Breeder
The fast reactor was developed to “breed” plutonium from an otherwise unusable form of uranium metal. The uranium metal was packed in a blanket around the core where it absorbed fast neutrons from the nuclear reaction, turning it into plutonium.
Immediately after closure of DFR in 1977, removal started of the fuel from the core and the surrounding breeder. The core and inner breeder were removed, except for a single burst fuel pin and two stuck breeder elements, and about a third of the outer breeder was also removed.
This work stopped in the 1980s because the fuel plants at Dounreay had reached capacity and a number of elements in the outer breeder were thought to be jammed. Today, about 10 per cent of the 975 elements in the outer breeder are thought to be stuck because of exposure to neutrons in the 1960s that warped their shape through a phenomenon discovered at Dounreay called void swelling.
In 2002, the site formed an alliance with five companies to develop equipment capable of entering the reactor and removing the remaining fuel pin and breeder material. High levels of radiation in this area mean the equipment needs to be operated remotely and workers protected from radiation throughout the handling process.
A breeder removal plant has been constructed at the base of the sphere. The fuel pin and breeder will be cut from their racks inside the reactor and transferred through an opening in the sphere to a series of shielded cells inside this plant. Here, the material will be cleansed of traces of liquid metal, examined, cut up and packed into storage containers.
All of this work will be done remotely to protect workers from the radiation. Subject to regulatory agreement, the removal of the fuel pin and remaining breeder will commence in 2011 once the primary coolant has been removed from the reactor system.
There are two options for managing the breeder once it has been packaged safely – to send it for conditioning as intermediate-level waste or treatment through a reprocessing plant. A review of these options is being carried out in conjunction with the NDA.
£50 million plant to take breeder from fast reactor
Click here for an animation showing how the breeder material
will be removed from the reactor using remotely-operated cutting
and retrieval tools
Inside the containment facility where breeder will be removed after processing
A dummy breeder sits in position ready to be cut open inside the cell of the containment building
Sphere is cut for breeder removal
Construction of breeder removal facility
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Construction of the breeder removal facility
