Engineering news
One of the UK’s most hazardous buildings is a step closer to being cleaned up after engineers at Sellafield took delivery of a key piece of decommissioning kit.
A 50 tonne ‘transfer tunnel’ arrived at the site at the end of last week ahead of being hoisted into place in the Magnox swarf storage silo building.
The tunnel is the main component of the first Silo Emptying Plant (SEP) – one of three massive 360-tonne machines which will scoop out the highly radioactive contents of the building as part of its decommissioning.
The silo, which was built in the 1960s, contains waste created during the early days of the nuclear industry. It is now well beyond its operational life and its contents must be removed, to be stored in more modern facilities before the material is ultimately consigned to the UK’s underground repository.
Installing such a large and weighty piece of kit into a 50-year-old building containing some of the most hazardous material stored anywhere in the UK is a huge logistical challenge. The metal structure, which was manufactured by Ansaldo NES at its engineering base in the West Midlands, first had to be transferred to a warehouse about two miles from the Sellafield site. It was then sent to the site at walking pace on a flat-bed truck operated by a ‘driver’ following behind the load.
The next morning it was hoisted up into the silo building through a gap with only 20mm clearance either side and secured in place.
Attention will now turn to delivering the remaining components of the SEP machine so it can be assembled in situ before it can begin retrieving waste, currently scheduled to start in 2018. Production of the two remaining SEP machines is still ongoing.
The start of waste retrievals at the silo will mark the beginning of approximately two decades of work, with the final material expected to leave the building in about 2038.
Chris Halliwell, head of the Magnox Swarf Storage Silo programme for Sellafield, said: “This is one of the nuclear industry’s most complicated engineering challenges being addressed before our very eyes. This is cutting edge technology at the world’s most complicated nuclear site.”
Sellafield announced in October that it expects the silo to be cleaned up quicker and for about £1bn less than originally planned following a switch to a simpler method of treating and storing the material.
The original plan to treat the waste via a complex 22-step method has been shelved in favour of a ‘raw waste’ storage option that simply places the material untreated into containers, with a final finishing step added prior to its consignment to the underground repository.