THE PEACEFUL ATOM




_by_

BERNICE KOHN




_illustrated by_
ZENOWIJ ONYSHKEWYCH




PRENTICE-HALL. INC.
ENGLEWOOD CLIFFS. NEW JERSEY




OTHER PRENTICE-HALL BOOKS BY THE SAME AUTHOR:

_Our Tiny Servants: Molds and Yeasts_
illustrated by John Kaufmann

_Computers at Your Service_
illustrated by Aliki

_The Peaceful Atom_, by Bernice Kohn




Copyright under International
Pan-American copyright conventions

©1963 by Bernice Kohn

All rights reserved, including the right to reproduce this book, or any
portions thereof, in any form except for the inclusion of brief
quotations in a review.


Library of Congress Catalog Card Number: 63-9054

Printed in the United States of America
65524-T




CONTENTS

1. The Atomic Age

2. The Smallest Thing There Is

3. The Mystery of the Rays

4. What's in an Atom?

5. A Search Begins

6. Journey to the New World

7. Tiny Atoms, Big Power

8. Atoms for Transport

9. Atoms That Trace

10. Atoms to Change Atoms

Appendix

Glossary




1

THE ATOMIC AGE


Do you ever look at the things around you and wonder what they are made
of? You may see a table that is made of wood. But what is _wood_ made
of? What are you made of? What are carrots made of, and birds, and
bikes, and baseballs?

[Illustration]

Every single thing in the world is made of _atoms_. Atoms are so tiny
that there are only a few microscopes in the whole world powerful enough
to show them. It would take about 20 million atoms to make a dot as big
as this one over the letter _i_. In fact, if you had one atom for every
single person in the states of Pennsylvania and California, you could
fit them all on the head of a pin!

But, small as they are, atoms are the building blocks that make
everything. You certainly don't look anything like an elephant--do you?
But you are both made of atoms! You don't look anything like a scrambled
egg, either--or a washcloth, or a refrigerator--but they are all made of
atoms, too!

Atoms are everywhere, they are everything--and you should learn
something about them because you live in the atomic age.

Why is this the atomic age? Were atoms just discovered? No, they
weren't. People have known about atoms for a long time.

Then what is different about this age? The difference that we have
learned how to make atoms work for us. We call this work _atomic
energy_.

When your father and mother were children, no one had ever heard of
atomic energy. Energy for heat, light, and to operate machinery came
from a few main sources. Some came from water power, a little from wind
power--but almost all energy came from burning fuels.

[Illustration]

The chief fuels of the world for many years have been coal, oil, and
natural gas. These are all _fossil fuels_. That means that they were
made millions of years ago and have lain trapped in the earth ever
since. Once these fuels are used up, there will be no way to replace
them. There just won't be any more.

By the early years of the 1900's, some people were beginning to worry
about fuel. There wasn't any shortage yet, and there wouldn't be for a
long time. There were still new coal mines and new oil wells being
discovered. But some day, the last one _would_ be discovered, the fuels
would be all used--and then what?

[Illustration]

As new industries developed all over the world, the need for power
grew--and so did the worry. And then suddenly, in 1942, one of the
greatest discoveries of all time was made. The atomic age was born and
the perfect fuel was found.

Atomic energy can do things never before dreamed of. Atoms, without any
fire, without any noise, can run a huge electricity plant. The atoms in
one pound of fuel can keep the lights burning in your home for 1000
years!

Atoms can send a large ship back and forth across the ocean many
times--on one small load of fuel!

Atoms can keep hamburger fresh for weeks without freezing!

Atoms can sometimes cure sick people!

Atoms can find leaks in pipes, and can test the rubber in a set of car
tires!

Atoms, in many ways, can make life easier, healthier, and better for us.

What are these wonderful atoms, anyway? Let's find out.

[Illustration]




2

THE SMALLEST THING
THERE IS


The story of atoms begins about two thousand years ago, in ancient
Greece. There, a wise man named Democritus started to think about what
things were made of. Democritus reasoned that you could take a little
piece of anything at all--wood, metal, even candy--and cut it in half.
Then you could cut the halves in half. Then you could cut _those_ pieces
in half. And so on. But finally, Democritus said, you would get to
particles so tiny that they could not be divided any more. He called
these smallest particles _atoms_, from the Greek word _atomos_ which
means _indivisible_.

It was hard for people to believe that everything in the world was made
of atoms. They soon forgot about Democritus and his strange ideas. Atoms
were forgotten for almost two thousand years.

But during the eighteenth century, European scientists again became
interested in the structure of things and began to experiment. There
were some curious discoveries.

[Illustration]

Chemists found that a substance like water could be separated into two
other substances, _hydrogen_ and _oxygen_. But hydrogen and oxygen
couldn't be broken down into any other chemicals no matter what the
chemists did. They could easily change table salt into _sodium_ and
_chlorine_. But no matter how hard they tried, they weren't able to
break down sodium and chlorine into anything else.

