My name is Ferenc Dalnoki-Veress, and I am a scientist-in-residence here at
the Monterey Institute of International Studies.
Welcome to module one.
We're going to be talking about the physics that you need to know.
As you know,
this problem of spent nuclear fuel is a very serious problem,
and it requires interdisciplinary thinking.
So we need to think about
culture, and
society, sustainability,
and also about science and engineering. That's what we're going to be
focusing on now.
You already have all of the tools you need to understand some of
the physics, so if you are a physicist,
you know this already,
but if you're not a physicist, don't worry,
because
you already have all the tools.
What I mean by that is you have your intuition,
and your intuition can go a very long way.
So for example, you have experience playing pool or playing billiards,
and all of these things will be important
for neutron interactions,
which is what I'm going to be talking about, for example, in the second module,
and how to understand nuclear reactors and so on.
your intuition will go a very long way,
so don't be nervous about
not being a physicist.
This is the outline for module one. The first chapter is
We are all made of Starstuff.
The second chapter is
Up Close and Personal to the Nucleus, so then we are going to focus on
the nucleus and the atom.
The third chapter is called Isotopes Pack a Punch,
and there I am really talking about the effect
of the particles that are released
on the environment.
The fourth chapter is called
The First Double Edge Sword.
There will be another double-edged sword, which we will talk about later,
in other modules:
The good and the bad of radiation and radioactivity.
We are all made of starstuff --
that's the first
chapter of this module.
That was coined by
Dr. Carl Sagan, who was an astrophysicist,
who has unfortunately passed away. He wrote a very popular
book called Cosmos and also had a tv series Cosmos,
and if you have any interest in this,
it's an amazing tv series
where he talks about
the origins of the universe and our place in it,
so it particularly
certainly has had a lot of influence on my career.
He has one quote in his book, or he has one quote called,
"the nitrogen in our DNA, the calcium in our teeth,
the iron in our blood,
the carbon in our apple pies,
were made in the interiors of collapsing stars.
We are all
made of starstuff.
The matter that we see
[we see around us, everywhere]
connects us to our past
and also our future.
What we see are basically atoms and molecules." Well, we don't actually see them,
but materials are made out of atoms and molecules,
and those molecules, those materials
have been made in collapsing stars.
That's really an amazing thing, if you think about it
that everything that we see around,
at least metals and these kinds of things,
are actually made in stars that have collapsed
and clouds that have come together and formed stars, and so on,
and formed planets, and so on.
That's actually what everything
...what we're made out of, and the materials that are around us
are made out of.
But to tell you --
what we see are atoms and molecules,
but we also know
that there's way more out there.
What we actually know, what we can actually
see around us, and what we can actually do experiments with around us,
is only four percent
So the matter that we see around us --
the atoms and all the visible stuff,
is only
four percent.
The rest is some very mysterious material
called dark matter
and dark energy.
So really the bottom line is
what we see around us is only four percent
of what we know there is there.
Doesn't that make you humble
as a physicist and as a person?
Humans like to classify what they don't know or don't understand.
What really happens is you look out
in the universe,
or you look out around you,
and you observe,
and you classify. So let's say
you look at a field, and you look at flowers, and then you sort of classify
the flowers,
you look for patterns,
and then you might form theories. This is what happens in physics a lot
-- you
look for patterns and then form theories to try to understand
the different patterns, and then you can test the theories by cleverly-designed
experiments
Then you gain a certain understanding, or you might think that you gain
a certain understanding,
and then you do other experiments and you look for inconsistencies
in..
in your results.
And so then you go through this whole process of classifying that, and then going
to look for patterns and form theories. So this is kind of the cycle
of trying to understand how
the universe works.
This was done historically,
when they were looking at the different materials that were around us,
the different elements, the different metals, the different gases, and so on.
And Mendeleev offered a new vision
of the nature of matter.
This is a very nice quote from him, "I saw in a dream a table, where all the elements
fell into place as required.
Awakening, I immediately wrote it down on a piece of paper. Only in one place
did a correction later appear necessary." So what Dmitri Mendeleev was able
to do
was basically classify empirically
all the materials that he sees around him into what he called elements.
This is the periodic table of the elements, and what you see
is different elements
are organized according to
different properties, such as
number of electrons, these kinds of things. The elements I want you to focus on
are things like hydrogen,
oxygen.
