Sellafield Ltd says it has taken the “most significant stride ever” in its 100 year mission to clean up the UK’s most complex nuclear site. 

Workers have now removed the entire bulk stocks of historic nuclear fuel from the Pile Fuel Storage Pond. 

The pond was used to cool nuclear fuel rods after they had been burned in nuclear reactors to create weapons material.

Retrieval of the pond’s ‘canned fuel’ inventory was successfully completed in October 2015. The work means radioactivity levels at the 68-year-old pond have been cut by 70 per cent, vastly reducing the risk it poses to people and environment. 

The milestone is the most visible sign yet of progress in the Nuclear Decommissioning Authority’s century long programme to clean-up the legacy of Britain’s early nuclear industry. 

The removed fuel has been transferred to a modern storage building at Sellafield where it can be held in a far safer environment. 

Attention will now switch to clearing the remaining contents of the pond – chiefly made up of a radioactive sludge-type residue. 

The facility is scheduled to be ready for 'dewatering' in 2019 – 21 years ahead of the original schedule date - it will then be fully decommissioned and demolished. 

This was at the height of the Cold War in the 1940s and 50s when a global arms race developed amid simmering tensions between the USA and the Soviet Union.

Some of the fuel used in that military campaign had sat in the murky depths of the Pile Fuel Storage Pond ever since. 

The pond also played a vital support role during Britain’s worst nuclear accident – the 1957 Windscale fire. 

Paul Foster, managing director of Sellafield Ltd, said: “This is a truly landmark moment in the decommissioning of Sellafield. “Removing decades-old corroded fuel from an aging facility and placing into modern containment makes Sellafield, and the whole of the UK, a far safer place. 

“The enormity of the challenge cannot be underestimated – the pond was built with no design for how its contents would be removed. We have had to retro-fit an export process and then safely execute it in one of the most challenging environments imaginable.”