Nuclear Power
entered from the vessel lining. A diverter is made up of the following components costing between £60,000 – £100,000:
● 48 Gasbox Inner Carrier (tiles) ● 48 Gasbox Outer Carrier (tiles) ● 48 Bulk Tungsten LBSRP (tiles) ● 48 Base Carriers (tiles)
Vectro is used to check any tile that is The JET nuclear fusion tokamak is the world’s largest nuclear fusion power experiment
fi elds. T erefore, as part of regularly scheduled maintenance procedures, the JET facility is closed for six months every two years for an overhaul, and this is when the Vectro comes into play. Due to the hostile environment of the
reactor, it is left to cool for a couple of months before the MRO begins; though even then it is still unsafe for humans to enter the tokamak safely without the use of protective suits. However, Vectro thrives and is eff ective under these conditions and so is operated remotely with a robotic device called MASCOT. MASCOT is mounted onto an in-vessel
transporter system to enable Vectro to check for damage to the surface of every single tile lining the reactor. Each tile is inspected to see if it needs to be replaced and if so, to ensure that the replacements are re-positioned in exactly the right place and orientation. MASCOT is a highly dextrous
haptic force-feedback master-slave telemanipulator, with each kinematically similar master or slave unit consisting of two seven-degrees-of-freedom arms. T e
MASCOT master station is driven by experienced remote handling operators and can be positioned around the vessel by a transporter system; a 12m-long articulated robot. James Kent, remote handling
development engineer at RACE, says: “Every tile we replace, we check with the Vectro system. T is speeds up our overhaul time, which means JET can be up and running again sooner, delivering the results that will help to make fusion a dependable source of energy in the future. GapGun and Vectro are very precise. We couldn’t position or check the tiles as accurately or effi ciently without them.” During a regularly scheduled shutdown,
around 600 tiles are removed and replaced during the six-month period including many sample divertor tiles for chemical and physical examination. T e divertor is a device within the JET tokamak that allows removal of waste material from the plasma while the reactor is operating. T is allows control over the build-up of fusion products in the fuel and removes impurities in the plasma that have
replaced and to quality check new tiles before they are installed into the JET wall. During the 2010-2011 shutdown, every single tile was replaced, which was in the region of 4-5,000 tiles. T e GapGun technology is the only way to check that the tiles are in the right position, within 10 microns, which ensures minimal damage when the reactor is operational. It is impossible for the human eye to detect to such accuracy. Before GapGun and Vectro, operators had to check quality by eye, using a standard gap fl ush test, compare against a checklist and manually input all data into a spreadsheet. T is was slow and prone to error. GapGun, and now Vectro, deliver the results immediately and electronically, so operators have a record of what has been done. Saving the project time and money, they deliver repeatable results time and time again. Using this inspection method means that not only is it possible to reduce the number of tiles that fail during experiments (allowing for a higher chance of successful tests), but that in the future it could also be possible to meet even tighter tolerances. Looking ahead to the next phase of
fusion power development, the ITER reactor in the south of France is currently being built and is due for completion in 2035. JET is carrying out technical preparations for ITER to ensure it is a success – playing a powerful role in the development of fusion energy. UKAEA’s RACE is now developing the next phase of the robot, MASCOT 6, to be launched in 2018. Robert Howell, Mechatronics Engineer at RACE, explains: “MASCOT 6 addresses the obsolescence issues present in the older MASCOT 4.5 system but also introduces performance improvements and new features. T is includes: new actuator designs for both the master and slave units; a modern control system; and improvements to the system software and the operator’s GUI.” ●
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