The real reason storing nuclear waste is expensive is... not something that is actually true. Storing nuclear waste isn't expensive. Nuclear waste could magically disappear and it would only have a very minor effect on the economics of nuclear power. Or, a country could splurge and reprocess spent fuel, at a higher cost than just storing it, and also not significantly change the economics (this is what France did.)

That seems like a "simple" matter of putting it in some container that survives a rocket crash intact.