The main motivation to not reprocess fuel was nuclear nonproliferation, because it frees up the plutonium for nuclear weapons. But on the off chance that govern

The main motivation to not reprocess fuel was nuclear nonproliferation, because it frees up the plutonium for nuclear weapons. But on the off chance that governments ever want to build a giant pile of nuclear weapons it’s sensible to not get rid of the nuclear waste, since if it ever turns out you do want it again it’s very expensive and time consuming to produce. Since you’ve already gone to all of the effort of mining the uranium and producing a bunch of plutonium, best to just keep it around somewhere in case you ever do want it for some reason.