and in-vessel inspection acquired momentum, and took the name of Remote Handling Development. A second group, called Remote Handling Applications, led by Alan Rolfe, dealt mainly with special tools to be used initially in the assembly phase. This group gradually expanded to include the organisation, planning and running of Remote Handling operations and related control room with virtual reality for preparation of interventions, using all robotics and tools quite successfully up to today. Both groups also had the help of a number of professionals and students, seconded to JET on a temporary basis from the Associations, using EC contracts. The development of robotics equipment was virtually finished and in the last couple of years before I retired I led the engineering analysis group studying the disruption forces to deduce the plasma instability modes, and the upgrade of JET to 4 Tesla.”
How did JET recruit personnel? What expertise are they looking for?
Tullio: “There was an efficient recruitment system. The various group leaders prepared vacancy notices as specific as possible, tailored to the tasks, but not neglecting a broader scope and expertise so that valuable candidates could be considered for alternative work. It was then the task of our personnel office to have the vacancies approved and published in the various associations in Europe, invite selected candidates and set up selection boards of potentially interested professionals with mixed skills.”
How was the atmosphere? Keen to pioneer an unknown field or afraid of an unmanageable challenge?
Tullio: “Both! I still remember vividly, just after my arrival in 1974, waking up with a panic attack at the long disappeared old Oriel Hotel, spreading sketchy blueprints of the JET layout on the beer-stained carpet of my room and trying to imagine the requirements and how to get a servo manipulator through the narrow vessel opening. That was just the first of many “working nights”. I could never have survived without the support and patience of my wife.”
What was from your personal point of view the biggest challenge in starting the research?
Tullio: “It is a bit difficult to remember now which technical difficulties were the greatest. I can mention the stability and accuracy of the large articulated boom, the design of actuators and controls, the upgrading of the manipulators with features made possible with present day computer technology, adding computer aided teleoperation algorithms to the man-in-the-loop controls and the in-vessel inspection system. These all presented great technical challenges. However, perhaps the most difficult task was to keep abreast of the continually changing requirements of an evolving JET machine even though we had a good system of interface and configuration control. If you look at early artists’ impressions of the Torus it looks so simple and clutter-free. Later additions like the additional heating, the divertor, the saddle coils, and diagnostics changed the picture and the ambition to replace an octant remotely had to be abandoned.”
You surely do remember some important incidents on the way to Remote Handling as we know it today.
Tullio: “One very bad moment was when an obstruction had been introduced into the access port in a last minute modification. The realisation hit me at 2am and I told my wife to be prepared to leave the country since I would probably have to resign in the morning. It turned out that there was a minimum residual gap and thanks to the accuracy of the control the articulated boom was still able to negotiate the entrance.
A nice example of an emergency repair was when a glass cylinder probe of the in-vessel inspection broke, causing a leak into the vessel and a potential traumatic delay to the first plasma operation. In desperate need of a quick fix I went to Braggs, the Abingdon cycle shop which has unfortunately closed down, and bought four of the best stainless spokes which were thin enough to be fitted as a cage protection around a new glass cylinder without impairing the view. This remained as a permanent solution.
The worst incident was when the synchronisation system of the two jacks
lifting one of the 1000ton shielding beams between the Assembly Hall and the Torus Hall failed. This system did not pertain to the Remote Handling Group but I acted as an advisor, alerted by a dramatic call at 1am. The beam was at quite an angle and a dangerous situation could have developed if the jacks had not been stopped in time. We used hardwood blocks to take the weight of the beam so that the repair could be done and safety devices were promptly added. I hope present and future officers in charge are conscious of the risks of lifting thousands of tons 20 metres above the ground and that the safety devices are continually monitored. This is obviously true also for the crane bridge and the remote handling booms.
As far as I know however, all in all the safety record of JET remained exceptionally good compared with many other big plants.”
Do you want to mention something else?
Tullio: “Twelve years have passed since I retired but I still feel an attachment to my large and small mechanical ‘babies’ in JET. The force-reflecting servo manipulator has been a great piece of equipment, but I would like to see new developments to reduce the cost and increase the load capacity, pursuing lines already explored.”