The Nuclear Decommissioning Authority

 

Removing spent fuel from a nuclear site takes away 99% of the radioactive hazard, but one of the major challenges remaining behind is the highly contaminated ponds.

Constructed above or below ground and lined with concrete, ponds are used to cool highly radioactive spent fuel, which is kept in skips, before being sent to Sellafield for reprocessing.

The water in the ponds serves the dual purpose of acting as a barrier against radiation and dispersing heat from the spent fuel.

Spent fuel can be stored safely in ponds, in skips, for long periods, sometimes for years.

Over time, however, the ponds have accumulated debris from the fuel elements and other items of 'furniture'. In some cases, sludge also accumulates from, for example, corroded fuel, making retrieval even more difficult. The skips and all pond contents require expert safe removal and disposal, while the ponds must be cleaned, drained and sealed before eventual demolition.

The clean-up process takes years and is extremely challenging, with high levels of protection needed for the workforce aided by regular use of remotely operated equipment.