Radioactive waste handling and storage poses challenges due to the inherent chemical and physical hazards of the waste. The wastes from decommissioning range from wet, mobile slurries and sludges to large heavy pieces of plant and building structures.
Individually these wastes may be problematic due to radiological and chemotoxic hazards that may preclude direct man access to facilities in order to deploy equipment. The facilities containing waste do not have man-access. Further waste arising from decommissioning may be mixed and potentially need further segregation, for example pieces of plant such as tanks and vessels may still contain residual liquors, slurries or deposits.
Innovative tools and techniques for the remote handling of waste are required to work alongside or replace baseline technologies so that waste handling is more efficient.
From design and consultancy to specification and planning, Abingdon-based Oxford Technologies Limited (OTL) have lengthy track record of solving engineering problems, specifically in the areas of complex remote handling operations.
Well versed in the sector, the OTL team delivered the world’s first remote handling equipment to operate inside a nuclear fusion reactor.
OTL’s application to the Game Changers programme has progressed to proof of concept stage with a live demonstration undertaken NNL’s facility in Workington.
The technology is designed to replace current glove boxes and would remove operators to a remote location away from any radiation dose.
This would essentially allow operations to be performed on much higher activity systems which otherwise would be challenging (or even impossible) to be performed manually.
The technology brings together two well-developed systems to a new area of application to form a new disruptive technology.
These sub-technologies are the remote Dexter™ Telemanipulator System that is a proven technology based upon the Mascot telemanipulator that has been used for many years at the JET fusion site in Culham.
The other technology is the glovebox which, again, is well developed but would have to be developed further to allow it to be used in a remote handling manner.
The Dexter™ slave arm would be located within a glovebox on a base rail that would allow it to be positioned as required within the glovebox. The slave arm would be controlled by a kinematically identical master that could be situated well away from any dose (up to 8km if required) in a control room environment.
By moving the master arms, the operator is able to interact with and feel the forces exerted upon objects. Moreover, using a range of cameras, the operator can see the operations taking place and gains a sense of telepresence similar to actually performing the operations at the work site itself.
By removing the need for sealed gauntlets and viewing windows, the gloveboxes are simplified and only require ports for entry and removal of equipment. This will reduce the costs associated with the gloveboxes.
Additional cost savings are made due to removal of requirement for operator barrier change facilities and PPE contaminated waste and the potential longer shift patterns both due to the time saving and no restrictions due to operator dose.
Trials at NNL’s Workington facility allowed demonstrations and operator testing of many operations.
During these trials it was indicated that sensitivity adjustment would be a useful development to the Dexter™ control system when manipulating low masses (e.g. spatulas) as well as devices with low mechanical compliance (e.g. fixed volume pipette plungers) that result in low contact forces.
This would allow sensitivity trials to investigate the adjustment to gripper closure and end-effector sensitivity and its effect on the force output and operator perceived haptic feedback.
The Dexter™ system is not a programmable robot but a manual tool operated by people 100% of the time – a “Man-in-the-Loop” system.
The operator controls a Master arm set and uses cameras to view the work area. When the operator moves the master arms, the slave arms located in the remote area respond instantly and exactly.
Importantly, the control system reads the feedback from the slave drives and reproduces any resistance back into the master in real time. The operator experience is nearly identical to operating a mechanical MSM.
There are, however, a number of additional features available to Dexter™ because of the electronic control such as force limiting, force scaling, virtual walls, keep out zones, and other aids.
Dexter™ has a payload of approximately 25kg and a sensitivity down to a few grams. It can perform almost any operation that a person can perform.