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Costing the Earth, Wednesday -- new nuclear build
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mobbsey



Joined: 24 Nov 2005
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PostPosted: Sun Mar 20, 2011 11:49 pm    Post subject: Costing the Earth, Wednesday -- new nuclear build Reply with quote

It's interesting they're looking at uranium supply!

You might like to read my contribution to the Oxford Institute for Energy Studies journal from May 2005 on the subject -- http://www.fraw.org.uk/mei/papers/index.shtml#oies


P.



Quote:
http://www.bbc.co.uk/programmes/b00zphnr

Britain's Nuclear Future

Wednesday 23rd March, 21:00 on BBC Radio 4

Britain is running out of power. Ten new nuclear reactors were supposed to provide the solution. In this week's 'Costing the Earth' Tom Heap asks if the events in Japan have dealt a fatal blow to the future of the industry.

Tom will be examining the changes in safety regimes that may be provoked by the ongoing disaster. He'll also be asking if the economic case for nuclear has changed and looking ahead to the future supply of uranium.
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An Inspector Calls
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PostPosted: Mon Mar 21, 2011 12:55 pm    Post subject: Reply with quote

An interesting article, but this paragraph is the crux of your argument, and is based on rather old research and opinions.

Quote:
Generally uranium reserves are classified according to the cost of recovery as a dollar value. Clearly this is an imprecise measure given that it does not reflect the net value of the energy produced from uranium less the energy used in its mining and processing and in the generation of power. Below a certain concentration the recovery of uranium will take more energy than it produces. The most productive uranium ores contain 1,000 to 20,000 parts per million of uranium (ppmU) [WNA 2004]. Other potential sources, such as igneous rocks, have concentrations of uranium of around 4ppmU. Sea water, also quoted as a future source of uranium, has an average uranium content of 0.003ppmU. In the 1970s Peter Chapman [Chapman 1975] calculated the cut-off value, at which the energy used to extract uranium from the ore exceeds the energy produced from the nuclear plant, at around 20ppmU. Even with advances in processing and reactor design this is unlikely to fall far below 10ppmU. This puts a limitation on the theoretical size of the uranium resource because a number of the potential sources fall below this level.


Take the extraction of uranium from seawater. If you can do this economically (which I take to be the same criteria as it being energy efficient), then there's plenty of uranium.

And there are articles which indicate that extraction from seawater is looking promising. For example:
http://large.stanford.edu/courses/2010/ph240/gorin2/
(yes, only an undergraduate resume, but the references are testable).

And again:
http://www.brynmawr.edu/geology/206/shea2.htm
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mobbsey



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PostPosted: Mon Mar 21, 2011 2:01 pm    Post subject: Reply with quote

An Inspector Calls wrote:
Take the extraction of uranium from seawater. If you can do this economically (which I take to be the same criteria as it being energy efficient), then there's plenty of uranium.

And there are articles which indicate that extraction from seawater is looking promising. For example:
http://large.stanford.edu/courses/2010/ph240/gorin2/
(yes, only an undergraduate resume, but the references are testable.


Ahem (clears throat in anticipation... have had this argument before...)

Yep, 3ppb of uranium dioxide in seawater, BUT:

Average 1GW power reactor consumes 27 tonnes of 3.5% enriched nuclear fuel each year. Enriching uranium from the background 0.7% U235 to 3.5% requires (3.5/0.7=) 5 times the original mass of uranium - so we require 135 tonnes U/year/1GW reactor capacity.

Density of uranium dioxide is 10.97g/cm3, and the uranium atom is about 74% of the mass of the uranium dioxide molecule; fiddle with the maths and I get that to 0.025gU/m3 seawater. Amount of seawater required to extract 135teU is therefore around 221 million m3, or 0.221 cubic kilometres. In more recognisable volume terms, that's about 1.4 billion oil barrels worth.

However, to make a dent in human power demand we really need 1,000 1GW reactors - even that is only going to increase global nuclear power contribution be around three times (current global capacity 377W). So we're now talking 221 cubic kilometres of sea water, or 140 billion barrels.

