Economics of Thorium and Uranium Reactors

Transcription

1 Sherman Lam HSA The Economics of Oil and Energy April 30, 2013 Economics of Thorium and Uranium Reactors In February 2012, the Nuclear Regulatory Commission (NRC) approved a license for two new nuclear reactors in Georgia. This was the first time a new nuclear reactor has been commissioned since The reactor to be used is the AP1000 built by Westinghouse, a 1154 MWe pressured water reactor that stresses economic competitiveness and safety. Like most traditional power plants, uranium is its primary fuel. However, despite its many revolutionary designs, the plant still faces problems associated with traditional power plants such as the disposal of radioactive waste, danger of meltdowns, reactor inefficiency, and high costs relative to other power plants (such as coal). In light of pushes for more clean energy, this investigation analyzes the current state of the U.S. s nuclear system and suggests an alternative to the uranium paradigm thorium. Thorium is an element that is more than 3 times more abundant worldwide and is an alternate source of nuclear power. This element itself is not fissile but when used in a Liquid Fluoride Thorium Reactor (LFTR), it can potentially be a source of nuclear power that is cheaper, cleaner, and safer compared to current uranium power plants. This investigation explores these potential benefits and analyzes the cost of thorium power in comparison to uranium power. I. Current State of U.S. Energy In 2002, the amount of energy produced to meet US energy demands was 3,858,452 GWh. By 2011, this had risen to 4,100,656 GWh. 2 Figure 1 illustrates how these demands were met. Of the total energy produced in 2011, 42% of the U.S. s energy was met by burning coal, 25% by burning natural gas, 20% by nuclear power, and only 13% by renewables (including hydroelectric power). Table 1 shows the relative cost Nuclear 20% Hydro 8% Natural Gas 25% Other Renewables 5% Coal 42% Figure 1: Breakdown of U.S. Energy Production in National Energy Institute, Net Generation by Energy Source: Total (All Sectors) 1

2 of nuclear with its largest competitors: coal and natural gas. 3 For comparison, the price of thorium nuclear power calculated in this paper is also listed. As energy demands continue to increase, energy production will need to increase as well. However, fossil fuels are limited and under the pressure for cleaner energy, they will someday no longer be able to sustain the power demands of the U.S. and other industrial nations. Given the power distribution in Figure 1, nuclear power is the energy source that has the capacity to fill this gap. II. Current Design Current nuclear reactors use uranium as their main source of energy and rely on the fuel cycle of U-235. U-235 is a fissile isotope of uranium. When a neutron hits and is absorbed by the nucleus, the nucleus becomes unstable and undergoes fission, splitting into two similar sized nuclei. In the process of doing so, three neutrons are released. These in turn collide with other U-235 nuclei and set off a chain reaction. This process generates large amounts of heat. Two main reactor designs are used in the United States: the pressurized water reactor (PWR) and the boiling water reactor (BWR). While there is a difference between how thermal energy from the reactor is transferred to the generator, both use the same fundamental system. In the reactor, the fuel is contained as small pellets that range anywhere between 5 and 20% U-235 content. These pellets are stacked into 12ft long fuel rods, which are placed by the hundreds in fuel assemblies. 4 These assemblies make up the reactor core and generate heat. This heat is transferred via pressurized water to a steam generator where the thermal energy is converted into electricity. The steam then is condensed into water in the cooling tower and set back to reactor where the process is repeated. 5 Note that for a PWR, the water in the Case Real Cost (base 2002) cents/kwh Nuclear 6.7 Pulverized Coal 4.2 Natural Gas 4.1 (moderate gas prices) Thorium 1.4 Table 1: Cost comparison between conventional nuclear, coal, natural gas, and thorium. Figure 2: Pressurized Water Reactor (PWR). Source:

