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Divers complete ponds mission at Sizewell A Site - safer, faster and cheaper

Specialist divers have completed their mission to deal with radioactive waste from Sizewell A Site’s nuclear fuel storage ponds, nearly two months ahead of schedule.

 The team of underwater experts explored new depths at Sizewell A, with the task of cutting up former fuel storage skips and other redundant equipment as part of the work to decommission the former nuclear power station.

The team tackled their first UK ‘nuclear dive’ at Magnox’s Dungeness A Site in 2016. Bringing valuable learning from their work at Dungeness, the team arrived on site at Sizewell A in October 2017.

The divers, who are shielded from radiation by the water in the ponds, successfully cut up and ‘size reduced’ all of the 35 skips left in Sizewell A’s ponds.

During the dives, the team also cut up around 100 tonnes of other redundant equipment before removing all the radioactive sludge from the pond floor.

During the operational life of the power station, the ponds were used to store thousands of used nuclear fuel elements, held in metal skips, after they were discharged from the reactors. After the last of the fuel was transferred to Sellafield for reprocessing, the skips and a range of other waste items – including radioactive sludge – were left behind under the water.

Conventionally, pond clean-out is done using remotely operated equipment to lift the whole radioactive skips and other pond furniture clear of the water, exposing them to the air, where they are carefully cut and decontaminated. This process is slow with potential radiation dose risks for workers.

Using this innovative underwater decommissioning technique, radiation levels for workers were around 20 times less than with conventional techniques of decommissioning the waste items in air.

As well as a reduction in the overall radiation dose for workers, the diving technique has a lower environmental impact, is quicker and more efficient – resulting in greater value for the UK taxpayer.

Steve Franks, Sizewell A Site Ponds Programme Delivery Manager, said: “This has been a major success for the site, using this technique has saved time on the project and money for the UK tax payer and provided a significant reduction in dose to workers. It is great that the learning from Dungeness A was employed here at Sizewell A and we have been able to now share our further learning across the Nuclear Decommissioning Authority estate which could, in future, provide yet more cost savings.”

David Rushton, Programme Manager for the Nuclear Decommissioning Authority who own Sizewell A and 16 nuclear sites in the UK, said: “Using divers at Sizewell is a fantastic example of Magnox taking an innovative approach to decommissioning and hazard reduction.

“The end of the work to remove radioactive waste from Sizewell’s ponds marks another successful step towards cleaning up the UK’s earliest nuclear sites.”

 Now that the divers have left, the next phase of work is to take the waste out of the ponds where it will be treated and safely packaged. The ponds are set to be completely emptied and drained by the end of 2019.

The team of 12 nuclear divers was supplied by Underwater Construction UK Ltd – you can watch a film of them in action below.