My knowledge about school level physics is admittedly not that fleshed out, but we were told that it is possible to convert mass to energy. My google-fu has sadly left me for my question here 🙁
So why can’t we just take e.g. nuclear waste and convert it to energy? After that so is my understanding it wouldn’t simply exist as matter anymore and wouldn’t require to store dangerous trash if you can convert it all to energy.
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Short answer is yes, there’s a different nuclear reactor that can do it.
There’s a few different ways to make nuclear energy, each uses different fuel and creates different types of waste. If you want to look up more, check out molten salt reactors
Mass is converted to energy in all exothermic reactions.
Nuclear reactions are just a special kind of exothermic reaction. Fissile material goes in and fission products (radioactive) and energy comes out. When you burn hydrocarbons, fuel and oxygen go in and water and CO2 and energy comes out.
To turn mass into energy, we have to select a source that has stored energy it can release by reducing it’s mass.
Fission products have already had a decent amount of their mass removed, radiation from the fission products is also a mass to energy conversion process that happens spontaneously. Eventually all the fission products will decay into stable isotopes. Iron has no spare nuclear energy.
We can “speed up” the fission product decay by bombarding them with other particles. This makes them more radioactive (short term) so they reach a stable state more quickly. This is call “nuclear waste transmutation”. It can be done with another reactor producing a neutron source, or it can be done with an accelerator (which can create a variety of particles that can result in nuclear reactions that transmute the waste). This isn’t particularly effective but there are lots of papers on this.
I hear there are other reactors that run on nuclear waste and are even safer but I guess as another person posted there’s no real need for them yet unless we’re just going to try to have less waste but I think it’s a cost-efficiency thing, basically why bother producing or utilizing nuclear waste when you can store it in a mountain or underground for a generation or so.
If fire burns wood, why do we have ash?
Because the reactions involved don’t produce *enough* energy to break apart some of the fuel. If you get a hot enough fire, wood will vaporize, but wood itself doesn’t burn that hot. Similarly (and also theoretically), with enough energy, you could rip apart the atoms and subatomic particles that make up nuclear waste in order to completely convert them to energy, but we just don’t have the energy capabilities to do that, nor do we really want to. When we use nuclear fuel in fission reactors we want a slow consistent reaction, like embers sitting in a fireplace. If you get a big fission reaction, that is called a nuclear bomb.
Also, a lot of nuclear waste isn’t actually fuel from reactors, but things like gloves, containers, and machinery that has processed or interacted with the fuel in some regard, becoming radioactive itself. Consider these things like the bricks in the fire place. They get stained with soot and smoke, but do not themselves burn.
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There’s high-level and low-level nuclear waste. Most nuclear waste is low-level nuclear waste — things like gloves, tools, protective suits, duct tape, and other things that may have some radioactive material on them.
High-level nuclear waste is stuff like nuclear fuel (heavy metals, mostly Uranium-235) that has degraded into other radioactive elements, some of which take a very long time to degrade to something harmless. Nuclear reactors don’t turn their fuel into energy. Their fuel are metals that decay (the atoms literally fall apart, which we call fission) and give off lots of heat in the process. That heat boils water to make steam, and steam turns an generator to make electricity.
We don’t turn the mass into energy. They do that in Star Trek using antimatter and some hypothetical future technology (that uses “dilithium crystals”), but we’re not there yet.
Mass doesn’t really like being converted to energy. You have certain ways we can shave off a little bit to create energy – like burning wood. But wholesale destruction of an atom is incredibly difficult and requires enormous amounts of energy.
That being said, the French have some breeder reactors that use waste from their regular nuclear plants as fuel.
All mass can probably be converted into energy but we haven’t figured out how to do that yet. We can currently convert only some of the mass of only some of the elements into energy. Whatever is left behind, becomes nuclear waste.
Just a quick side note: we can actually derive power from nuclear waste. The technology has existed since the 60’s. But the non-proliferation movement in the states in the 70’s resulted in a ban on its recycling (as you effectively refine uranium again and again into higher grade/plutonium) .
Japan does this now in their reactors, so it is commercially viable
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