"Uranium reactors, regardless of 'Gen' use fuel that is enriched to about 6%. That means 6% fissionable Uranium, 94% non fissionable."
Two words to learn:
Fissile: Can be easily fissioned with "thermal" neutrons (typically, neutrons around 0.025 eV... also known as "slow" or "low energy" neutrons).
Fissionable: Can fission. Period.
U-235 is "fissile" while U-238 is "fissionable".
The "94%" you talk about (BTW: in the U.S. the limit for enrichment is 5%, most fuel is enriched to 4.8% or so to leave a little bit of headroom) is U-238 and is definitely "fissionable". Several types of reactors have been built over the years that can burn U-238 directly including fast reactors and others that are "high neutron economy" reactors like CANDU, Magnox and AGR which can burn Uranium with very little or no added enrichment.
Fast reactors can work with U-238 because above 1 MeV the fission cross-section for U-238 is large enough (and the capture cross-section simultaneously low enough) that U-238 can sustain the nuclear reaction. This works because neutrons are born with energies ranging from keV up to 20 MeV (although, the average is around 2 MeV).
CANDU can burn natural uranium (Which is only about 0.7% U-235) because of good neutron economy. It utilizes "heavy water" (deuterium/H-2) to slow down the neutrons. H-2 has an almost negligible capture cross-section meaning that nearly all of the neutrons that are born make it down to "thermal" energies where it will fission with U-235. However, since it is still relying on the small amount of U-235 the fuel is depleted fairly quickly, requiring constant refueling (not joking, it is literally refueled continuously). It would certainly be able to burn "spent" light-water reactor fuel though... that "measly" less than 1% (not 3% like you state) enriched stuff would actually be more than the amount of U-235 that typically goes into a CANDU reactor! Of course, some of the built up fission products are neutron poisons, so that would reduce the neutron economy a bit... but it would still be able to maintain a critical reaction.
However, this is not done because it's just not economically feasible. Getting the old fuel from LWRs and shipping it somewhere to be disassembled (which has to be done carefully because when it comes out of the reactor it stays hot (both thermally and radioactivity wise) for quite a while) and put into fuel forms that would work in a CANDU reactor would cost way more than the effort is worth.
It is interesting that you simultaneously insult someone else, screw up a bunch of facts AND manage to make a (terrible) misogynistic joke all in the same post. That certainly undermines your credibility in my eyes...