Reprocessed Nuclear Waste Reprocessing Is Possible

We can run the entire global economy off of nuclear energy from spent fuel for something between a few centuries to a few thousand years if we have a total recycling process. You would probably need to switch to a reprocessing method that does not fully separate out uranium and plutonium, that would be best. Even if you did use recycled spent nuclear waste from today's reactors, the plutonium is not going to be super effective for high yield nuclear weapons. There's debate out there about whether you could make a little one that would pop and do a lot of fear mongering.