> I didn't claim all radioactivity would be gone, just that overall it will be comparable to uranium ore in a reasonable timeframe.

As you correctly pointed out, radioactivity is inversely proportional to half-life. Or in other words, given the same chemical concentration the net half-life of the remaining nuclear waste would be on the same timescale as the of uranium ore.

The most abundant uranium isotope us U238, with a half life of about 703Ma. Here's a list of half-lifes of the most common fission and spallation products:

99Tc	211ka (side note: used as radioactive tracer nuclear medicine)
126Sn	230ka
79Se	327ka
93Zr	1.53Ma
135Cs	2.3Ma
107Pd	6.5Ma
129I	15.7Ma

Three things to note here:

- Those are all isotopes, which you can't actively "break down" further without making things worse. A couple of those above are very efficient at neutron capture, thereby getting slightly more radioactive, still not enough to significantly shorten the half-life.

- Those are still about 1000 to 20000 times more radioactive than U238, so it's a far cry to call that "comparable to uranium in a reasonable timeframe"

- We're definitely in the Ma timescale here. Say you want that nuclear waste decay down to 0.1% of the original material. How long does it take? Easy enough to figure out: 0.001 > 2^-n → n = log2(1000) =~= 10. Or in other words, it takes 10 half life periods for the stuff to break down to a concentration, that's still far from being homeopathic.

When it comes to technology IMHO a reasonable timeframe to deal with technological aftermath is 50 years (and not more). Anything beyond that and it will become a clusterfuck simply due to "human nature". Heck, today we've even got problem erecting structures that will last longer than 50 years without requiring major maintenance. And if you're honest about it, except for the few outliers of historical significance (the pyramids, port walls built by the Romans with their "super concrete" we still haven't reverse engineered, and such) we humans are quite terrible in building stuff that can go by without maintenance for more than a few decades.

And that's the core problem in nuclear waste management. A problem I'd like to point out, we have to solve, because there's already plenty of nuclear waste around.

Oh and then there's of course the problem how to treat and prepare the highly radioactive waste for long term storage in the first place. One of the proposed methods (and already employed by some nuclear energy companies) is to melt it into glass. But here's the problem: Glass is a quite complex material and its mechanical properties largely depend on its chemical composition. Radioactivity however means, that the chemistry is changing over time. Not to mention that some stages of the decay chain have a very high vapour pressure or are gaseous at ambient temperature/pressure. Which in turn means: Your once solid and smooth slab of glass will form lots of cracks, may even break down at some spots into fine sand (which could become air or waterborne).

I did my graduation thesis at an accelerator facility where also some aspects of nuclear waste treatment were researched. If you see some of the principal investigators in that area doing research on the renewable energy stock market or even having invested in family members green energy startups and advertising for them, that's a very strong signal.