Peak uranium

10 countries are responsible for 94% of all uranium extraction.

World production of uranium 1995–2006[47]

Peak uranium refers to the peak of the entire planet's uranium production. Like other Hubbert peaks, the rate of uranium production on Earth will enter a terminal decline. According to Robert Vance of the OECD's Nuclear Energy Agency, the world production rate of uranium has already reached its peak in 1980, amounting to 69,683 tonnes (150×10^⁶ lb) of U₃O₈ from 22 countries. However, this is not due to lack of production capacity. Historically, uranium mines and mills around the world have operated at about 76% of total production capacity, varying within a range of 57% and 89%. The low production rates have been largely attributable to excess capacity. Slower growth of nuclear power and competition from secondary supply significantly reduced demand for freshly mined uranium until very recently. Secondary supplies include military and commercial inventories, enriched uranium tails, reprocessed uranium and mixed oxide fuel.[48]

According to data from the International Atomic Energy Agency, world production of mined uranium has peaked twice in the past: once, circa 1960 in response to stockpiling for military use, and again in 1980, in response to stockpiling for use in commercial nuclear power. Up until about 1990, the mined uranium production was in excess of consumption by power plants. But since 1990, consumption by power plants has outstripped the uranium being mined; the deficit being made up by liquidation of the military (through decommissioning of nuclear weapons) and civilian stockpiles. Uranium mining has increased since the mid-1990s, but is still less than the consumption by power plants.[49]

The world's top uranium producers are Kazakhstan (39% of world production), Canada (22%) and Australia (10%). Other major producers include Namibia (6.7%), Niger (6%), and Russia (5%).[9] In 1996, the world produced 39 kilotonnes (86×10^⁶ lb) of uranium.[50] In 2005, the world primary mining production was 41,720 tonnes (92×10^⁶ lb) of uranium,[47] 62% of the requirements of the power utilities. In 2017 the production had increased to 59,462 tonnes, 93% of the demand.[44] 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.[51] The plutonium from dismantled Cold War nuclear weapon stockpiles will be exhausted by 2013. The industry is trying to find and develop new uranium mines, mainly in Canada, Australia and Kazakhstan. Those under development in 2006 would fill half the gap.[52]

Of the ten largest uranium mines in the world (Mc Arthur River, Ranger, Rossing, Kraznokamensk, Olympic Dam, Rabbit Lake, Akouta, Arlit, Beverly, and McClean Lake), by 2020, six will be depleted, two will be in their final stages, one will be upgrading and one will be producing.[53]

World primary mining production fell 5% in 2006 over that in 2005. The biggest producers, Canada and Australia saw falls of 15% and 20%, with only Kazakhstan showing an increase of 21%.[54] This can be explained by two major events that have slowed world uranium production. Canada's Cameco mine at Cigar Lake is the largest, highest-grade uranium mine in the world. In 2006 it flooded, and then flooded again in 2008 (after Cameco had spent $43 million – most of the money set aside – to correct the problem), causing Cameco to push back its earliest start-up date for Cigar Lake to 2011.[55] Also, in March 2007, the market endured another blow when a cyclone struck the Ranger mine in Australia, which produces 5,500 tonnes (12×10^⁶ lb) of uranium a year. The mine's owner, Energy Resources of Australia, declared force majeure on deliveries and said production would be impacted into the second half of 2007.[56] This caused some to speculate that peak uranium has arrived.[57] In January 2018, McArthur River mine in Canada suspended production, the mine was producing 7000-8000 tonnes of Uranium per year from 2007 to 2017. The mine's owner, Cameco cited low uranium market prices as the reason to halt production and claims ramping production up to normal will take 18–24 months when the decision to re-open the mine is made.[58]

About 96% of the global uranium reserves are found in these ten countries: Australia, Canada, Kazakhstan, South Africa, Brazil, Namibia, Uzbekistan, the United States, Niger, and Russia.[59] Out of those the main producers are Kazakhstan (39% of world production), Canada (22%) and Australia (10%) are the major producers.[9] In 1996, the world produced 39,000 tonnes of uranium,[60] and in 2005, the world produced a peak of 41,720 tonnes of uranium,[47]. In 2017 this had increased to 59,462 tonnes, 93% of the world 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.[61] The world's present measured resources of uranium, economically recoverable at a price of US$130/kg according to the industry groups Organisation for Economic Co-operation and Development (OECD), Nuclear Energy Agency (NEA) and International Atomic Energy Agency (IAEA), are enough to last for "at least a century" at current consumption rates.[62][63] According to the World Nuclear 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 (4.7–5.5 Mt[62]) are enough to last for some 70–80 years.[64]

