Liquid Fluoride Thorium Reactors

OverviewOverview• Introduction to nuclear reactors• Fundamentals of LFTR (Liquid Fluoride

Thorium Reactors)• Economic viability• LFTR safety• Environmental impact• Challenges• Conclusion• Recommendations

http://www.thoriumenergyalliance.com/downloads/American_Scientist_Hargraves.pdf

Traditional Nuclear Reactors• Traditional nuclear reactors use fuel rods

made up of enriched Uranium oxide.• Energy is generated when Uranium-235

receives a neutron and undergoes fission, breaking apart to create smaller elements as well as neutrons to sustain further fission of other U-235 atoms.

• The heat from this reaction evaporates water to drive a steam turbine, creating electricity

http://www.biofuelswatch.com/wp-content/uploads/2010/01/nuclear-fission-196x300.png

Traditional Nuclear Reactors IssuesTraditional Nuclear Reactors Issues

2,859 GRADUATE

• Large amounts of nuclear waste

• Some nuclear waste take over a millennium to degrade.

• Potential for runaway reaction (i.e. a “meltdown”).

http://static.guim.co.uk/sys-images/Guardian/About/General/2009/10/19/1255947981833/nuclear-waste-001.jpg

• Operated under pressure with water at high temperature. A tank rupture can cause radioactive material to flash to the atmosphere.

Liquid Fluoride Thorium ReactorsLiquid Fluoride Thorium Reactors• Uses Thorium-232 as fuel, with a small amount of Uranium-233 undergoing fission to initiate reaction before becoming self-sustaining.• Thorium-232 accepts a neutron to become Thorium-233, eventually decaying into more Uranium-233 to continue the cycle.

Liquid Fluoride Thorium ReactorsLiquid Fluoride Thorium Reactors

http://www.viewzone.com/thorium+cycle.gif

Liquid Fluoride Thorium ReactorsLiquid Fluoride Thorium Reactors

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• Fuel for the LFTR is a Thorium tetrafluoride – Beryllium salt.• The salt is solid at room temperature, but becomes at liquid in the high operating temperatures found in the LFTR.

http://energyfromthorium.com/images/LFTR_TMRgraphic.png

Economic ViabilityEconomic Viability• Price of thorium is comparable to

that of uranium. • 1 tonne of Thorium can produce

approximately 1 gigawatt of energy compared to the needed 177 tonnes of Uranium for the same amount of energy in a conventional reactor.

• No need for cooling towers, smaller equipment than traditional nuclear plant, and less land area required for site reduce fixed capital investments.

http://www.thorium.tv/images/thorium_metal_ingot.jpg

LFTR SafetyLFTR Safety• LFTR feed and wastes

cannot be weaponized without advanced separation facilities.

• U233 (bomb making material) is recycled back into the cycle and consumed.

• This U233 is also contaminated with U232 which is very radioactive and hard to separate

http://pfpfp.org/wp-content/uploads/2012/01/nuclear-explosion.png

LFTR SafetyLFTR Safety• LFTR’s operate at atmospheric

pressure and cannot flash radioactive material in case of tank rupture.

• LFTR’s operate at high temperature (~ 800 )℃ to keep the thorium-fluoride salt in the liquid state.

• LFTR’s have a passive meltdown safety measure. A solidified plug of thorium-fluoride is maintained electrically. If power/cooling should fail, the plug will melt, dumping the reactor contents into tanks. http://www.viewzone.com/thorium.html

EnvironmentalEnvironmental ImpactImpact• LFTR’s burn

almost all fuel, producing very little waste.

• After processing, 83% of the waste degrades within 10 years. Approximately 17% of the waste degrades in under 300 years.

Sustainability• Thorium is the 36th

abundant element on Earth.

• A US geological study from 2010 estimated the global Thorium reserves to be approximately 1.66 million tonnes.

http://thoriumenergyalliance.com/downloads/usa_thorium_map.gif

ChallengesChallenges • Reactor still requires some U233 to start the

reaction.• There is limited information on the chemical

and physical properties of liquid thorium-fluoride salt.

• Very small amount of long-lasting radioactive wastes that still lack a method of separation from short-term waste. Viable methods have been suggested but are untested.

• Properties of Thorium fuel cycles are not well documented compared to traditional fission routes. More research needs to be done before investing in LFTR’s.

ConclusionConclusion• Thorium is abundant

enough to sustain current global energy needs for the next thousand years.

• Thorium is a profitable and more environmentally friendly than other nuclear alternatives.

• The LFTR has much greater inherent safety over traditional nuclear reactors.

RecommendationsRecommendations• Invest further research in the

properties the chemical and physical properties of liquid thorium-fluoride.

• Place a higher focus on designing separation methods for the LFTR waste products.

• Build more pilot plants to better understand nuances of LFTR’s.

http://www.thoriumenergyalliance.com/downloads/American_Scientist_Hargraves.pdf

ReferencesReferences1. Hargraves, R., & Ralph, M. (2010). Liquid fluoride thorium reactors. American

Scientist, 98, 304-313. Retrieved from http://www.thoriumenergyalliance.com/downloads/American_Scientist_Hargraves.pdf

2. Arjun, M., & Michele, B. (2009). Thorium fuel: No panacea for nulcear power. PSR, 1-3. Retrieved from http://ieer.org/wp/wp-content/uploads/2012/04/thorium2009factsheet.pdf

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