You know what hydrogen and oxygen do, they form together to form water, right?
H2O
two Hs and an O
makes water.
But then you also have other
important elements, such as Rubidium,
Strontium, and Cesium, Barium,
Lanthanum,
all these other types of elements, which become very important,
because these will end up becoming fission products,
and that will be important when we talk about nuclear waste in general.
At the very bottom there, what you see is a row
called the Actinide series,
and this is where you have a lot of the important fissile isotopes, such as
Thorium, Uranium, Neptunium, Plutonium, and these kinds of things, and we're going
to talk a lot about those too.
Actually, very little was known about the atoms themselves at the
time when they sort of
built up this
first periodic table.
Now comes the dreaded stamp-collecting guide. This is, of course,
Lord Rutherford, who said that basically all science is either physics
or stamp-collecting,
and he did a very, very important experiment called the gold leaf experiment,
or the Geiger-Marsden experiment.
And what he did is he had an alpha emitter,
I think it was a polonium source,
that emitted particles, called these alpha particles.
And he hit a very, very thin
gold leaf foil,
and then surrounding it,
he had
basically a detecting screen.
So if the alpha particle would go through,
then you would see it go straight through the gold foil
and fall onto the detecting screen on the back, or perhaps it could bounce off
and hit the slit itself.
An alpha particle, by the way,
is basically a helium nucleus,
and a helium nucleus is basically two protons,
two neutrons, adding up to four, so the mass is four.
And of course there's electrons around it, but a helium nucleus
is without the electrons.
What Rutherford discovered was that,
well, let me say his quote here.
"I had observed a scattering of alpha particles, and it was as if he had fired
a fifteen-inch naval shell
at a piece of tissue paper
and the shell came right back and hit you...
it was then
that I had an idea
of an atom with a minute
massive center,
carrying a charge."
What he discovered was that,
once he sent these alpha particles through this very thin gold leaf,
he was able to sort of understand or get to an understanding of what
is the structure of these atoms,
and he found out,
surprisingly,
that the center
was very hard material, that...the alpha particle just simply
bounced off.
and the rest
was basically empty space. The modern view
of the atom
is more like a positively-charged nucleus
and a negatively-charged sort of
electron cloud,
with the total charge being the same as the positive charge of the protons
in the nucleus.
So you have a very
hard, dense center. Remember, as I was saying, the alpha particles sort of
bounced off. You have a very hard
recoil,
very hard bouncing off,
and you have a much less dense
cloud.
So it really meant
that all the mass
is in the center,
in the center where the nucleus is. The electrons themselves
have a very low mass compared to the nucleons, the protons, and the neutrons
that are in this
nucleus.
Now chemistry versus nuclear physics: it's important to sort of distinguish
between the two.
Atoms bond to form molecules. We all know this...that's kind of the field of
chemistry. And that really has to do
with electrons.
In the case of
nuclear physics, it's protons and neutrons that are bound in the nucleus.
So you have a positively-charged nucleus,
with protons which are positively charged and neutrons that are neutral
inside the nucleus.
Now if you compare the amount of energy involved
in chemistry,
let's set that equal to E(CHEM).
Compare that to energy in the nuclear world.
It's incredible.
In the nuclear world, the energy
is about 10^6 -- a million
to a hundred million times
the energy of chemistry,
and that's really the big advantage
of nuclear power
compared to, say, coal-burning power, which depends on chemistry.
Now I'm showing you the chemical and nuclear binding energy compared.
And so what you see is you see a graph where you have the atomic number,
which is essentially the proton number,
which distinguishes different elements.
And on the abscissa, the horizontal scale, what you see
is the binding energy,
and the binding energy basically represents the energy
which holds the atom together.
In this case of chemistry, it holds the atom together.
And we're talking about hundreds of electron volts.
Now an electron volt is a very, very small unit of energy
that's very relevant for atoms.
We'll talk about that later. So just remember the number
hundreds of electron volts or hundreds of eV.
That's the binding energy when we're talking about the chemical world.
Now we're talking about the nuclear world.
And this is something very similar, except this is the binding energy
per nucleon, so now
we're looking inside
the nucleus
and we're asking what is the binding energy
per proton or
per neutron. And here the scale is very, very different.
Here we're talking about not eV,
but here we're talking about
millions of eV.
One MeV is
one million electron volts.
So remember that one electron volt is the energy in the world of chemistry.
