Office for Nuclear Regulation

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Underwater innovation

25 February, 2019

At Sizewell A in Suffolk, we’ve been regulating an innovative operation to clear radioactive waste from spent fuel storage ponds.

Magnox Ltd used specialist divers to cut up pond skips and equipment underwater and remove radioactive sludge, rather than the conventional method of using remotely operated machinery to lift the skips from the water.

The underwater method exposed workers to 20 times less radiation than the conventional technique and was quicker – the sites were cleared nearly two months ahead of schedule.

Rowland Cook, Principal Inspector, said: “Although diving had already been used for decommissioning in other countries, using divers to decommission nuclear ponds was novel in the UK, and we assessed the licensee’s proposals to make sure they were safe and compliant.

“While it may seem counter-intuitive to use divers with plasma cutters to remove items underwater in a nuclear pond, we kept an open mind – and found there were significant benefits, particularly in dose reduction. The accrued dose was reduced by around half for the same tasks completed previously outside of the ponds by operators using long-handled tools. Magnox was also able to save money through the work being done more quickly.”

David Rushton, Programme Manager for the Nuclear Decommissioning Authority, added: “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 will mark another successful step towards cleaning up the UK’s earliest nuclear sites. We’ve learned valuable lessons and gained some useful experience in ponds decommissioning which could help our work to reduce the hazards at the NDA’s other nuclear sites.”