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Thorium required a breeder reactor in order to produce the U-233 necessary for fission, and as stated in another comment, these reactors are still in experimental stages and have a much lower level of operational safety record.

A thorium breeder is not the same thing as a uranium breeder.

http://thoriumenergy.blogspot.com

Only a tiny fraction of the uranium is in concentrated enough deposits to allow for economic recovery of the mineral.

Given that that very point was addressed at the link I provided, one might suspect that you did not visit it before answering.

It is not merely 40 trillion tons of uranium that are in the crust. It is 40 trillion of uranium that is also economically-recoverable. Why is nearly all of the uranium in the crust is economically-recoverable? It is because the energy density of uranium is so high. The same goes for thorium.

On the contrary the article you provided did not once mention the words 'economically recoverable'. What you are looking for is the reserves of Uranium in the world. Reserves, in mining means the amount of ore that can be economically removed from the earth. For those numbers please refer to the link that I listed previously. If the percent of uranium oxide in an ore is less than 0.1% (by weight) then it is not economical to mine.

Reserves, in mining means the amount of ore that can be economically removed from the earth.

No, it doesn't.

http://www.google.com/search?q=site%3Ajuliansimon.com%2Fwrit...

Julian Simon was a professor business administration, not a mining engineer. Those articles refer to scare tactics presented in terms of resource scarcity by environmental fanatics. He says nothing about the definition of a mineral reserve. But I can help us with that.

Reserve definition

Reserve definition is undertaken to convert a mineral resource into an ore reserve, which is an economic asset. The process is similar to resource evaluation, except more intensive and technical, aimed at statistically quantifying the grade continuity and mass of ore.

Reserve definition also takes into account the milling and extractability characteristics of the ore, and generates bulk samples for metallurgical testwork, involving crushability, floatability and other ore recovery parameters.

Reserve definition includes geotechnical assessment and engineering studies of the rocks within and surrounding the deposit to determine the potential instabilities of proposed open pit or underground mining methods. This process may involve drilling diamond core samples to derive structural information on weaknesses within the rock mass such as faults, foliations, joints and shearing.

At the end of this process, a feasibility study is published, and the ore deposit may be either deemed uneconomic or economic.

from http://en.wikipedia.org/wiki/Mineral_exploration

For resources to be counted as reserves, they have to be found. If no one bothers finding more resources, the resources that lie in wait are not counted as reserves. Here is some finding-cost data:

http://www.world-nuclear.org/info/inf75.html

the finding costs of crude oil have averaged around US$ 6/bbl over at least the past three decades. When finding costs of the two fuels are expressed in terms of their contained energy value, oil, at US$ 1050/MJ of energy, is about 300 times more expensive to find than uranium, at US$ 3.4/MJ. Similarly, the proportion of current market prices that finding costs comprise are lower for uranium. Its finding costs make up only 2% of the recent spot price of US$ 30/lb ($78/kgU), while the oil finding costs are 12% of a recent spot price of US$ 50/bbl.

By these measures, uranium is a very inexpensive energy source to replenish, as society has accepted far higher energy replacement costs to sustain oil resources.

If those finding costs were considered too high, one would additionally have to hope that no one would be able to find the sea, or that if anyone were able to find the sea, that they would not be able to figure out how to extract uranium from it for, perhaps, only several hundred dollars per kg -- something which in fact has already been done, and which is being improved-upon by current research conducted by Japan and India.

Current extraction from sea water runs over 4 times the current spot price for Uranium. It is currently an UNECONOMICAL way to get Uranium.

Please reread the original article I linked to regarding the 1000 year supply. It actually deals with undiscovered reserves.

In addition to these identified resources, the category of uranium that could be expected to be found based on the geologic characteristics of known resources has grown by 500,000 tonnes to 10.5 million tonnes.

The data comes from Uranium 2007: Resources, Production and Demand - often known as the Red Book - published every two years by the OECD Nuclear Energy Agency (NEA) and the International Atomic Energy Agency (IAEA).

from: http://www.world-nuclear-news.org/ENF_Exploration_drives_ura...

It is currently an UNECONOMICAL way to get Uranium.

The word "currently" is important here. It means that the statement containing the word is irrelevant in the long-term. Resource supply-size increases exponentially to linear increase in price. How high of a price increase can the market accept? The current uranium prices contribute about .2 cents per kWh of electricity produced.

http://www.world-nuclear.org/info/inf02.html

Multiplying the uranium price by 10 causes it to contribute only 2 cents to the cost of each kWh of electricity produced. That is before further fuel-efficiency advances are applied, which the higher fuel prices would incentivize.

Do you mean to suggest that at some $1,000/kg, it would not be possible to profitably extract some 60,000 tons or more of uranium per year from seawater? What about at $2000/kg? $3,000? $4,000? $5,000? We can keep going, since fuel-efficiency of the plants can continue to be improved. $6,000? $7,000? $8,000? $9,000? $10,000?

Where is your cutoff for economic seawater uranium mining?

Current extraction from sea water runs over 4 times the current spot price for Uranium.