And of course, once you start taking the UO2 out of the sea you're onto a diminishing return -- you'll always have to pump fractionally more sea water every year because, even extracting from ocean currents, the rate of natural turnover/mixing in the oceans isn't that great (as I remember some ocean currents take 1,000 years to complete one circuit because the dense bottom water moves at a fraction of the speed of the lighter surface water).

So, yes, I absolutely accept the THEORY of the extraction of uranium from seawater; what I doubt is the practical REALITY of being able to do that at a economic value that doesn't nullify the effects of feeding that energy into the global economy. If it's a choice between incredibly expensive seawater sourced uranium electricity, and just doing without the energy because the costs destabilise the economic equilibrium, I think you'll find that the global economy will contract because it will be unable to afford the costs involved. Nuclear power is barely economic today, and we're still utilising some of the richest terrestrial resources -- if $100+ oil can destabilise the economic equilibrium, extracting uranium from seawater would seem to make little sense.

Ultimately what we're talking about here is a problem of thermodynamics. The UO2 in sea water represents an extremely high entropy source of material; consequently it takes a large input of energy in order to render that to a low entropy uranium metal resource. For uranium ores the Earth's geophysical processes have already done a lot of the work for us, partly because volcanism taps the metal-rich mantle for its source material. In contrast uranium in sea water represents the dissolved run-off from 4 billion years of rock weathering - and consequently it's way further down the entropy curve than using lower quality ores on land. In order to generate (in Georgescu-Rogen's terms) sufficient "economic entropy" to motivate the human economy to operate (similar to the 'maximum entropy principle' upon which natural life processes operate), we have to utilise low entropy/high quality resources (e.g. oil, gas) in order to render sufficient value from them. Uranium from sea water just doesn't fit into such a category. In short, you can't burn energy to create energy.
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DominicJ



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PostPosted: Mon Mar 21, 2011 2:33 pm    Post subject: Reply with quote

Mobbsey
Interesting numbers, thanks
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biffvernon



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PostPosted: Mon Mar 21, 2011 2:47 pm    Post subject: Reply with quote

mobbsey wrote:
In more recognisable volume terms, that's about 1.4 billion oil barrels worth...... So we're now talking 221 cubic kilometres of sea water, or 140 billion barrels.
Yeah, but what's that in Olympic sized swimming pools, the standard measure of big amounts of liquid stuff?
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JohnB



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PostPosted: Mon Mar 21, 2011 2:59 pm    Post subject: Reply with quote

biffvernon wrote:
Yeah, but what's that in Olympic sized swimming pools, the standard measure of big amounts of liquid stuff?

Or how many times the size of Wales?
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mobbsey



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PostPosted: Mon Mar 21, 2011 3:32 pm    Post subject: Reply with quote

biffvernon wrote:
Yeah, but what's that in Olympic sized swimming pools, the standard measure of big amounts of liquid stuff?


Rounding down (Olympic pools have a minimum volume of 2,500m3); 88,000/year for one reactor -- 88,000,000 for 1,000 reactors.

That's 110 square kilometres for one reactor, which I think is about the size of Bristol. For 1,000 reactors that's going to be something like 70-odd London's, which is about five times the size of Wales.
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biffvernon



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PostPosted: Mon Mar 21, 2011 4:12 pm    Post subject: Reply with quote

Ah, thanks, that's all clear now. Nuclear power obviously has little future.
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mobbsey



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PostPosted: Mon Mar 21, 2011 4:19 pm    Post subject: Reply with quote

biffvernon wrote:
Ah, thanks, that's all clear now. Nuclear power obviously has little future.


Nuclear power, or rather it's residues, have an extremely long future! Wink

I'm waiting to hear what the programme will say on Wednesday because, after talking about the uranium issue for eight or nine years (this is my tenth year of working on peak oil Shocked ) it seems the penny might have finally dropped... pity they had to irradiate the north-east cost of Japan to do it. Crying or Very sad
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An Inspector Calls
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PostPosted: Mon Mar 21, 2011 7:12 pm    Post subject: Reply with quote

Ahem, I've seen your points as well (as well as your agenda).

So two points in reply:

There are billions of tons of uranium in the sea, albeit at low concentrations. Any extraction rate we might contemplate will have negligible impact on the concentration level. Moreover, seawater is being replenished with uranium at a huge rate in the run-off from land erosion. And further, there is also an abundance of uranium lying on the sea bottom from past run-offs.

