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?”
In: Physics
The “green goo” is radioactive for thousands of years which makes it incredibly harmful for thousands of years.
It is the uranium / radioactive material that has been used up enough so it can no longer be used in a power station however it is not totally used up.
Any kind of byproduct that is radioactive. The main one is spent fuel. Nuclear power plants take a fuel (typically enriched uranium). When this fuel us used (fission) other radioactive elements are produced until what you have is a mixture that can no longer undergo fission anymore, but is still radioactive.
This waste is either recycled, or if that’s deemed to expensive, put in a barrel, allowed to cool off in a vat of water, then stuck somewhere relatively safe for the next thousand years (e.g. concrete bunker underground).
The firemen’s equipment that was used for Chernobyl is one of the most radioactive places in the world that you could theoretically just walk to
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).
It’s not just the spent fuel. It’s all sorts. Gloves that workers used. Paint scrapings from the last time the teacher hall was refurbished. Pipes from the coolant system. They might be low-level but they’re still radioactive and into the figurative barrel they go.
Mt grandfather briefly hauled low grade waste from the Pickering nuclear facility in Ontario. What he hauled were booties, masks, coveralls and such, any low grade contamination. That all got put into barrels, which was then sealed in over-barrels and hauled away somewhere. No body worries too much about that stuff though.
The dangerous stuff is the spent fuel from the reactor. Calling it spent though is very misleading. It is still quite radioactive and will be for a very VERY long time. It’s just that the active isotopes in it have decayed to the point where it just doesn’t get hot enough for efficient operation of the reactor. In addition, depending on the exact fuel in question, the products made by nuclear decay can themselves inhibit nuclear reactions. So not only does it not get “hot” enough any more, it will actively absorb “hot” from the neighbouring rods. This stuff amounts to **small rods of black ceramic material** that would feel quite hot to the touch. They could be hot enough to burn you from thermal energy alone, in addition to the radiation burns you’d receive. So at most generation facilities, they have cooling ponds full of water. Water is a decent moderator of radiation. Depending on how deep the top layer of barrels are, you could survive swimming across the pool. But diving down to touch them would kill you.
The big problem with these cooling ponds is that they are only so big. They were designed to be _temporary_ holding pens until they were safe enough to shop to a central facility for disposal or re-processing. But, for a variety of reasons, fear of nuclear power being high on the list, the central facility never got built and power companies haven’t been able to get permission to build bigger pools. (many of American reactors are still inn use decades after their design life and keep getting recertified because they don’t have a good way to get rid of the waste, they can’t get permission to build new reactors and we need the power too much to shut them down.) As a result, we have quite elderly reactor designs chugging away producing power and cooling ponds that are over capacity.
And, as others have said, having a facility to reprocess that fuel into new fuel comes up hard against fears of nuclear proliferation. The reason we have spent fuel that can be turned into weapons is because of a political choice made in the US during the Cold War. Thorium cycle reactors could produce just as much power or more from an even more abundant fuel than uranium. The down side was that it doesn’t produce Uranium-238 or Plutonium-239 which are needed for nuclear weapons. So the gov’t supported the development of Uranium-235 reactors.
The total amount of “spent fuel” amounts to a football field sized stack of ceramic slugs six and a half stories high. But, for a number of reasons, it can’t be stored that compactly.
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