Reserves are the most readily available resources. Resources that are known to exist and easy to mine are called "Known conventional resources". Resources that are thought to exist but have not been mined are classified under "Undiscovered conventional resources".[65]

The known uranium resources represent a higher level of assured resources than is normal for most minerals. Further exploration and higher prices will certainly, on the basis of present geological knowledge, yield further resources as present ones are used up. There was very little uranium exploration between 1985 and 2005, so the significant increase in exploration effort that we are now seeing could readily double the known economic resources. On the basis of analogies with other metal minerals, a doubling of price from price levels in 2007 could be expected to create about a tenfold increase in measured resources, over time.[66]

Known conventional resources are "Reasonably Assured Resources" and "Estimated Additional Resources-I".[65]

In 2006, about 4 million tons of conventional resources were thought to be sufficient at current consumption rates for about six decades (4.06 million tonnes at 65,000 tonnes per year).[67] In 2011, this was estimated to be 7 million tonnes. Exploration for uranium has increased. From 1981 to 2007, annual exploration expenditures grew modestly, from 4 million US$ to 7 million US$. This skyrocketed to US$11 million in 2011.[39] Consumption of uranium runs at around 75 000 t a year. This is less than production, and requires draw down of existing stocks.

About 96% of the global uranium reserves are found in these ten countries: Australia, Canada, Kazakhstan, South Africa, Brazil, Namibia, Uzbekistan, the United States, Niger, and Russia.[59] The world's largest deposits of uranium are found in three countries. Australia has just over 30% of the world's reasonably assured resources and inferred resources of uranium – about 1.673 megatonnes (3.69×10^⁹ lb).[35] Kazakhstan has about 12% of the world's reserves, or about 651 kilotonnes (1.4×10^⁹ lb).[64] And Canada has 485 kilotonnes (1,100×10^⁶ lb) of uranium, representing about 9%.[35]

Several countries in Europe no longer mine uranium (East Germany (1990), France (2001), Spain (2002) and Sweden (1969)); they were not major producers.[17]

Undiscovered conventional resources can be broken up into two classifications "Estimated Additional Resources-II" and "Speculative Resources".[65]

It will take a significant exploration and development effort to locate the remaining deposits and begin mining them. However, since the entire earth's geography has not been explored for uranium at this time, there is still the potential to discover exploitable resources.[68] The OECD Redbook cites areas still open to exploration throughout the world. Many countries are conducting complete aeromagnetic gradiometer radiometric surveys to get an estimate the size of their undiscovered mineral resources. Combined with a gamma-ray survey, these methods can locate undiscovered uranium and thorium deposits.[69] The U.S. Department of Energy conducted the first and only national uranium assessment in 1980 – the National Uranium Resource Evaluation (NURE) program.[70]

Secondary resources are essentially recovered uranium from other sources such as nuclear weapons, inventories, reprocessing and re-enrichment. Since secondary resources have exceedingly low discovery costs and very low production costs, they may have displaced a significant portion of primary production. Secondary uranium was and is available essentially instantly. However, new primary production will not be. Essentially, secondary supply is a "one-time" finite supply, with the exception of the re-processed fuel.[71]

Uranium mining activity is cyclical, in 2009 80% of the requirements of power utilities were supplied by mines, in 2017 this had risen to 93%.[44][9] 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.[72]

The plutonium from dismantled cold war nuclear weapon stockpiles was a major source of nuclear fuel under the "Megatons to Megawatts" program which ended in December 2013. The industry developed new uranium mines, especially in Kazakhstan which now attributes to 31% of the world supply.[44][9]

Inventories are kept by a variety of organizations – government, commercial and others.[73][74]

The US DOE keeps inventories for security of supply in order to cover for emergencies where uranium is not available at any price.[75] In the event of a major supply disruption, the Department may not have sufficient uranium to meet a severe uranium shortage in the United States.

