These are constructed in reinforced concrete and with the aid of two pond gates can be separated into three bays — a flask bay for the storage of road transport flasks and two skip bays. The latter contain rectangular box-shaped stainless steel storage skips divided into compartments by fixed boron steel in­serts, so that each is capable of holding 20 unbottled or 12 bottled fuel elements.

Each. skip bay is provided with a reception tube which is placed at the opening of the appropriate IFD discharge tube to receive the fuel elements as they arrive from, the cell. An element washing system is provided in conjunction with the reception tubes, the objective of which is to restrict the spread of par­ticulate matter to the main ponds. Deionised water is used in the ponds and is dosed with boron in the form of boric acid. It is continuously cooled and cleaned by circulation through specially provided cool­ing and filtration systems whilst the element washing system uses its own independent cleaning loop. Since the fuel still generates heat during pond storage, the water acts as a coolant as well as a radiological shield and unacceptable radiation levels are further prevented by handling equipment design features which prevent fuel being raised too high during lifting operations.