Uranium and Thorium World Reserves, Alternative Nuclear Fuels and Fuel Cycle for Fusion Materials

Sajjad Rasool ChaudhryReg. No.: MS-PE-1233

Department of Chemical Engineering (DChE)Pakistan Institute of Engineering & Applied Sciences (PIEAS)Nilore, PakistanDate: 19th Feb, 2014Table of Contents1.1 Uranium Reserves11.2 Secondary Sources of Uranium32.1 Thorium Reserves43.1 Alternative Nuclear Fuels64.1 Fusion Fuel Cycle7References10

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1.1 Uranium Reserves [1][2][3]Uranium is a relatively common element in the crust of the Earth very much more than in the mantle. It is a metal approximately as common as tin or zinc, and it is a constituent of most rocks and even of the sea. Some typical concentrations are given in table 1.1.Table 1.1 Typical Worldwide Uranium Concentrations [1]LocationConcentration

Very high-grade ore (Canada) - 20% U200,000 ppm

High-grade ore - 2% U,20,000 ppm

Low-grade ore - 0.1% U,1,000 ppm

Very low-grade ore (Namibia) - 0.01% U100 ppm

Granite3-5ppm

Sedimentary rock2-3 ppm

Earth's continental crust2.8 ppm

Seawater0.003 ppm

Measured resources of uranium, the amount known to be economically recoverable from orebodies, are thus also relative to costs and prices. They are also dependent on the intensity of past exploration effort, and are basically a statement about what is known rather than what is there in the Earth's crust - epistemology rather than geology. Changes in costs or prices, or further exploration, may alter measured resource figures markedly. At ten times the current price, seawater might become a potential source of vast amounts of uranium. Thus, any predictions of the future availability of any mineral, including uranium, which are based on current cost and price data and current geological knowledge are likely to be extremely conservative.This is in fact suggested in the IAEA-NEA figures if those covering estimates of all conventional resources (U as main product or major by-product) are considered - another 7.6 million tonnes (beyond the5.3 Mt known economic resources), which takes us to 190 years' supply at today's rate of consumption. This still ignores the technological factor mentioned below. It also omits unconventional resources (U recoverable as minor by-product) such as phosphate/ phosphorite deposits (up to 22 Mt U), black shales (schists) and lignite (0.7 Mt U), and even seawater (up to 4000 Mt), which would be uneconomic to extract in the foreseeable future, although Japanese trials using a polymer braid have suggested costs a bit over $250/kgU Table 1.2 Country Wise Recoverable Reserves of Uranium (As of 2011) [2]Countrytonnes of U% of world

Australia1,661,00031%

Kazakhstan629,00012%

Russia487,2009%

Canada468,7009%

Niger421,0008%

South Africa279,1005%

Brazil276,7005%

Namibia261,0005%

USA207,4004%

China166,1003%

Ukraine119,6002%

Uzbekistan96,2002%

Mongolia55,7001%

Jordan33,8001%

other164,0003%

World total5,327,200

It can be seen that Australia has a substantial part (about 31 percent) of the world's uranium, Kazakhstan 12 percent, and Canada and Russia 9 percent each. Currently global uranium production meets only 58 per cent of demand, with the shortfall made up largely from rapidly shrinking stockpiles. The shortfall is expected to run at 51 million pounds a year on average from next year to 2020.During the last 15 years, the shortfall between production and requirements was made up by excess commercial inventories, uranium released from military use and other secondary sources. These are now in decline, and the shortfall will increasingly need to be made up by primary production.

