Uranium depletion

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Uranium depletion is the inescapable result of extracting and consuming uranium since it is a finite resource. The journal Environmental Science and Technology argues that the availability of high-grade uranium ore will deplete over time making the fuel more environmentally and economically expensive to extract.^[1]

Contents 1 Uranium production 1.1 Primary sources 1.2 Secondary resources 1.3 Unconventional resources 1.3.1 Phosphates 1.3.2 Seawater 1.3.3 Uraniferous coal ash 1.3.4 Oil shales 2 Countries whose uranium has already depleted 3 Pessimistic uranium depletion outlook 4 Optimistic uranium depletion outlook 5 See also 6 References

[edit] Uranium production

[edit] Primary sources

About 96% of the global uranium reserves are found in these ten countries: Australia, Canada, Kazakhstan, South Africa, Brazil, Namibia, Uzbekistan, USA, Niger, and Russia^[2] Out of those Canada (28% of world production) and Australia (23%) are the major producers.^[3] In 1996, the world produced 39,000 tonnes of Uranium.^[4] And in 2005, the world produced a peak of 41,720 tonnes of uranium,^[5] although the the production continues to not meet demand.

Various agencies have tried to estimate how long these primary resources will last, assuming a once-through cycle. The European Commission said in 2001 that at the current level of uranium consumption, known uranium resources would last 42 years. When added to military and secondary sources, the resources could be stretched to 72 years. Yet this rate of usage assumes that nuclear power continues to provide only a fraction of the world’s energy supply. If electric capacity were increased six-fold, then the 72-year supply would last just 12 years.^[6] The world's present measured resources of uranium, economically recoverable at a price of 130 USD/kg according to the industry groups OECD, NEA and IAEA, are enough to last for some 80 years at current consumption ^[7] According to the Australian Uranium Association, yet another industry group, assuming the world's current rate of consumption at 66,500 tonnes of Uranium per year and the world's present measured resources of uranium (4.7 Mt) are enough to last for some 70 years.^[8]

[edit] Secondary resources

Only 62% of the requirements of power utilities are supplied by mines. The balance comes from inventories held by utilities and other fuel cycle companies, inventories held by governments, used reactor fuel that has been reprocessed, recycled materials from military nuclear programs and uranium in depleted uranium stockpiles.^[9]

The plutonium from dismantled cold war nuclear weapon stockpiles is drying up and will end by 2013. The industry is trying to find and develop new uranium mines, mainly in Canada, Australia and Kazakhstan. However, those under development will fill only half the current gap.^[10]

[edit] Unconventional resources

Unconventional resources are occurrences that require novel technologies for their exploitation and/or use. Often unconventional resources occur in low-concentration. The exploitation of unconventional uranium requires additional research and development efforts for which there is no imminent economic need, given the large conventional resource base and the option of reprocessing spent fuel.^[11] Phosphates, seawater, uraniferous coal ash, and some type of oil shales are examples of unconventional resources being considered.

[edit] Phosphates

The soaring price of uranium may cause long-dormant operations to extract uranium from phosphate.^[12] The technology for recovering uranium from phosphate mines is mature.^[11]

Worldwide, there were approximately 400 wet-process phosphoric acid plants in operation. Assuming an average recoverable content of 100 ppm of uranium, this scenario would result in a maximum theoretical annual output of 3700 tonnes U₃O₈.^[13] Historical operating costs for the uranium recovery from phosphoric acid range from $48-119/Kg U₃O₈.^[14] These operating costs are by far higher than uranium market prices, and most uranium recovery plants have been closed.

[edit] Seawater

The uranium concentration of seawater is approximately 3 parts per billion but the quantity of contained uranium is vast. Researchers estimate there are some 4 billion tonnes. This amounts to 700 times more than known terrestrial resources recoverable at a price of up to $130 per kg of U₃O₈.^{[citation needed]} If half of this resource could ultimately be recovered, it could support for 6,500 years 3,000 GW of nuclear capacity.^{[citation needed]}

One method of extracting uranium from seawater is using a uranium-specific nonwoven fabric as an absorbent. The total amount of uranium recovered from three collection boxes containing 350 Kg of fabric was >1 kg of yellow cake after 240 days of submersion in the ocean.^[15] According to the OECD, uranium may be extracted from seawater using this method for about $300/KgU ^[16] The experiment by Seko et al was repeated by Tamada et al in 2006. They found that the cost varied from ¥15,000 to ¥88,000 (Yen) depending on assumptions and "The lowest cost attainable now is ¥25,000 with 4g-U/kg-adsorbent used in the sea area of Okinawa, with 18 repetitionuses [sic]." With the May, 2008 exchange rate, this was about $240/Kg U ^[17]

Among the other methods to recover uranium from sea water, two seem promising: algae bloom to concentrate Uranium^[18] and nanomembrane filtering.^[19]

