eli5 If nuclear waste is radioactive, can’t we generate electricity from it emitting radioactive particles?


eli5 If nuclear waste is radioactive, can’t we generate electricity from it emitting radioactive particles?

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We could, I suppose, but it’s super toxic and dangerous. It could be packed into a radioisotope thermoelectric generator (RTG), and a small amount (2KW) of electricity produced. But it would have to be in a super secure facility, and powering the lights to keep evildoers from stealing it at night might take more electricity that the facility produces.

Waste is not super radioactive like the fuel is. It’s not hot enough to power a steam turbine like in a reactor, but it is hot enough to poison you.

There just isn’t enough energy density, and that’s why it is waste.

Its not super radioactive. When something has a super long half life it means it will put out less energy in the same time frame as something with a shorter half life. Nuclear waste is like the embers after a fire. Its still there and doing something, but not enough to do anything interesting,

Nuclear waste is radioactive, but we can’t tell it when to give off energy. It just does. We can’t decide when we want power, we just get a steady stream, and usually not near as much.

Technically? Yes

Usefully? No

[Betavoltaics](https://en.wikipedia.org/wiki/Betavoltaic_device) are a thing where you put a strong beta emitter inside the right materials and capture the electrons(Beta particles) that it throws off and use that to generate power. They’re not good for anything but tiny tiny power sources. There are some that exist for pacemakers but a “high powered” beta voltaic source will generate 100 uW

Gammavoltaic cells have been considered but not built. Gamma rays are really hard to collect, they just ignore most things

One of the big components of spent nuclear fuel is Caesium-137 which has a half life of 30 years making it quite radioactive. When it decays it gives off a Beta particle with about 0.5 MeV of energy and a Gamma ray with 0.66 MeV for a total of 1.1 MeV of energy which isn’t zero but isn’t a ton.

When you fission a single atom of Pu-239 you get 207 MeV of energy, so one atom of Plutonium splitting gives off as much energy as 200 of its longer lived decay products decaying.

To get a lot of power from the decay products you start needing a large amount of them because they’re not energy dense and that large amount of them results in lots of gamma rays and handling challenges. Its far far easier to just put them in the ground and add in fresh U-238 that’ll turn into Pu-239 and give off the big chunk of energy.