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Wouldn’t it be great if we had an energy source for electricity that was…

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Wouldn’t it be great if we had an energy source for electricity that was…

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  1. “We Americans want it all: endless and secure energy supplies; low prices; no pollution; less global warming; no new power plants (or oil and gas drilling, either) near people or pristine places. This is a wonderful wish list, whose only shortcoming is the minor inconvenience of massive inconsistency.” —Robert Samuelson

  2. Wouldn’t it be great if we had an energy source for electricity that was…

  3. The liquid-fluoride thorium reactor is incredibly stable against nuclear reactivity accidents—the type of accident experienced at Chernobyl. It is simply not possible because any change in operating conditions results in a reduction in reactor power. The LFTR is also totally, passively safe against loss-of-coolant accidents—the type of accident that happened at Three Mile Island. It is simply not possible because in all cases the fuel drains into a passively safe configuration. …inherently safe to operate,

  4. …resistant to sabotage and attack, • Basing thorium reactors in submarines would enable them to withstand horrible weather and aircraft attack. • It would also enable them to be built in shipyards and moved close to coastal population centers, minimizing transmission losses.

  5. …does not produce weapons-grade material,

  6. …300 times more energy-dense than uranium, Uranium-fueled light-water reactor: 35 GW*hr/MT of natural uranium Conversion and fabrication 32,000 MW*days/tonne of heavy metal (typical LWR fuel burnup) 33% conversion efficiency (typical steam turbine) Conversion to UF6 293 MT of natural U3O8 (248 MT U) 1000 MW*yr of electricity 365 MT of natural UF6 (247 MT U) 39 MT of enriched (3.2%) UO2 (35 MT U) 3000 MW*yr of thermal energy Thorium-fueled liquid-fluoride reactor: 11,000 GW*hr/MT of natural thorium Thorium metal added to blanket salt through exchange with protactinium 914,000 MW*days/MT 233U (complete burnup) 50% conversion efficiency (triple-reheat closed-cycle helium gas-turbine) Conversion to metal 0.9 MT of natural ThO2 0.8 MT of thorium metal 1000 MW*yr of electricity 0.8 MT of 233Pa formed in reactor blanket from thorium (decays to 233U) 2000 MW*yr of thermal energy Uranium fuel cycle calculations done using WISE nuclear fuel material calculator: http://www.wise-uranium.org/nfcm.html

  7. Today’s Uranium Fuel Cycle vs. Thoriummission: make 1000 MW of electricity for one year 35 t of enriched uranium (1.15 t U-235) Uranium-235 content is “burned” out of the fuel; some plutonium is formed and burned • 35 t of spent fuel stored on-site until disposal at Yucca Mountain. It contains: • 33.4 t uranium-238 • 0.3 t uranium-235 • 0.3 t plutonium • 1.0 t fission products. 250 t of natural uranium containing 1.75 t U-235 215 t of depleted uranium containing 0.6 t U-235—disposal plans uncertain. Within 10 years, 83% of fission products are stable and can be partitioned and sold. One tonne of natural thorium One tonne of fission products; no uranium, plutonium, or other actinides. Thorium introduced into blanket of fluoride reactor; completely converted to uranium-233 and “burned”. The remaining 17% fission products go to geologic isolation for ~300 years.

  8. …virtually limitless in availability, • Thorium is abundant around the world and rich in energy. • There will be no need to horde or fight over this resource—there’s enough for millions of years! The United States has buried 3200 metric tonnes of thorium nitrate in the Nevada desert. There are 160,000 tonnes of economically extractable thorium in the US, even at today’s “worthless” prices!

  9. …produces far less waste… 1 GW*yr of electricity from a uranium-fueled light-water reactor Conversion to natural UF6 (247 MT U) Mining 800,000 MT of ore containing 0.2% uranium (260 MT U) Milling and processing to yellowcake—natural U3O8 (248 MT U) Generates 170 MT of solid waste and 1600 m3 of liquid waste Generates ~600,000 MT of waste rock Generates 130,000 MT of mill tailings 1 GW*yr of electricity from a thorium-fueled liquid-fluoride reactor Mining 200 MT of ore containing 0.5% thorium (1 MT Th) Milling and processing to thorium nitrate ThNO3 (1 MT Th) Generates 0.1 MT of mill tailings and 50 kg of aqueous wastes Generates ~199 MT of waste rock Uranium fuel cycle calculations done using WISE nuclear fuel material calculator: http://www.wise-uranium.org/nfcm.html

