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 Post subject: Amount of uranium in the earth's crustPosted: Jan 21, 2015 6:17 am

Joined: Jul 14, 2008 3:12 pm
Posts: 5045
"Deffeyes & MacGregor, "World Uranium resources" Scientific American, Vol 242, No 1, January 1980, pp. 66-76."

http://nuclearinfo.net/Nuclearpower/Ura ... stribution

How accurate is this information?

Is there really that much of this stuff in higher concentrations?

I mean, just look at black shales alone, est. 20-100 ppm. 20 billion tonnes! And the calculations from the nuclearinfo.net authors clearly show that much lower concentrations of 10-20 ppm would still mean EROEI >16. With a 1970 vintage LWR that is!

To get a feel of how much that black shale resource alone is, consider we build and maintain indefinately 10x the LWRs we have today. We'd need about half a million tonnes a year. Black shales alone would last 40000 years.

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 Post subject: Re: Amount of uranium in the earth's crustPosted: Jan 21, 2015 10:32 am

Joined: Jun 19, 2013 11:49 am
Posts: 1553
If we assume 50ppm and 100% recovery that is roughly 50g per tonne of rock material processed.
If we assume LWRs/HWR the utilisation is roughly 7GWd/t (or roughly 168kWh/g -> 600MJ/g).
That means that the 'calorific value' is roughly 30GJ/t of material.

The calorific value of coal is 24GJ/t.

So it would require mining black shale like its coal - not too likely to go down too well.

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 Post subject: Re: Amount of uranium in the earth's crustPosted: Jan 21, 2015 1:37 pm

Joined: Jul 14, 2008 3:12 pm
Posts: 5045
E Ireland wrote:
If we assume 50ppm and 100% recovery that is roughly 50g per tonne of rock material processed.
If we assume LWRs/HWR the utilisation is roughly 7GWd/t (or roughly 168kWh/g -> 600MJ/g).
That means that the 'calorific value' is roughly 30GJ/t of material.

The calorific value of coal is 24GJ/t.

So it would require mining black shale like its coal - not too likely to go down too well.

Good point.

People hate mining anything whether its a 1 million or 100 million ton/year mine. That doesn't stop us from doing it. Iron, cement, it gets mined and the environmental impact always gets disputed. Those same people who oppose mining shamelessly use metals in a lavish and oblivious manner. These are the people who turn up in an anti-mine demonstration in their cars with 1000+ kg of metals in it. Last I checked cement production was like 4 billion tonnes/year and iron ore 2 billion tonnes a year, with overburden in it'd be a small multiple of that. That would be similar figures to what black shale uranium in 10x LWRs of today would need.

But cleary there's much richer deposits that would still last centuries at 10x today's LWRs.

Question I have is how accurate are the concentration vs mass figures.

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 Post subject: Re: Amount of uranium in the earth's crustPosted: Jan 21, 2015 2:26 pm

Joined: Jun 05, 2011 6:59 pm
Posts: 1335
Location: NoOPWA
E Ireland wrote:
So it would require mining black shale like its coal - not too likely to go down too well.
Hmmm, but then again, coal ASH has about the same concentrations as black shale. We could mine the coal ASH piles and clean them up a bit.

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 Post subject: Re: Amount of uranium in the earth's crustPosted: Jan 21, 2015 4:06 pm

Joined: Jul 14, 2008 3:12 pm
Posts: 5045
KitemanSA wrote:
E Ireland wrote:
So it would require mining black shale like its coal - not too likely to go down too well.
Hmmm, but then again, coal ASH has about the same concentrations as black shale. We could mine the coal ASH piles and clean them up a bit. ;)

There's only so much coal ash. Black shale is much more common. Like, orders of magnitudes.

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 Post subject: Re: Amount of uranium in the earth's crustPosted: Jan 22, 2015 1:23 pm

Joined: Jun 05, 2011 6:59 pm
Posts: 1335
Location: NoOPWA
Cyril R wrote:
KitemanSA wrote:
E Ireland wrote:
So it would require mining black shale like its coal - not too likely to go down too well.
Hmmm, but then again, coal ASH has about the same concentrations as black shale. We could mine the coal ASH piles and clean them up a bit.

There's only so much coal ash. Black shale is much more common. Like, orders of magnitudes.

True, but given we have used coal for most of our energy supply for over a centuryand there is almost 10X as much energy in the U in coal ash as the coal the ash came from, it still seems a worthwhile target.

_________________
DRJ : Engineer - NAVSEA : (Retired)

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 Post subject: Re: Amount of uranium in the earth's crustPosted: Jan 22, 2015 9:57 pm

Joined: Apr 19, 2008 1:06 am
Posts: 2246
It would be better still to use the fast breeder technology, either with solid or liquid fuel and mine the used fuel and DU stocks for more energy by two orders of magnitude. Russians are already doing it with solid fuel.

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 Post subject: Re: Amount of uranium in the earth's crustPosted: Jan 22, 2015 10:00 pm

Joined: Apr 19, 2008 1:06 am
Posts: 2246
If you are meanwhile successful with thorium breeders, you get thorium at a few percent of the ore.

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 Post subject: Re: Amount of uranium in the earth's crustPosted: Feb 07, 2015 11:06 pm

Joined: Jun 19, 2013 11:49 am
Posts: 1553
And I just had a look at the DMSR figures - this convinces me this is the closest to the breeder we ever need to get.

If we assume an equivalent efficiency of ~33% for an LWR (1GWe DMSR has an effective thermal power of 2.85GWt) then the effective thermal burnup of uranium is 24GWd/t (0.1% tails assay for enrichment as always), compared to roughly 7 for a PHWR and an LWR.

If we can get a DMSR to work then we can cut Uranium use by 70% without any massively high tech pyroprocessing systems.
Assuming my mathematics is correct that is.

(7.85t of 235U - so roughly 40t of ~19.7% enriched uranium - 1293 tonnes of feed NU, 2.85GWt-effective for 10950 FPD)

And that is without re-enrichment of your End-of-life inventory (which is difficult due to 232U contamination, but on the other hand it is still 9.5% and thus very much more valuable than natural uranium - it would cut 20% LEU input requirements by 15.9t [40%] which increases effective NU burnup to something like 60GWd/t).
60GWd/t means that uranium prices an order of magnitude higher than today's would be very easily tolerable - something like \$710/kg (\$375/lb) which makes seawater extraction economically viable.
Supporting a 30GWe fleet of DMSRs with one unit replacing its fuel load every year would only require 73000SWU/yr capacity of specialist reenrichment equipment.
73000SWU is tiny even for a centrifuge plant. So a specialist one with expensively shielded centrifuges for continuous handling of 232U doesn't sound too ridiculous.

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