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Diamond Wire Cutter
The Diamond Wire Cutter was developed by Eadon Consulting in response to Sellafield Ltd’s LINC 19 challenge.
During an underwater survey an obstruction was found in front of A-ST bay entrance to First Generation Magonx Storage Pond (FGMSP) 2A. The object, a 4m x 1m wide frame, fabricated from approximately 100mm x 10mm stainless steel plate, was preventing ROV access required for spent fuel removal and other decommissioning activities. The First Generation Magonx Storage Pond decommissioning programme driver is to remove fuel from A-ST Bay, to enable this work, bay access is required. Sellafield therefore needed a method of remotely cutting the object to reduce its size and allow access to the pond.
Our experience of developing innovative solutions for the nuclear sector meant we were able to quickly develop and adapt an appropriate concept for use in a live, highly contaminated area.
Following an in-depth optioneering exercise, we identified diamond wire cutting as being the most appropriate technique that would meet the requirements in terms of remotely and reliably cutting the metal. While this technique is typically used on large-scale demolition projects, we found the same technique being used on a smaller-scale for gem cutting and decided that this method could be adapted for the Sellafield application. We found a fundamental benefit of diamond wire cutting was the low reaction force it gives. This was important because it meant disturbance of the sludge at the bottom of the pond could be minimised and the chance of contamination was reduced. Other key benefits included its ability to be used underwater and to be able to cope with different materials. Also, the machine could be built to be small and lightweight to allow for use in hard to reach areas.
After identifying diamond wire cutting as being the most appropriate technique, we built a test rig to test, check and prove our method and to gain an understanding of the process.
We developed a design for the overall operation; including the cutting head, a means of deployment, and a remote control and monitoring system. Using our experience from the test rig development, as well as drawing on other ongoing research and development projects, we were able to use a number of off-the-shelf components and technologies, accelerating the development time whilst also reducing cost and improving reliability.
Successful factory acceptance tests were carried out prior to successful deployment on plant. The tool has received positive feedback from Sellafield. We are now looking at adapting the system for cutting different materials so it can be used for further decommissioning applications.