It would obviously be absurd to pump the sea water for extraction, you rely on ocean currents to bring the seawater to you - that's made perfectly clear in the Japanese prototyping of the technique. The scientists who conducted the protype trial in Japan were fully aware of the energy budget constraints of the system they were attempting to demonstrate. There they used suspended arrays of filtrate to extract the uranium.

I think your calculation of the seawater volume is too low. There's about 3 milligrams of uranium per ton of sea water. To get 135 tons for one reactor you'd therefore need to sweep 45*10^9 m^3 of seawater. Sounds huge? It isn't. In a slow ocean current of 2 knots (4*10^3 m/h, 35*10^6 m/annum), you'd need an array of cross sectional area ~1,200 m^2 to sweep that. In fact, you need much bigger areas than that, but the concept is manageable. The prototype trial was able to extract uranium cake at costs which, whilst not economic at the moment because of competitive, cheaper, sources, would sustain future economic operation of nuclear power.

It should also be pointed out that a side-benefit of uranium extraction from the sea is the collection of valuable materials such as platinum.

You're attempting to argue that nuclear power will fail through lack of uranium fuel. But your argument is transparently weak because you have set the goalposts for an economc extraction rate at a preposterously low level. Moreover, you have done this with a complete absence of any study of the sensitivity of nuclear generation costs to fuel costs.
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RGR
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PostPosted: Mon Mar 21, 2011 7:48 pm    Post subject: Reply with quote

[quote="An Inspector Calls"]

Last edited by RGR on Thu Aug 11, 2011 1:31 pm; edited 1 time in total
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An Inspector Calls
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PostPosted: Mon Mar 21, 2011 8:07 pm    Post subject: Reply with quote

Since your argument for a viable minimum concentration of uranium in whatever mined deposit is based on a paper as old as 1975, I thought I'd bring the discussion much further forward into the future and consider Hoyle: Energy or Extinction from 1977!

He's trying to assess an electricity price sensitivity for uranium cake extraction costs. He argues as follows (and his figures are time insensitive and perfectly relevant to today's costings):

Quote:
At a 5% burn-up 1 kg of uranium/thorium fuel would produce 10^6 kWh of heat energy. Conversion of this heat to electricity at an efficiency of 30 % gives 300 kWh of electrical energy. Given 1/3p/kWh of electricity as our payment towards the cost of fuel, we could evidently afford to pay 1,000 per kilogram of uranium/thorium.


And of course, if we drive towards higher and higher burn efficiencies, which we are, the viable cost for cake goes up. With a 50 % burn rate, we could stand 10,000 per kilogram.

At those sorts of prices, it would be coming out of our ears.
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biffvernon



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PostPosted: Mon Mar 21, 2011 9:07 pm    Post subject: Reply with quote

Here's a big list for the anoraks:
http://www.guardian.co.uk/news/datablog/2011/mar/18/nuclear-reactors-power-stations-world-list-map
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mobbsey



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PostPosted: Mon Mar 21, 2011 9:48 pm    Post subject: Reply with quote

An Inspector Calls wrote:
It would obviously be absurd to pump the sea water for extraction, you rely on ocean currents to bring the seawater to you - that's made perfectly clear in the Japanese prototyping of the technique.


Err, how exactly would you take the water from the current into the processing plant? Even a short run of piping requires a force to move the water to overcome internal friction; if the plant isn't located below sea level you'll also have to pump the water against gravity; if your using ion exchange or permeable membranes that takes even more energy. The Indians were experimenting with a modified polymer that could pull metals from the sea water, but as that's powered by diffusion it has low yield.

An Inspector Calls wrote:
I think your calculation of the seawater volume is too low. There's about 3 milligrams of uranium per ton of sea water.


My figure for the calculations was 0.024g/m3, which is roughly 24mg/tonne -- ten times higher than your figure. Remember, "ppb" isn't a straight dilution factor, it's dependent upon density/molar mass.