Both the US and Russia have committed to recycle their nuclear weapons into fuel for electricity production. This program is known as the Megatons to Megawatts Program.[76] Down blending 500 tonnes (1,100×10^³ lb) of Russian weapons high enriched uranium (HEU) will result in about 15 kilotonnes (33,000×10^³ lb) of low enriched uranium (LEU) over 20 years. This is equivalent to about 152 kilotonnes (340×10^⁶ lb) of natural U, or just over twice annual world demand. Since 2000, 30 tonnes (66×10^³ lb) of military HEU is displacing about 10.6 kilotonnes (23×10^⁶ lb) of uranium oxide mine production per year which represents some 13% of world reactor requirements.[77]

Plutonium recovered from nuclear weapons or other sources can be blended with uranium fuel to produce a mixed-oxide fuel. In June 2000, the US and Russia agreed to dispose of 34 kilotonnes (75×10^⁶ lb) each of weapons-grade plutonium by 2014. The US undertook to pursue a self-funded dual track program (immobilization and MOX). The G-7 nations provided US$1 billion to set up Russia's program. The latter was initially MOX specifically designed for VVER reactors, the Russian version of the Pressurized Water Reactor (PWR), the high cost being because this was not part of Russia's fuel cycle policy. This MOX fuel for both countries is equivalent to about 12 kilotonnes (26×10^⁶ lb) of natural uranium.[78] The U.S. also has commitments to dispose of 151 tonnes (330×10^³ lb) of non-waste HEU.[79]

The Megatons to Megawatts program came to an end in 2013.[76]

Nuclear reprocessing, sometimes called recycling, is one method of mitigating the eventual peak of uranium production. It is most useful as part of a nuclear fuel cycle utilizing fast-neutron reactors since reprocessed uranium and reactor-grade plutonium both have isotopic compositions not optimal for use in today's thermal-neutron reactors. Although reprocessing of nuclear fuel is done in a few countries (France, United Kingdom, and Japan) the United States President banned reprocessing in the late 1970s due to the high costs and the risk of nuclear proliferation via plutonium. In 2005, U.S. legislators proposed a program to reprocess the spent fuel that has accumulated at power plants. At present prices, such a program is significantly more expensive than disposing spent fuel and mining fresh uranium.[12]

Currently, there are eleven reprocessing plants in the world. Of these, two are large-scale commercially operated plants for the reprocessing of spent fuel elements from light water reactors with throughputs of more than 1 kilotonne (2.2×10^⁶ lb) of uranium per year. These are La Hague, France with a capacity of 1.6 kilotonnes (3.5×10^⁶ lb) per year and Sellafield, England at 1.2 kilotonnes (2.6×10^⁶ lb) uranium per year. The rest are small experimental plants.[80] The two large-scale commercial reprocessing plants together can reprocess 2,800 tonnes of uranium waste annually.[81]

Most of the spent fuel components can be recovered and recycled. About two-thirds of the U.S. spent fuel inventory is uranium. This includes residual fissile uranium-235 that can be recycled directly as fuel for heavy water reactors or enriched again for use as fuel in light water reactors.[82]

Plutonium and uranium can be chemically separated from spent fuel. When used nuclear fuel is reprocessed using the de facto standard PUREX method, both plutonium and uranium are recovered separately. The spent fuel contains about 1% plutonium. Reactor-grade plutonium contains Pu-240 which has a high rate of spontaneous fission, making it an undesirable contaminant in producing safe nuclear weapons. Nevertheless, nuclear weapons can be made with reactor grade plutonium.[83]

The spent fuel is primarily composed of uranium, most of which has not been consumed or transmuted in the nuclear reactor. At a typical concentration of around 96% by mass in the used nuclear fuel, uranium is the largest component of used nuclear fuel.[84] The composition of reprocessed uranium depends on the time the fuel has been in the reactor, but it is mostly uranium-238, with about 1% uranium-235, 1% uranium-236 and smaller amounts of other isotopes including uranium-232. However, reprocessed uranium is also a waste product because it is contaminated and undesirable for reuse in reactors.[85] During its irradiation in a reactor, uranium is profoundly modified. The uranium that leaves the reprocessing plant contains all the isotopes of uranium between uranium-232 and uranium-238 except uranium-237, which is rapidly transformed into neptunium-237. The undesirable isotopic contaminants are:

• Uranium-232 (whose decay products emit strong gamma radiation making handling more difficult), and
• Uranium-234 (which is fertile material but can affect reactivity differently from uranium-238).
• Uranium-236 (which affects reactivity and absorbs neutrons without fissioning, becoming neptunium-237 which is one of the most difficult isotopes for long-term disposal in a deep geological repository)
• Daughter products of uranium-232: bismuth-212, thallium-208.[86]

At present, reprocessing and the use of plutonium as reactor fuel is far more expensive than using uranium fuel and disposing of the spent fuel directly – even if the fuel is only reprocessed once.[85] However, nuclear reprocessing becomes more economically attractive, compared to mining more uranium, as uranium prices increase.

