Eli5 why can’t radioactive waste be used again? Why is it waste?
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It can, but doing so requires a fair amount of extra work as well as specialized nuclear reactors which could also be used to make bombs.
So, instead waste is thrown out.
The way that a nuclear reaction works is that a stable nucleus absorbs an extra neutron, and that causes the nucleus to become unstable, thus undergoing radioactive decay – becoming a different element, releasing more neutrons, and releasing a bunch of energy.
In a nuclear power plant, it’s desirable to have a chain reaction, where you have sufficient amounts of the radioactive material so that each decaying atom launches a neutron at another nucleus, causing it to delay in turn.
What makes the waste, well, waste, is that it will still undergo radioactive decay, but it won’t sustain a chain reaction, and it won’t produce enough energy to power the reactor.
When nuclear fuel decays it will break apart into lighter atoms. There is a whole cascade of different elements they go through by decaying further and yes this does release more heat.
At some point they turn into stuff that is still radioactive but only decaying very slowly. That means the energy output is extremely low, and it will take very long until it stops being radioactive.
We have spent fuel treatment centers. What they do is seperating that crazy mix of different decay stages in reusing the parts that are still usefull while sealing away the parts that are useless and just a hazard
In nuclear fission, the fissile atom splits into smaller atoms, releasing energy in the process. The smaller atoms have too many neutrons so they arent super stable but they kind of pass the extra neutrons around and remain radioactive, launching neutrons and gamma rays out of the spent fuel for like 10,000 years. It’s waste because the smaller atoms aren’t fissile and they are too radioactive to be used in most chemistry. I failed physics and chemistry so dont quote me.
“Waste” is stuff that’s worth less than what it costs to get rid of it. Spent nuclear fuel contains various elements that have *some* value, but not enough to justify separating them.
… Currently, but that could change. Kirk Sorensen explains:
> “So the upshot from all this would seem to be, let’s go and take the spent nuclear fuel and let’s go and burn up the [plutonium in it] and let’s make money selling the electricity from it.”
“Is Nuclear Waste Really Waste?” https://youtu.be/rv-mFSoZOkE?t=1455
While the other posters are correct and that nuclear waste has far less nuclear fuel then it started with, It still has more fuel than a uranium mine will have. So I think your question is a good one. This is the answer:
> [In 1977, the President decided to indefinitely defer commercial nuclear spent fuel reprocessing in the United States because of the risks of nuclear technology and/or materials being diverted from such plants.](https://www.gao.gov/products/emd-80-38)
I think that is silly.
Radioactive materials can be used till they are damn near inert. Breeder reactors create more fuel than they use. It’ the nature of that fuel that countries don’t like as it can be used to make weapons. There are newer reactors that mitigate this, but the world is so damn scared of the word ‘nuclear’ that it’s very difficult to build ANY reactor.
The overwhelming majority of radioactive waste isn’t spent fuel. It doesn’t matter how many contaminated gloves or boots you can find. You’ll never be able to harvest a meaningful amount of fuel from them. The small portion of waste that is spent fuel can often be recycled, however cost, infrastructure, or legislature make it unfeasible in many locations.
>The vast majority of the waste (90% of total volume) is composed of only lightly-contaminated items, such as tools and work clothing
>
>By contrast, high-level waste – mostly comprising used nuclear (sometimes referred to as spent) fuel that has been designated as waste from the nuclear reactions – accounts for just 3% of the total volume of waste
>
>France, Japan, Germany, Belgium and Russia have all used plutonium recycling to generate electricity, whilst also reducing the radiological footprint of their waste
[https://world-nuclear.org/nuclear-essentials/what-is-nuclear-waste-and-what-do-we-do-with-it.aspx](https://world-nuclear.org/nuclear-essentials/what-is-nuclear-waste-and-what-do-we-do-with-it.aspx)
Remember the periodic table ? All element have a little number. That number is amount of proton and neutron inside the element. The higher the number is, the less stable is the element. If there is more proton and neutron, it is hard for the nucleus (the proton and neutron stuff) to keep itself together. It will have a tendency to eject a neutron or a proton out which will reduce its number, creating a new, more stable, element.
Ejecting a proton/neutron is what we call radioactive. If you take an unstable element in your hand aka a radioactive element, your skin would be bombarded by those proton/neutron..
So, after a while, your original element is kind of not what it used to be. A part of it has been transformed into a stable element that is now stable while the other part is still radioactive. This mean that your fuel does not eject as much proton/neutron as it used to be so it generates less heat. It is still radioactive but not enough to do its job properly.
The part that is being reused is not called waste.
By quantity, most of it is conventional waste that had some contact with radioactive material and has tiny traces stuck on it. Handle some radioactive material with gloves and traces of it will stick to the gloves. They are now radioactive waste. The container it was in is probably radioactive waste, too. Generally the activity here is very low (few decays per second), so it’s no problem to store these materials safely.
If we look at spent fuel from nuclear reactors: The reactors don’t run on radioactive decays. They use a chain reaction where neutrons hit an uranium nucleus and split it, a process which releases more neutrons that can then split more uranium nuclei and so on. There is a bit of radioactivity as well but that’s just an unwanted side effect. We would love to use non-radioactive elements in nuclear reactors, but it turns out that there are none that could do this chain reaction.
Spent fuel has largely three components:
* some of the original uranium. That is obviously useful, it’s like unburnt fuel in a fire. In Europe this is commonly extracted and reused. The US doesn’t do this for political reasons.
* The elements produced from splitting the uranium – some are radioactive, some are not. There is no practical use for them – it’s like the ash of a fire, you can’t burn that (and unlike actual ash, you definitely don’t want to use this as plant fertilizer!).
* A bit of other stuff that is produced as side effect in a reactor, mostly from neutrons hitting uranium without splitting it (generally radioactive). This can be used as fuel in specialized reactors.
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