Not a better plan but just a curiosity as a physicist enthusiast.

Regarding nuclear fission and nuclear waste (and ignoring the big elephant in the room that are nuclear weapons)....

What are the technical difficulties to turn the radiation emitted by nuclear waste into electricity?

I mean, if the nuclear waste is still radiating, it has stored energy that is radiated as photons, right?

Then, we have the photo-electric effect which turns photons into moving electrons as long as the frequency surpasses a minimum threshold.

Given that the radiation of nuclear waste has frequency way higher than UV, why can't it be used to feed a photoelectric generator?

Also, we have tons of nuclear waste, so the argument that a single rod doesn't generate enough radiation seems kinda bogus since we could just store the nuclear waste into a safer recipient that turns the harmful rays directly into electricity and we have a shit-ton of them stored in thick lead or concrete barrels just so this radiation don't harm the surroundings.

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It is a genuine question that I had, but never had enough physics class to understand where this logic falls apart.

Because, if it were feasible and "cheap", I bet that the US would already be doing it and having access to "free energy" (not really, but a long-standing generator that doubles as removing nuclear waste from the ambient).