So scientists decided that most of the things around us--water, salt,
wood, animals--were made of combinations of substances. They called the
combinations _chemical compounds_. They called the substances that
couldn't be broken down _elements_.

We now know of more than one hundred elements. In the year 1800, about
half that number had been discovered. And it was at about this time that
an Englishman, John Dalton, came along with the first really scientific
_atomic theory_.

Dalton said that all elements are made of atoms, and the atoms of any
particular element are always the same. An atom of carbon is always like
every other atom of carbon. And, Dalton went on, atoms of different
elements have different weights. An atom of carbon weighs more than an
atom of hydrogen. An atom of oxygen weighs more than an atom of carbon.

Dalton noticed that atoms combined in different ways according to their
weights. Water is made of hydrogen and oxygen. But it takes _two_
hydrogen atoms with _one_ oxygen atom to make water. This smallest unit
of water is called a _molecule_. A molecule is the smallest possible
amount of any chemical compound.

Another contribution that Dalton made was the use of shorthand symbols
to stand for chemical elements. Today, we use a system which grew out of
Dalton's.

[Illustration]

Instead of calling the water molecule "two atoms of hydrogen
and one atom of oxygen," we call hydrogen "H" and oxygen "O" and write,
simply, H_{2}O. The symbol for carbon is "C" and carbon dioxide may be
written CO_{2}. This means that one carbon atom and two oxygen atoms
combine to form one molecule of carbon dioxide.

John Dalton was a great scientist and almost everything in his atomic
theory turned out to be correct. Only one of his ideas we now know to be
wrong. And that idea went all the way back to Democritus. They both
thought that the atom was the smallest possible particle, and that it
could never be divided.

It certainly seemed to be so. But astonishing things about atoms began
to turn up around the end of the 1800's. No one knew it yet, but men
were going to change atoms--and atoms were going to change the world!




3

THE MYSTERY OF THE RAYS


In 1895, a German scientist, Wilhelm K. Roentgen (RENT-gen), was
experimenting with a special kind of electrical tube. He had covered one
end of the tube with black paper. Nearby was a screen that glowed when
light shone on it.

Roentgen happened to glance at the screen--and could hardly believe his
eyes. It was glowing--but there was no light coining from the covered
tube! This seemed impossible--but there it was.

Later, when someone asked Roentgen what he thought, he made a true
scientist's reply.

He said, "I did not think. I investigated!"

Roentgen didn't know what the rays were, so he decided to call them _X
rays_. He found that they could pass not only through black paper, but
through many other substances as well. They went easily through cloth or
wood, but were slopped by metal. Roentgen found that the mysterious rays
could shine right through the soft parts of the body, but they were
stopped by bones.

[Illustration]

[Illustration]

Here was a useful discovery, indeed. Just imagine how valuable it was to
a doctor to be able to take a shadow picture of a broken bone so that he
could see how to set it. Your dentist probably uses Roentgen's X rays to
take pictures of your teeth to look for cavities.

Roentgen's discovery stirred up a great deal of interest. Perhaps there
were other kinds of rays. Scientists began to search for them.

One of the searchers was Antoine Henri Becquerel (Beck-er-EL), a
Frenchman. In 1896, Becquerel was experimenting with some crystals of a
uranium salt. These crystals gave off a glow after being exposed to
sunlight.

One day, Becquerel was all ready to test the glow on a photographic
film. But just as he was about to start, the sky turned cloudy. The
experiment couldn't be done without sunlight, so Becquerel wrapped his
film in a piece of black paper, put the crystal on top, and put the
package away in a drawer.

[Illustration]

[Illustration]

The sun stayed hidden for several days and Becquerel couldn't continue
with his experiment. But he decided to develop his film anyway. He was
astonished to find a black spot right in the middle, just where the
uranium crystal had been! That meant that even without any sunlight, the
crystal had given off rays of its own! Another mystery!

Becquerel tested several compounds that contained uranium and found that
they all gave off similar rays. Why?

[Illustration]

One of the scientists who heard about Becquerel's work was a young
Polish woman working in Paris. Her name was Marie Curie (Cu-REE).

Madame Curie wondered if uranium were the only element to give off rays.
With the help of her husband, Pierre, she began to test every known
element for rays. She decided to call this ability to give off rays
_radioactivity_.

After many tests, Madame Curie found that the element _thorium_ was also
radioactive. So, the Curies reasoned, if there were _two_ radioactive
elements, there were probably more. And they continued to search.

Then one day, a strange thing happened. The Curies were busy refining
uranium from its ore, _pitchblende_. But they suddenly noticed that the
ore seemed to be more radioactive than the uranium itself! How could
this be? The only explanation, Madame Curie thought, was that there must
be another, stronger, radioactive element in pitchblende.

In 1898, after working through tons of pitchblende, the Curies succeeded
in separating a speck of a new element that was 900 times more
radioactive than uranium! They named the new element _radium_.

