The humble coffee bag was the inspiration for a storage technique developed at Culham that is helping the UK nuclear industry make radioactive waste management safer and more efficient.
CCFE came up with the idea of a sealed plastic aluminium foil bag – dubbed the ‘JET bag’ – as a way of safely packaging items that have come into contact with tritium, a radioactive gas which is one of the fuels expected to be used in commercial fusion reactors. Small amounts of tritium have been used in experiments at JET in the past and will be again over the next two years. Careful stewardship of tritium and of ‘tritiated’ waste is therefore an absolute priority for CCFE, which operates JET on behalf of EUROfusion.
The JET bags – manufactured at Culham – provide very effective waste storage, are inexpensive and can be made to bespoke sizes.
Now the bags are set to be used by Magnox Ltd at the Chapelcross nuclear power station in Scotland. Tritium is one of the hazards involved in decommissioning Chapelcross, which closed in 2004.
The Magnox Ltd team witnessed the bags in action during a knowledge-sharing visit to Culham and spotted the potential for using them in their own operations. Now, following successful trials – aided by training from Culham staff – the technique is being used on items of waste at Chapelcross.
This was a very valuable industry share
While the JET bags must be filled remotely and operators need to be suited-up to seal them, they can then be transported to the ventilated areas of the plant where workers can safely handle the packages without the need for respiratory protection.
Greg Wotherspoon, a Magnox decommissioning manager at Chapelcross, said: “We saw the guys using the bags at Culham and thought it could work for us. You can cut the foil to any size you want. Using heat tongs, the packages are then sealed with five or six lines across the top, like a super-strength coffee bag, creating a really good seal.”
Dave Coombs, Waste Management Group Leader for CCFE, said there was a long-standing relationship with Magnox through the Tritium User Group to enable effective training and the sharing of good practice.
He said: “This waste management solution for tritium builds on our experience using the JET machine.
“We make the foil bags ourselves, and they provide a flexible enclosure, large and small. We trained the operators from Chapelcross to make the packages and they saw how it could bring practical benefits.”
Val Drake, Magnox Waste Strategy and Permissioning Manager, added: “Our trials showed that the JET bag material could contain off-gassing tritium waste, so that wastes can be safely transferred into drums for sealing and storage, without the need for respiratory protection.
“The positive results mean we will be able to weld seal the drum lids in a less constrained working environment, which in itself is also safer. This was a very valuable industry share and undoubtedly simplified the process.”