progress in the search for clean, safe and affordable energy that
doesn't destroy the environment.
At the moment most nuclear reactors use uranium as the main fuel. The
uranium fission process is pretty volatile and this can lead to a
meltdown but safety systems such as carbon control rods which SCRAM the
reaction mean disaster can be averted. A nuclear meltdown can be
catastrophic as the images from Chernobyl show. Just Google that and see
the devastating effects.
There was a competing technology involving Thorium that was developed in
the mid-20th century. It wasn't used commercially though.
Uranium needed for modern extractors is hard to find and takes a lot of
refining. Sophisticated techniques have been developed such as
bioengineering bacteria to get the elusive U-235. It means operating
costs are expensive however capital outlay costs are lower.
The by-products of uranium fission are much more difficult to dispose of
than those from thorium reactors (both kinds) but there's an important
by-product which is a significant reason for the popularity of the
uranium reactor over the thorium one: the former produces plutonium. The
needs of the Cold War could be met by uranium reactors but not the
thorium design.
Today one of the unique selling points of thorium reactors is they don't
produce plutonium. Plutonium is hard to detect because it releases alpha
particles which are easily shielded whereas the products of thorium
decay product gamma rays which can penetrate lead and be detected.
Thorium reactors mean there's no risk of proliferating weapons-grade
nuclear material.
The very latest thorium reactor designs are art. The reaction is primed
with a proton accelerator which generates neutrons to keep the process
going. Without the beam of protons producing neutrons to smash up the
thorium nuclei the reaction quickly stops. There's no need for carbon
control rods because the system
can't self-perpetuate.
Thorium is also a relatively abundant material with enough easily
available through modern mining techniques to power the human race for a
thousand years. The operating costs are significantly less.
The thorium is contained in small beads that are encased in tennis balls
sized containers. Layers of some of the toughest material in the world
encase the beads and balls. I think they use silicon carbide. Reactors
are expected to have a life measured in decades and these structures
have to survive the heat of a nuclear process. This is one of the
reasons why the capital cost is so high. The big unknown is whether
these structures can last the length of time thorium reactors are meant
to last. The capital outlay is significant - over a billion dollars for
a plant. The significant amount of energy produce in its lifetime and
the low operating costs mean it has the best value and offers the
greatest potential for profit unless there are unforeseen problems with
thorium reactors in the ultra-long term, i.e. if the silicon carbide
bombarded with neutrons and kept at a high temperature breaks down after
30 years.
It takes a massive shift in thinking though and this seems like the
barrier at the moment. The capital outlay and the undetermined risk may
also be a problem. Uranium reactors have amazing safety systems now and
the technology is cheaper in the short term.
There's a middle ground which combines the relatively low outlay of
uranium reactors with some of the safety aspect, such as gamma breakdown
fission products, but still has the problem of a meltdown. The mature
safety systems mean the probability is low. The lower cost to modify an
existing plant makes economic sense. The wired.com article explains the
technology.
So there may be no energy crisis in 30-40 years when global prices of
carbon-based fuels will rise significantly as the costs of extraction
sky rocket. There's one problem which as far as I am aware can't be
fixed by any of the current power generation methods apart from coal and
oil but I know little of this fringe area. The working week creates two
massive spikes in demand in the day. To meet this demand coal and oil
stations can "quench", a process whereby production is ramped up for a
short burst to meet the peak demand. It's sort of like why bipolar
people are good at media jobs. Two things I've guessed at are advances
in energy storage and a European or international power grid. Society
may change as well. Already flexi-time means more people are spreading
out when they get to work. 40 years can bring a lot of change in the
working week and it may be what's required if the technology to meet the
peak demand can't be developed to replace fossil fuel plants. Energy
generation may also decentralise though I think we're still a long way
off from a nuclear power plant in everyone's home. It's possible though.
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