The total recovery rate 5 kilotonnes (11×10^⁶ lb)/yr from reprocessing currently is only a small fraction compared to the growing gap between the rate demanded 64.615 kilotonnes (142.45×10^⁶ lb)/yr and the rate at which the primary uranium supply is providing uranium 46.403 kilotonnes (102.30×10^⁶ lb)/yr.

Energy Returned on Energy Invested (EROEI) on uranium reprocessing is highly positive, though not as positive as the mining and enrichment of uranium, and the process can be repeated. Additional reprocessing plants may bring some economies of scale.

The main problems with uranium reprocessing are the cost of mined uranium compared to the cost of reprocessing,[12][87] nuclear proliferation risks, the risk of major policy change, the risk of incurring large cleanup costs, stringent regulations for reprocessing plants, and the anti-nuclear movement .

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.[88] Phosphates, seawater, uraniferous coal ash, and some type of oil shales are examples of unconventional uranium resources.

The soaring price of uranium may cause long-dormant operations to extract uranium from phosphate. Uranium occurs at concentrations of 50 to 200 parts per million in phosphate-laden earth or phosphate rock. As uranium prices increase, there has been interest in some countries in extraction of uranium from phosphate rock, which is normally used as the basis of phosphate fertilizers.[89]

Worldwide, approximately 400 wet-process phosphoric acid plants were in operation. Assuming an average recoverable content of 100 ppm of uranium, and that uranium prices do not increase so that the main use of the phosphates are for fertilizers, this scenario would result in a maximum theoretical annual output of 3.7 kilotonnes (8.2×10^⁶ lb) U₃O₈.[90]

Historical operating costs for the uranium recovery from phosphoric acid range from $48–$119/kg U₃O₈.[91] In 2011, the average price paid for U₃O₈ in the United States was $122.66/kg.[92]

There are 22 million tons of uranium in phosphate deposits. Recovery of uranium from phosphates is a Mature technology;[88] it has been utilized in Belgium and the United States, but high recovery costs limit the utilization of these resources, with estimated production costs in the range of US$60–100/kgU including capital investment, according to a 2003 OECD report for a new 100 tU/year project.[45]

Unconventional uranium resources include up to 4,000 megatonnes (8,800×10^⁹ lb) of uranium contained in sea water. Several technologies to extract uranium from sea water have been demonstrated at the laboratory scale.

In the mid-1990s Extraction costs were estimated at 260 USD/kgU (Nobukawa, et al., 1994) but scaling up laboratory-level production to thousands of tonnes is unproven and may encounter unforeseen difficulties.[93]

One method of extracting uranium from seawater is using a uranium-specific nonwoven fabric as an absorbent. The total amount of uranium recovered in an experiment in 2003 from three collection boxes containing 350 kg of fabric was >1 kg of yellow cake after 240 days of submersion in the ocean.[94] According to the OECD, uranium may be extracted from seawater using this method for about US$300/kgU.[45]

In 2006 the same research group stated: "If 2g-U/kg-adsorbent is submerged for 60 days at a time and used 6 times, the uranium cost is calculated to be 88,000 JPY/kgU, including the cost of adsorbent production, uranium collection, and uranium purification. When an extraction 6g of U per kg of adsorbent and 20 repetitions or more becomes possible, the uranium cost reduces to 15,000 yen. This price level is equivalent to that of the highest cost of the minable uranium. The lowest cost attainable now is 25,000 yen with 4g-U/kg-adsorbent used in the sea area of Okinawa, with 18 repetition uses. In this case, the initial investment to collect the uranium from seawater is 107.7 billion yen, which is 1/3 of the construction cost of a one million-kilowatt class nuclear power plant."[95]

In 2012, ORNL researchers announced the successful development of a new absorbent material dubbed HiCap, which vastly outperforms previous best adsorbents, which perform surface retention of solid or gas molecules, atoms or ions. "We have shown that our adsorbents can extract five to seven times more uranium at uptake rates seven times faster than the world's best adsorbents", said Chris Janke, one of the inventors and a member of ORNL's Materials Science and Technology Division. HiCap also effectively removes toxic metals from water, according to results verified by researchers at Pacific Northwest National Laboratory.[96][97][98][99][100]