The Curies and other scientists were very excited. Here were three
elements--uranium, thorium, and radium--all giving off powerful rays.
Where did the rays come from? Scientists were sure they could only come
from the atoms of the elements themselves. But how could that be? There
couldn't be anything smaller than an atom. Or could there? The
scientists didn't know. It was a real mystery.




4

WHAT'S IN AN ATOM?


Every mystery is sure to attract some people who wish to solve it. And
the mystery of radioactivity was no exception. Scientists in many parts
of the world began to search for clues. Little by little, they found
them. It wasn't until the 1930's that the last pieces of the puzzle
began to fall into place--the structure of the atom was finally clear.

But before we talk about the structure of atoms, let's talk about the
structure of houses. Many houses are built of wood, shingles, and glass.
However, even though the houses are built of the same materials, they
may not look anything alike. Some are ranch houses, some are split
levels, and some are colonial houses.

On the other hand, sometimes a builder puts up a large development in
which all the houses are exactly the same. If a new friend tells you
that he lives in the Shady Acres development, you can picture his house.
It is just like every other house in Shady Acres.

Are you wondering what this has to do with atoms? Well, all atoms are
built of the same principal materials.

[Illustration]

They are called _protons_, _electrons_, and _neutrons_. And just as a
ranch house never looks exactly like a colonial house, an atom of one
element never looks exactly like the atom of another element.

[Illustration]

But like the Shady Acres houses, every atom of the same element looks
exactly like every other. A hydrogen atom looks like every other
hydrogen atom. A carbon atom looks like every other carbon atom. But a
hydrogen atom never looks like a carbon atom.

Atoms are like houses in still another way, too. Even though the
building materials used in two houses or two atoms are the same, the
finished structure of a house or an atom depends on the way the
materials are arranged.

If an atom could be made large enough for you to see, you might think
you were watching a satellite (or a fleet of satellites) going around
and around one or more planets.

[Illustration]

The planet--or center of the atom--is called the _nucleus_. It is made
mostly of protons and neutrons. The little satellites circling around
the nucleus are always electrons.

Ordinary atoms always have the same number of protons as they do of
electrons. This number is called the _atomic number_. No two elements
have the same atomic number. It is the number of protons and electrons
that tells us what kind of atom it is. When there are two protons in the
nucleus and two electrons circling around it, we know that we have an
atom of _helium_. If it doesn't have two protons and two electrons, it
isn't helium.

[Illustration]

A helium atom also has two neutrons in its nucleus. Usually, no atom can
change its number of protons or electrons and remain the same kind of
atom--but it _can_ change its number of neutrons.

Atoms of the same element, but with different numbers of neutrons in the
nucleus, are called _isotopes_. Some elements have only one isotope,
some have as many as eight or ten.

[Illustration]

Uranium has three main isotopes. The most common kind of uranium has 92
protons, 146 neutrons, and--of course--92 electrons. (Did you remember
that the number of electrons has to match the number of protons?)

Adding up the total particles in the nucleus, we see that 92 + 146 =
238, so this kind of uranium is called uranium-238. There is an isotope
that has 143 neutrons, so this is uranium-235 because 92 + 143 = 235.
The last isotope has 142 neutrons and is uranium-234.

The heaviest part of any atom is the nucleus. Protons and neutrons are
very much heavier than electrons. And then there is lots and lots of
empty space. If the nucleus of the hydrogen atom (which has only one
proton) were enlarged to the size of a tennis ball, the electron would
be a half mile away!

A whole atom is so tiny that it is almost impossible to imagine anything
so small. It would take 250 million of some kinds of atoms to measure
one inch. But it would take _fifty thousand_ times as many electrons to
cover the same inch!

[Illustration]




5

A SEARCH BEGINS


Now we know a lot about the structure of the atom--but we still haven't
solved the mystery of the rays. So let's do that right now.

A radioactive atom is really a temporary atom. It is unbalanced and
shoots off parts of itself in order to become balanced. As the atom
gives up protons, neutrons, and electrons, we say that it _decays_. If
your tooth decays, a small part of it crumbles away. And the same thing
happens to an atom.

We know that if an atom changes its number of protons it becomes a
different kind of atom. And that is just what happens to radioactive
elements. Uranium, thorium, and radium all change into lead. Other
radioactive elements decay to different elements.

When an atom decays, it gives off three different kinds of particles.
These are named for the first three letters of the Greek alphabet and
are called _alpha_ particles, _beta_ particles, and _gamma_ rays.

[Illustration]

Some radioactive elements decay very quickly--in a few seconds--but some
take millions of years. As the element decays, its atoms shoot off
particles. The larger the amount of the element, the more particles it
shoots off. But as the element decays, there is less and less of it
left. If at first it gives up 100 particles a second, it will, as its
size decreases, give up only 90 particles a second. Then it will give up
only 80 particles a second, and so on.

