The first nuclear reactor to be built in Europe has been emptied ahead of its demolition later this month.
A business centre will be built on the site of the old reactor
Energy Minister Stephen Timms took part in the decommissioning of the reactor at Harwell, Oxfordshire, on Thursday.
The reactor became a centre for research into civil nuclear power from the 1940s.
The United Kingdom Atomic Energy
Authority (UKAEA) is decommissioning sites in Scotland and at Windscale in Cumbria and Winfrith in Dorset.
While at the site, Mr Timms also launched START Oxford, a project which will use the space created by the removal of the GLEEP (Graphite Low Energy Experimental Pile) reactor to build a business centre.
Mr Timms said: "With the final decommissioning of GLEEP, we have demonstrated that we can deal with the legacy of the past."
Two reactors have already been taken out of service at Harwell, and will be left for around 40 years before they are dismantled.