JET’s first remote handling operation
JET, the Joint European Torus based in the UK (Oxfordshire), recently completed the first series of nuclear fusion experiments using deuterium-tritium fuel in the geometry of the proposed International Thermonuclear Experimental Reactor (ITER) (see NEI, February 1998, pp36-37). Starting in February the divertor of the JET machine, a key in-vessel component, will be modified to a new design appropriate for the next experimental phase of JET which is directed at testing the divertor concept used in the ITER design.
The increased level of background radiation inside the torus which has resulted from the deuterium-tritium experiments means that the divertor exchange operations must be performed entirely using remote handling equipment.
Preparations to undertake this work have been proceeding since 1993 and have resulted in the establishment of a comprehensive operational strategy and the implementation of a suite of remote handling equipment suitable for the tasks defined.
The development of the remote handling capability for JET has taken into account that the experimental conditions may cause unforeseen complications which require to be remotely handled. This has resulted in the adoption of a remote handling philosophy which relies almost entirely on man-in-the-loop operations. The operations will be performed by a skilled operator making use of the JET bi-lateral, force-reflecting, master-slave, servo-manipulator which will be transported and positioned inside the torus.
The job requires removal of 144 divertor modules each weighing typically 35+ kg and replacing them with 192 new modules. In addition to a full remote inspection of the inside of the JET vessel, it is required to remove and replace various individual protective tiles, to replace a number of small diagnostic components including electrical connections, to vacuum clean the divertor region, to remove the oxide layer from four beryllium evaporator heads and also to undertake a full dimensional survey of the divertor region to a positional accuracy of 0.1 mm. All removed components are transferred from the torus into sealed containers using a second remote handling system which facilitates their storage in parallel with the operations inside the torus.
It is planned to undertake this work within a four month period.
U/MRUG to stage 1998 meeting at Sequoyah
The 1998 meeting of the Utility/Manufacturers Robotic Users Group, U/MRUG, will be hosted by TVA at the utility’s Sequoyah nuclear station on 18-19 May.
Formed in 1986, U/MRUG provides an annual forum which brings together users and manufacturers to identify new application areas, propose the development of new technologies and assess their cost-benefit potential. The group is now driving to push the technology from inspection and data retrieval to processes that will remotely do real work. U/MRUG now includes more than 700 engineers and scientists world-wide.
Besides the presentation of a series of technical papers at the meeting, utilities will bring to the forum their latest experiences, problems and solutions involving robotic technology.
For more information, contact Rick Munson, Chair, U/MRUG, Byron nuclear station. Tel: +1 815 234 5441, x-2873; Fax: x-2983; e-mail: firstname.lastname@example.org
EMMA’s long arm makes clean up easy
EMMA™ – Easily Manipulated Mechanical Armature – is a remotely controlled, multiple-stage robotic arm developed by GreyPilgrim* which is suitable for use in high radiation and high temperature environments, notably for decontamination, decommissioning and general radwaste handling work.
As a modular, multiple stage, system, EMMA can be assembled in task-specific configurations to provide the right curves in the right places. It can therefore be easily customised for many different applications, including dismantlement, retrieval, characterisation, and tool deployment tasks (eg for positioning, inspection, welding, cutting, painting etc).
A cable driven serpentine system, actuation can be electric, hydraulic or pneumatic. Hollow throughout its length, supply and retrieval hoses associated with tools and conveyance systems, including waste removal, can be routed through the center or along the outside of the manipulator. A sheath can be employed to minimise contamination.
The manipulator shown was used in June 1997 to demonstrate EMMA’s capability to retrieve simulated nuclear waste from large radwaste tanks under the Hanford Tanks Initiative. The 33-foot long, 24 inch diameter manipulator arm, weighing 975 lbs, handled payloads of 200 lbs with 10 degrees of freedom to ensure complete obstacle avoidance. The illustration shows how it works.
Other features of the system include the following:
• Actuation and control components are located out of the work environment to limit exposure and provide easy maintenance.
• The enhanced machine controller ensures smooth repeatable motion.
• Force control methodology provides inherent obstacle contact awareness.
• Ultra-high pressure tools maximise conveyance rates of stubborn wastes and minimises necessary time in a tank.
• A simple deployment structure minimises set-up and take down.
• After particularly high-rad operations, the relatively low-cost manipulator portion of the system can be disposed of and replaced rather than having to be expensively decontaminated.
Houdini goes on European stage
RedZone Robotics will be taking its “Houdini” vehicle on a demonstration visit to Britain where it will be performing at BNFL’s Capenhurst site during the week starting 6 April. Houdini is the basis of the Pioneer robotic system that will be used to inspect inside of the Chernobyl Sarcophagus later this year (see previous article).
At Capenhurst, RedZone and its UK representative, UK Robotics, will use Houdini to perform remote-controlled tank clearance tasks to show its capabilities. Houdini, a collapsible tracked vehicle, will fold small enough to fit through a 22-inch tank entry port before expanding to become a fully tracked vehicle with full vision manipulation and digging capability. The demonstration will show how the robot clears extremely difficult sludge which is similar to quicksand in texture and also how it interfaces to control and communications sited remotely away from the tank.
To witness Houdini, contact Andrew Bailey, Commercial Director, UK Robotics, at Clarence Avenue, Trafford Park, Manchester M17 1QS UK. Tel: +44 161 876 3200; Mobile: 0410 951999.