Table 1.3 Uranium demand, mining production and deficit (in tonns) [4]CountryUranium Required2005% of world demandIndigenous Mining Production 2004Deficit

USA22,3973383521,562

France10,43115010,431

Japan8,1841208,184

Germany3,7085773,631

Russia3,40952890519

South Korea3,011403,011

UK2,409302,409

Rest ofthe world14,8082235,49820,690

Total68,35710039,30029,057

1.2 Secondary Sources of Uranium[1]The most obvious secondary source iscivil stockpilesheld by utilities and governments. The amount held here is difficult to quantify, due to commercial confidentiality.As at January 2009 some 129,000 tU total inventory was estimated for utilities, 10,000 tU for producers and 15,000 tU for fuel cycle participants, making a total of 154,000 tU. These reserves are expected not to be drawn down, but to increase steadily to provide energy security for utilities and governments.Recycled uranium and plutoniumis another source, and currently saves 1500-2000 tU per year of primary supply, depending on whether just the plutonium or also the uranium is considered. In fact, plutonium is quickly recycled as MOX fuel, whereas the reprocessed uranium (RepU) is mostly stockpiled. Re-enrichment of depleted uranium(DU, enrichment tails) is another secondary source. There is about 1.5 million tonnes of depleted uranium available, from both military and civil enrichment activity since the 1940s, most at tails assay of 0.25 - 0.35% U-235. Non-nuclear uses of DU are very minor relative to annual arising of over 35,000 tU per year. This leaves most DU available for mixing with recycled plutonium on MOX fuel or as a future fuel resource for fast neutron reactors. However, some that has relatively high assay can be fed through under-utilised enrichment plants to produce natural uranium equivalent, or even enriched uranium ready for fuel fabrication. Russian enrichment plants have treated 10-15,000 tonnes per year of DU assaying over 0.3% U-235, stripping it down to 0.1% and producing a few thousand tonnes per year of natural uranium equivalent. This Russian program treating Western tails has now finished, but a new US one is expected to start when surplus capacity is available, treating about 140,000 tonnes of old DU assaying 0.4% U-235. 2.1 Thorium ReservesCanada,China,Germany,India, theNetherlands, theUnited Kingdomand theUnited Stateshave experimented with using thorium as a substitute nuclear fuel in nuclear reactors. When compared to uranium, there is a growing interest inthorium-based nuclear powerdue to its greater safety benefits, absence of non-fertileisotopes and its higher occurrence and availability.India's three stage nuclear power programis possibly the most well-known and well funded of such efforts.Present knowledge of the distribution of thorium resources is poor because of the relatively low-key exploration efforts arising out of insignificant demand. There are two sets of estimates that define world thorium reserves, one set by the US Geological Survey (USGS) and the other supported by reports from the OECD and the International Atomic Energy Agency (the IAEA). Under the USGS estimate,USA,Australia, andIndiahave particularly large reserves of thorium.India and Australia are believed to possess about 300,000tonneseach; i.e., each has 25% of the world's thorium reserves. In the OECD reports, however, estimates of Australia's Reasonably Assured Reserves (RAR) of thorium indicate only 19,000 tonnes and not 300,000 tonnes as indicated by USGS. The two sources vary wildly for countries such as Brazil, Turkey, and Australia, however, both reports appear to show some consistency with respect to India's thorium reserve figures, with 290,000 tonnes (USGS) and 319,000 tonnes (OECD/IAEA). Both the IAEA and OECD appear to conclude thatIndiamay possess the lion's share of world's thorium deposits.The IAEA's 2005 report estimates India's reasonably assured reserves of thorium at 319,000 tonnes, but mentions recent reports of India's reserves at 650,000 tonnes. A government of India estimate, shared in the country's Parliament in August 2011, puts the recoverable reserve at 846,477 tonnes.The Indian Minister of StateV. Narayanasamystated that as of May 2013, the country's thorium reserves were 11.93 million tonnes (monazite, having 9-10% ThO2).Table 2.1 World Wide Thorium Reserves by USGS (As of 2013) [4]Sr. No.CountryReserves

1United States440,000

2Australia300,000

3Brazil100,000

4Canada35,000

5India16,000

6Malaysia4,500

7South Africa90,000

8Other countries1,913,000

9World total440,000

Table 2.2 World Wide Thorium Reserves by IAEA (As of 2005) [5]Sr. NoCountryRAR ThEAR Th