This slowing down makes it very hard to measure how long it will take
the element to completely decay. It is much easier to figure out when it
will be _half_ decayed. And so we never speak of the life of a
radioactive element. We speak of its _half-life_.

When the radioactive element that started giving up 100 particles a
second gets down to losing only 50 particles a second, we know that half
of its radioactivity has been used up. Radium has a half-life of 1,690
years. Uranium has a half-life of 4,500 million years!

Radioactivity is very interesting, but before we can understand its real
importance, we must learn a little about energy.

To most of us, energy means "pep." To a scientist, energy means _the
ability to do work_. Energy is not a "thing." You can't see it. You can
only see--or hear--or feel--what it does. Energy never disappears, but
it can be changed from one form to another.

When you swing a bat and wallop a ball, part of the energy you use makes
the ball whiz through the air. If you use energy to clap your hands,
part of the energy is changed to sound, and you hear a noise. If
electrical energy is used in a light bulb, part of the energy is changed
into light and part into heat.

[Illustration]

When we burn wood for heat, we are using energy that the tree took from
the sun. When we burn coal or oil, we are using the energy of sunlight
that was stored many millions of years ago.

All of this energy is stored in the atoms of the wood, coal, or oil. But
when we burn these materials for fuel, we release only the energy of the
_electrons_.

Now do you remember, back in the last chapter, we said that the nucleus
is the heavy part of the atom? And that the electrons are very light?
Well, the nucleus is so very, very heavy for its tiny size, that it
cannot be compared to anything else in the world. If a nucleus were as
large as a grain of rice, it would weigh two million tons! Nothing so
small could weigh so much unless it were extremely tightly packed
together. It takes a great deal of energy to pack anything that solidly.

By the middle of the 1930's, scientists were beginning to think about
the huge amount of energy that would be released if the nucleus could be
split. The scientific name for splitting is _fission_.

Just suppose, the scientists thought, you could split a nucleus and its
neutrons would come flying out--and each neutron would strike like a
bullet at another nucleus and make that one split? And all the new
flying neutrons would split other atoms? This would be a _chain
reaction_.

If man could produce a chain reaction, there would be such energy as the
world never dreamed of! In many different countries, men thought, and
dreamed, and worked--the search for the nuclear chain reaction was on!




6

JOURNEY
TO THE NEW WORLD


It was a gray winter morning. The date was December 2, 1942. The place,
The University of Chicago. Here at Stagg Field, under the football
stands, was a large empty room that had once been a squash court.

None of the students who hurried by on the way to class paid much
attention to a few men who passed through the door into the long unused
room. No one knew that in that room one of the greatest events in the
history of science was about to take place. No one knew that the atomic
age would be born that day.

The men who had gathered in the secret room were some of the finest
scientists in the world. The leader of the group was Enrico Fermi
(En-REE-ko FER-mee), an Italian scientist who had come to the United
States.

For some weeks the men had been quietly at work, carefully stacking a
huge pile of pure graphite bricks. Here and there among the bricks they
placed pieces of uranium. Fermi believed that when the pile reached a
certain size, a chain reaction would start. By December 2, the size
seemed to be right.

[Illustration]

Inside the pile were three control rods. They were made of cadmium, an
element which soaks up flying neutrons like a sponge. With the rods in
place, no reaction could take place. When the rods were withdrawn, the
reaction would begin.

To make sure that the pile would not get out of hand, the three control
rods were operated in three different ways. The first one was controlled
by an electrical switch and was completely automatic. The second, called
ZIP, was tied to a rope in the balcony. In case of emergency, there was
a man ready with an axe. He had only to chop the rope and ZIP would go
crashing back into the pile. The third rod was moved by hand.

It was time to begin. Fermi gave the signal for the automatic rod to be
withdrawn. Immediately, the counters which measured radioactivity began
to tick.

Then Fermi gave the command, "ZIP out!" ZIP was drawn up on its balcony
rope and the ticking of the counters at once became faster.

Then Fermi turned to the man who controlled the last rod. This rod was
marked in feet and inches, and Fermi said: "Pull it out to thirteen
feet."

All eyes were on the instruments. Not yet. A little more. Pull it out
another foot. Not yet. The men grew more and more tense as the careful
work went on.

[Illustration]

Finally, at about 3:25 in the afternoon, Fermi made a last check of his
instruments and his calculations. Then he said: "Pull it out another
foot. This is going to do it!"

No one dared breathe. The ticks of the counters became so rapid they
sounded like a steady hum. The pointers on the instruments swung all the
way over--and stayed there. The first atomic chain reaction had been
achieved!

The pile was allowed to run for 28 minutes. Then the control rods were
put back. Suddenly, all was quiet. There were no ticks from the
counters.

Not only had these men started a chain reaction, they had also been able
to stop it. At last man could control the energy of the atom.

One of the men present, Arthur H. Compton, ran to the phone to call
James B. Conant, chairman of the U. S. National Defense Research
Committee. But since our country was at war in 1942, it wasn't safe to
talk about this important secret over the telephone. And so, on the spur
of the moment, a quick-witted and historic conversation took place.