  10. …than a comparable uranium reactor, 1 GW*yr of electricity from a uranium-fueled light-water reactor Enrichment of 52 MT of (3.2%) UF6 (35 MT U) Fabrication of 39 MT of enriched (3.2%) UO2 (35 MT U) Irradiation and disposal of 39 MT of spent fuel consisting of unburned uranium, transuranics, and fission products. Generates 314 MT of DUF6; consumes 300 GW*hr of electricity Generates 17 m3 of solid waste and 310 m3 of liquid waste 1 GW*yr of electricity from a thorium-fueled liquid-fluoride reactor Disposal of 0.8 MT of spent fuel consisting only of fission product fluorides Conversion to metal and introduction into reactor blanket Breeding to U233 and complete fission Uranium fuel cycle calculations done using WISE nuclear fuel material calculator: http://www.wise-uranium.org/nfcm.html

  11. 1998 World Energy Consumption The Future: Energy from Thorium 5 billion tonnes of coal (112 quads) 27 billion barrels of oil (156 quads) 82 trillion ft3 of natural gas (84 quads) 5,000 tonnes of thorium (376 quads) 65,000 tonnes of uranium ore (24 quads)

  12. Energy Comparison 230 train cars (25,000 MT) of bituminous coal or, 600 train cars (66,000 MT) of brown coal, (Source: World Coal Institute) = or, 440 million cubic feet of natural gas (15% of a 125,000 cubic meter LNG tanker), 6 kg of thorium metal in a liquid-fluoride reactor has the energy equivalent (66,000 MW*hr) of: or, 300 kg of enriched (3%) uranium in a pressurized water reactor.

  13. Fluoride reactor technology to utilize thorium was demonstrated at Oak Ridge National Lab in the 1960s. They also developed a complete approach to nuclear reprocessing—closing the nuclear fuel cycle inside the reactor itself! …utilizes existing technology,

  14. Alvin Weinberg: Why wasn’t this done? “Why didn't the molten-salt system, so elegant and so well thought-out, prevail? “I've already given the political reason: that the plutonium fast breeder arrived first and was therefore able to consolidate its political position within the AEC. “But there was another, more technical reason. The molten-salt technology is entirely different from the technology of any other reactor. To the inexperienced, [fluoride] technology is daunting… Perhaps the moral to be drawn is that a technology that differs too much from an existing technology has not one hurdle to overcome—to demonstrate its feasibility—but another even greater one—to convince influential individuals and organizations who are intellectually and emotionally attached to a different technology that they should adopt the new path. “It was a successful technology that was dropped because it was too different from the main lines of reactor development… I hope that in a second nuclear era, the [fluoride-reactor] technology will be resurrected.”

  15. “Mac” MacPherson: Why wasn’t this done? • The political and technical support for the program in the United States was too thin geographically. Within the United States, only in Oak Ridge, Tennessee, was the technology really understood and appreciated. • The thorium-fueled fluoride reactor program was in competition with the plutonium fast breeder program, which got an early start and had copious government development funds being spent in many parts of the United States. When the fluoride reactor development program had progressed far enough to justify a greatly expanded program leading to commercial development, the Atomic Energy Commission could not justify the diversion of substantial funds from the plutonium breeder to a competing program.

  16. Reference Slides

  17. Thorium was discovered in 1828 by the Swedish scientist Jons Jacob Berzelius. Berzelius named thorium after Thor, the Norse god of thunder. There was little to say about thorium when it was first discovered apart from its specific weight and its high-temperature capabilities. “thallium, thorium, thulium…” The Discovery of Thorium

  18. Thorium and Uranium Abundant in the Earth’s Crust -235 0.018

  19. In 1898, Marie Curie made a remarkable discovery: Thorium and uranium were radioactive! But with a 15 billion-year half-life (older than the universe), it didn’t decay very often and had very low radioactivity… Eventually thorium decays to lead-208. Thorium is Radioactive

  20. Can Nuclear Reactions be Sustained in Natural Uranium? Not with thermal neutrons—need more than 2 neutrons to sustain reaction (one for conversion, one for fission)—not enough neutrons produced at thermal energies. Must use fast neutron reactors.

  21. Can Nuclear Reactions be Sustained in Natural Thorium? Yes! Enough neutrons to sustain reaction produced at thermal fission. Does not need fast neutron reactors—needs neutronic efficiency.

