Workers using remote technology are successfully dealing with the irradiated ‘breeder’ fuel elements from the Dounreay Fast Reactor.
DFR was a fast breeder reactor, capable of producing more fuel than it consumed. In the reactor core, a ‘blanket’ of depleted uranium breeder elements surrounded the core fuel rods and bred plutonium by absorbing neutrons from the core fission reaction. The plutonium would then be extracted during reprocessing to make more fuel.
Eleven tons of these breeder fuel elements were removed from the Dounreay Fast Reactor during its operational life and stored in drums in the Fuel Cycle Area.
A team of decommissioning experts, consisting of workers from DSRL and Doosan Babcock, headed by project manager Stuart Andrew, were recently tasked with the job of developing, commissioning and operating a process to remove the stainless steel cladding from the elements. This is an essential stage in the life cycle of the breeder elements.
The team faced a number of challenges, not least because the cladding surrounding the fuel slugs was too active for the operators to handle manually.
The team designed and developed an innovative machine capable of stripping the cladding from the fuel slugs remotely using a cold cutting process. The remotely-controlled machine, which was manufactured locally by Nicholson Engineering, was installed by the team in an existing radiological area.
Some of the breeder elements had become swollen in the reactor, and the cladding had split open, buckling the elements. These were not straightforward to work with, but the machine’s clever design meant that it was able to remove the cladding in spite of the distortion.
The team successfully completed the active commissioning in March 2008 by decladding two drums of breeder fuel, paving the way for the remaining drums to be dealt with over the next three years.