It is likely that UK will opt for underground storage of their radioactive wastes. The DEFRA document discusses some of the other options that have been considered for waste disposal and why they are unsuitable.
The surface level repositories in which UK stores its ILW and HLW may be considered as a long-term option but there is constant threat of human intervention, which can be risky. Also designing structures and packaging of these wastes could be difficult as a significant portion of the wastes could emit radiation for over 10,000 years. Other options include disposal at sea and in empty offshore oil and gas fields. However these been ruled out under the 1997 London Convention and Convention for the Protection of the North-East Atlantic (OSPAR). This agreement calls for UK to stop sea dumping and using sea beds for storing wastes. Disposal in outer space has also been ruled out as a large number of rocket launches would be required and the potential dangers of a launch failure. Two other options that have been considered are the subduction zones and ice sheets. Subduction zones are areas where a geological plate is driven towards the earth’s core by collision with another plate and ice-sheets are the polar ice caps under which the wastes may be disposed. However both these are not considered suitable as there is uncertainty about the fate of these wastes in the long term. .( Department for Environment, Food and Rural Affairs.