U.K. Nuclear Decommissioning Authority (NDA) completed the shipment of 11 tonnes of "breeder material" from the Dounreay site to Sellafield. The material consists of natural uranium fuel rods that were irradiated in the Dounreay Fast Reactor before it was shut down in 1977. The first shipment took place in December 2012. Further 33 tonnes of the material remain in Dounreay. According to NDA, this material will sent to Sellafield as well. The transfer is expected to be completed in 2017.

At Sellafield, the breeder material is being reprocessed. Plutonium that is produced in a breeder reactor blanket would normally be a weapon-grade plutonium. Although there was no official information about the amount of plutonium separated from the fuel or its disposition, it is probably added to the U.K. stock of plutonium reported as civilian. Since the United Kingdom does not classify this material as spent fuel, it is not clear whether it is included in the INFCIRC/549 declarations. In its 2012 and 2013 INFCIRC/549 declarations, the United Kingdom declared "less than 500 kg" of plutonium in "spent fuel held elsewhere."