3 reactor loop (shown in Figure 2 in red) is never allowed to evaporate into steam and must be held under very high pressure. 6 III. Current Cost When analyzing the cost of nuclear power, there are main several areas that must be taken into consideration that include: cost of fuel, capital costs, and operating and maintenance costs. Note, the following cost estimates will use 2011 USD values. The cost of fuel spans the entire production process of reactorready uranium pellets, starting from mining through enrichment. Uranium ore is typically mined as UO 2, UO 3, and U 2 O 5. These are collectively referred to as U 3 O 8, the most common form of uranium ore. 7 According to World Nuclear Association, it takes 8.9kg (19.6lbs) of U 3 O 8 to produce 1kg of enriched uranium. In 2011, the cost of U 3 O 8 was $55.6/lb. 8 This means that the cost of 8.9kg (19.6lbs) of U 3 O 8 was $ Once mined, the 8.9 kg of ore must be converted into uranium hexafluoride gas (UF 6 ). In this process, impurities are removed and uranium is mixed with fluoride gas to form UF 6. This gas is then compressed into a liquid in preparation for the enrichment process. This process is carried out because it is easier to remove impurities from uranium as a liquid rather than as a solid. The cost of this conversion is $98 per 1 kg of enriched uranium. 9 Figure 3: Yellowcake is a common name for U3O8. The UF 6 produced in the conversion process however is not high enough in U-235 concentration to be used in a typical nuclear reactor. Ore is Fuel Cost Summary typically mined with a U-235 concentration of 0.7% and must be enriched to 5%. 10 Cost (2011 USD)/1kg This can Process of enriched uranium occur through gaseous diffusion, gas centrifuge, or laser separation. The average Mining Ore (U 3 O 8 ) 1090 cost is of enriching the UF 6 produced in the previous step is $1132. Conversion Enrichment Once enriched, the UF 6 is processed into pellets. These pellets are loaded into tubes and constructed into fuel rods and fuel assemblies. The cost of this process is $240. Fuel Fabrication 240 Total 2560 Table 2: A cost breakdown of the production of 1kg of enriched uranium from 8.9kg of uranium ore EIA s 2011 Uranium Marketing Annual Report 9 The following price estimates of the uranium fuel production process also come from this source

4 According to the World Nuclear Association, the production of 1 kg of enriched uranium ready for use in a nuclear reactor requires 8.9kg of U 3 O 8. The cost of processing this ore into 1kg of enriched uranium through the process described above is: total cost = ore + conversion + enrichment + fuel fabrication = $ $98 + $ $240 = $ kg of fuel can produce 360,000 kwh so the kwh cost of uranium fuel is 0.71 c/kwh ( c denotes cents). $ ,000 kwh = The cost of operating managing the plant nearly doubles that of the fuel costs. These costs include payments for the use of the land, employee salaries, licensing fees, and contractor services. The National Energy Institute estimates that the O&M cost in 2011 was 1.51c/kWh. 11 The final costs that must be taken into consideration are the capital costs and decommission costs. The capital cost is the cost of building a new plant and for the sake of this analysis will be taken as the overnight cost (the cost of building a plant without including interest). The decommissioning cost on the other hand is the cost of disassembling a reactor at the end of its life. This includes waste disposal and properly storing the hazardous nuclear waste. For this assessment, the Diablo Canyon Nuclear Power Plant in San Luis Obispo, CA will be used as a model. The EIA s 2011 Annual Energy Outlook (AEO) estimates that a nuclear power plant s 2011 overnight cost is $5,335/kW. 12 The Diablo Canyon Power Plant has two 1,100MW reactors that give the plant a power output of 2,200MW. 13 The overnight cost is then $1.1737x10^10 = $11.7 billion. The Nuclear Energy Institute (NEI) estimates that the decommissioning cost per plant is $ million. This analysis will use $500 million for a conservative cost calculation. 14 The total capital and decommissioning cost of the Diablo Canyon Power Plant is thus $1.1742x Assuming a 60yr project life and a 6% annual discount rate, the total cost of the project is amortized to $4.3253x In 2011, the Diablo Canyon reactors generated in total 18,000GWh = 18x10 9 kwh. The lifetime of a nuclear power plant is 60years. Assuming that the plant maintains this power output over the duration of its life, the Diablo Canyon reactors can generate a total of (18x10 9 kwh/yr)(60yr) = 1.08x10 12 kwh over the duration of their life. The capital and decommissioning cost of the Diablo Canyon Power Plant is thus U.S. Energy Information Administration, Annual Energy Outlook 2011, pg This and the following annual kwh output of the Diablo Power Plants come from the NEI s U.S Nuclear Operating Plant Basic Information