Compton said: "Jim, you'll be interested to know that the Italian
navigator has just landed in the new world."

Conant, who knew of the experiments that had been going on, understood
at once. He said: "Is that so? Were the natives friendly?"

And Compton replied: "Everyone landed safe and happy."

This was the first day of the atomic age. The reactor had been started,
had been stopped--and had produced enough power to light one small
flashlight bulb!




7

TINY ATOMS, BIG POWER


Atomic power has grown quickly since that day in 1942. Atomic power
plants now make electricity to light large cities in many parts of the
world.

Atomic power doesn't make electricity directly. It makes heat. The heat
turns into steam. Then the steam turns turbines and the spinning
turbines drive the generators which make electric current.

Ordinary steam power plants depend on fossil fuels--coal, oil, or
gas--to make heat. It has been figured out that if only coal were used
for fuel, the world's supply would be used up in 350 years. Oil and gas
would last for 40 years. But there are enough nuclear fuels to last for
at least 8,500 years!

There are several kinds of atomic power plants, but the best known is
the Pressurized Water Reactor. This long name is usually abbreviated to
PWR.

The PWR isn't really very different from Fermi's pile in Chicago. There
is the same big stack of atomic fuel--usually uranium--with control rods
sticking out of holes in the fuel bars. Just like Fermi's pile, when the
control rods are pushed in they soak up the flying neutrons and there is
no reaction. When the control rods are pulled out, the chain reaction
takes place.

[Illustration]

One of the curious things about a chain reaction is that it won't work
if the neutrons are flying too fast. They hit the new atoms at such
great speed that they just bounce off and keep going. In order for the
neutrons to do their splitting job, they have to be slowed down. Fermi
used graphite bricks for this purpose. The PWR uses water, which works
very well. And the water also serves another purpose. It absorbs the
great heat which is formed in the reactor.

Now, everyone knows that when water is heated to a high temperature, it
boils. But _this_ water must not boil. To prevent its boiling, the water
is kept under very high pressure, and that is how the Pressurized Water
Reactor got its name.

The water is sealed in special tubes and reaches a temperature of about
600° F. The tubes then heat _other_ water which turns into steam.

A simpler kind of atomic power plant is the Boiling Water Reactor, or
BWR. The BWR is just a tank which holds a reactor and water. In this
case, the water is _not_ under pressure and the heat released by the
chain reaction makes it boil. The steam which comes from the boiling
water goes directly to the turbine.

Whether they use PWRs or BWRs, atomic power plants don't look very much
like ordinary plants. There is no smoke, no dirt, and no fire.
Everything is controlled by automatic switches and there may be no more
than two or three men in sight.

[Illustration]

The first atomic power plant in the world was built in the U.S.S.R. and
went into service in 1954. There are now a number of such plants in the
United States. Two of the largest are the Duquesne Light Company at
Shippingport, Pennsylvania, near Pittsburgh, and Consolidated Edison's
Indian Point Plant, in New York State.

[Illustration]

Important as atomic power is to cities, it is of even greater importance
to faraway places where fuel is hard to get. For example, at the U.S.
Army's Camp Century in Greenland, far above the Arctic Circle, obtaining
power had always been a problem. The cost of shipping coal or oil to
such a place was so high that it was impractical. People had to get
along with very little heat or power. But not any more.

Camp Century's new atomic power plant supplies heat and electricity for
all. In a whole year the plant uses only 40 pounds of atomic fuel. If it
ran on diesel fuel, it would need 850,000 gallons a year!

One of the strangest things about some atomic reactors (called _breeder
reactors_), is that they make new fuel as they go along. If the fuel is
uranium, it is usually a mixture of uranium-235 and uranium-238. Only
the U-235 can be used for the chain reaction. But when the flying
neutrons from the U-235 strike the U-238, it turns into a new element,
_plutonium_. Plutonium is a fine atomic fuel, just like U-235. In some
atomic furnaces there is more fuel at the end of the reaction than the
furnace had to start with!

Just look at all the advantages of the atomic power plant: It solves the
problem of the disappearing fossil fuels. The plant is almost completely
automatic and can be run by just a few men. It saves the cost of
shipping heavy fuels to distant places. Some atomic plants make new fuel
as they run. Also, the ashes of an atomic furnace are highly valuable
for a number of purposes, as you will soon see.

With so many advantages, there is no question that the coal or oil power
plant will soon be a thing of the past. It may be that during your
lifetime, most of the world's power will come from atomic reactors.




8

ATOMS FOR TRANSPORT


In the year 1819, the world was agog because a steamship had crossed the
Atlantic Ocean. How wonderful it seemed! The ship was called the
_Savannah_. She carried wood and coal for her steam boilers, but the
ship wasn't large enough to carry fuel for the 30-day trip. There was
steam for the first seven days, and then the _Savannah_ continued under
sails.

