In the period between the 1950's and 1970's considerable discoveries were made and vast amounts of uranium were mined, much of it for weapons work. In those times it was expected that nuclear power would grow rapidly.
Reactor technology was complex and untested, the infrastructure new, and in a effort that can only be considered noble, at least in an ethical respect, if not an economic sense, nuclear energy was the
only energy industry that attempted to consider the whole impact of it's fuel cycle - including the question of dealing with its
waste. Of course every energy industry has wastes and/or impacts, but many of them - notably fossil fuels - simply
ignored these issues - public be damned.
Since the issue of waste was discussed by the
nuclear industry itself - this allowed certain slick hysterics - Ralph Nader being the most famous, but certainly not the
only example - to make rather extreme statements about the impact of nuclear technology that were actually not justified by experiment.
In the meantime, there was a great deal of confusion about the types of reactors that should be built. No one had ever used uranium before except as pottery glaze and staining glass. It was thought to be a rare element, and it was also thought that it would be necessary to obtain the full energy potential of the fuel, including the U-238, through the use of breeder reactors. Many reactors of this type were explored, with mixed success. However uranium proved to be a much more common element that previous supposed, about as common as tin. Thus breeding became
economically unjustifiable.
In the meantime a major market for uranium, that of the weapons industry, disappeared. Happily, treaties between the United States and Russia lead to the creation of a
surplus of enriched uranium because the only effective way to permanently destroy weapons grade material is to fission it in a nuclear reactor. For more than a decade the world has been living off this surplus, much of it imported from Russia.
Thus uranium prices have been depressed for quite some time and no one has been bothering with uranium prospecting. Some old previously discovered mines have been reopening however or are being developed for the first time. The price of uranium is beginning to rise to the point where these operations become economic.
Because uranium (and thorium) resources can be used in so many ways, there is considerable confusion on the part of the general public about uranium reserves. You hear - especially from poorly educated people - that "uranium resources will only last for 40 years," and nonsense of this type. This is true
only if we do things exactly the way we have always done them
in the United States, and use the once through low enriched uranium fuel cycle. However, the once through cycle has already been rejected by several countries with major commitments to nuclear power, notably France and Japan. While uranium is very cheap - and it still is - as the price of uranium rises many opportunities for the improvement in fuel utilization and recovery become available. When the price reaches $200-400/kg, recovery from seawater becomes economic. When the price reaches $1000/kg, recovery of plutonium becomes economic. (Improvements in actinide chemistry - a major area of research will actually reduce this price level considerably.)
Moreover thorium reserves vastly exceed land based uranium resources. Since thorium was removed from gas mantles, mostly it is dumped as a waste product from the lanthanide mining industry.
In the case of ocean, it is
saturated with respect to uranium. It has dissolved all that it can. Thus if one removes uranium from the ocean using the Japanese amidoxime resin technology that has run all the way through pilot, new uranium is charged to the ocean from the weathering of rocks.
Also reactor burn-ups are rising. In the old days it was considered good to get 20,000-30,000 MW-day/MT from uranium charged into a reactor. Now numbers approaching 50,000 MW-day/MT are more typical. Using thorium cycles, it is expected that current burn-ups can be tripled. With continuous plutonium recycling, plutonium burnups as high as 575,000 MW-day/MT are possible.
http://www.iaea.org/inis/aws/htgr/fulltext/htr2002_205.pdf#search=%22corail%20plutonium%22I have discussed some implications briefly elsewhere:
http://www.democraticunderground.com/discuss/duboard.php?az=show_topic&forum=115&topic_id=65597#65599When we move to full fuel recycling, we will have vast resources that have already been mined. For instance, the energy content of the much maligned "DU," depleted uranium, is roughly 5400 exajoules in the DOE stockpiles alone (around 700,000 MT). Transmuted into plutonium, this is enough to supply every single joule of energy on earth at current consumption levels, around 450 exajoules per year, for well over a century without operating a single mine. Taking advantage of this possibility will involve more expense than simply mining virgin uranium, but should virgin uranium become less readily available, it is clearly an option.
Finally many types of mining that were previously not used have been technically proved. In situ leach mining of uranium is now industrial. Many different technologies have been employed, the best of which is through the injection of oxygen and sodium carbonate into uranium bearing rocks which removes uranium as a carbonate complex, leaving the radioactive decay daughters like radium in the original formation. This technology is used in the US. These "mines" do not disturb the ground much, they are rather like natural gas wells - they have some impact, but most of it is minor.
Maybe someday we can use that technology here in New Jersey. We have lots of uranium in our bedrock around here, and it makes for problems with radon in our basements.
My gut feeling is that uranium resources can be considered almost infinite. This should not be read as a call to forget about conservation and population control however. No one should construe that I have said that nuclear energy is risk free. Rather it is risk minimized with respect to the
other options.
I do believe that we should employ - for ethical reasons - one of the more expensive supply options - continuous fuel recycling. There is no reason why we should consume the cheap stuff so that
everything future generations use will be expensive. This will minimize the number of mines necessary, as well as maximize the prospect for peace, by changing the isotopic nature of
all the world's plutonium so that it is highly unsuitable for weapons use. Nuclear disarmament depends on a vibrant power industry to succeed: Again, the only way to totally destroy weapons material is to fission it. I also believe that we should move aggressively into the thorium cycle, which is superior to the other fuel cycles in many ways. It also seems that this gives us the best shot at leaving a legacy for future generations. It will also reduce the radiotoxicity of the planet to levels that have never been seen before throughout geological time. (Note that this may not actually be desirable - life has always existed bathed in radiation.)
Thanks for your question. Please let me know if I can answer any further questions this discussion may have raised.
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