Civil intermediate level solid waste is largely stored at Sellafield awaiting a decision on a national storage facility. Both civil and military high level solid waste is generally moved to Sellafield for temporary storage. Because of this very long time scale, it can never be sealed up and forgotten. Containers corrode with time. There are earth movements.
Water seeps through rocks.
The waste will have to stored in such a form that it cannot be stolen and misused and in such a way that it can be inspected and if necessary retrieved and moved. Plans to dig a trial deep storage facility under the Sellafield site were thrown out in 1997. Geological evidence suggested that the local rock was too fissured and liable to be affected by water seepage. This threw all the nuclear industry's plans into confusion. Instead of having a storage site ready by 2010, the earliest possible date has been put back more or less indefinitely.