Fusion: When? And what happens?

[tharkûn]

One, the fissionable products are a limited resource. This can be overcome to some extent with breeder reactors, but there really is only so much uranium in the ground.

You can pull uranium out of the seas, as well as build thorium reactors. The only reason we don't have millenia worth of terrestrial fission products is because so many cheaper alternatives exist.

Three, and perhaps more to the point, nuclear waste IS a real problem. Not in the quantities we do now, and certanly less than the massive poisoning that we get from fossel fuels, but anything with a half life measured in millions of years is good cause to say "Do we really want to be using this?"

Anything with a half-life measured in millions of years is just about harmless. Quite frankly something like DU is less hazardous that Hg, and Hg is "eternal".

If you are really worried about waste you can neutron shread it into something which quickly decays to a safe material.

Fission should be ramped up yesterday.

[kaikatsu]

You can pull uranium out of the seas, as well as build thorium reactors. The only reason we don't have millenia worth of terrestrial fission products is because so many cheaper alternatives exist.

Uranium out of the seas? Do you mean, in the water? This is new to me. It also reminds me of a time when there was research into pulling gold out of the seawater... Or do you mean from the seabeds? That would make more sense.

Regardless, commercial viability IS the ultimate driving force. Uranium which is expensive to aquire counts as a problem, even if it's economic and not technological.

Anything with a half-life measured in millions of years is just about harmless. Quite frankly something like DU is less hazardous that Hg, and Hg is "eternal".

Not sure that that necessarily follows. Hg is hazardous as a toxin, yes -- and to release it into the environment would be insane because it simply won't go away. The same applies to nuclear fuels.

DU less hazardous than Hg? That's... counterintuitive. I suppose you might be right, I never did any research into how toxic Hg is.

That being said DU is NOT pretty when it's released into the environment. It's not so radioactive that it decays rapidly, but it decays energetically enough that it can destroy the DNA -- including reproductive DNA -- of any life form that ingests it. I am not sure how you get "harmless" out of the deal... am I missing something?

Take a look at the birth defects taking place in Iraq. I'm not saying that your typical nuclear reactor is going to drop tonnes of DU around the same way that the US Army did... but it's got to be stored somewhere and, while there's a definite OVERREACTION -- this definitely falls into the "We do not want too much of this stuff laying around"

If you are really worried about waste you can neutron shread it into something which quickly decays to a safe material.

Fission should be ramped up yesterday.

If this (neutron shredding) was already done everywhere, I'd feel a lot better about that. I have a feeling this falls under the "too expensive" category.

Dispite all this, I am a fission supporter. No matter what you say about nuclear fuel, it beats fossel fuels... and it's the logical transition to a hydrogen/fuel cell energy structure.

[sketerpot]

I wonder if Greenpeace will protest fusion the way they did fission. If so, may Zod have mercy on us all...

Their position on fusion is that it has "all the problems of fission", despite the fact that this is completely false.

[Xon]

Uranium out of the seas? Do you mean, in the water? This is new to me. It also reminds me of a time when there was research into pulling gold out of the seawater... Or do you mean from the seabeds? That would make more sense.

Nope, from actual seawater.

Regardless, commercial viability IS the ultimate driving force. Uranium which is expensive to aquire counts as a problem, even if it's economic and not technological.

The easily accessable uranium reserves, which by easy they mean less than $30/kg or something like that in already developed areas. There is a fuckload more if you are going to dig for it like we dig for everything else(like say iron or coal).

And those cheap reserves would last us thousands of years, never mind the more extensive reserves.

That being said DU is NOT pretty when it's released into the environment. It's not so radioactive that it decays rapidly, but it decays energetically enough that it can destroy the DNA -- including reproductive DNA -- of any life form that ingests it. I am not sure how you get "harmless" out of the deal... am I missing something?

Take a look at the birth defects taking place in Iraq. I'm not saying that your typical nuclear reactor is going to drop tonnes of DU around the same way that the US Army did... but it's got to be stored somewhere and, while there's a definite OVERREACTION -- this definitely falls into the "We do not want too much of this stuff laying around"

DU is not radioactive in any meaningful way. It is still a fucking heavy metal, so it is chemically toxic.

But thats just a matter of handling, and handling chemically toxic stuff is trivial compared to radioactive stuff.

Dispite all this, I am a fission supporter. No matter what you say about nuclear fuel, it beats fossel fuels... and it's the logical transition to a hydrogen/fuel cell energy structure.

Yup.

[kaikatsu]

DU is not radioactive in any meaningful way. It is still a fucking heavy metal, so it is chemically toxic.

DU itself is not especially radioactive yes. On the other hand the decay products... Thorium 234 and Protactinium 234 - are beta particle emitters with half-lives about 20 days and one minute respectively. With sufficent DU (and let's be honest, not all depleted uranium is going to be perfectly depleted) you are looking at dangerous levels of radioactivity if handled carelessly.

And regardless, depleted uranium is not the only end product of fission. Spent nuclear fuel is by NO means a non radioactive material. Something has to be done with it. How much this gets blown out of proportion is another issue all together, but it has concerns above and beyond heavy metals.

Radioactive wastes -are- a natural problem for fission. Not an unsolveable one, but one that makes fusion more attractive.

$30 a kilogram? Uranium is really that cheap? I had no idea..... ok. I'll toss out the point that we once saw oil as cheap and almost unlimited... but depending on the scale we're looking at that analogy might not hold.

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A final note, regarding the extraction of the uranium from the sea. I did some quick lookups and got an estimate of 0.003 ppm U in seawater. Working this out by mass...

One metric ton of seawater would be a thousand kilograms, or a million grams. So for every ton of seawater... 0.003 grams.

Now, working from the Us Department of Energy page
(http://www.ne.doe.gov/uranium/facts.html)

* "Natural Uranium - uranium that contains 99.3 percent of the isotope uranium-238 and 0.7 percent of the fissionable isotope uranium-235."

So we're down to 0.000021 grams.

* "One ton of natural uranium can produce more than 40 million kilowatt-hours of electricity."

So one gram is 40 kilowatt hours. Fine. 40 * 0.000021 = 0.00084 kWh.

That should be about 3000 joules. Well, lifting a ton of seawater one meter into the air requires about three times that energy. Either I screwed up in my maths, my initial figure is wrong, or there had better be some VERY efficent method to extract this uranium.

Can anyone see any obvious mistakes?