Because a considerable part of this accumulated activity will be due to strontium-90 and other long-life radionuclides, methods for ultimate waste disposal of these wastes must provide containment and control for at least several hundred years. It is doubtful whether any man-made structure could be guaranteed to provide permanent containment, so that the use of deep geological formations (salt deposits, antarctic ice, ocean deeps, etc.) seems more suitable. High-level wastes are at present stored mainly in liquid form, and some constituents will remain dangerously radioactive for several hundreds of thousands of years. There is at present no generally accepted means whereby high-level waste can be permanently isolated from the environment and remain safe for very long periods.
More than a million gallons (3.8 million litres) of low-level waste in steel drums was dumped in the ocean near San Francisco between 1946 and 1962, and about 25% of these drums are now leaking. The USA Environmental Protection Agency (EPA) estimates that there could be as much as 400 million cubic feet (11.3 million cubic meters) of low-level waste in the USA alone by the year 2000.
Accumulated radioactivity dumped into the Atlantic by the UK and other countries totals over 1 million curies and has raised radiation levels near Windscale four thousand time. By the year 2000, there will be 100,000 lorry loads of radioactive waste in store in the UK alone.