The Reactor
Charlie Earl
In our two
previous columns we provided an introductory overview and a closer look at
Thorium as an energy source. Some mode of processing is necessary to transform
Thorium from mere particles of soil into a reliable energy source. A reactor is
needed, but not the huge dome-like structures we see dotting our horizons. The
Liquid Fluoride Thorium Reactor (LFTR or “lifter”) can be a much smaller
version than its monstrous cousin. Although not too hip, the LFTR is a much
cooler dude than its hotter uranium-based counterpart. Cooler is better and
less dangerous for local communities than is the current technology for nuclear
electricity generation. Although nuclear energy has an amazing safety record,
the echoes of Chernobyl still linger and decrease the opportunities for
developing new plants. LFTR technology using Thorium as a fuel source can allay
the fears of many and meet our power requirements.
Once again
we turn to our legion of buddies on Wikipedia to explain the differences:
Reactors that use the uranium-plutonium fuel cycle
require fast
reactors to sustain breeding, because only with fast moving neutrons, the
fission process provides more than 2 neutrons per fission. With thorium, it is
possible to breed using a thermal reactor. This was proven to work in the Shippingport Atomic Power Station,
whose final fuel load bred slightly more fissile from thorium than it consumed,
despite being a very neutron inefficient reactor type (Shippingport was a
fairly standard light water reactor). Such thermal reactors
require much less of the expensive fissile fuel to start and have a slow,
gentle response in power changes.
It’s that “slow gentle response in power changes” that
illustrates a primary safety-related aspect of the Thorium/LFTR union. A LFTR
malfunction will cool down rather than meltdown. A recent illustration might be
the Japanese reactors that were affected by the tsunami. When the operating
situation was radically altered by atmospheric conditions and structural
breaches, the units moved into meltdown and critical mass modes before
technicians or operators could fully shut them down. In other words…the soup
continued boiling after the stove was turned off. The LFTR reactor’s natural
state is to cool down rather than accelerate the heating process.
The safer aspects of LFTR technology are advantageous
when locating the power plants. Because the plant cools down if it malfunctions,
it does not have to be located adjacent to bodies of water as do our present
nuclear plants. Smaller units can be constructed to serve smaller geographical
areas thus providing an extensive backup or redundancy if a plant had to be
shut down for routine maintenance, expansion or any other reason. As a
consequence, the cost per unit, transmission costs and power losses are
reduced. Each unit would require a much smaller footprint than the present
plants, and would not disturb a community’s community aesthetic appeal. Some
experts in the field believe that it may ultimately be possible to construct
smaller units that might serve a huge industrial plant, an industrial park or
perhaps a subdivision. Safety and savings will be radically enhanced when our power
generation is in not concentrated in a very few vulnerable locations.
There are multiple side benefits that accrue when LFTR
technology is utilized.
Fission products of a LFTR include stable rare elements
such as rhodium, ruthenium, palladium, xenon, neodymium, molybdenum, zirconium
and cesium, which are relied heavily on in modern electronics and industrial
processes. Xenon is easily removable during normal operation since it is a gas
and has a low solubility in the fluoride fuel salt. The radioactive isotopes of
xenon decay quite quickly leaving radioactive cesium behind, which is easily
separated from the stabilized xenon. Xenon and krypton, the remaining noble
gasses, can be readily separated by their mass or boiling point (cryogenic
separation) after the initial short term decay holdup period. Xenon-136 has
high value in physics experiments
Conventional
reactors consume less than one percent of their uranium fuel, leaving the rest
as waste. With well working reprocessing LFTR may consume over 99% of its
thorium fuel. The improved fuel efficiency means that 1 tonne 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),[6]
or 4,166,000 tonnes of black coal in a coal power plant.
More efficient,
safer and more flexible are reasons enough for supporting LFTR technology.
Cheaper to construct, lower transmission costs and numerous application
possibilities are mere icing on the cake.
Energy From Thorium Foundation: www.th90.org
Coalition of Freedom: www.coalitionoffreedom.com
Charlie Earl
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