There's a lot of talk about nuclear technology,
what with Iran and Fukushima and Green Energy
being thrown around every day.
But how do we even MAKE nuclear fuel?
Howdy atomic children, Trace here for DNews…
Despite the controversy they often raise,
nuclear power plants are a huge source of
energy.
The Environmental Protection Agency says nuclear
power accounts for about 20% of electricity
production in the U.S.
One of the reasons why is because it’s the
most efficient means of extracting energy
from a fuel source - about 8,000 times more
efficient than coal or oil.
According to the Nuclear Energy Institute,
a fingertip-sized pellet of nuclear fuel contains
as much energy as "17,000 cubic feet of natural
gas, 1,780 pounds of coal, or 149 gallons
of oil."
Nuclear energy comes in two flavors, fusion
or fission.
Fusion is when two hydrogen atoms fuse -- this
happens in stars; and fission is when large
"heavy" atoms are broken apart.
Both release energy, and both have pros and
cons, but so far, we've only figured out nuclear
fission; so when I say fuel, I'm talking about
fuel for nuclear fission.
Nuclear fuel is commonly referred to in the
news, as "highly-enriched Uranium," but getting
it to that point requires a LOT of effort.
In 1941, Enrico Fermi, created the first controlled
nuclear chain reaction using a small amount
of uranium-235; and since then we've gotten
much better at taking uranium and creating
usable fuel from it.
Uranium ore is most commonly mined in Canada,
Australia, Niger, Kazakhstan, Russia, and
Namibia; though it's not THAT rare -- it's
40 times more prevalent than silver in the
Earth's crust.
Once drilled or dug out of the ground, the
uranium atoms are mixed in with the surrounding
minerals -- so it has to be processed -- this
involves some pretty intense chemistry.
First, the ore is crushed, and then heated,
to dry out carbon content (like clay) so it
can be washed away.
That slurry of ore and water is leached with
sulfuric acid.
These processes cause the uranium atoms to
bond with the sulfur and oxygen forming uranium
oxide liquid.
To get it to that yellow powder we recognize
from movies, the uranium is pulled out of
solution using ammonia.
This "yellow cake" uranium is put in barrels
and shipped off to be purified even MORE.
At this point the uranium isn't super radioactive,
yet…
If you stood one meter from a barrel full
of U three O eight, you'd get no more radiation
than from the cosmic rays hitting passengers
on a commercial airplane.
This uranium still needs to then be enriched
before it can be used in power generation.
That yellow cake uranium is 99.3 percent Uranium
238 and only 0.7 percent of uranium-235.
To make the fuel, scientists need that U235
isotope -- this is where the now-famous nuclear
centrifuges come in.
If you watch the news, you know Iran is developing
a nuclear program -- whether for energy or
weaponry, I'll leave that to the experts;
but they use centrifuges to enrich that uranium.
As things go forward from here, it gets more
dangerous, and more radioactive, so the engineering
has to be VERY precise or people can die.
First, they take the yellowcake uranium and
they turn it into a gas by creating a reaction
with fluorine -- the resulting uranium hexafluoride
gas is even MORE pure than yellowcake and
ready to go in a centrifuge.
A centrifuge is a giant spinning container
designed to use physics in order to separate
materials.
When you donate plasma, doctors draw blood
and spin it in a centrifuge.
During the spinning, centrifugal -- or center
fleeing -- forces cause the heavier red blood
cells to come out of solution and collect
as far from the center as possible; lighter
plasma stays nearer the inside!
In the case of uranium, it's the same.
The heavier U238 isotopes get thrown outward,
allowing the lighter U235 to stay closer to
the middle.
It's not as good as blood, because there's
only a 1 percent difference in mass; so it
has to be spun again and again in centrifuge
after centrifuge THOUSANDS of times.
Eventually, the gas in the middle of the centrifuge
gets more and more concentrated -- or ENRICHED!
The gas is MORE U235!
Once the fuel is 5 percent U235 (95 percent
U238) it's suitable for some nuclear reactors.
Others require as high as 20 percent.
But that's nowhere NEAR enriched enough for
nuclear weapons, which can require as high
at 90 percent U235.
Once it's reached the desired enrichment for
the type of power plant you want to run, the
enriched uranium hexafluoride has to be turned
into a solid by adding calcium.
The calcium and fluoride react, creating a
salt, leaving behind only uranium oxide, which
is heated to 1400C and extruded into tiny
ceramic pellets.
Those uranium pellets are, in turn, put into
rods, and then hundreds or thousands of those
rods can be placed in various configurations
inside a nuclear power plant.
When we talk about nuclear energy programs
in other countries, world leaders get nervous.
And now that you know the process, can you
see why?
The massive centrifuges used make nuclear
fuel, are the same ones that could create
weapons grade uranium.
It requires a lot of technical and chemical
knowledge to GET to that point, but in the
end it's dig uranium out, clean it up, and
then spin it!
Nuclear energy continues to be a controversial
choice for powering the future, and it's connection
to nuclear weapons is clear, but how do you
feel about 
nuclear energy?