Today, there is a new Savannah which can travel for three and one half
years on one load of fuel! She is called the Nuclear Ship _Savannah_ and
her fuel is uranium. Instead of a steam boiler she has a Pressurized
Water Reactor.

The _Savannah_ is a beautiful white ship nearly 600 feet long. But when
you look at her, there seems to be something missing. There aren't any
smokestacks! Of course there aren't any smokestacks, because there isn't
any smoke!

The N.S. _Savannah_ has a speed of 21 knots. She can carry 9,400 tons of
cargo, 60 passengers, and a crew of 110. On only 700 pounds of fuel, she
can take this heavy load around the world 12 times!

[Illustration]

Atomic reactors are already in use on ships and submarines and they may
soon be used for other types of transportation. Experiments have been
made on atomic tractors which would pull long trains of sleds in the
Arctic. And there has been some interest among railroad people in atomic
locomotives.

The most serious experiments, so far, with atomic locomotives, have been
made in the U.S.S.R. That country, because of its vast size, has an
unusual amount of freight traffic. Trains now use up one quarter of all
the coal and oil produced there. The Russians have completed the design
for an atomic locomotive that will have a speed of 75 miles an hour
while pulling a load of 4,000 tons. It will travel for almost a year
without new fuel, and will go from Moscow to Riga and back (about 1,000
miles) on a piece of uranium the size of a marble!

Designers here and abroad have also started to think about atomic
airplanes. One type of design would use a reactor similar to the power
plant reactor. It would make steam, the steam would drive a turbine, and
the turbine would turn the propellers.

Another design would work on the turbojet principle and wouldn't need
steam. Air would be scooped in and heated by the reactor, then shot out
of the rear jets, driving the plane ahead.

[Illustration]

However, there are serious problems in designing an atomic plane. One of
the hardest to solve is the radioactive exhaust that would come from the
reactor. All of the waste products of an atomic furnace are highly
radioactive and very dangerous to humans. They can cause serious injury
or death. People have to be protected from radioactive materials by
heavy shielding of concrete or lead. On a plane, of course, the weight
of such a heavy shield would create a difficult problem. The shield
would weigh more than the gasoline the atomic fuel replaced.

In time, however, there will probably be a solution to the problem, and
atomic planes will be made. There will be no worry about running out of
fuel. Such things as head winds, long flights across water, and fuel
leaks will no longer be threats to the safety of plane passengers. And
when the shielding, problem is solved, instead of carrying 50 tons of
gasoline, a big plane will be able to carry 50 tons more of people or
cargo.

All of these possibilities are just ideas now. But someday, perhaps, you
will chuckle over the old-fashioned days before A-trains and
A-planes--or, even A-cars!




9

ATOMS THAT TRACE


Do you remember what isotopes are? They are atoms of the same element,
which have different numbers of neutrons in their _nuclei_
(NEWK-lee-eye), the plural of nucleus. Some isotopes, when struck by
flying neutrons in a reactor, begin to give off rays, like radium. These
isotopes are called _radioisotopes_.

Some radioisotopes are made on purpose by putting certain elements into
a reactor. But many radioisotopes are made in all atomic reactors as a
natural product of the chain reaction. After the fuel has been used, the
radioisotopes are removed from the ashes.

Most elements have at least one radioisotope and many have several. They
have thousands of important uses and new ones are found every day.

[Illustration]

[Illustration]

There are a few properties of radioisotopes which make them useful. One
of them is the fact that they give off radiation and so they can always
be found with a Geiger (GUY-ger) counter. This is an instrument which
ticks when it is struck by an atomic ray. With the help of a counter,
radioisotopes can be used as tracers, or tags.

Tracers are used in dozens of interesting ways. One is to find leaks in
pipes. Sometimes there is a leaky pipe buried in the floors or walls of
a building. How can you find out where the leak is without tearing the
building apart? It is very simple. Just add a tiny bit of a radioisotope
to the water in the pipe. Then move a Geiger counter along the floor or
wall in which the pipe is enclosed. When the ticks stop--or continue,
but spread out over a large area--you have found the leak.

A similar trick is often used in the oil industry. Sometimes the same
pipeline is used for oil and for gasoline. A worker at the far end of
the pipeline has the job of turning off a valve when the oil stops
coming through, and turning on a different valve to send the gasoline to
the proper tank. But how does he know when the oil is finished and the
gasoline is about to start? There's nothing to it. A dash of
radioisotope is mixed with the last gallon of oil. The worker keeps his
Geiger counter on the pipe. When it begins to tick, it's time to make
the change.

If you had a tire factory, how would you find out which kind of rubber
gave the best wear? You could make four different kinds of tires and add
a bit of radioisotope to the rubber of each. With the tires on a car,
instead of driving thousands of miles, as in the past, you could drive
just a short distance. As the tires turned, tiny bits of rubber would
wear off. A Geiger counter moved over the tire tracks would tell you
right away which tire lost the least rubber. Tire companies use this
test widely.

