Sellafield - Decommissioning of two condemned waste storage silos at Sellafield has given a taste of challenges to come, discovers Jon Young.
Engineers at the UK’s largest nuclear site are squaring up to some of the toughest and most complex technical challenges in the decommissioning business.
Once the cradle of the UK’s military and civil nuclear industry, Sellafield in west Cumbria now accounts for £31.5bn of client the Nuclear Decommissioning Agency’s (NDA) estimated £56bn total clean up bill.
Such is the size of the clean up that the government-owned NDA will only be letting site management contracts once contractors are in place at all of its 19 other UK nuclear sites. The NDA says it needs time to assess the true scale and nature of the projects to be tackled.
But two projects now under way illustrate what may lie ahead.
Interim site manager and prime contractor British Nuclear Group (BNG) is in the early stages of taking apart and disposing of two superannuated waste storage silos. It is these, rather than the nuclear reactors, that pose the greatest threat to the environment and human health at Sellafield, says BNG information officer and former nuclear engineer Neil Stagg.
Lacking ccurate inventories, original designs and construction details, engineers were left guessing what might lie in store at the reinforced concrete Pile Fuel Cladding Silo, known as B41. After 50 years, and out of use for 25 of them, the structure is cracked and crumbling.
Sitting by B41’s side, the Magnox Swarf Storage Facility, or B38, developed cracks soon after construction, allowing radioactive sludge to leak into the surrounding soil and posing a threat to groundwater.