To godelski point yes there is low level stuff that really isn't a concern except to jandrese's point it's political. If I walk out of a reactor room and my gloves from my contamination suit pop too high they get put in a bag that is marked nuclear waste.
Granted the too high mark could still be perfectly fine to throw into a landfill and not impact anything, but nobody wants that in their neighborhood.
As to high level stuff which is what you are asking about, the spent stuff is really hot. To recycle, it would need to cool down first. Commercial plants place that in cooling pools, which is kind of bad if you have a Tsunami hit your plant (Japan), our something else.
So as to the waste element think I have 2% enriched object that is 100 cubic meters. The same in a highly enriched say 90% would only be about 2 cubic meters. This means my pools would be smaller, my overall size is smaller, and I can contain the smaller pool easier preventing the release.
On the politics side the idea of highly enriched is dangerous because it could be used for other purposes, however when those decisions were made I don't think anyone every imagined the concept of a dirty bomb in which enrichment is really going to matter one bit.
Due to some logistics complexities recycling fuel doesn't make as much economic sense as it does for places like France. Though if we did have 1000 plants it would make a lot of sense haha.
But besides that there is always waste. The key part is understanding what level of waste. There's a fair amount of low level waste (low radiation levels). In fact, this is like 90% of total waste (even more if you count my volume). But this type of waste is not the kind people are typically concerned with because it isn't radioactive for long nor is it producing dangerous levels. These types are not really recyclable though (concrete, steel beams, etc).
I do suggest reading up on our own AcidburnNSA's post about waste[0]
Recycling used fuel still doesn't make much sense. It's very expensive to recycle and new nuclear fuel is cheap. Storing the waste isn't technically difficult either. The total quantity of waste is tiny, but politically it's very difficult to deal with.
Granted the too high mark could still be perfectly fine to throw into a landfill and not impact anything, but nobody wants that in their neighborhood.
As to high level stuff which is what you are asking about, the spent stuff is really hot. To recycle, it would need to cool down first. Commercial plants place that in cooling pools, which is kind of bad if you have a Tsunami hit your plant (Japan), our something else.
So as to the waste element think I have 2% enriched object that is 100 cubic meters. The same in a highly enriched say 90% would only be about 2 cubic meters. This means my pools would be smaller, my overall size is smaller, and I can contain the smaller pool easier preventing the release.
On the politics side the idea of highly enriched is dangerous because it could be used for other purposes, however when those decisions were made I don't think anyone every imagined the concept of a dirty bomb in which enrichment is really going to matter one bit.