Binding energy is the energy required here
to keep the nucleus together.
So here we're talking about very, very different scales of energy.
And that's the big nuclear advantage.
So now that you're
fully immersed in all this,
how do you make sense of all these energies? I talk about eV,
millions of electron volts, and now I'm going to talk about joules.
There's a lot of these different types of units, and they really talk about
different applications, different uses.
Energy is the capacity of the system to perform work.
Really the way I look at it is it makes everything happen.
And everyday energy is measured in joules and power in watts.
We'll talk about power when we talk about nuclear power.
How much is a joule?
Well, one knee bend (and I'm not going to do it here), but if you go up and down
like this, you bend your knee,
that's the equivalent of about a hundred joules.
How much is a hundred joules?
Well, let's compare it to something like...
the incredible energy of the yield when the bomb
was dropped on Hiroshima
If the whole world would do one knee bend,
everybody all at once,
that would amount to
one hundredth of the yield of Hiroshima.
That's how much energy it is.
That's actually equivalent to
ten grams of
fissioning
U-235.
Ten grams.
So if you think about what immense energy is actually embedded
in the atom
through fissioning.
Now let's talk about the energy of particles in MeV.
Now, the energy of particles in MeV
is actually enormously small!
One MeV, which I said was SUCH a large number in the previous slide,
is actually enormously small
compared to
the human world,
the energy in joules in the human world.
One MeV
is one millionth
times one millionth times one tenth of a joule.
The joule is actually immensely larger
compared to the MeV.
The eV is even smaller, because the eV is
one millionth
of an MeV.
So there you're talking about 1.602e-19
joules.
Right...very, very small number.
However,
what's different about all this
is that there are many, many atoms and materials, and we'll talk about that next, but
you may know about this from chemistry,
about Avogadro's number.
You know that there are, in general, in about a hundred grams, there are
ten to the exponent twenty-four
nuclei,
ten to the twenty-four nuclei. So if you multiply that times the energy of
1.602e-19 joules for an eV
or 1.602e-13 for an MeV,
then you realize that actually,
there's an awful lot of energy just in a very small amount.
In this slide, on the vertical axis, what you see
is the log of a kiloton
of TNT yield,
meaning the explosive yield for one kiloton of TNT.
What's one kiloton? Well, it's
1000
tons of TNT,
an immense amount.
Well 1 ton
is 1,000 kilograms, so 1 kiloton is
1 million
kilograms yield.
So what you see here is it going from minus thirty
all the way up to one
all the way up
to higher, higher numbers.
And this is a logarithmic scale, so it goes up by a factor of ten.
What you see at the very bottom at
ten to the minus thirty kiloton TNT yield,
you see the binding energy of atoms. That's what I said is right at the
bottom of the scale, so that's basically
ten or hundreds of eV.
The next one up is the binding energy of nucleons in a nucleus.
And then you see this huge jump
to 100 joules,
a knee bend
of the human world.
Then you see the 1 kg of TNT,
and you see 23 kg of TNT, which is
basically the energy a large
power plant produces
per second,
23 kg of TNT.
Then the next one up is basically
the first Hiroshima bomb, which is one kg of U-235.
So that's where I show this arrow going from 1 kg TNT to 1 kg
of U-235, which is basically the previous slide.
And then the largest bomb,
which is called the "Tsar Bomba." This was 57 metric tons
of TNT. That would be the equivalent yield.
And then this very sad
earthquake
that we had last year,
which is the Tohoku
earthquake
in Japan. And this graph
kind of shows you the scale of the different energies.
As you go from the smallest electron volts
all the way up
to the Tsar Bomba
and the Tohoku Earthquakes and other earthquakes.
So now, a summary:
first, we are all made of star-stuff.
I talked about that....
how stars,
when they explode, they produce different
materials, and this is the materials that we're made out of.
. What we see around us is not all there is, and that is the startling fact that
always amazes me and always makes me humble,
the fact that we see is basically four percent of
what we know there is there.
The universe is vast -- from the very tiniest particle to the size of the
universe, there is a huge variation in scale. That's why I always say that physics is
all about scales, and understanding physics is all about scales.
The tiny atom is almost all empty space, with a very hard center,
with a negatively charged
cloud of electrons.
And the last thing is, I want you to think about energy scales from the tiniest atom
to the largest bomb.
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