5 $4.3253x x10 12 kwh = $ = 4.005c/kWh kwh According to this estimate, the total kwh cost of energy from a plant similar to that of the Diablo Canyon Power Plant is total cost = fuel + O&M + capital total cost = 0.71c kwh c kwh c kwh total cost = 6.22c/kWh This estimate agrees with the Organization of Economic Consideration and Development s (OECD s) estimate of 5-8c/kWh. 15 IV. The Future of Nuclear Power As the effects of global warming increase, the push for 0-emission energy resources will increase as well. In the current state of energy production, nuclear power produces 20% of the net energy consumed in the US. It is the largest non-fossil fuel based energy source and is the only one with the capability to replace much of the energy supplied by coal and natural gas. This would tend to push the expansion of nuclear power. However, another aspect that must be taken into consideration is the source of uranium. While the U.S. has its own uranium mines, much of the uranium used in reactors is imported. Figure 4 shows that for the past decade, the amount of foreign imports of U 3 O 8 nearly triples the amount of foreign exports. 16 Figure 4 shows that this is due to both the low supply of uranium in comparison to other countries and the cost of mining this uranium. For example, while Canada and Kazakhstan have relatively similar uranium resources as the U.S., most of their uranium (about 80% for Kazakhstan and about 90% for Canada) is less than $80/kg. However, most of the uranium in Figure 4: U.S. Imports vs Exports from 1994 to Net Generation by Energy Source 2011: Total (all Sectors). 5

6 the U.S. costs $80-130/kg to extract. 17 The U.S. is currently dependent on foreign uranium to maintain its current nuclear power programs. If the U.S. wishes to be more energy independent, this dependency on foreign uranium may discourage the growth of nuclear power. World supplies of uranium are estimated to be at 5.3 million tons. The rate of uranium usage is 68,000 tons a year so the estimated uranium supplies will last 80 years. 18 Figure 5: World Nuclear Resources by country Figure 6 shows how the cost of uranium ore (in the form of U 3 O 8 ) has changed over the past two decades. As can be seen, since 2005, there has been a steady rise in uranium prices between 2005 and This was in part due fears of uranium shortages in 2007 due to the flooding of the Cigar Lake mine, one of the world s largest supply of high grade uranium ore. 19 Since 2009, there has been a slight decrease in Figure 6: U3O8 prices in 2011 dollars per lb ( ) prices. However, while prices may continue to decrease as production of uranium at Cigar Lake Mine continues, prices had been rising prior to 2007 and may continue

7 to rise. There is not enough information to accurately predict the future of uranium prices. However, while fuel cost is small in comparison to the overall cost of nuclear power, an increase in prices to over $100/lb will cause a c/kWh increase in prices. This would make nuclear power less competitive compared to fossil fuels and slow growth in nuclear power. While the cost and availability of uranium are important, the most significant factor to determine the future of nuclear power is the public opinion regarding its safety. In 2011, the Fukushima Daiichi disaster showed that a technologically advanced country such as Japan was not impervious to accidents. After a tsunami, the failure of back up cooling systems, and a hydrogen explosion, the power plant suffered a partial meltdown of its core. This has resulted in many countries temporarily decreasing the power output of their nuclear power plants and reevaluating their safety. Some countries such as Germany have aimed to close all nuclear power plants and Italy has banned nuclear power. V. Disadvantages of the Current Nuclear System Figure 7 - Fukushima 2 weeks after the 2011 Fukushima Diiachi Disaster. There are two main areas of the current nuclear program that will be addressed in this portion of the analysis: safety and efficiency. Figure 8: The physics of a heat engine. Note, the larger the temperature differential, the larger the efficiency. An inherent danger of current nuclear power plants is the use of high pressure water in the reactor to cool the reactor and move heat to the steam generators. The reason for keeping this water under high pressure is simple to increase the efficiency of the power plant. A steam generator is a heat engine and according to thermodynamics, the larger the temperature differential across the hot and cold sides of the heat engine, the more work can be extracted. Nuclear power plants thus pressurize this water so that its boiling point is raised and the water can be heated to a higher temperature. This higher temperature yields more work and increases the efficiency of the plant. However, this means that highly pressurized pipes and pressure vessels must be used. This is dangerous because any break in the water line results in an explosion of steam and releases radioisotopes. The last line of defense against releasing radiation into the 7

