The most radioactive fraction has relatively short lifetimes. (There is only so much energy that can be radiated out.) Even the Elephant's Foot in Chernobyl is much less radioactive now, mere 35 years after the accident.
The less radioactive fraction will indeed stay active for thousands of years, but its level of radiation will be closer to natural sources than to an atomic bomb.
There's a sour spot of isotopes with half-lives of 1-100 thousands years, these are still very radioactive but will not decay in any forseeable future.
And other countries have much higher volume of waste stored, how about 40000m3? https://en.m.wikipedia.org/wiki/Morsleben_radioactive_waste_...