Radioisotopes mixed with wax or polish tell how much is left on a car
after washing. Radioactive dirt smeared on cloth tells which detergent
does the best washing job. If radioisotopes are mixed with the liquid in
a tank, a Geiger counter on the outside of the tank can tell where the
top of the liquid is. This is much easier than sending a man all the way
to the top of the tank to measure the contents with a dip stick.

[Illustration]

Scientists have made great use of the radioisotope carbon-14. Carbon-14
occurs naturally in the air and is taken in by all living plants. It is
also taken in by all people or animals who eat plants. Once a living
thing dies, however, it does not take in any more carbon-14. Now it
happens that carbon-14 has a very long half-life--about 5,000 years. So
even if a plant or an animal has been dead for 25,000 years, there are
still slight traces of carbon-14 left. By measuring the quantity with a
counter and comparing it to the quantity in a living plant or animal of
the same kind, scientists can tell the age of very old things.

[Illustration]

When ancient writings about Biblical times, called the Dead Sea Scrolls,
were found, they were wrapped in linen. The linen, made from the fibers
of the flax plant, was tested for carbon-14. It was found to be about
2,000 years old. The same method has been used to find the age of
ancient wood, leather, cloth, bones--and even mummies!

Radioisotope tracers have been of great benefit to farmers. Mixed with
fertilizers, they can be followed with a Geiger counter to see just how
the plant uses the fertilizer and how fast. Tracers have shown how
certain feeds make animals grow fatter. They help in the study of milk
production by cows, egg production by chickens, and growth of wool on
sheep.

Perhaps the most important of all tracer uses is in medicine.
Radioactive iodine, or iodine-131, is used to find diseases of the
thyroid gland. The patient swallows a small dose of the tracer and a
counter shows how fast it is taken in by the thyroid gland. This shows
how active the gland is. Tracers also help to find brain tumors. And
they can be used to follow the circulation of the blood. If an artery is
blocked, a person may die because his blood can't circulate. A counter
can find the trouble spot and help save a life.

Radioisotopes which are used as medical tracers are not harmful to the
body. They are carefully selected to have a very short half-life. Their
radioactivity is gone before it can do damage. Also, they are used in
tiny quantities.

While radioisotopes do wonderful jobs as tracers, they can do some other
very interesting things, too. Let's see what some of them are.




10

ATOMS TO CHANGE ATOMS


When the rays of a radioactive substance strike the atoms of another
substance, they may cause changes. We call the exposure to rays
_irradiation_ (ir-rade-ee-AY-shun). One of the changes caused by
irradiation is called ionization (eye-on-i-ZAY-shun).

Radioisotopes do many important jobs for us by irradiation. In industry,
certain petroleum and other materials are changed by irradiation into
special fuels, oils, and even synthetic rubber.

Irradiation is used to improve the quality of plastics and to vulcanize
rubber. It used to take several hours to vulcanize with heat. A few
minutes of irradiation does the same job.

The food industry has begun to experiment with irradiation as a new way
to sterilize food. Items which normally spoil quickly, such as
hamburger, sausage, cheese, and bread, are exposed to radiation. The
rays destroy all of the bacteria that cause food to spoil. The food is
immediately sealed in airtight plastic bags. It will remain perfectly
fresh for months--or even years. This process may make the canning or
freezing of food completely unnecessary.

[Illustration]

[Illustration]

Even foods which generally keep well, such as onions or potatoes, can be
helped by irradiation. The treatment kills any insects that might be in
the sack, and also keeps the vegetables from sprouting. A treated potato
will keep for a very long time. A number of experiments have been done
with potatoes. Before long you will probably see irradiated potatoes for
sale in your market.

Irradiation can even improve food crops and other plants while they are
still being grown. Changes caused by the rays have already created new
and better varieties of corn, peanuts, and oats. The same dose of
irradiation works in another way, too--it kills the insects which damage
the crops.

Irradiation used in certain medicines can destroy a patient's diseased
tissue. Many forms of cancer are treated by this method. In some cases,
the patient is injected with a radioisotope. In other cases, he is just
exposed to its rays, which are projected from a special machine.
Sometimes, tiny bits of isotope, called _seeds_, are actually placed
directly in the cancer. Other patients are asked to drink the isotope in
a special preparation called a "radioactive cocktail."

[Illustration]

Besides their many uses as tracers and irradiators, isotopes have great
value as substitutes for expensive X-ray machines. The rays can pass
through many materials and, by making a picture on a film underneath,
can show differences in thickness or other flaws. Some of the materials
that are inspected this way are sheet metal, paper, rubber, and
plastics. Also, piston rings for auto engines, and airplane engine
valves.

Doctors, too, can use radioisotopes instead of X rays. An X-ray machine
is a huge piece of equipment which needs a special room and costs
thousands of dollars. A radioisotope machine is about the size of a
large can of fruit juice and weighs only ten pounds. It can be carried
about easily and is most valuable in an emergency or at a place where
there is no X ray available.

