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/nuk/ - Nuclear thread

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For all things related to nuclear power.

Discussion topic of the day: Should we be building new nuclear capacity alongside renewables, or instead of them?
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>>7637298

Focus on nuclear power, renewable energy is pretty much a joke compared to nuk.
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>>7637298
I've heard that fusion power could run on seawater, using heavy water as fuel. It would only create helium (a useful resource in itself), and could last for a very long time (thousands of years, I think; long enough to find a replacement or leave the planet).
Is this reasonable, assuming we can get fusion to work, or is the an oversimplification?
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>>7637314
That's the gist of it really - the main assumption there is that we can get a working commercial reactor at all. But if we can, it's effectively a renewable resource (I think that it's more than just thousands of years, but don't quote me on that).
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We should build more nuke plants. I'm still bummed that my local plant closed down. Fucking Mitsubishi and their defective steam generators. .
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>>7637324
We should have built more and should have kept funding for new generations and types of reactors.
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>lets have a bunch of retards with no working knowledge discuss something amongst themselves, spread misinformation, and walk away even more retarded than when they entered the thread.
nah, we don't need another thread like this on /sci/
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Nope. Heat pollution is very serious
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There are alternative energies that could yield the same amount of aggregate output in power, it's just uranium is also available as a commodity.
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>>7637314
It's a bit of an oversimplification, but overall it's fairly accurate.

Two points:
>You'd have to actually extract and purify the heavy water first to get pure deuterium; you couldn't run on straight seawater

Fortunately, enriching hydrogen is MUCH easier when enriching uranium, because the relative mass difference between 1 and 2 amu is much larger than the difference between 235 and 238; you can actuallly distill the deuterium out because it has a slightly higher boiling point. (About 101 C vs. 100 C)

>It would only create helium

This sort of depends on what reactions you're using. The two easiest fusion reactions are fusing two deuterium nuclei, and fusing a deuterium and a tritium.

D-T fusion (the easiest) creates Helium-4 (ordinary helium) and a very high-energy neutron. The intense neutron radiation (estimated to be 100 times greater than ordinary nuclear reactors) would mean that D-T reactors would actually produce significant amounts of dangerous nuclear waste, because the neutron radiation would transmute the reactor's inner walls into heavier, more unstable elements. Also, the neutrons carry off 80% of the energy, so you have to capture and absorb them somehow.

Also, tritium does not occur naturally (it's radioactive and unstable, although fairly harmless if not inhaled) and must be made artificially by neutron irradiation of materials.

In theory, the neutron radiation off of the reactor would be absorbed by a "lithium blanket", which would absorb the neutrons created by the reaction to make more tritium, while also being heated by the radiation so you could extract thermal power. However, because we haven't even gotten a reactor working properly yet, this crucial component has not yet been tested.

[cont]
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>>7639274

D-D fusion (the second easiest) creates much lower-energy neutrons, but has two possible reactions: About 50% of the time you'll get a tritium and a regular hydrogen, and 50% of the time you'll get a neutron and helium-3 (a rare stable isotope of helium). The problem is, the tritium produced will then very quickly react with the deuterium, and you're back to the same problems as D-T only slightly less so. If all the tritium is burned up, you'll only get about an 18% reduction in neutron radiation compared to D-T, so the main advantage is basically just that you don't need the tritium breeding thing.

If you could somehow quickly remove the tritium so it didn't react, then you'd get less energy out of the reaction on the whole, but you'd at least get fewer high-energy neutrons and so less really dangerous radioactive waste, but now you've got radioactive tritium gas to deal with. It's not terribly dangerous - you've probably seen a glowing green light powered by decaying tritium in an EXIT sign - and it's fairly short-lived (half-life of 12.5 years), but you do not want to breathe that shit. It decays to Helium-3, which is also a potential fusion fuel that you could recycle.

Deuterium + Helium-3 is also a potential reaction, which is significantly harder than the previous two but in theory produces no neutrons - just helium-4 and regular hydrogen. Helium-3 is extremely rare naturally, however*, and the lack of neutron production doesn't really work in practice because you inevitably get a bunch of D+D side reactions and now you've got neutrons to deal with. However, if you could push a D+D reactor hot enough to also burn the helium-3 it produces, then you'd be able to get more extractable energy out of the fuel - especially if you were able to remove the tritium, let it decay to Helium-3, and recycle it back in.

Anyway, my point is that helium's not the only product to deal with, and you probably wouldn't want a fusion reactor in your basement.
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>>7639287
Oh, and as for the "Thousands of years" comment on deuterium? That's underestimating it, a lot.

Deuterium occurs in seawater at a concentration of about 33 mg/L, so there's about 44 trillion tons of it in the oceans altogether. Taking all the side reactions into account, and assuming you're doing D-D with recycling of Helium-3, 6 deuterium nuclei (equivalent to 12 amu of mass) will produce 2 helium-4 nuclei, 3 hydrogen nuclei, a neutron, and 43.9 MeV.

So if we could extract and fuse all the deuterium in the oceans and capture its energy with 100% efficiency, along with its side products, we'd get [math]1.5 \times 10^{31} [/math] J of maximum theoretical energy. Current world energy usage is 156 petawatt-hours per year, so at that rate of energy consumption we've got enough deuterium to last about 28 billion years.

(Of course, we won't be able to burn it with 100% efficiency, and our energy needs will go up with time, so maybe it only lasts a million years or so.)
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>>7637314
Good job, was thinking about that too.
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>>7639312
Not that it's ever likely to be an issue, but if we actually managed to remove significant amounts of the heavy water from the world's oceans, it would take more and more energy to extract.
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>>7637298
>Should we be building new nuclear capacity alongside renewables
no.
>instead of them?
yes.

Germany could've built themself a larger nuclear fleet than france. Instead they wiped their arse with the money and built a shitload of renewables that directly harm the national economy.

Good job germany, just clone Hitler already and get a competent leader back in place.
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>>7639326
>if we actually managed to remove significant amounts of the heavy water from the world's oceans, it would take more and more energy to extract.

In the year 20015 we can presumably lift fusion material off the sun itself, reducing the need for seawater extraction.
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>>7637298
Cherenkov radiation is so beautiful

https://www.youtube.com/watch?v=mgNwtepP-6M
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>>7637298
>Should we be building new nuclear capacity alongside renewables
No. Nuclear technology as it currently exists takes a very long time to pay off, if you can really say it ever does, but energy technology in general is moving very quickly, and so is production technology. This is a time for short-term solutions.

Don't want to build a nuclear reactor that takes 10 years to build and 20 years to pay off, and in 15 years it will get shut down because nobody's comfortable with risks that were seemed acceptable a generation ago and power's cheap now anyway.

If I wanted to spend money on fission, what I'd put it into is researching fission fragment reactors. They have potential far beyond grid power, and for grid power, they have the potential of cleaning up their own waste as they make it, by sorting their own fission fragments, driving fusion reactions to produce additional neutrons, and having their output converted to energy so efficiently that you can afford to spend more electricity than you could generate from a conventional reactor just running particle accelerators to clean its waste up.
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>>7639332
>clone Hitler already and get a competent leader back in place.
>implying Hitler was competent
[opinion discarded]
Thread posts: 19
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