Sizewell A begins defuelling

18 August 2009

The UK's Sizewell A Nuclear Site, owned by the Nuclear Decommissioning Authority, has begun defuelling, when the first spent fuel flask since it ceased generating on 31 December 2006 was dispatched to Sellafield.

This is the start of a key phase in the site's decommissioning plan. The flask dispatch programme will continue for the next three years until all the fuel, which is currently stored safely in Sizewell's twin reactors, has been shipped to Sellafield for processing.

Defuelling was expected to commence following the end of generation on 31 December 2006, however, challenges presented at the Sellafield processing plant have resulted in fewer flasks being available. Generating sites are given priority which is why Sizewell's defuelling has been delayed.

Since shutdown, a programme of retraining and reskilling has enabled the workforce to carry out small scale decommissioning projects. Projects completed so far include the removal of pipebridges, which previously connected the boilers to the turbines, and also the removal of redundant pond equipment.


During its operational lifetime, over 3000 fuel flasks have been dispatched to Sellafield from Sizewell A. It will take approximately 310 flasks to clear the inventory of fuel present on the site.

Spent nuclear fuel has been transported by rail since the 1960s travelling more than 7 million miles without any incident involving the release of radioactivity.

The fuel is transported in a flask which is heavily shielded and purpose built. Constructed from forged steel more than 30cm thick, each flask weighs more than 50 tonnes and holds no more than 2.5 tonnes of fuel.

Direct Rail Services is the company responsible for providing tailor-made rail transport services to the nuclear industry.

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