So far, no more than a very small amount of uranium has been recovered from sea water in a laboratory.^[11]

[edit] Uraniferous coal ash

An international consortium has set out to explore the commercial extraction of uranium from uraniferous coal ash from coal power stations located in Yunnan province, China.^[11]

[edit] Oil shales

Some oil shales contain uranium as a byproduct. Between 1946 and 1952, a marine type of Dictyonema shale was used for uranium production in Sillamäe, Estonia, and between 1950 and 1989 alum shale was used in Sweden for the same purpose.^[20]

[edit] Countries whose uranium has already depleted

Many countries are not able to supply their own uranium demands anymore. Eleven countries have already exhausted their uranium resources: Germany, the Czech Republic, France, DR Congo, Gabon, Bulgaria, Tajikistan, Hungary, Romania, Spain, Portugal and Argentina have already peaked their uranium production and exhausted their uranium resources and must rely on imports for their nuclear programs or abandon them.^[21][22]

[edit] Pessimistic uranium depletion outlook

Various agencies have tried to estimate how long these resources will last.

• European Commission

The European Commission said in 2001 that at the current level of uranium consumption, known uranium resources would last 42 years. When added to military and secondary sources, the resources could be stretched to 72 years. Yet this rate of usage assumes that nuclear power continues to provide only a fraction of the world’s energy supply. If electric capacity were increased six-fold, then the 72-year supply would last just 12 years.^[6]

• OECD

The world's present measured resources of uranium, economically recoverable at a price of 130 USD/kg according to the industry groups OECD, NEA and IAEA, are enough to last for some 80 years at current consumption ^[23]

• Australian Uranium Association

According to the Australian Uranium Association, yet another industry group, assuming the world's current rate of consumption at 66,500 tonnes of Uranium per year and the world's present measured resources of uranium (4.7 Mt) are enough to last for some 70 years.^[8]

[edit] Optimistic uranium depletion outlook

All the following references claim that the supply is far more than demand. Therefore, they believe that uranium will not deplete in the near future or ever.

• M. King Hubbert

In his 1956 landmark paper, M. King Hubbert wrote "There is promise, however, provided mankind can solve its international problems and not destroy itself with nuclear weapons, and provided world population (which is now expanding at such a rate as to double in less than a century) can somehow be brought under control, that we may at last have found an energy supply adequate for our needs for at least the next few centuries of the "foreseeable future.""^[24] Hubbert's study assumed that breeder reactors would replace light water reactors and that uranium would be bred into plutonium (and possibly thorium would be bred into uranium). He also assumed that economic means of reprocessing would be discovered. For political, economic and nuclear proliferation reasons, the plutonium economy never materialized. Without it, uranium is used up in a once-through process and will peak and run out much sooner.^[25] However, at present, it is generally found to be cheaper to mine new uranium out of the ground than to use reprocessed uranium, and therefore the use of reprocessed uranium is limited to only a few nations.

• IAEA

The IAEA estimates that using only known reserves at the current rate of demand and assuming a once-through nuclear cycle that uranium will deplete in 85 years. However, if all primary known reserves, secondary reserves, undiscovered and unconventional sources of uranium are used, uranium will be depleted in 47,000 years.^{[citation needed]}

• OECD

The OECD estimates that with 2002 world nuclear electricity generating rates, with LWR, once-through fuel cycle, there are enough conventional resources to last 270 years. With breeders, this is extended to 8,500 years.^[26]

If one is willing to pay $300/KgU uranium, there is a vast quantity available in the ocean.^[27]

• Kenneth S. Deffeyes

Deffeyes estimates that if one can accept ore one tenth as rich then the supply of available uranium increased 300 times.^[28][29] His paper shows that uranium is log-normal distributed. There is relatively little high-grade uranium and a nearly inexhaustibly large supply of very low grade uranium.

• Huber and Mills

Huber and Mills believe the energy supply is infinite and the problem is merely how we go about extracting the energy.^[30]

• Bernard Cohen

In 1983, physicist Bernard Cohen proposed that uranium is effectively inexhaustible, and could therefore be considered a renewable source of energy.^[31] He claims that fast breeder reactors, fueled by naturally-replenished uranium extracted from seawater, could supply energy at least as long as the sun's expected remaining lifespan of five billion years.^[31] - whilst uranium is a finite resource mineral resource within the earth, the hydrogen in the sun is finite too - thus, if the resource of nuclear fuel can last over such time scales, as Cohen contents, then nuclear energy is every bit as sustainable as solar power or any other source of energy, in terms of sustainability over the finite realistic time scale of life surviving on this planet.

We thus conclude that all the world’s energy requirements for the remaining 5×10⁹ yr of existence of life on Earth could be provided by breeder reactors without the cost of electricity rising by as much as 1% due to fuel costs. This is consistent with the definition of a “renewable” energy source in the sense in which that term is generally used.

[edit] See also

• Peak uranium

[edit] References