These are only some of the things that atoms can do for us. Atomic
energy is still young. In the years to come, there will be many changes.
During your lifetime, the peaceful atom should make the world an easier,
healthier, happier place!

[Illustration]




APPENDIX

Some other important atomic pioneers:

Chadwick, James: Discovered the neutron in 1932.

Joliot-Curie, Irene and Frederic: Daughter of Marie and
    Pierre Curie, and her husband. Were the first to
    make artificial radioisotopes in 1933.

Rutherford, Ernest: Worked out the nature of radioactivity
    in 1902, discovered the nucleus of the atom
    in 1911, and split the first atom in 1919.

Soddy, Frederic: Discovered isotopes in 1910.

Urey, Harold: Discovered hydrogen's heavy isotope,
    deuterium, in 1932.




GLOSSARY


_AEC_           Atomic Energy Commission (U.S.) All
                atomic energy in the United States is under
                the control of the AEC. The Commission is
                in charge of the sources, manufacture, and
                uses of all fissionable materials. It has important
                programs of research, building,
                training, and information.

_artificial_    A chemical element that does not exist in
_element_       nature but which can be made in an atomic
                reactor.


_atomic_        An atomic reactor.
_furnace_

_canal_         A tank of water which is used to hold dangerously
                radioactive materials in order to protect workers.

_coffin_        A thick metal box which is used to hold very
                radioactive material.

_contaminated_  Anything that has accidentally become radioactive.

_cool off_      To stop being radioactive. Some materials
                have to cool off before they can be handled
                safely.

_critical size_ The smallest amount of atomic fuel that will
                allow a chain reaction to take place.

_curie_         The unit used to measure radiation. It is
                equal to the amount of radiation given off by
                one gram of radium in one second.

_Einstein_,     (1879-1955), born in Germany, fled under
_Albert_        Hitler, and became an American citizen in
                1940. In 1955 he published a brilliant theory
                which became the basis for the discovery of
                atomic energy. The theory stated that neither
                matter nor energy can ever be destroyed,
                but that matter can be changed into energy.
                Einstein expressed this in the equation
                E = mc^2. It means that energy (E) is equal
                to mass (m) multiplied by the speed of light
                (c), multiplied by itself. Mass is the amount
                of material or matter in anything. The speed
                of light is 186,000 miles a second.

_emit_          To give off. Radioactive substances emit rays.

_enriched_      Ordinary uranium which has fissionable
_uranium_       uranium added to it.


_fissionable_   Usable as an atomic fuel. A material whose
                atoms will split.

_fusion_        A source of atomic energy which is the opposite
                of fission. Instead of nuclei being
                split, they are forced together. The energy
                of the sun is released by fusion.

_hot_           Radioactive.

_moderator_     A material which is used in an atomic reactor
                to slow down the speed of the neutrons.
                Graphite and water are common moderators.

_nuclear_       The correct name for energy produced by
_energy_        changes in atomic nuclei. _Atomic energy_ is
                the common name for nuclear energy.

_pig_           Heavy metal container for radioactive material.
                Similar to _coffin_.

_pitchblende_   The ore richest in uranium.

_remote_        A device that can handle radioactive materials
_manipulator_   mechanically while the operator remains
                safe behind a shield. (Also called a
               _master slave manipulator_.)

_scram_         To stop an atomic reactor. An emergency
                stop is called a _fast scram_.

_transmute_     To change one kind of atom into another kind.




INDEX


alpha particle, 30
atomic energy, 8
atomic number, 27
atomic pile, 36
atomic power, 42
atomic theory, 15

Becquerel, Antoine Henri, 20
beta particles, 30
boiling water reactor, 44
breeder reactor, 46

cadmium, 38
carbon-14, 56
chain reaction, 35, 36, 44
chemical compound, 15
Compton. Arthur H., 40
Conant, James B., 40
control rod, 38
Curie, Marie, 22
Curie, Pierre, 22

Dalton, John, 15
Dead Sea Scrolls, 57
decay, 30
Democritus, 13

electron, 26, 29
element, 15
energy, 32

Fermi, Enrico, 36
fission, 34
fossil fuels, 9, 46

gamma rays, 30
Geiger counter, 53
graphite, 36, 44

half-life, 32
helium, 28

Iodine-131, 57
ionization, 60
irradiation, 60
isotopes, 28

neutron, 26, 28
nucleus, 27, 29

pitchblende, 23
plutonium, 46
power plant, 42
pressurized water reactor, 43
proton, 26

radioactivity, 22
radioactive cocktail, 64
radioactive iodine, 57
radioisotope, 52, 64
radium, 23, 30, 32

Roentgen, Wilhelm K., 18

_Savannah_, 48, 49

thorium, 23, 30
tracers, 53

uranium, 20, 29, 30, 32, 43

uranium-234, 29
uranium-235, 29, 46
uranium-238, 29, 46

X rays, 18, 64