Among the other methods to recover uranium from sea water, two seem promising: algae bloom to concentrate uranium[101] and nanomembrane filtering.[102]

So far, no more than a very small amount of uranium has been recovered from sea water in a laboratory.[88]

Annual release of "technologically enhanced"/concentrated Naturally occurring radioactive material, uranium and thorium radioisotopes naturally found in coal and concentrated in heavy/bottom coal ash and airborne fly ash.[103] As predicted by ORNL to cumulatively amount to 2.9 million tons over the 1937–2040 period, from the combustion of an estimated 637 billion tons of coal worldwide.[104]

In particular, nuclear power facilities produce about 200,000 metric tons of low and intermediate level waste (LILW) and 10,000 metric tons of high level waste (HLW) (including spent fuel designated as waste) each year worldwide.[105]

Although only several parts per million average concentration in coal before combustion (albeit more concentrated in ash), the theoretical maximum energy potential of trace uranium and thorium in coal (in breeder reactors) actually exceeds the energy released by burning the coal itself, according to a study by Oak Ridge National Laboratory.[104]

From 1965 to 1967 Union Carbide operated a mill in North Dakota, United States burning uraniferous lignite and extracting uranium from the ash. The plant produced about 150 metric tons of U₃O₈ before shutting down.[106]

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.[88] The first laboratory scale amount of yellowcake uranium recovered from uraniferous coal ash was announced in 2007.[107] The three coal power stations at Xiaolongtang, Dalongtang and Kaiyuan have piled up their waste ash. Initial tests from the Xiaolongtang ash pile indicate that the material contains (160–180 parts per million uranium), suggesting a total of some 2.085 kilotonnes (4.60×10^⁶ lb) U₃O₈ could be recovered from that ash pile alone.[107]

Some oil shales contain uranium, which may be recovered 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.[108]

A breeder reactor produces more nuclear fuel than it consumes and thus can extend the uranium supply. It typically turns the dominant isotope in natural uranium, uranium-238, into fissile plutonium-239. This results in hundredfold increase in the amount of energy to be produced per mass unit of uranium, because U-238, which constitute 99.3% of natural uranium, is not used in conventional reactors which instead use U-235 which only represent 0.7% of natural uranium.[109] In 1983, physicist Bernard Cohen proposed that the world supply of uranium is effectively inexhaustible, and could therefore be considered a form of renewable energy.[7][110] He claims that fast breeder reactors, fueled by naturally-replenished uranium-238 extracted from seawater, could supply energy at least as long as the sun's expected remaining lifespan of five billion years.,[7] making them as sustainable in fuel availability terms as renewable energy sources. Despite this hypothesis there is no known economically viable method to extract sufficient quantities from sea water. Experimental techniques are under investigation.[111][112]

There are two types of breeders: Fast breeders and thermal breeders.

A fast breeder, in addition to consuming U-235, converts fertile U-238 into Pu-239, a fissile fuel. Fast breeder reactors are more expensive to build and operate, including the reprocessing, and could only be justified economically if uranium prices were to rise to pre-1980 values in real terms. About 20 fast-neutron reactors have already been operating, some since the 1950s, and one supplies electricity commercially. Over 300 reactor-years of operating experience have been accumulated. In addition to considerably extending the exploitable fuel supply, these reactors have an advantage in that they produce less long-lived transuranic wastes, and can consume nuclear waste from current light water reactors, generating energy in the process.[113] Several countries have research and development programs for improving these reactors. For instance, one scenario in France is for half of the present nuclear capacity to be replaced by fast breeder reactors by 2050. China, India, and Japan plan large scale utilization of breeder reactors during the coming decades.[114] (Following the crisis at Japan's Fukishima Daiichi nuclear power plant in 2011, Japan is revising its plans regarding future use of nuclear power. (See: Fukushima Daiichi nuclear disaster: Energy policy implications.))

The breeding of plutonium fuel in Fast Breeder Reactors (FBR), known as the plutonium economy, was for a time believed to be the future of nuclear power. But many of the commercial breeder reactors that have been built have been riddled with technical and budgetary problems. Some sources critical of breeder reactors have gone so far to call them the Supersonic Transport of the '80s.[115]

Uranium turned out to be far more plentiful than anticipated, and the price of uranium declined rapidly (with an upward blip in the 1970s). This is why the US halted their use in 1977[116] and the UK abandoned the idea in 1994.[117]

Fast Breeder Reactors, are called fast because they have no moderator slowing down the neutrons (light water, heavy water or graphite) and breed more fuel than they consume. The word 'fast' in fast breeder thus refers to the speed of the neutrons in the reactor's core. The higher the energy the neutrons have, the higher the breeding ratio or the more uranium that is changed into plutonium.

