[jjk166]

> If it's too diluted, you can purify it with normal chemical processes and then make your bombs. It's not like uranium where you need a monstrously expensive isotope separation process to get the fissionables out.

While technically it is possible to separate plutonium out chemically, it is extremely difficult to do in practice. Plutonium separation plants are more expensive than uranium enrichment plants, and that's the reason states pursuing clandestine nuclear weapons programs choose uranium enrichment over plutonium. Uranium enrichment was much more expensive in the 40s and 50s when the US built up its plutonium production infrastructure, all of which was shut down in the 80s. Modern centrifuges make uranium enrichment cheap and simple, and the only economical source of plutonium is dismantled nuclear weapons.