1India519,00021%

2Australia489,00019%

3USA400,00013%

4Turkey344,00011%

5Venezuela302,00010%

6Brazil302,00010%

7Norway132,0004%

8Egypt100,0003%

9Russia75,0002%

10Greenland54,0002%

11Canada44,0002%

12South Africa18,0001%

13Other countries33,0002%

14World total2,810,000

3.1 Alternative Nuclear Fuels [6]Thorium is under consideration as alternative to uranium for nuclear power generation. The naturally occurring isotope Thorium-232 is afertile material, and with a suitable neutron source can be used asnuclear fuelinnuclear reactors, includingbreeder reactors. In 1997, the U.S. Energy Department underwrote research into thorium fuel, and research also was begun in 1996 by theInternational Atomic Energy Agency(IAEA), to study the use of thorium reactors. Nuclear scientistAlvin RadkowskyofTel Aviv Universityin Israel founded a consortium to develop thorium reactors, which included other companies:RaytheonNuclear Inc.,Brookhaven National Laboratoryand theKurchatov Institutein Moscow. Radkowsky was chief scientist in the U.S.nuclear submarineprogram directed byAdmiral Hyman Rickoverand later headed the design team that built the USA's first civiliannuclear power plant at Shippingport, Pennsylvania, which was a scaled-up version of the first naval reactor.The third Shippingport core, initiated in 1977, bred thorium.Even earlierexamplesof reactors using fuel with thorium exist, including the first core at theIndian Point Energy Centerin 1962. Some countries, includingIndia, are now investing in research to build thorium-based nuclear reactors. A 2005 report by theInternational Atomic Energy Agencydiscusses potential benefits along with the challenges of thorium reactors. Indiahas also made thorium-based nuclear reactors a priority with its focus on developingfast breedertechnology. Some benefits of thorium fuel when compared with uranium were summarized as follows. Weapons-grade fissionable material (233U) is harder to retrieve safely and clandestinely from a thorium reactor; Thorium mining produces a single pure isotope, whereas the mixture of natural uranium isotopes must be enriched to function in most common reactor designs. The same cycle could also use the fissionable U-238 component of the natural uranium, and also contained in the depleted reactor fuel; Thorium cannot sustain anuclear chain reactionwithout priming,so fission stops by default in an accelerator driven reactor.When used in a breeder-like reactor, however, unlike uranium-based light water reactors, thorium requires irradiation and reprocessing before the above-noted advantages of Thorium-232 can be realized, which initially makes solid thorium fuels more expensive than uranium fuels. But experts note that "the second thorium reactor may activate a third thorium reactor. This could continue in a chain of reactors for a millennium if we so choose." They add that because of thorium's abundance, it will not be exhausted in 1,000 years. TheThorium Energy Alliance(TEA), an educational advocacy organization, emphasizes that "there is enough thorium in the United States alone to power the country at its current energy level for over 10,000 years. 4.1 Fusion Fuel Cycle [7]Many fusion reactions have been tested. However, the fuels considered for power have all been light elements like the isotopes of hydrogen, for exampledeuterium-tritium. Other reactions like the deuterium and Helium3reaction or the Helium3and Helium3reactions, would require a supply of Helium3. This can either come from other nuclear reactions or from extraterrestrial sources. Finally, researchers hope to do the p-11Breaction, because it does not directly produce neutrons, though side reactions canDeuterium- Tritium reaction is the easiest nuclear reaction, at the lowest energy. Its given by:

This reaction is common in research.Deuteriumis a naturally occurringisotopeof hydrogen and is commonly available. The large mass ratio of the hydrogen isotopes makes their separation easy compared to the difficulturanium enrichmentprocess.Tritiumis a natural isotope of hydrogen, but due to its tinyhalf-lifeof 12.32 years, it hard to find, store, produce and is expensive. Consequently, the deuterium-tritium fuel cycle requires thebreedingof tritiumfromlithiumThe second easiest fusion reaction is the fusing of deuterium with itself. This reaction has two branches that occur with nearly equal probability. Reactions occur as:

