Opening doors to legacy waste

The Pile Fuel Cladding Silo (PFCS) at Sellafield is effectively a giant concrete safe in which historic nuclear waste is stored.  The 21 metre high building is celebrating its 60th anniversary this year and preparations are being made to start removing the radioactive waste for treatment.

In order to retrieve the waste, extreme safe breaking skills are required to breach the thick concrete walls.  Another complication is that the decommissioning team has to break through the silo walls without releasing any radiation into the environment.  Key to achieving this is the specially designed silo doors which allow the retrieval modules to dock onto the side of the PFCS similar to a space station docking.

A significant stride forward has been taken with the successful completion of the detailed design of six silo containment doors – one for each compartment in the PFCS.  These doors are critical to the success of the decommissioning programme and will be used to maintain the argon atmosphere within the silo under which the waste is stored.  They will also provide radiation shielding to protect the workforce and the environment.

Approximately 20,000 man hours have gone into the design process.  A key challenge was to make the silo doors capable of being docked, with a gas tight seal, whilst remaining seismically independent of the modules.  The silo doors have also been designed to guide the cutting of the 2 metre x 3 metre holes with a high degree of precision.

Roger Hyde, Project Engineering Manager, Sellafield Ltd, said: “These doors are the lynchpin of the entire retrievals process. To see the detailed design completed is to recognise the innovation and determination of our design teams, as well as our integrated team philosophy between Sellafield Ltd and Bechtel Babcock Nuclear Solutions (BBNS).”

The project will now concentrate on accelerating the procurement and manufacture of the six doors to meet the PFCS’ accelerated high hazard reduction programme.