Significant technical and materials problems were encountered with FBRs, and geological exploration showed that scarcity of uranium was not going to be a concern for some time. By the 1980s, due to both factors, it was clear that FBRs would not be commercially competitive with existing light water reactors. The economics of FBRs still depend on the value of the plutonium fuel which is bred, relative to the cost of fresh uranium.[118] Research continues in several countries with working prototypes Phénix in France, the BN-600 reactor in Russia, and the Monju in Japan.[119]

On February 16, 2006 the United States, France and Japan signed an arrangement to research and develop sodium-cooled fast breeder reactors in support of the Global Nuclear Energy Partnership.[120] Breeder reactors are also being studied under the Generation IV reactor program.

Early prototypes have been plagued with problems. The liquid sodium coolant is highly flammable, bursting into flames if it comes into contact with air and exploding if it comes into contact with water. Japan's fast breeder Monju Nuclear Power Plant has been scheduled to re-open in 2008, 13 years after a serious accident and fire involving a sodium leak. In 1997 France shut down its Superphenix reactor, while the Phenix, built earlier, closed as scheduled in 2009.[121][122]

At higher uranium prices breeder reactors may be economically justified. Many nations have ongoing breeder research programs. China, India, and Japan plan large scale utilization of breeder reactors during the coming decades. 300 reactor-years experience has been gained in operating them.[114]

As of June 2008 there are only two running commercial breeders and the rate of reactor-grade plutonium production is very small (20 tonnes/yr). The reactor grade plutonium is being processed into MOX fuel. Next to the rate at which uranium is being mined (46,403 tonnes/yr), this is not enough to stave off peak uranium; however, this is only because mined and reprocessed uranium oxide is plentiful and cheap, so breeding new fuel is uneconomical. They can switch to breed large amounts of new fuel as needed, and many more breeding reactors can be built in a short time span.

Thorium is an alternate fuel cycle to uranium. Thorium is three times more plentiful than uranium. Thorium-232 is in itself not fissile, but fertile. It can be made into fissile uranium-233 in a breeder reactor. In turn, the uranium-233 can be fissioned, with the advantage that smaller amounts of transuranics are produced by neutron capture, compared to uranium-235 and especially compared to plutonium-239.

Despite the thorium fuel cycle having a number of attractive features, development on a large scale can run into difficulties:[123]

• The resulting U-233 fuel is expensive to fabricate.
• The U-233 chemically separated from the irradiated thorium fuel is highly radioactive.
• Separated U-233 is always contaminated with traces of U-232
• Thorium is difficult to recycle due to highly radioactive Th-228
• If the U-233 can be separated on its own, it becomes a weapons proliferation risk
• And, there are technical problems in reprocessing.

Advocates for liquid core and molten salt reactors such as LFTR claim that these technologies negate the above-mentioned thorium's disadvantages present in solid fueled reactors.

The first successful commercial reactor at the Indian Point power station in Buchanan, New York (Indian Point Unit 1) ran on Thorium. The first core did not live up to expectations.[124]

Indian interest in thorium is motivated by their substantial reserves. Almost a third of the world's thorium reserves are in India.[125] India's Department of Atomic Energy (DAE) says that it will construct a 500 MWe prototype reactor in Kalpakkam. There are plans for four breeder reactors of 500 MWe each - two in Kalpakkam and two more in a yet undecided location.[126]

China has initiated a research and development project in thorium molten-salt breeder reactor technology.[127] It was formally announced at the Chinese Academy of Sciences (CAS) annual conference in January 2011. Its ultimate target is to investigate and develop a thorium based molten salt breeder nuclear system in about 20 years.[128][129][130] A 5 MWe research MSR is apparently under construction at Shanghai Institute of Applied Physics (under the Academy) with 2015 target operation.[131]

In 1943, Alvin M. Weinberg et al. believed that there were serious limitations on nuclear energy if only U-235 were used as a nuclear power plant fuel.[146] They concluded that breeding was required to usher in the age of nearly endless energy.

