CANDU has pretty solid safeguards against weaponization, but it's not like enrichment is all that difficult. Calutrons are fairly simple and old tech you can build in a garage (though you may not want to actually start processing material there if you enjoy being alive for long). You won't get amazing stuff out of them, but if all you're looking for is a uranium gun device, they'll do the job. If you're going with a plutonium based device, the synchronized, symmetric implosion is really your long pole anyway. Getting the plutonium will never be the real challenge there and an unlimited supply won't help you if it just blows itself apart prior to criticality.
CANDU designs are already prepared for MOX fuel cycles (and theoretically, they'll run on thorium as well but nobody's ever actually implemented it to the best of my knowledge), but you'll want to take that into account when actually building the plant or you'll be in for some expensive refitting later. They don't do it in Canada for the same reason we don't in the US: policy says don't do it. But they've reprocessed used fuel in Europe, Russia, Japan, and other places around the world for a long time. You can actually also feed weaponized material from decommissioned nuclear weapons into these reactors as well (a process the US Department of Energy is looking into, since we have a whole lot of that stuff sitting around now thanks to START, START II, etc).
That cuts a significant amount of your high level waste. You feed the rest into a fairly small number of fast neutron reactors. Yes, they'll be more expensive to run, but they're serving a greater purpose (turning dangerous waste into power and vastly less dangerous waste with significantly diminished time to reach non-hazardous status). House them in very safe, stable places like the US, Canada, and western Europe. We'll take what's left of the reprocessed material that the CANDU plants can't use anymore and extract most of what's left of its energy until there's just a tiny amount of waste with very little remaining energy. What remains is very easy to safely store and there's not much of it anyway.
And before you tell me the fast neutron reactors are a pipe dream of the future, EBR-II ran for 30 years (until Congress pulled its budget in 1994 - thanks GOP!) without issue. Not only did it work and actually produce electricity, but it was truly passively safe (tested in 1986 in a complete pull-the-plug test with all emergency systems offline - the physics of the design itself caused it to shut down naturally on its own in the absence of the systems that normally run it). The design was commercialized, but hasn't yet been picked up - largely due to NIMBY and the economic and political problems it creates with state and local governments. So we already have the tech developed and tested; we're merely choosing not to implement it via incompetence and ignorance.
None of this is politically feasible. It would require human beings behaving rationally and in the interests of the species as a whole. People on the right (no, not all of them) don't want to buy into the idea that fossil fuels are bad for the environment (even in cases where it's unquestionable that they are like towns buried under radioactive coal slurry) and people on the left (no, not all of them) have an irrational fear of radiation that rivals the anti-vaccine hysteria. Between that and the international cooperation it'd take, plus all the money required to get it kicked off, plus the coordination required, bureaucratic red tape to cut through, corruption to deal with, general incompetence, etc, it isn't going to happen anytime soon. But there's no technical reason we couldn't do it if we suddenly starting thinking and acting rationally in the best interests of our own species.