  22. Thorium-Uranium Breeding Cycle Protactinium-233 decays more slowly (half-life of 27 days) to uranium-233 by emitting a beta particle (an electron). Thorium-233 decays quickly (half-life of 22.3 min) to protactinium-233 by emitting a beta particle (an electron). It is important that Pa-233 NOT absorb a neutron before it decays to U-233—it should be from any neutrons until it decays. Pa-233 Th-233 U-233 Uranium-233 is fissile and will fission when struck by a neutron, releasing energy and 2 to 3 neutrons. One neutron is needed to sustain the chain-reaction, one neutron is needed for breeding, and any remainder can be used to breed additional fuel. Thorium-232 absorbs a neutron from fission and becomes thorium-233. Th-232

  23. Lifetime of a Typical Uranium Fuel Element • Conventional fuel elements are fabricated from uranium pellets and formed into fuel assemblies • They are then irradiated in a nuclear reactor, where most of the U-235 content of the fuel “burns” out and releases energy. • Finally, they are placed in a spent fuel cooling pond where decay heat from radioactive fission products is removed by circulating water.

  24. Ionically-bonded fluids are impervious to radiation • The basic problem in nuclear fuel is that it is covalently bonded and in a solid form. • If the fuel were a fluid salt, its ionic bonds would be impervious to radiation damage and the fluid form would allow easy extraction of fission product gases, thus permitting unlimited burnup.

  25. Neutrons are moderated through collisions Neutron born at high energy (1-2 MeV). Neutron moderated to thermal energy (<<1 eV).

  26. Nuclear Aircraft Concept • Convair B-36 X-6 • Four nuclear-powered turbojets • 200 MW thermal reactor Liquid-Fluoride Reactor

  27. 1954 Aircraft Reactor Experiment (ARE)

  28. ARE Demonstrated Liquid-Fluoride Reactor Technology • Evolution of Na-cooled, solid fuel design • Fuel: NaF-ZrF4-UF4 (53-41-6) (mole%) • Operated > 100MW-hr • Max. fuel temp. 882°C • Very large neg. temp. coeff (-6.1E-5) • Reactor was slave to load Core Vol.: 1.37 ft3 Loop Vol.: 3.60 ft3 Pump Vol.: 1.70 ft3 (Na)

  29. 60 MWt Aircraft Reactor Test 55.62 in. Island 10.75 in. • 1.3 MW/L (max. design) • 1144K core outlet temp. • 1500 hr. design life • 10 ft3 total fuel volume • 3.2 ft3 core fuel volume

  30. Molten-Salt Reactor Program (MSRP) began in 1958 Core Vol.: 113.2 ft3 Loop Vol.: 57.5 ft3 LiF-BeF2-UF4 Fuel 6 ft

  31. MSBR’58 Reactor Plant Isometric Image source: ORNL-2634: MSRP Status Report, pg 3

  32. Earliest Concept of the MSRE Image source: ORNL-3014: MSRP-QPR-07/60, pg 4, 7

  33. 1967 Molten Salt Breeder Reactor (MSBR) Was Two-Region, Two-Fluid Design • 1000 MW(e) • Fuel: 7LiF-BeF2-UF4 • Blanket: 7LiF-BeF2-ThF4 • Continuous on-line fuel processing • 45% thermal efficiency • Many fission products removed on-line allowing reactor to operate with less fuel

  34. Two-Fluid LFRs were easy to process

  35. 1969 Molten Salt Breeder Reactorwas Two-Region, One-Fluid Design • Molten Salt Breeder Reactor (MSBR) • 1000 Mw(e) (2250 MWt) • 2-region-two-fluid system • Fuel: 7LiF-BeF2-ThF4-UF4 • Breeding ratio: 1.06

  36. One-Fluid LFRs were more challenging

  37. Gen-4 Molten-Salt Reactor Concept

  38. Decay Chain Fission Yield Gadolinium Europium Samarium 6.0% Promethium Neodymium Praseodymium Cerium Lanthanum 5.0% Barium Cesium Xenon Iodine Tellurium Antimony 4.0% Tin Indium Cadmium Silver Palladium 3.0% Rhodium Ruthenium Technetium Molybdenum Niobium Zirconium 2.0% Yttrium Strontium Rubidium Krypton Bromine 1.0% Selenium Arsenic Germanium Gallium Zinc Copper 0.0% 75 77 79 81 83 85 87 89 91 93 95 97 99 101 103 105 107 109 111 113 115 117 119 121 123 125 127 129 131 133 135 137 139 141 143 145 147 149 151 153 155 157 159

  39. Kentucky Dam Hydro 223 Pickwick Hydro 240 Wilson Hydro 675 Wheeler Hydro 412 Browns Ferry Nuclear 2285 Guntersville Hydro 140 Nickajack Hydro 104 Chickamauga Hydro 160 Sequoyah Nuclear 2320 Watts Bar Nuclear 1167 Watts Bar Hydro 175 Fort Loudoun Hydro 156 Douglas Hydro 166 Johnsonville Coal 1254 Colbert Coal 1198 Widows Creek Coal 1629 Kingston Coal 1456 John Sevier Coal 712 Bull Run Coal 870 Power Generation along the Tennessee River

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