The Silo Emptying Plant – a kind of giant fairground grabber machine on wheels – will painstakingly remove waste from the Magnox Swarf Storage Silo (MSSS), an aging storage plant prioritised for clean-up by the site’s owners, the Nuclear Decommissioning Authority (NDA).
This nationally important decommissioning challenge is just part of the UK nuclear story being explored in an ‘access all areas’ BBC 4 documentary, ‘Inside Sellafield’ to be broadcast on Monday 10th August at 9pm.
In the coming months, the Silo Emptying plant will arrive in 33 separate deliveries, brought by road from Wolverhampton to the Sellafield site where the bespoke machine will be assembled by nuclear experts.
This is the first of three plants of its kind to arrive in West Cumbria and marks an important step forward in the decommissioning programme at Sellafield. The removal of decades-old material from the legacy plants is taking place on a daily basis, significantly reducing the risk and hazard on the site.
The Silo Emptying Plant (SEP), is essentially a huge grabbing machine which will run on rails above the waste compartments. It has been developed specifically to deal with historical nuclear waste from the MSSS, which contains a quarter of Sellafield Ltd’s intermediate level waste inventory.
It will lock onto the silo hatches, lower specialist grabs into the 16-metre-deep waste compartments to bring up the waste, pack it into nuclear boxes and safely transfer it to one of the site’s modern stores where it will be kept safe and secure until a decision has been made on a long term storage solution.
The three plants were developed with Ansaldo NES, who successfully tested and dismantled them within a replica of the MSSS store at their factory in the midlands. Each weighs more than 30 double decker buses and will be re-assembled and re-tested at Sellafield before waste retrieval operations begin at the silo.
“The SEP design is complex, it has to be to deal with the significant challenge of retrieving wastes from MSSS, but is based on simple, robust concepts.” Alan Haile, head of MSSS projects said.
“Think of one of those fairground machines with a metal arm that struggles to grab soft toys, but imagine it on a huge scale within a radioactive environment, grabbing huge volumes of potentially hazardous material with absolute precision from 22 underwater compartments and transferring into safe storage, with no room for error.”
The SEP machines will have to operate in a radioactive environment where operator access is restricted due to the radiation levels and are therefore heavily shielded. They will play a vital part in the Sellafield clean-up, with an estimated 11,000m3 of historic waste and 60,000 items of Miscellaneous Beta Gamma Waste to be removed from the 22 underwater MSSS compartments.
Sellafield Ltd is making significant progress in cleaning up the UK’s nuclear legacy, having recently began removing sludge from the First Generation Magnox Storage Pond and the dismantling of ‘Cockcroft’s Folly’ at the top of the Windscale pile chimney, marking a significant change to the Sellafield skyline.