8 atmosphere is the concrete containment building surrounding the reactor. 20 The second disadvantage to the current design of nuclear power plants is the inefficiency of the consumption of uranium. By mass, only about 3% of the uranium put into the reactor is consumed before the fuel rods must be switched out. This is because elements such as krypton, xenon, and other fission products build up in the rods as the uranium reacts. These elements can absorb neutrons, thus preventing a chain reaction from being effectively maintained. The fuel rods must then be replaced before all the uranium has reacted. 21 This is not only inefficient but also leaves highly radioactive transuranic elements (elements on the periodic table with atomic numbers greater than uranium) products. The presence of these elements is what makes nuclear waste highly radioactive and their long half-lives make storing this waste a challenge. Figure 9: The composition of conventional nuclear fuel from beginning to end of the fission process. VI. Thorium Given the information above, nuclear power seems like an inexpensive energy resource. If so why bother with thorium? First, thorium is much more abundant than uranium. Secondly, liquid fluoride thorium reactors are much safer and efficient than conventional nuclear reactors. Both will be discussed in further depth later. These advantages are important because they give the 20 American Scientist, Liquid Fluoride Thorium Reactors, 2010, pg American Scientist, Liquid Fluoride Thorium Reactors, 2010, pg

9 nuclear energy industry the opportunity to be more efficient and economical, all the while maintaining high safety standards. VII. The Thorium Fuel Cycle and the LFTR Thorium s most abundant, naturally occurring isotope is Th-232. It is quite stable with a half-life of 14 billion years. 22 It cannot undergo nuclear fission, which makes it a fertile isotope. However, Th-232 can be converted into a fuel that does fission (known as a fissile isotope) and be used to fuel nuclear reactors. This conversion occurs when Th-232 absorbs a neutron and transforms into U-233, a fissile isotope. If properly controlled, this process can be used to breed U-233 from Th-232 and also maintain the U-233 nuclear decay chain reaction. Figure 10 depicts the fuel cycle of thorium. Figure 10: The Thorium Fuel Cycle In a liquid fluoride thorium reactor (LFTR), the thorium fuel is dissolved in a mixture of liquid fluoride salts. These salts can be LiF, BeF 2 23, as well as NaF, ZrF These salts are used to transfer heat from the core to the generator. Fluorides are used because they are very stable Molten-Salt Reactors History, Status, and Potential,

10 chemicals, are good at transferring heat, have a low vapor pressure when heated, and are not damaged by radiation, and are inert to some common structural metals. 25 This mixture is circulated between the reactor and a treatment plant where the waste can be removed. The reactor is separated into two parts: the core and the thorium blanket. In the core, U-233 reacts to product neutrons. The excess neutrons exit the core and fuse with Th-233 atoms in the blanket. When the Th-232 in the blanket transmutes into U-232, it is sent back to the reactor to fission. This system allows the reactor to breed fuel because fissile U-233 is created from the fertile Th-232 in the reactor s blanket. VIII. Technological Advantages LFTRs have technological advantages in 3 particular areas: safety, fuel efficiency, and the lack of nuclear waste. Each of these will be briefly explored to create a basis of understanding of how the LFTR differs from conventional uranium-based reactors. The economic effects of these differences will be used to estimate the cost of using thorium-based reactors. 1. Safety One of the main safety features in a liquid fluoride thorium reactor is that the reactor is held at atmospheric pressure during operation. Between 1966 and 1968, Oak Ridge National Laboratories built the Molten Salt Reactor Experiment. This was meant to investigate the performance and the technology needed to build a molten salt reactor. This reactor was operated above 707 C safely. 26 The fluoride salts have boiling points around 1400 C. Because of this, the salt does not need to be pressurized to remain a liquid and the reactor can operate at atmospheric pressure. This is not the case in a conventional PWR because the water is highly pressurized to keep it a liquid at the operational temperatures of the reactor. Without highly pressurized liquid, the LFTR does not risk explosions and would not require large containment infrastructure. 27 Figure 11: Layout of a LFTR. Note the freeze plug and emergency tank. 25 Molten-Salt Reactors History, Status, and Potential, Molten-Salt Reactors History, Status, and Potential, 1969, pg.2 27 American Scientist, Liquid Fluoride Thorium Reactors, 2010, pg

