Good morning, John.
Suddenly, along with the disaster in Japan,
it has become kind of necessary to understand
a little bit about how nuclear reactors work.
And so I hope that you will excuse me postponing
my Thoughts from Haiti and instead giving
in direction as to how nuclear reactors work
and how that pertains to the situation in
Fukushima right now.
So first things first, you are welcome to
say "nookyoolar" but you should know that
there will always be a certain percentage
of the population who will assume that you
are a dumbass. I personally have no problem
with "nookyoolar" but if you want fewer people
to think you're an idiot, probably, you should
just switch over to nuclear.
Now for terminology! One: nuclear, pertaining
to the nucleus, which is the center of the
atom that contains the protons and the neutrons.
Nuclear reaction: a reaction that changes
the nucleus. This happens either by an atom
splitting apart or by two atoms fusing together.
Radiation is any particle or wave that goes
through the air or goes through other things
besides the air, like your body. But generally,
when we're talking about nuclear radiation,
we're talking about ionizing radiation which
is the kind of radiation that has enough energy
to ionize an atom. Radiation can be harmless
but it can also be not harmless.
Radioactive decay: this is important, it will
come up again soon - is when an unstable atom
loses energy by emitting radiation.
Fission: when an atom breaks apart into two
or more atoms that are an entirely different
kind of atom than the original atom. During
fission a great deal of radiation and energy
is expelled and the fission products, which
are whatever is left over, are always lighter
than the original atom. Now where did that
mass go? It was converted into energy in a
way that is described by a very famous equation.
Notice, in that very famous equation, that
we are multiplying by the speed of light,
squared. You may have noticed, the speed of
light... very big number. And so, when you
convert a tiny, tiny amount of mass into energy,
you get a great deal of energy, which is why
- something in my ear - a pound of Uranium
235 can be converted into as much energy as
about a million gallons of gasoline.
Speaking of which, Uranium 235 is a rare isotope
of uranium that has very unique properties.
First very unique property: when you hit it
with a neutron - it doesn't even have to be
a special neutron - it fissions. Second, when
Uranium 235 splits, it creates more neutrons
which then go on to hit more atoms of Uranium
235, which then go on to create more neutrons,
which then goes on to create a chain reaction
that can be turned into either a nuclear bomb
or a nuclear energy reactor.
So in a nuclear power plant, you have Uranium
235 and you have it mixed into these ceramic
pellets. And through the majesty of science,
these little guys can never explode like a
nuclear bomb. These pellets are placed into
tubes of zirconium alloy that is extremely
strong and heat-resistant. That tube, with
the uranium pellets in it, is what we call
a fuel rod. When a bunch of these rods are
placed together, the uranium begins to fission,
creating energy and radiation and neutrons
and fission products, which are the stuff
that's left over after the uranium splits
apart.
All of this stuff is what is called the reactor.
And it's encased inside a thick steel box,
like eight-inches-thick steel. That steel
box is called your primary containment, and
then that is inside of a giant concrete and
steel box which is your secondary containment.
So in the reactor, the fuel rods are hot,
water is pumped through the fuel rods, it
turns into steam, the steam drives a turbine,
the turbine creates electricity, and that
is how we get electricity from nuclear power.
Now if you want to turn it off, we have what
are called control rods. Control rods absorb
neutrons. You stick 'em in between the fuel
rods, and it absorbs all the neutrons. No
neutrons are left to continue the chain reaction,
and the reaction stops. Ideally, that would
be where it ends, but it's not, because we
have those fission products.
All those fission products leftover from the
uranium splitting are unstable isotopes, and
this is where we come back to radioactive
decay. Because they are unstable isotopes,
they decay. And as they decay, they produce
radiation and energy. And that energy becomes
heat, and it's not nearly as much heat as
you get at the center of a reactor when it's
running, but it is still a lot of heat. In
fact, it is so much heat that if you don't
cool it down, the fuel rods themselves will
eventually break and you will have what we
call a meltdown.
And this is what happened in Fukushima. As
soon as the earthquake happened, the control
rods slammed into place, the reaction stopped,
but we still had the fission products creating
a lot of heat.
The grid power immediately got taken down
by the earthquake, and the backup diesel generators,
they got wiped out by the tsunami. And so
there was nothing left to power the coolant
system, the system that keeps water running
through the reactor so that the fuel rods
don't get too hot, they don't break, and they
don't melt down.
So it appears that some of the fuel rods did
break. That created an environment, combined
with the heat, that could actually split water
into hydrogen and oxygen, creating hydrogen,
which we all know is explosive. And we've
seen the effects of that in a series of hydrogen
explosions throughout the plant that had damaged
both primary and secondary containment of
at least one of the reactors.
Additionally, just like the reactor, when
it's turned off, still produces heat we have
what are called spent fuel rods. These are
fuel rods that no longer contain any uranium,
but they do contain all of those great radioactive
fission products. Spent fuel rods can spend
years at the bottom of giant pools while we
wait for the radioactive materials in them
to decay enough that they are not producing
so much heat that they cannot be dealt with
in a different way. And the same way that
the cooling system for the reactor isn't working,
the cooling for those spent fuel rod pools
is also not working.
There's another difference between the reactor
rods and the spent fuel rods, and that is
that the spent fuel rods do not have a primary
containment vessel. So there is less protection,
and if the water in those pools boils off,
the spent fuel rods could melt down, creating
a fire that would spew radioactive dust into
the air, and it would be bad.
The men and women who remain at the site trying
to keep the situation under control are very
literally risking and possibly sacrificing
their lives for their country. Those men and
women are made of some tough stuff and I wish
them a great deal of luck in getting this
under control.
You'll notice that throughout this video I
have not been making judgments about whether
or not we should be using nuclear power. That's
because I simply do not know. I can see and
understand both sides of this argument very
well.
I do not know whether or not the benefits
of nuclear power outweigh the risks. I do
know that most of the ways that we generate
the majority of our power now are dangerous
and bad, but that we need electricity for
our society to function and for people to
be happy and healthy and safe.
Quite frankly, I think it's kind of ridiculous
that so many people seem to have made up their
minds about this issue when obviously it's
a very complicated one. It's almost as if
our society values opinions more than it values
knowledge.
I can only hope that this situation simply
doesn't get any more severe than it already
is, and that the people working at that plant
and the people living nearby are able to safely
return to their homes in a relatively short
amount of time. And I hope that the people
who watch this video can understand a little
bit better the situation and, uh, not panic
unduly.
John, I'll see you on Friday.