In 1956, M. King Hubbert declared world fissionable reserves adequate for at least the next few centuries, assuming breeding and reprocessing would be developed into economical processes.[6]

In 1975 the US Department of the Interior, Geological Survey, distributed the press release "Known US Uranium Reserves Won't Meet Demand". It was recommended that the US not depend on foreign imports of uranium.[146]

Panel from All-Atomic Comics (1976) citing pessimistic uranium supply predictions as an argument against nuclear power.[147]

All the following sources predict peak uranium:

• Edward Steidle

Edward Steidle, Dean of the School of Mineral Industries at Pennsylvania State College, predicted in 1952 that supplies of fissionable elements were too small to support commercial-scale energy production.[148]

• 1980 Robert Vance

Robert Vance,[149] while looking back at 40 years of uranium production through all of the Red Books, found that peak global production was achieved in 1980 at 69,683 tonnes (150×10^⁶ lb) from 22 countries.[48] In 2003, uranium production totaled 35,600 tonnes (78×10^⁶ lb) from 19 countries.

• 1981 Michael Meacher

Michael Meacher, the former environment minister of the UK 1997–2003, and UK Member of Parliament, reports that peak uranium happened in 1981. He also predicts a major shortage of uranium sooner than 2013 accompanied with hoarding and its value pushed up to the levels of precious metals.[150]

• 1989–2015 M. C. Day

Day projected that uranium reserves could run out as soon as 1989, but, more optimistically, would be exhausted by 2015.[147]

• 2034 van Leeuwen

Jan Willem Storm van Leeuwen, an independent analyst with Ceedata Consulting, contends that supplies of the high-grade uranium ore required to fuel nuclear power generation will, at current levels of consumption, last to about 2034.[151] Afterwards, the cost of energy to extract the uranium will exceed the price the electric power provided.

• 2035 Energy Watch Group

The Energy Watch Group has calculated that, even with steep uranium prices, uranium production will have reached its peak by 2035 and that it will only be possible to satisfy the fuel demand of nuclear plants until then.[152]

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.[61]

• OECD

The world's present measured resources of uranium, economically recoverable at a price of US$130/kg according to the industry groups OECD, NEA and IAEA, are enough to last for 100 years at current consumption.[63]

• 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 70 years.[64]

All the following references claim that the supply is far more than demand. Therefore, they do not predict peak uranium.

• 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.'"[6] 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.[153] 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.

• OECD

The OECD estimates that with the world nuclear electricity generating rates of 2002, with LWR, once-through fuel cycle, there are enough conventional resources to last 85 years using known resources and 270 years using known and as yet undiscovered resources. With breeders, this is extended to 8,500 years.[154]

If one is willing to pay $300/kg for uranium, there is a vast quantity available in the ocean.[63] It is worth noting that since fuel cost only amounts to a small fraction of nuclear energy total cost per kWh, and raw uranium price also constitutes a small fraction of total fuel costs, such an increase on uranium prices wouldn't involve a very significant increase in the total cost per kWh produced.

• Bernard Cohen

In 1983, physicist Bernard Cohen proposed that uranium is effectively inexhaustible, and could therefore be considered a renewable source of energy.[7] 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.[7] While uranium is a finite 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 contends, then nuclear energy is every bit as sustainable as solar power or any other source of energy, in terms of sustainability over the 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.

His paper assumes extraction of uranium from seawater at the rate of 16 kilotonnes (35×10^⁶ lb) per year of uranium.[7] The current demand for uranium is near 70 kilotonnes (150×10^⁶ lb) per year; however, the use of breeder reactors means that uranium would be used at least 60 times more efficiently than today.

• James Hopf

A nuclear engineer writing for American Energy Independence in 2004 believes that there is several hundred years' supply of recoverable uranium even for standard reactors. For breeder reactors, "it is essentially infinite".[155] All the following references claim that the supply is far more than demand. Therefore, they believe that uranium will not deplete in the foreseeable future.

• IAEA

The IAEA estimates that using only known reserves at the current rate of demand and assuming a once-through nuclear cycle that there is enough uranium for at least 100 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.[63]

• Kenneth S. Deffeyes

Kenneth S. Deffeyes estimates that if one can accept ore one tenth as rich then the supply of available uranium increased 300 times.[46][156] His paper shows that uranium concentration in ores is log-normal distributed. There is relatively little high-grade uranium and a large supply of very low grade uranium.

