Dungeness decommissioning goes underwater

Divers are carrying out underwater work in the former cooling ponds at the Dungeness A nuclear power plant in a first for UK nuclear decommissioning. Magnox intends to roll out the technique, which brings safety and environmental benefits, to other decommissioning sites.

Divers are carrying out underwater work in the former cooling ponds at the Dungeness A nuclear power plant in a first for UK nuclear decommissioning. Magnox intends to roll out the technique, which brings safety and environmental benefits, to other decommissioning sites.

A diver enters a Dungeness A pond (Image: Magnox)

The divers are cutting up the pond skips that were once used to store used nuclear fuel at the site, and packaging them for disposal. The water that remains in the ponds acts as additional radiation protection for the divers. Meanwhile, cutting the skips while they remain in the ponds avoids the potential for airborne contamination. Extra steps would have had to be taken to prevent such contamination if they were removed from the water before being cut up.

The cut-up skips, which are classed as intermediate level waste, will be stored in approved waste containers in a shielded storage area on site before they are packaged for interim storage. An additional 20 tonnes of pond furniture, including framework and machinery and classed as low-level waste, will also be removed and cut up before being disposed of at the UK's Low Level Waste Repository in West Cumbria.

Dungeness A site closure director, Paul Wilkinson, said the use of divers was a change in the company's way of working. "We have successfully shown through trials that this work can be carried out safely and we can now make good progress in the clean-up of the cooling ponds," he said.

The work in Dungeness A's ponds is expected to be completed in early 2017, and Magnox will pass on its learnings to other sites where similar work is to be carried out. The next site to benefit from the use of the new approach will be Sizewell A, in Sussex.

Dungeness A's two 225 MWe Magnox reactors operated from 1965 to 2006 and has been fuel free since June 2012. The defuelling program saw the removal of 99% of the Kent site's radioactive hazard.

Magnox, owned by Cavendish Fluor Partnership, is the management and operations contractor responsible for managing the UK's former Magnox nuclear power plants on behalf of the country's Nuclear Decommissioning Authority (NDA).

John Clarke, NDA chief executive, said the authority encourages its contractors to adopt the highest standards of safety, security and environmental responsibility. "This work by Magnox Ltd shows that they are making real progress in clearing the ponds at Dungeness, in a way that is not only safe for the environment, but is also saving time and money," he said.

Researched and written
by World Nuclear News