Sellafield processes last of fast reactor fuel

24 June 2022

The Magnox reprocessing plant at the Sellafield site in Cumbria has reprocessed the final box of used fuel from the UK's fast reactor programme being stored in the plant's ponds. Meanwhile, preparations are being made for the demolition of the iconic Pile One chimney that dominated the landscape over Sellafield for decades.

The Magnox Reprocessing Plant (Image: Sellafield Ltd)

The Magnox reprocessing plant, which began operations in 1964, had been scheduled to close in 2020 but disruption caused by the COVID-19 pandemic meant the schedule was moved back. It was announced in May that the facility will now finish reprocessing on 18 July and enter a new era of decommissioning and clean-up.

The UK's fast reactor, at Dounreay in Scotland, was built during the 1950s and became the world's first fast reactor to provide electricity to a national grid before shutting down in 1977. Fast reactors came to an end in the UK in the 1980s. However, the programme left behind a legacy of used fuel with a unique chemical composition. This fuel remained at Dounreay for 35 years until the Nuclear Decommissioning Authority (NDA) and nuclear regulators agreed it could be brought to Sellafield for storage and reprocessing.

Sellafield Sites said reprocessing the final box of Dounreay fuel being held at the Magnox plant marks the completion of a 10-year programme. It said it was important to reprocess the fuel to minimise the amount requiring future dry storage.

A small amount of fuel remains at Dounreay which will be transferred to Sellafield for dry storage before being disposed of in the UK's planned Geological Disposal Facility.

"Throughout its history, the Magnox Reprocessing Plant has delivered on behalf of the UK," said Sellafield Ltd CEO Martin Chown. "The current workforce has carried on this proud tradition by achieving another significant milestone in its final weeks of operations. "It's a significant achievement and another demonstration of us delivering our purpose to create a clean and safe environment for future generations."

Chris Wratten, Dounreay Fast React Reactor senior project manager, added: "This has been a key project for the NDA and the entire UK nuclear industry. By blending and consolidating the material with routine Magnox fuel, the teams have also supported the UK's non-proliferation and security objectives."

Dummy run for chimney demolition

Two 125-metre-tall chimneys providing ventilation for the Windscale piles - early reactors built to produce plutonium for the UK's nuclear weapons programme - were sealed after Pile One was damaged beyond repair in a 1957 fire. The Windscale chimneys, with the characteristic bulge of the filters at their top, remained a feature of the Sellafield skyline until 2001 when the chimney servicing Pile Two was reduced to the height of adjacent buildings. After three years of careful dismantling, the square-shaped diffuser was removed from the top of the Windscale Pile Chimney in November last year.

A sketch of the hydraulic SPIDA machine set to be used to demolish an iconic chimney at Sellafield (Image: Forth)

Ahead of the demolition of the Pile One chimney in the coming years, a collaboration of Cumbrian firms plan to construct a replica of the chimney and then use new hydraulic equipment to demolish it to ensure working practices are safe and sustainable ahead of any demolition work on an active, potentially hazardous, site.

A planning application has been submitted to Copeland Borough Council to demolish the bespoke concrete ring which will be created to accurately replicate the chimney with the same circumference of 15 metres, but only 7 metres in height. The dummy structure will be cut down with a newly developed hydraulic SPIDA machine designed by ADAPT, a joint venture between Doosan Babcock, Atkins and Orano.

The SPIDA structure is being fabricated by Cairnhill Structures of Glasgow. It is planned that the machine and the mock concrete barrel will be transported to Leconfield Industrial Estate, in Cleator Moor, Cumbria, to be tested and commissioned before two rows are cut out as a trial ahead of the actual work at Sellafield.

The trial - which could last up to two years - is being facilitated by engineering firm Forth at the request of ADAPT. Forth has bases across Cumbria including the proposed trial site at Leconfield. On completion of the trial work, the site at Leconfield will be cleared and returned to a similar condition to its current state.

Researched and written by World Nuclear News