"In an effort to reduce costs, the Energy Department developed a plan to ship nearly 75 percent of the fissile materials in Building 3019, as is, to a landfill at the Nevada Nuclear Security Site by the end of 2014. Because such disposal would violate the agency’s formal safeguards and radioactive waste disposal requirements, the Energy Department changed those rules, which it can do without public notification or comment. Never before has the agency or its predecessors taken steps to deliberately dump a large amount of highly concentrated fissile material in a landfill, an action that violates international standards and norms."
[0] https://thebulletin.org/2014/05/thorium-the-wonder-fuel-that...
https://en.wikipedia.org/wiki/Yucca_Mountain_nuclear_waste_r...
Anti-nuclear activists are right when they say that nuclear energy is politically impossible but only because they're the ones making it politically impossible.
Rust and corrosion will attack the strongest container – all they need are the right conditions and enough time to work. Not only that, but metals behave differently (and chemical reactions proceed more quickly) at higher temperatures – such as those produced by the decay of fission products. So the thermal effects also have to be factored in when designing the things.
So here’s the bad news about long-term disposal of spent reactor fuel – and the containers meant to hold it. Nobody knows how a container is going to hold up over even 100,000 years, let alone a million years (the time span required by EPA).