11 A second safety feature of using a LFTR is the inability for the core to meltdown. A meltdown occurs when the core overheats, causing the fuel assemblies to melt their casings and fall to the bottom of the reactor pool. This has the ability to melt through the concrete containment building and risks releasing highly radioactive isotopes into the environment. In the 2011 Fukushima Diiachi Accident, one of the cores underwent a partial meltdown but did not release radioactive material into the environment. In the LFTR, a meltdown can t occur because the fuel is already liquid! Figure 12 However, LFTRs also have a safety feature called a freeze plug. This is a portion of salt at the bottom of the reactor that is kept frozen by a fan (or other means of active cooling). In the event of a power outage (which occurred at Fukushima), the active cooling stops and allows the plug to melt. This causes the fuel to drain into a tank below the reactor that safely contains the fuel. In this tank, the reaction quickly stops because thorium is no longer being bred into U-233 to fuel the reaction Radioactive Waste One of the problems with conventional nuclear power is the production of large amounts of radioactive waste. Such waste is very radioactive and must be carefully stored. To understand the creation of nuclear waste, one must first understand a phenomenon known as neutron poisoning. Xe-135 is formed as a result of fission and is a so called poison. This is because it absorbs neutrons that would otherwise be used to react other nuclei. In a conventional reactor Xe-135, other noble gases, and fission products build up in the solid fuel arrays and the fuel pellets must be changed out before all the available uranium has undergone fission. However, in a liquid fuel, such wastes can be easily removed. For example, the xenon bubbles out of the fuel as the liquid salt is circulated through the reactor. 29 Figure 13: Nuclear waste still poses a problem to the nuclear power industry. When a nucleus absorbs a neutron, it does not always undergo fission. This causes transuranics, elements with atomic numbers larger than uranium, to form. These include curium, plutonium, and americium. Transuranics are the main cause of long term American Scientist, Liquid Fluoride Thorium Reactors, 2010, pg

12 radioactivity of nuclear waste. 30 Typically, these transuranics can be allowed to undergo fission inside the nuclear reactor. However, due to the problem of xenon poisoning mentioned above as well as the build-up of other fission products, conventional solid fuel can no longer sustain the nuclear chain reaction. It must be removed before all the uranium or the transuranics are used. This is very inefficient and yields radioactive waste. However, in a liquid fuel, fission products can be removed and transuranics can be left in the fuel to be consumed. In fact, transuranics from nuclear waste can be disposed of by being put in a LFTR. 31 While LFTRs produce some fission products as radioactive waste, these have shorter half-lives and after 300 years, are less radioactive than uranium ore. 3. Efficiency As described in the section above, traditional nuclear power plants must remove their fuel assemblies before all the uranium has undergone fission because waste products such as Xe-135 buildup. However, the liquid fluoride thorium reactor uses liquid fuel where waste products can be easily removed. Portions of the fuel can be consistently rerouted through an onsite reprocessing facility and the waste removed. This allows all the thorium fuel to be fissioned and gives LFTRs a greater efficiency than traditional nuclear power plants. IX. Economic Advantages 1. Availability of Fuel Uranium ore makes up % of the Earth s crust. However, thorium makes up % of the Earth s crust. 32 This is means that thorium is more than 3 times as abundant as uranium. Figure 14 shows the distribution of uranium resources in the US. Compare this to the distribution of thorium resources in the US (Figure 15). Notice that while the red in the uranium concentrations map is 5ppm, the red in the thorium map is 16ppm. The green in the thorium map is about 5ppm, which is the equivalent of the red in the uranium concentrations map. From these maps, we see that thorium and Figure 14: Uranium resources in the US. Note the scale is different than that of the thorium concentrations map. uranium deposits are similar in their distribution in the US but the amount of thorium is approximately 3 times more than uranium

