Fusion vs. Fission

If polywell fusion is developed, in what ways will the world change for better or worse? Discuss.

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jsbiff
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Fusion vs. Fission

Postby jsbiff » Wed Jun 23, 2010 11:10 pm

I've been thinking about this recently. . .

Is it "too soon" for fusion?

Here's what I mean:

There has been work in the past (c.f. Integral Fast Reactor), and receently (TerraPower's Travelling Wave Reactor idea) on fission reactors that can use our current 'nuclear waste' from PWRs and BWRs in such a way that the 'waste' from such reactors is only radioactive for a relatively short period of time (I think a couple hundred years, instead of 100,000+ years).

It seems like the ultimate 'solution' to our current nuclear waste 'problem' is wide-scale deployement of such reactor designs, so we can burn off that waste (and get lots of hopefully cheap power from it).

The thought occured to me recently that *if* IEC fusion works out, and *if* we are able to build and operate the reactors cheap enough, not only might fusion power out-compete 'traditional' fossil fuels, but it might kill such waste-reduction power plant designs in their infancy. If such designs are more expensive to build, operate, and decommission than polywell's, might it mean that we never get around to cleaning up our 'nuclear waste'?

I'm just afraid that, without a profitable way to get rid of nuclear waste (something like an IFR or TWR would hopefully make waste disposal an enterprise which pays for itself in the long run, which means it *will happen*), to something which is just a money-losing cost, then how will we ever get rid of the waste in a safe manner?

WizWom
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Postby WizWom » Thu Jun 24, 2010 2:11 am

Burn-down ADS or ADEP plants are under development in almost every first world country. Polywell could come out today and it would not stop.
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clonan
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Postby clonan » Thu Jun 24, 2010 5:08 pm

Plus you can burn DT in a Polywell and use the neutrons to burn up the waste. Even if it does kill the other reactor types a Polywell could reduce the fuel radioactivity directly.

cksantos
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Re: Fusion vs. Fission

Postby cksantos » Thu Jun 24, 2010 7:42 pm

Do depleted uranium rounds make a dent in the waste volume? or is production volume to low to make a difference. Because Iraq and Afganistan sound like good places to store the waste, preferably near potable water sources.

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Re: Fusion vs. Fission

Postby MSimon » Thu Jun 24, 2010 9:15 pm

cksantos wrote:Do depleted uranium rounds make a dent in the waste volume? or is production volume to low to make a difference. Because Iraq and Afganistan sound like good places to store the waste, preferably near potable water sources.


Undepleted uranium is in contact with every water supply in the world. It is ubiquitous (in very small quanties) in sand.
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cksantos
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Re: Fusion vs. Fission

Postby cksantos » Fri Jun 25, 2010 2:23 am

MSimon wrote:
cksantos wrote:Do depleted uranium rounds make a dent in the waste volume? or is production volume to low to make a difference. Because Iraq and Afganistan sound like good places to store the waste, preferably near potable water sources.


Undepleted uranium is in contact with every water supply in the world. It is ubiquitous (in very small quanties) in sand.


So, why is depleted uranium so "dangerous".

BTW what are the waste products of peaceful fission? DU?, Plutonium?

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Postby MSimon » Fri Jun 25, 2010 2:30 am

So, why is depleted uranium so "dangerous".


For the same reason CO2 is so "dangerous". Some one has a political agenda.
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Postby kunkmiester » Fri Jun 25, 2010 9:43 pm

When depleted uranium pulls it's pyrophoric stunt on impact, you pretty much get aerosol uranium. It settles down pretty quick, and isn't very soluble, but it is a concern.

The main danger with DU isn't radiation, by the way, it's chemical. Uranium is a heavy metal, has quirks lead and such don't have.

http://www.ibilabs.com/URANIUM-MSDS.htm
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Postby D Tibbets » Fri Jun 25, 2010 11:25 pm

Depleted uranium is just that. It is the uranium 238 left over after government weopens and reactor fuel efforts have extracted all of the uranium 235 they can. Presumably, this depleted uranium has less U 235 than native ores, and as such, from a radioactive perspective it is safer than making rounds out of non depleted ore. Also, as mentioned, heavy metal poisoning is probably the greatest concern, Not to mention that in acute exposure (your tank gets hit), the vaporized and pulverized uranium metal getting into your lungs will spontaneously burn (if it has not already burned/oxidized and ignited every flammable thing around you). Sort of like white phosphorous.

So, depleted uranium is less of a radiation hazard than the in situ uranium ore- so long as you do not concentrate it too much- and again the heavy metal toxicity concerns probably dominate.

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krenshala
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Postby krenshala » Fri Jun 25, 2010 11:43 pm

I've always considered the radiation concerns about DU to be the same as the lead-poisoning concerns for standard bullets. If you've been shot (at) by one, the lead (or radiation) content is not what you are supposed to be concerned about. ;)

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Re: Fusion vs. Fission

Postby KitemanSA » Sat Jun 26, 2010 1:35 am

cksantos wrote: BTW what are the waste products of peaceful fission? DU?, Plutonium?
Depends on the fuel cycle and reactor design.

As a fairly universal state, fission results in "fission products" (duhh). Since most fissile materials average about 240 mass units, the fission products average about 120 (minus a couple spare neutrons). These "fission products" are fairly short lived, with half lives in the 10s to low hundreds of years.

The less desirable "products" are the higher actinides (including Pu) that are bred by neutron impact of non-fissile material. These materials can have radio-active decay chains that go on for millions of years. Some of these materials become fissile and will fission with another properly energetic neutron. Others become "poisons" which just uselessly absorb neutrons and become HIGHER actinieds. And they all do various interesting things to solid fuel elements.

And since there is a political prohibition in this country against re-processing fuel, used fuel elements just sit around in "swimming pools" at the varios nuclear power plants.

Thorium cycle Molten Salt Reactors don't have solid fuel, can be used to burn the higher actinides, and the fuel starts at a lower mass number so has a better chance of breeding into fissile materials and fissioning before they breed to the HIGHER actinide states.

For a much better description of the issues, read some of the papers at http://www.world-nuclear.org/infomap.aspx which even mentions Polywell. :)

cksantos
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Postby cksantos » Sat Jun 26, 2010 5:36 pm

So why dont we have bombs filled with powered DU?

KitemanSA
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Postby KitemanSA » Sat Jun 26, 2010 5:58 pm

cksantos wrote:So why dont we have bombs filled with powered DU?
Why would you? What folks have just said is that the danger from DU is chemical, not radiological. And chemical weapons are banned.

cksantos
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Postby cksantos » Mon Jun 28, 2010 6:21 pm

KitemanSA wrote:
cksantos wrote:So why dont we have bombs filled with powered DU?
Why would you? What folks have just said is that the danger from DU is chemical, not radiological. And chemical weapons are banned.


Ahh I see. So radiological weapons are not mentioned in international law?


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