Sellafield silo sort-out

06 July 2011

A project worth £160 million ($255 million) will see radioactive waste removed from an overloaded and inadequate silo built in the 1950s and kept in a form ready for final disposal. 


The facility is called the Pile Fuel Cladding Silo and it contains cladding materials removed from fuel assemblies used in some of the UK's earliest reactors at Windscale and Chapelcross. Irradiated cladding had to be removed before used fuel assemblies could be reprocessed to recover the uranium and plutonium they contained for the purposes of the joint power and weapons nuclear program run by the UK in the 1950s and 1960s.


The simple concrete silo, which is based on facilities normally used to keep grain, was in operation from 1951 to 1964 with some other additions up to 1968. Since then it has remained in the status of 'care and maintenance', benefiting in later years from the removal of an external shielding wall for better seismic safety and the injection of inert argon gas to its six storage chambers. The current situation has been described as 'not sustainable' by managers due to a reliance on active engineered systems to maintain safety.


Today Sellafield Ltd announced three contracts for the future of the silo, worth a total of £160 million. Retrieving the wastes from the store will require an £8 million ($12 million) superstructure, to be built by Sir Robert McAlpine. Modules to handle the waste and pack it into 3x3 metre concrete storage boxes will be constructed by Bechtel Babcock Nuclear Services for £150 million ($239 million). The storage boxes will weigh about 60 tonnes when fully loaded, and so a £3 million ($4 million) crane has been ordered from Clarke Chapman Group.


Removal operations should begin in 2017.


Similar boxes are used nearby to store wastes from the decommissioning of the Windscale Advanced Gas-cooled Reactor, which was officially completed last month. Ultimately all the boxes will be stored underground in a centralised national radioactive waste disposal site most likely in Sellafield's home county of Cumbria, where the communities of Allerdale and Coperland have expressed interest in a voluntary site selection procedure.


Head of the retrieval project, Tim Davies, said the project was one of the most challenging decommissioning projects in Britain. He said, "we're pulling out all the stops to drive forward this project by bringing in specialist contractors."
Researched and written
by World Nuclear News