13 LFTRs would be able to tap into these vast resources. Because LFTRs are also much more efficient than conventional nuclear reactors, developing a national energy system based on thorium will allow the United States to lean away from its addiction to petroleum. An energy system based on thorium has the potential to replace the current oil economy and help the US develop energy independence, relying on US thorium rather than foreign petroleum. 2. Decreased Cost Figure 15: Thorium resources in the US. Note the scale is different than that of the uranium concentrations map. In the nuclear power section of this investigation, the cost of nuclear power was estimated to be 6.22c/kWh using the Diablo Canyon Reactors as a model. Assuming the technology for LFTRs is fully developed, the cost of a liquid fluoride thorium reactor can be lower than that of conventional nuclear. As mentioned in the technological advantages section, LFTRs do not use pressurized water to transfer heat from the core. Conventional nuclear power plants do, and consequently require large, expensive containment structures to keep in radioactive steam in the event of a leak. LFTRs would still need containment structures to contain radiation in the event of an accident but because they do not need to worry about large volumes of steam, the structures can be much smaller and thus less expensive. 33 Another source of economic savings is in disposal of nuclear waste. As previously discussed, traditional nuclear power plants have large quantities of unused uranium, fission products and transuranic waste. A LFTR however would be able to fission the majority of the thorium fuel and transuranic waste. The only waste that would need to be stored is fission products. This reduces the disposal costs, and thus the overall cost, of a LFTR. Figure 16: The layout of the Molten Salt Reactor Experiment built by Oak Ridge Laboratory in American Scientist, Liquid Fluoride Thorium Reactors, 2010, pg

14 X. Cost of a Liquid Fluoride Thorium Reactor 1. Assuming the Research has been Developed In this first case, the assumption will be made that the LFTR technology has matured enough for large scale production and use. The focus will be on the capital, fuel, and operating and maintenances costs. This analysis is comparable to that used in calculating the cost of conventional nuclear power. Figure 17: ORNL Director Alvin Weinberg (far left, standing) 1968 In a 1969 publication titled Molten Salt Reactors History, Status, and Potential, scientists at the Oak Ridge National Laboratory (ORNL) estimated that the cost of a molten salt reactor (under which liquid fluoride thorium reactors are categorized), can be 0.5 to 1 mill/kwh (this translates to c/kWh in 2012) lower than that of light-water reactors given the cost of uranium in If the price of uranium increases (which was shown to be true in the conventional nuclear section), then the cost differential will be even larger. On page 4, under the cost analysis of current nuclear power, the Diablo Canyon reactors were determined produce power at a cost of 6.22c/kWh. Using the Oak Ridge National Laboratory estimate, a molten salt reactor of the same power output as the Diablo Canyon reactors could cost between 5.46c/kWh to 4.72c/kWh. A second approach can be taken to estimate the cost of a LFTR. The cost of building a LFTR can also be estimated by analyzing the Oak Ridge National Laboratory s Molten Salt Reactor Experiment (MSRE). This experimental reactor was built in 1962 and aimed to show that a liquid fluoride thorium reactor was feasible. A report published in 1966 analyzed the total cost of a 1000MWe power plant equivalent of the test-scale MRSE 34. In this model, the cost of a LFTR in 2012 in estimated to be. total plant cost = cost of reactor plant + cost of processing plant total plant cost (in 1966) = $113,583,000 + $5,300,080 total plant cost (in 1966) = $118,883,080 The producer price index for energy products and services in 1966, taking 2012 as the base year, was Using this to deflate the total plant cost in 1966 to a 2012 cost,

