Liquid Fluoride Thorium Reactors
Overview
• 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 Issues
• Large amounts of
nuclear waste
• Some nuclear waste
take over a millennium
2,859
GRADUATE
to degrade.
• Potential for runaway
reaction (i.e. a
“meltdown”).
• Operated under pressure with water at high
temperature. A tank rupture can cause radioactive
material to flash to the atmosphere.
http://static.guim.co.uk/sys-images/Guardian/About/General/2009/10/19/1255947981833/nuclear
waste-001.jpg
Liquid Fluoride Thorium Reactors
• Uses Thorium-232 as fuel,
with a small amount of
Uranium-233 undergoing
fission to initiate reaction
before becoming selfsustaining.
• Thorium-232 accepts a
neutron to become Thorium233, eventually decaying into
more Uranium-233 to continue
the cycle.
Liquid Fluoride Thorium Reactors
http://www.viewzone.com/thorium+cycle.gif
Liquid Fluoride Thorium Reactors
• 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://img3.imageshack.us/img3/2999/saltmelt1.gif
http://energyfromthorium.com/images/LFTR_TMRgraphic.png
Economic 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 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 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 thoriumfluoride 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
Environmental Impact
• 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
Challenges
• Reactor still requires some U233 to start the
reaction.
• There is limited information on the chemical
and physical properties of liquid thoriumfluoride 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.
Conclusion
• 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.
Recommendations
• 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_Hargrav
es.pdf
References
1. Hargraves, R., & Ralph, M. (2010). Liquid fluoride thorium reactors. American
Scientist, 98, 304-313. Retrieved from
http://www.thoriumenergyalliance.com/downloads/American_Scientist_Hargra
ves.pdf
2. Arjun, M., & Michele, B. (2009). Thorium fuel: No panacea for nulcear power.
PSR, 1-3. Retrieved from http://ieer.org/wp/wpcontent/uploads/2012/04/thorium2009factsheet.pdf
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