page_title: Liquid fluoride thorium reactor
section_title: Economy and efficiency
hierarchical_section_title: Liquid fluoride thorium reactor / Advantages / Economy and efficiency
caption_attribution_description: English: A comparison of annual fuel requirement of 1GW classic uranium-fueled LWR power plant and 1GW thorium-fueled LFTR power plant
context_page_description: The liquid fluoride thorium reactor is a type of molten salt reactor. LFTRs use the thorium fuel cycle with a fluoride-based, molten, liquid salt for fuel. In a typical design, the liquid is pumped between a critical core and an external heat exchanger where the heat is transferred to a nonradioactive secondary salt. The secondary salt then transfers its heat to a steam turbine or closed-cycle gas turbine.
  Molten-salt-fueled reactors supply the nuclear fuel mixed into a molten salt. They should not be confused with designs that use a molten salt for cooling only and still have a solid fuel. Molten salt reactors, as a class, include both burners and breeders in fast or thermal spectra, using fluoride or chloride salt-based fuels and a range of fissile or fertile consumables. LFTRs are defined by the use of fluoride fuel salts and the breeding of thorium into uranium-233 in the thermal neutron spectrum.
  The LFTR concept was first investigated at the Oak Ridge National Laboratory Molten-Salt Reactor Experiment in the 1960s, though the MSRE did not use thorium. The LFTR has recently been the subject of a renewed interest worldwide.
context_section_description: Thorium abundance. A LFTR breeds thorium into uranium-233 fuel. The Earth's crust contains about three to four times as much thorium as U-238 (thorium is about as abundant as lead). It is a byproduct of rare-earth mining, normally discarded as waste. Using LFTRs, there is enough affordable thorium to satisfy the global energy needs for hundreds of thousands of years. Thorium is more common in the earth's crust than tin, mercury, or silver. A cubic meter of average crust yields the equivalent of about four sugar cubes of thorium, enough to supply the energy needs of one person for more than ten years if completely fissioned. Lemhi Pass on the Montana-Idaho border is estimated to contain 1,800,000 tons of high-grade thorium ore. Five hundred tons could supply all U.S. energy needs for one year. Due to lack of current demand, the U.S. government has returned about 3,200 metric tons of refined thorium nitrate to the crust, burying it in the Nevada desert.
  No shortage of natural resources. Sufficient other natural resources such as beryllium, lithium, nickel and molybdenum are available to build thousands of LFTRs.
  Reactor efficiency. Conventional reactors consume less than one percent of the mined uranium, leaving the rest as waste. With perfectly working reprocessing LFTR may consume up to about 99% of its thorium fuel. The improved fuel efficiency means that 1 ton of natural thorium in a LFTR produces as much energy as 35 t of enriched uranium in conventional reactors (requiring 250 t of natural uranium), or 4,166,000 tons of black coal in a coal power plant.
  Thermodynamic efficiency. LFTRs operating with modern supercritical steam turbines would operate at 45% thermal to electrical efficiency. With future closed gas Brayton cycles, which could be used in a LFTR power plant due to its high temperature operation, the efficiency could be up to 54%. This is 20 to 40% higher than today's light water reactors (33%), resulting in the same 20 to 40% reduction in fissile and fertile fuel consumption, fission products produced, waste heat rejection for cooling, and reactor thermal power.
  No enrichment and fuel element fabrication. Since 100% of natural thorium can be used as a fuel, and the fuel is in the form of a molten salt instead of solid fuel rods, expensive fuel enrichment and solid fuel rods' validation procedures and fabricating processes are not needed. This greatly decreases LFTR fuel costs. Even if the LFTR is started up on enriched uranium, it only needs this enrichment once just to get started. After startup, no further enrichment is required.
  Lower fuel cost. The salts are fairly inexpensive compared to solid fuel production. For example, while beryllium is quite expensive per kg, the amount of beryllium required for a large 1 GWe reactor is quite small. ORNL's MSBR required 5.1 tons of beryllium metal, as 26 tons of BeF₂. At a price of $147/kg BeF₂, this inventory would cost less than $4 million, a modest cost for a multibillion-dollar power plant. Consequently, a beryllium price increase over the level assumed here has little effect in the total cost of the power plant.  The cost of enriched lithium-7 is less certain, at $120–800/kg LiF. and an inventory (again based on the MSBR system) of 17.9 tons lithium-7 as 66.5 tons LiF makes between $8 million and $53 million for the LiF. Adding the 99.1 tons of thorium at $30/kg adds only $3 million. Fissile material is more expensive, especially if expensively reprocessed plutonium is used, at a cost of $100 per gram fissile plutonium. With a startup fissile charge of only 1.5 tons, made possible through the soft neutron spectrum this makes $150 million. Adding everything up brings the total cost of the one time fuel charge at $165 to $210 million. This is similar to the cost of a first core for a light water reactor. Depending on the details of reprocessing the salt inventory once can last for decades, whereas the LWR needs a completely new core every 4 to 6 years (1/3 is replaced every 12 to 24 months). ORNL's own estimate for the total salt cost of even the more expensi
caption: Comparison of annual fuel requirements and waste products of a 1 GW uranium-fueled LWR and 1 GW thorium-fueled LFTR power plant.[58]
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