It's not 3mg/te because those 3ppb of uranium oxide don't have the same density as sea water -- UO2 density is nearly 11 times greater (10.97g/cm3 rather than 1.03g/cm3 for sea water -- not taking temperature and pressure into account of course!); and it's not 30mg either because of adjusting for the relative density of sea water and uranium.

An Inspector Calls wrote:
You'd need an array of cross sectional area ~1,200 m^2 to sweep that. In fact, you need much bigger areas than that, but the concept is manageable.


What do you mean by "an array". It's rather an ambiguous term.

If you're using diffusion pressure to exchange ions then not only would you're yield rate too low to extract significant quantities of uranium from the passing seawater (which means filtering far higher volumes), but if you were to take a large proportion of the ions out of solution the growing partition ratio would force them back into solution again (and the yield is ultimately dependent upon the partition constant that your absorption medium is able to generate).

If you try an drive the process by diffusion yes, it's far more energy efficient, but the price will be the elongated time period for collection -- which in turn multiplies the size of installation required and we're back, once more, to the issue of low return rates on high entropy materials.

If you want to get a faster return rate you have to pump, and that takes energy.

An Inspector Calls wrote:
The prototype trial was able to extract uranium cake at costs which, whilst not economic at the moment because of competitive, cheaper, sources, would sustain future economic operation of nuclear power.


That assumes that prices do not fluctuate. As energy prices rise generally you're not going to "price in" uranium because it relies on cheap energy to process it into yellow cake. Therefore, the cost of uranium won't be "priced in" because it is inextricably linked to the availability of cheap fuels, and supplementing/replacing those energy sources with uranium derived electricity would make it's price rise to reach a new, much higher price equilibrium.

The "unique selling proposition" for nuclear only works for power generation, where you're exchanging the value of a "known" (or known unknown?) high capital cost against a longer-term variable fuel cost for conventional generation (which is why the economics of nuclear is so sensitive to discount rates). If you take other low cost power sources off the grid, or you try to replace the present role of petroleum in uranium processing with nuclear derived electricity, you're whole cost structure changes, and so the final economic value of uranium shifts accordingly.

What you're proposing is the same kind of economic con that the finance industry perpetrated in the British population: people bought houses and believe they were "rich" because the price of their house went up by X%/year; in reality the entire market was rising in price and so, relatively, no one was any more wealthy than before (unless of course they cashed out, and had nowhere to live, or they died and the tax man gobbled it up).

An Inspector Calls wrote:
You're attempting to argue that nuclear power will fail through lack of uranium fuel. But your argument is transparently weak because you have set the goalposts for an economc extraction rate at a preposterously low level. Moreover, you have done this with a complete absence of any study of the sensitivity of nuclear generation costs to fuel costs.


What is the "economic" extraction rate?

What I work upon is the thermodynamics of extraction, and that doesn't change with time. Irrespective of the economic cost, the dynamics of extracting uranium from sea water, of processing it into yellow cake and then fabricating it into fuel, and then extracting energy from that fuel and generating power, do not change.

Yes, we could talk about the use of multi-stage gas turbines and high temperature cores to boost the efficiency of power generation to nearer 50% (if only they could manufacture a ceramic composite that was stable under neutron bombardment and thermal stress). Yes, we could go for high enrichment to boost power output per fuel cycle. Yes, we could even run off to fairy land where it was possible to build a reactor able to withstand fast neutrons without embrittlement of the the core and fuel assemblies and burn-up the other 99% of the uranium that rejected from the thermal fuel cycle....

But, what we can't talk about are the economics of price over-riding the laws of thermodynamics -- that's economic mysticism. And if you want to prove that economics can over-ride thermodynamics then please, as I said to the last person who made that argument to me, levitate for me! Wink


You know, I really don't like writing geeky replies like this -- I'm always afraid that the Powerswitch moderators will banish me to The Oil Drum.
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mobbsey



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PostPosted: Mon Mar 21, 2011 9:52 pm    Post subject: Reply with quote

biffvernon wrote:
Here's a big list for the anoraks:
http://www.guardian.co.uk/news/datablog/2011/mar/18/nuclear-reactors-power-stations-world-list-map


Where's all the military plants floating around off-shore, or in port (or, in the case of Russian subs, popping rivets at the bottom of the ocean)
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