• Ernest Moniz

Ernest J. Moniz, a professor at the Massachusetts Institute of Technology and the former United States Secretary of Energy, testified in 2009 that an abundance of uranium had put into question plans to reprocess spent nuclear fuel. The reprocessing plans dated from decades previous, when uranium was thought to be scarce. But now, "roughly speaking, we’ve got uranium coming out of our ears, for a long, long time," Professor Moniz said.[157]

Monthly uranium spot price in US$.[162]

The uranium spot price has increased from a low in Jan 2001 of US$6.40 per pound of U₃O₈ to a peak in June 2007 of US$135. The uranium prices have dropped substantially since.[162] Currently (15 July 2013) the uranium spot is US$38.[163]

The high price in 2007 resulted from shrinking weapons stockpiles and a flood at the Cigar Lake Mine, coupled with expected rises in demand due to more reactors coming online, leading to a uranium price bubble. Miners and Utilities are bitterly divided on uranium prices.[164]

As prices go up, production responds from existing mines, and production from newer, harder to develop or lower quality uranium ores begins. Currently, much of the new production is coming from Kazakhstan. Production expansion is expected in Canada and in the United States. However, the number of projects waiting in the wings to be brought online now are far less than there were in the 1970s. There have been some encouraging signs that production from existing or planned mines is responding or will respond to higher prices. The supply of uranium has recently become very inelastic. As the demand increases, the prices respond dramatically.

As of 2018 the price of nuclear fuel was stable at around US$38.81 per pound, 81 cents more than in 2013 and 1 cent more than in 2017, way lower than inflation. At such a low and stable price, breeding is uneconomical.

Unlike other metals such as gold, silver, copper or nickel, uranium is not widely traded on an organized commodity exchange such as the London Metal Exchange. It is traded on the NYMEX but on very low volume.[165] Instead, it is traded in most cases through contracts negotiated directly between a buyer and a seller.[166] The structure of uranium supply contracts varies widely. The prices are either fixed or based on references to economic indices such as GDP, inflation or currency exchange. Contracts traditionally are based on the uranium spot price and rules by which the price can escalate. Delivery quantities, schedules, and prices vary from contract to contract and often from delivery to delivery within the term of a contract.

Since the number of companies mining uranium is small, the number of available contracts is also small. Supplies are running short due to flooding of two of the world's largest mines and a dwindling amount of uranium salvaged from nuclear warheads being removed from service.[167] While demand for the metal has been steady for years, the price of uranium is expected to surge as a host of new nuclear plants come online.

Rising uranium prices draw investments into new uranium mining projects.[164] Mining companies are returning to abandoned uranium mines with new promises of hundreds of jobs and millions in royalties. Some locals want them back. Others say the risk is too great, and will try to stop those companies "until there's a cure for cancer."[168]

Since many utilities have extensive stockpiles and can plan many months in advance, they take a wait-and-see approach on higher uranium costs. In 2007, spot prices rose significantly due to announcements of planned reactors or new reactors coming online.[169] Those trying to find uranium in a rising cost climate are forced to face the reality of a seller's market. Sellers remain reluctant to sell significant quantities. By waiting longer, sellers expect to get a higher price for the material they hold. Utilities on the other hand, are very eager to lock up long-term uranium contracts.[164]

According to the NEA, the nature of nuclear generating costs allows for significant increases in the costs of uranium before the costs of generating electricity significantly increase. A 100% increase in uranium costs would only result in a 5% increase in electric cost.[65] This is because uranium has to be converted to gas, enriched, converted back to yellow cake and fabricated into fuel elements. The cost of the finished fuel assemblies are dominated by the processing costs, not the cost of the raw materials.[170] Furthermore, the cost of electricity from a nuclear power plant is dominated by the high capital and operating costs, not the cost of the fuel. Nevertheless, any increase in the price of uranium is eventually passed on to the consumer either directly or through a fuel surcharge. As of 2020, this has not happened and the price of nuclear fuel is low enough to make breeding uneconomical.

An alternative to uranium is thorium which is three times more common than uranium. Fast breeder reactors are not needed. Compared to conventional uranium reactors, thorium reactors using the thorium fuel cycle may produce some 40 times the amount of energy per unit of mass.[171] However, creating the technology, infrastructure and know-how needed for a thorium-fuel economy is uneconomical at current and predicted uranium prices.

If nuclear power prices rise too quickly, or too high, power companies may look for substitutes in fossil energy (coal, oil, and gas) and/or renewable energy, such as hydro, bio-energy, solar thermal electricity, geothermal, wind, tidal energy. Both fossil energy and some renewable electricity sources (e.g. hydro, bioenergy, solar thermal electricity and geothermal) can be used as base-load.