How to dispose of them has been discussed all around the world. We have to choose the way which we don’t need control over long time period. There were five options geological disposal, disposal in space, sub-seabed disposal, ice sheet disposal and long-term management.
There are the reasons why we can’t chose other ways.
Disposal in Space
→Issue of technical reliability - launching may fail.
Sub-Seabed Disposal
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London Convention prohibits ocean dumping.
Disposal in ice sheet
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Treaty prohibits it. The characteristic of ice sheet isn’t known very much.
Long-Term Waste Management
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We will put a heavy burden to the future generation.
Some people suggest that we should ask foreign countries to dispose of them for us. But we have to be responsible for what we produced by ourselves. The international treaty about safety of spent fuel management and radioactive waste management, signed by Japan, states that each country should take care of its own waste.
Source : https://www.numo.or.jp/q_and_a/faq/faq100068.html