Sellafield teams deliver complex flocculant retrieval safely

Sellafield teams deliver complex flocculant retrieval safely
Sellafield teams safely removed radioactive material from a legacy tank into modern containment.
We have recently completed a complex operation to remove radioactive material from a legacy storage tank. This is a key risk reduction activity on the Sellafield site.
The storage tanks, constructed in the 1950s, contain complex radioactive sludge known as flocculant. This ‘floc’ was created as a by-product during early reprocessing operations.
Over time, the radioactive material settled and compacted. This increased the technical challenge of its safe removal and continued storage.
Our teams developed a method to resuspend the settled solids. Converting the material back into sludge allowed for safer transfer into a modern storage tank.
The modern tank feeds into Sellafield’s Enhanced Actinide Removal Plant. This is where the material will be treated to ensure safe, stable storage.
A useful way to picture the challenge is a snow globe. When left undisturbed, particles settle to the bottom. To mix them back into the liquid, they must be lifted and redistributed throughout the vessel.
Our teams achieved the industrial equivalent in a highly controlled environment.
To deliver this capability, engineers and operators recommissioned specialist resuspension equipment. They rebuilt and tested the system. They ensured it could operate continuously over extended periods.
Water was added to the tank and specialist equipment continuously mixed the contents. Over time, the settled material at the bottom of the tank was gradually broken up. It was then brought back into suspension.
The process ran continuously, 24 hours a day, for around three weeks. Once the contents formed a uniform mixture, it could be safely transferred.
This approach enabled the removal of 1302-metre cubed of flocculant. This volume equates to over half an Olympic-sized swimming pool.
Head of Operations, Alan Prince said:
Reducing legacy risk safely is central to our mission. Our teams collaborated to deliver this complex, high‑hazard operation, efficiently. It demonstrates the expertise we have to execute demanding engineering and operational work.
Completing this activity removes radioactive material from ageing infrastructure. Placing it into modern containment means it will have a clear treatment route.
There are two remaining legacy tanks that will require emptying using a similar method.
This work supports our commitment, as part of the Nuclear Decommissioning Authority, to reduce risk, protect the environment, and deliver value for taxpayers.