A new three-step method for treating nuclear waste could speed up decommissioning of the Sellafield nuclear site and help save hundreds of millions of pounds.
Developed by a team led by Sellafield Ltd and the National Nuclear Laboratory, the method focuses on the so-called intermediate-level waste, the type of waste that requires shielding but doesn’t need to be cooled.
Intermediate-level waste, usually including resins, chemical sludge and metal nuclear fuel cladding, has previously been treated in a 22-step mechanical and encapsulation process developed about 50 years ago.
The new simpler technique was developed after a major advance in the understanding of the long-term behaviour of the waste.
“This research has delivered the underpinning to what could be a paradigm shift in the management of nuclear waste,” said Adrian Simper, the strategy and technology director of the UK Nuclear Decommissioning Authority.
“Having a greater understanding of the long-term behaviour of this material allows us to design a truly fit-for-purpose approach to its management and disposal.”
The new approach shortens the time of the treatment but also radically simplifies packaging and disposal.
Developed during a four-year study at the Magnox Swarf Storage Silo, which is one of the UK’s most hazardous buildings, the three-step technique stores the waste raw with concrete grout inside a shielded container. On average, the time of treatment could be shortened by several years.
The key to the improvement is the understanding of the corrosion behaviours of magnesium and uranium.
The waste package produced with this method would be suitable for interim storage at Sellafield and then, once grouted, final disposal in a UK geological disposal facility.
An added benefit of the alternative approach is the reduction in ‘secondary wastes’ created during the treatment phase, resulting in an estimated 10 per cent fewer waste packages being produced during the decommissioning.