This reaction is also common in research. This fuel is commonly used byamateurswho fuse. The optimum energy to initiate this reaction is 15keV, only slightly higher than the optimum for the D-T reaction. The first branch does not produce neutrons, but it does produce tritium, so that a D-D reactor will not be completely tritium-free, even though it does not require an input of tritium or lithium. Unless the tritons can be quickly removed, most of the tritium produced would be burned before leaving the reactor, which would reduce the handling of tritium, but would produce more neutrons, some of which are very energetic. The neutron from the second branch has an energy of only 2.45MeV (0.393pJ), whereas the neutron from the D-T reaction has an energy of 14.1MeV (2.26pJ), resulting in a wider range of isotope production and material damage. When the tritons are removed quickly while allowing the 3He to reactor, the fuel cycle is called "tritium suppressed fusion.The removed tritium decays to 3He with a 12.5 year half-life. By recycling the 3He produced from the decay of tritium back into the fusion reactor, the fusion reactor does not require materials resistant to fast 14.1MeV (2.26pJ) neutrons.A second-generation approach to controlled fusion power involves combiningHelium-3(3He) andDeuterium(2H):

This reaction produces a helium-4 nucleus (4He) and a high-energy proton. As with the p-11Baneutronic fusionfuel cycle, most of the reaction energy is released as charged particles, reducing activationof the reactor housing and potentially allowing more efficient energy harvesting via any of several speculative technologies.In practice, D-D side reactions produce a significant number of neutrons, resulting in p-11B being the preferred cycle for aneutronic fusion.Ifaneutronic fusionis the goal, then the most promising candidate may be the Hydrogen-1-Boronreaction:

Under reasonable assumptions, side reactions will result in about 0.1% of the fusion power being carried by neutrons. At 123 keV, the optimum temperature for this reaction is nearly ten times higher than that for the pure hydrogen reactions, the energy confinement must be 500 times better than that required for the D-T reaction, and thepower densitywill be 2500 times lower than for D-T.

Figure 4.1 Deuterium-Tritium Fuel Cycle [8]

Figure 4.2 Deuterium-Tritium Fuel Cycle [9]

References1. Supply of Uranium,World Nuclear Association, August 2012. http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Uranium-Resources/Supply-of-Uranium/Retrieved 19-02-20122. J. Busby,"Why Nuclear Power is not a Sustainable Source of Low Carbon Energy", Hubbert Peakhttp://www.hubbertpeak.com/nuclear/WhyNuclearNotSustainable.htm Retrieved 19-02-20123. S. Hall & M. Coleman, Critical Analysis of World Uranium Resources, U.S. Scientific Investigations Report 20124. U.S. Geological Survey, Mineral Commodity Summaries Thorium, 2013, http://minerals.usgs.gov/minerals/pubs/commodity/thorium/index.html, Online, Retrieved 19-02-20125. IAEA: Thorium fuel cycle, Potential benefits and challenges. pp.45(table 8), 97(ref 78).http://www-pub.iaea.org/MTCD/publications/PDF/TE_1450_web.pdf Retrieved 19-02-20126. http://en.wikipedia.org/wiki/Thorium-based_nuclear_power, Online, Retrieved 19-02-20127. http://en.wikipedia.org/wiki/Fusion_power#Mechanism Online, Retrieved 19-02-20128. For Establishment Fusion Fuel Cycle, Naka Fusion Institute, Japan Atomic Energy Agency.http://www.naka.jaea.go.jp/english/kougaku-e/TPL/page3.html, Online, Retrieved 19-02-20129. Fusion Fuel Cycle, ITER, http://www.iter.org/mach/fuelcycle, Online, Retrieved 19-02-2012