Engineering news
The decommissioning of one of Sellafield’s most hazardous buildings has taken a step forward with the arrival of a machine that will scoop out its radioactive contents.
The 360 tonne 'SEP' machine called the Silo Emptying Plant will grab radioactive waste from 22 compartments in the Magnox Swarf Storage Silo (MSSS), an ageing storage plant prioritised for clean-up by the site’s owners, the Nuclear Decommissioning Authority (NDA).
In the coming months the machine will be brought from Wolverhampton to the Sellafield site in 33 different parts and assembled by nuclear experts. The concept of building a machine to grab the waste was first agreed in 1997.
The machine will be responsible for collecting 60,000 items of Miscellaneous Beta Gamma Waste including radioactive magnesium swarf, irradiated uranium metal and contaminated engineering debris out of the building and into safer, more modern containment. This process will start in 2017 and take until around 2038 and marks an important step forward in the decommissioning programme at Sellafield.
The 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's intermediate level waste inventory.
The machine has been tested on a life size replica of one of the containers which is 16m deep and big enough to hold six double decker buses. Each SEP machine contains 13,500 different parts and ensuring the machine works correctly will be essential, as there will be no access to large parts of it for repairs or maintenance once it starts its job due to the radioactivity levels inside.
“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,” said Alan Haile, head of MSSS projects.
“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 project is another step in cleaning up the UK’s nuclear legacy. Other recent project include the removal of 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.