That would make it cost less than a penny per kWh. Are you meaning to suggest that the electricity market would not accept a fuel-price of under a penny per kWh?

It's good to know that there are other people who are great promoters of nuclear power (I am a huge fan), but you're not reading your sources very well (the last article you linked to put the cost of uranium as nuclear fuel at 0.5c/kWh at a spot price of $53/kg), your math is full or errors and you clearly haven't researched exactly what goes into taking uranium from the ground and using it to produce power, or the related fields, such as energy production and consumption in general, mineral exploration and mining, or waste management. You fail to take into account production levels (which are currently only about 65% of consumption), an increase in uranium demand (based on new and proposed build will double by 2020), increased costs of actual mining and transportation of the resource just to name a few, or the effect of mining and extracting ever bit of uranium from the planet. There are limits to fuel efficiencies increases and as well to the economic viability of nuclear power. This is why it's a good idea to invest in new technologies now, such as fusion (the whole reason this discussion began). Sure we can take every last particle of uranium out of the Earth's crust and ocean's but I think we can spend our time, energy and effort doing something more productive. Uranium and thorium are finite resources and no amount of water extraction will make them not so. We once believed oil would last us forever and we have come to realize that this is not so. Let's not make the same mistake by promoting unsubstantiated and irrational ideas that nuclear (fission) will last us for half a trillion years when very educated and informed people who are actual experts put the number at 1000 years. As a nuclear enthusiast, I'm fine with the 1000 years because I hope that by then we have something better that nuclear (fission) to get our power from.

It's good to know that there are other people who are great promoters of nuclear power (I am a huge fan)

Please keep your bigotries to yourself, and don't speak for what mine might be.

you're not reading your sources very well (the last article you linked to put the cost of uranium as nuclear fuel at 0.5c/kWh at a spot price of $53/kg)

That would be the total cost of the fuel after conversion, enrichment, and fabrication. The U3O8 cost of $472 is .264 of the total cost of $1787, which indeed works out to less than 0.2c/kWh (about 0.131c/kWh, actually) if $1787/kg of fabricated-fuel works out to 0.5c/kWh.

2007 fabricated-fuel costs at U.S. nuclear powerplants were 0.47c/kWh. http://www.nei.org/resourcesandstats/nuclear_statistics/cost...

your math is full or errors

Please provide at least a single example of any math errors I might have made.

We once believed oil would last us forever and we have come to realize that this is not so.

Indeed, there might only remain some 70,000 years' worth of oil.

http://www.google.com/search?q=oil+70000+dabasteroid

Is there reason to believe otherwise?

http://www.world-nuclear-news.org/ENF_Exploration_drives_ura...

Those are "identified resources", which means that they are irrelevant. There are 2 trillion tons (5 billion years' worth) of economically-recoverable uranium in granite, alone.

http://nuclearinfo.net/Nuclearpower/UraniuamDistribution

You're using a link that claims the resource limit to be 1000 years (the first one).

And did you really state that taking uranium out of granite is economical? The granite you want to mine is worth more than the uranium in it, not to mention that it would take more energy to mine it than you would get from it. There are only 3-10 part per million of uranium in granite.

it would take more energy to mine [granite] than you would get from it. There are only 3-10 part per million of uranium in granite.

Have you read this?:

http://nuclearinfo.net/Nuclearpower/UraniuamDistribution

The Rossing mine in Nambia mines Uranium at an Ore concentration of 300 ppm at an energy cost 500 times less than the energy it delivers with current thermal-spectrum reactors. If the energy cost increases in inverse proportion to the Ore concentration, shales and phosphates, with a Uranium abundance of 10 - 20 ppm, could be mined with an energy gain of 16 - 32.

Extrapolating from that, the energy gain is 1.6 for every ppm of uranium. As you say, granite contains 3-10 ppm of uranium. Therefore, mining granite for its uranium would provide an energy gain of 4.8 to 16. That would be without improving current reactor thermal-efficiency at all, and without improving current reactor breeding efficiency at all (all fission-reactors fueled with a mixture of U235 and U238 breed to some extent).

Running a uranium economy off of such a low-grade ore would, of course, in the real world provide incentive to improve fuel-efficiency (thermal; breeding-ratio; etc.) of reactors (even thermal-spectrum reactors can have their breeding-efficiencies improved). Thus, in the real world, the energy gain from mining granite for uranium would likely be higher than 4.8 to 16.

You're using a link that claims the resource limit to be 1000 years (the first one).

It's your link. I was quoting you and commenting on it.

The higher output is a function of the higher energy density.

That might have cleared everything up for me, except that I do not know what you mean by "higher output". Are you referring to power output? You are saying that, generally, in a given case of equal-sized reactors, a fusion reactor would be able to produce higher power than a fission reactor?

U-235, the fissile isotope of natural uranium, occurs in only 0.711% of uranium

If I had disregarded that, how do you figure I got a 60x energy boost by applying fuel-breeding?

I'm really not sure, I have no idea where you are getting a 60x energy boost from.