5 ms·
Fusion produces neutrons, not photons.
by u320 4y ago
Fusion produces neutrons, not photons.
- DFHippie 4y agoI'm pretty sure it produces both.
- fy20 4y agoIs there an equivalent of the photoelectric effect for neutrons?
- ncmncm 4y agoNone. Hot neutrons are the lowest-grade sort of energy.
- blincoln 4y agoMaybe a dumb question, but could one use bricks of depleted fission fuel as the neutron shield in a fusion reactor, and swap them back into a fission reactor every time they become fuel-grade again?
- ncmncm 4y agoIt would be an overwhelmingly smarter and better use of money to burn uranium in an ordinary fission plant, and maybe breed up extra fuel there. But we already know that fission, too, is uncompetitive, moreso each day as costs for renewables and storage continue relentlessly downward. Fusion has no chance of ever catching up.
- blincoln 4y agoSorry, maybe I was unclear. I wasn't asking about using the fusion reactor just to produce fission fuel. I was asking "if the fusion reactor produces a bunch of extra neutrons as a side effect, is this a way to use them to produce more energy later instead of throwing away that energy, or letting the neutrons actively damage the fusion reactor?" i.e. one needs to prevent the neutrons from escaping or degrading the material the reactor is made out of, so instead of just adding a throwaway shielding layer, would it work to use something that is not only super dense, but is currently a waste product[1], and also becomes more valuable in the process of being used as the shield? Seems like it would be vaguely equivalent to a photoelectric collector for neutrons, but I am not a physicist or reactor engineer. [1] I do think it's a shame that we stopped building breeder reactors, but that's a separate discussion.
- ncmncm 4y agoBreeder reactors are not used because refining the bred fuel costs more than processing mined uranium. The overarching requirement on fusion neutron absorption material, besides delivery of heat to process steam, is that it needs to produce more tritium to burn. You don't get that if the neutrons are absorbed in something other than lithium.
- scarmig 4y agoFusion covers a lot of different types of processes, some of which release most of their energy in charged particles and photons. Though you'd need something very different from existing photovoltaics to capture the energy from those x-rays.
- ncmncm 4y agoThe fusion they are working on emits hot neutrons. It will never produce so much as one kWh of commercial power.
- ben_w 4y agoAnything hot produces photons, and a working reactor would necessarily produce a lot of heat. These photons can’t usefully be converted directly into electricity with the photoelectric effect, but they sure could be converted indirectly via the same mechanism that the fusion in the core of the sun is reduced to the band that current PV runs at. Not sure if it’s worth doing that (may well be such a diffuser would be so large it would be easier to do something completely different), but that’s very different thing to your dismissal.