The Sellafield plant is the UK's largest and most hazardous nuclear site, storing enough high and intermediate level radioactive waste to fill 27 Olympic-sized swimmingpools.
The United Downs tip is 15m (49ft) deep and has a volume of 250, 000 cubic metres (8.8m cubic ft) - the equivalent of 125 Olympic-sized swimmingpools - but the council predicts it will be full by 2010.