British Nuclear Group has begun the lengthy process to decommission the world's two oldest commercial nuclear power facilities, Dungeness A in Kent and Sizewell A in Suffolk.

The two atomic energy facilities were shut down on January 1, 2007, bringing to an end their 40-year life spans. The plants will now begin a two to three year process of defuelling to remove their radioactive content, The Scotsman has reported.

The decommissioning represents the start of a period of shutdowns marking the end of cycle for the UK’s first wave of nuclear power plants. All but one of Britain’s nuclear energy facilities are due to be decommissioned by 2023.

According to reports, Dungeness A and Sizewell A have been closed down because they are now significantly less efficient than other power station in Britain’s nuclear portfolio and because the Sellafield reprocessing plant, which is necessary to make their spent fuel safe, is due to close in 2012.