15 total plant cost (in 2012) = $118,883,080 (100) = $1.7883x Assuming the life span of this plant is the same as that of a conventional nuclear power plant of 60yrs, amortized cost of the plant at a 6% discount rate is: Variable Annual Cost = $109.79x10 6 The ORNL report also estimated the yearly operating and management costs to be Deflating this to a 2012 cost, The total annual cost, without fuel, is thus: O&M (in 1966) = $721,230 O&M (in 2012) = $721,230 (100) = $10.850x total annual cost (without fuel) = $120.6x10 6 The molten salt reactor under consideration is this publication is a 1000MW reactor. Because the reactor can be run continuously without shutting down for refueling, let s assume that the reactor is operated continuously for a full year. Under this condition, it produces: Energy produced = 1,000,000kW(8760hr) = 8.76x10 9 kwh This means that the cost/kwh is: c/kwh (no fuel) = total annual cost annual energy produced = $120.6x x10 9 kwh = 1.37c/kWh This publication also estimates the overall fuel cost to be: fuel cost (in 1966) = mills/kWh = c/kWh The price of thorium from 1966 to 1978 had dropped by more than 50% and prices for commercial quantities of thorium have not been kept track of since. 36 From Figure 18, if the trend in thorium prices continued since 1980, we can extrapolate that the cost per kg of thorium in 2012 is very small

16 Figure 18: Price of thorium since Prices dropped so low that it was no longer kept track of after Figure 19 compares the fuel requirements of a LFTR against conventional nuclear. 37 Figure 19: Comparison of fuel-input and energy-output of conventional nuclear and LFTRs

17 The amount of energy yield by thorium is 11,000 GWh/MT of thorium. This translates to 11,000 GWh MT = 11,000x106 kwh 10 9 = 11kWh kg kg kg = kg kwh Therefore the amount of thorium needed to produce 1 kwh of energy is 1. If the 11 kwh price of thorium as seen in Figure 18 is very low, the cost/kg of thorium is even lower. This fuel cost is negligible in comparison to the capital and O&M costs of LFTRs. The cost of a LFTR in 2012 would approximately be 1. 37c/kWh. Compare this to the cost of nuclear power which was estimated to be 6. 22c/kWh. From this comparison, thorium is a much less costly source of nuclear energy compared to conventional nuclear. Conventional Nuclear Liquid Fluoride Thorium Reactor (LFTR) Capital Cost (USD 2012 base) 4.00 c/kwh 1.25 c/kwh O&M Cost (USD 2012 base) 1.51 c/kwh 0.12 c/kwh Fuel Cost (USD 2012 base) 0.71 c/kwh Negligible Total 6.22 c/kwh 1.37 c/kwh Table 3: Cost Breakdown comparison between conventional nuclear and thorium. XI. Conclusion Traditional nuclear power is an alternative to fossil fuels and is a very competitive source of energy compared to other green sources of energy. The estimated cost is only 6.22 c/kwh. However, as demonstrated by the Fukushima-Diiachi 2011 accident, conventional nuclear power has its flaws. Not only is it capable of a meltdown and requires large containment units, it is also very inefficient and results in large quantities of radioactive waste. An alternative to uraniumbased nuclear is thorium-based nuclear. Thorium is more abundant in the United States and less expensive than uranium. Liquid fluoride thorium reactors (LFTRs) are capable of using up a larger percentage of the fuel and so are more efficient. LFTRs also have inherent safety features that virtually eliminate the possibility of a meltdown. Best of all, the estimated cost of a LFTR is 1.37 c/kwh lower than conventional nuclear, coal, and natural gas! This investigation has shown that LFTRs are technologically and economically superior to conventional nuclear. In order for the United States to satisfy its rapidly growing energy demands, it would be beneficial and worthwhile for the United States to reinvest in the development and wide-spread production of liquid fluoride thorium reactors. [Word Count: 5190] 17

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