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Googling the topic seems to indicate that fusion reactors will produce less waste and less toxic radioactivity, but this fact never seems to be mentioned during the current debate over nuclear power. Will fusion reactors be cleaner than fission reactors? If so, how much cleaner?

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Are you sure about that? As far as I was aware, that was one of the main, if not the main selling points that are typically argued when advocating fusion research. – DumpsterDoofus Mar 24 '14 at 0:57
The question in the title is a good one, but the rest of the text seems to assume the answer, so I can't vote for it. – Nathaniel Mar 24 '14 at 8:50
(The reason it's not obvious is that fusion power does produce radioactive waste, due to the reactor walls being bombarded by neutrons and becoming radioactive as a result. It would be pretty nice to know the rate at which this waste would be produced in comparison to a fission reactor producing similar power output, and how it compares to fission waste products in terms of safety and environmental concerns.) – Nathaniel Mar 24 '14 at 9:34

2 Answers 2

up vote 4 down vote accepted

Here they say that there is no waste per se only that some parts can become contaminated and they'll refurbish them onsite. The rest will be handed over to the authorities.

The Hot Cell Facility will be necessary at ITER to provide a secure environment for the processing, repair or refurbishment, testing, and disposal of components that have become activated by neutron exposure. Although no radioactive products are produced by the fusion reaction itself, energetic neutrons interacting with the walls of the vacuum vessel will 'activate' these materials over time. Also, materials can become contaminated by beryllium and tungsten dust, and tritium.

This one is about how much fuel is needed for the reaction(s). Based on how little is being used you could deduce on how little waste is being produced.

In fact, a fusion reaction is about four million times more energetic than a chemical reaction such as the burning of coal, oil or gas. While a 1,000 MW coal-fired power plant requires 2.7 million tons of coal per year, a fusion plant of the kind envisioned for the second half of this century will only require 250 kilos of fuel per year, half of it deuterium, half of it tritium.

In addition, fusion emits no pollution or greenhouse gases. Its major by-product is helium: an inert, non-toxic gas. There is no possibility of a "runaway" reaction because the conditions for fusion are precise—any alteration in these conditions and the plasma cools within seconds and the reaction stops. Fusion has the capacity to furnish large-scale quantities of energy, with a low burden of waste for future generations.

Also a relevant link posted by anna_v in a comment is:

Proponents believe that much of the ITER criticism is misleading and inaccurate, in particular the allegations of the experiment's "inherent danger." The stated goals for a commercial fusion power station design are that the amount of radioactive waste produced should be hundreds of times less than that of a fission reactor, and that it should produce no long-lived radioactive waste, and that it is impossible for any such reactor to undergo a large-scale runaway chain reaction.

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Thanks. Only criticism is when you presented amounts of fuel per year, you used two different units. – Enjoys Math Mar 25 '14 at 1:39

That's right. I'm really out of the loop regarding nuclear fusion shielding so feel free to correct me, but the only radioactive waste will be the reactor's inner walls (because of the radiation). The only other 'waste' that a fusion reactor produces is helium.

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IIRC, if the DD reaction doesn't pan out, you'd have to deal with tritium, which is radioactive and penetrates rubber, concrete & steel. – Kyle Kanos Mar 24 '14 at 0:48
@KyleKanos aren't they manufacturing Tritium on the site of the reactor though, and then "burning" all of it up as it's made? – Enjoys Math Mar 24 '14 at 0:50
@EnjoysMath: AFAIK, tritium is being used as part of the reactor for DT (deuterium-tritium) reactions. The DD (deuterium-deuterium) reactions would create tritium as a byproduct. In either network, I don't believe that the tritium is all burned up, some of it remains behind. – Kyle Kanos Mar 24 '14 at 0:57
please read the info at the site. Tritium is used in medicine and there are good methods already developed for treating tritium gas. Perusing will answer the question. Also response to criticism . The number there is 100 times safer than fission reactors, as fusion reactors cannot melt or explode. – anna v Mar 24 '14 at 4:39

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