system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When people talk about nuclear waste, what are they really talking about? Whats in those scary barrels buried deep in a bunker if it isn't "glowing green goo?"
gpt
There are different classes of nuclear waste. Low level radioactive (rad) waste is broken down into different classifications. It can be anything from gloves and paper suits worn in containment or resin beds or filters. It’s disposed in special facilities based on its classification. 

High level waste includes spent fuel. Nuclear fuel is uranium pellets (sort of the size of an eraser on top of a pencil) that are assembled into rods and then the rods make up a bundle. Once the fuel is removed from the core, it goes into spent fuel pools, which are literally just pools of water. The spent fuel will hang out there for a while, just chilling (literally and figuratively). Eventually, the rods will be moved into longer-term storage. This was originally supposed to be Yucca Mountain (in the US at least). That facility was paid for by operating nuclear plants, but was never opened. Instead, nuclear plants usually move their spent fuel into dry cask storage. This is a big coke can looking thing that just holds the fuel. The fuel is, remember, still in rods. So you just plop it in the giant coke can and seal it up. They hang around outside the nuclear plant. Not in a deep bunker, just like chilling outside. 

Although it sounds like there’s just nuclear waste everywhere, it’s important to keep in mind that it’s not a sludge (if you’re talking about fuel). It’s a stable solid rod. And the amount of rods we’re talking here is not a lot. In fact, it’s really not an issue at all for plants to continue to store spent fuel on site, it’s just kind of a paperwork pain. 

At this time, there’s no way to recycle spent fuel in the US (I don’t think).